CN111094798A

CN111094798A - Pulley and transmission system

Info

Publication number: CN111094798A
Application number: CN201880058821.7A
Authority: CN
Inventors: 约亨·弗兰卡
Original assignee: Advanced Transmission Systems Holdings Ltd
Current assignee: Advanced Transmission Systems Holdings Ltd
Priority date: 2017-07-13
Filing date: 2018-07-13
Publication date: 2020-05-01
Also published as: EP3652469A4; EP3652468A1; EP3652468A4; EP3652469A1; AU2018299208A1; AU2018299210A1; WO2019010539A9; CN111448405A; WO2019010541A1; WO2019010539A1; WO2019010541A9

Abstract

A transmission system (12) is provided that includes a first pulley (211) connected to an input (11) by a cable (40) such that movement of the input causes rotation of the first pulley. The first pulley includes an annular groove (25) between a first side (17) of the first pulley and a second side (19) of the first pulley. The annular groove is adapted to receive the cable such that the cable is supported by the first pulley. The first pulley further comprises a pair of support surfaces (31) located in the annular groove, the support surfaces being movable in a transverse direction relative to the sides of the pulley between a spaced condition and an engaged condition, wherein the spaced condition is the first pulley at the first diameter and the pair of support surfaces are not engaged with the cable; wherein the engaged state is the first pulley at a second diameter, the second diameter being greater than the first diameter, and the pair of support surfaces supporting the cable.

Description

Pulley and transmission system

Technical Field

The present invention generally relates to a pulley. In particular, the invention relates to a pulley capable of exhibiting a variable diameter. The invention also relates to a transmission system or pulley drive system incorporating the pulley.

Background

The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to was or was part of the common general knowledge as at the priority date of the application.

Transmission systems are used in various vehicles and industrial equipment to transmit power from a power source to an output, typically to drive wheels to move the vehicle. One type of vehicle that employs such a drivetrain is a bicycle.

The drive train of a bicycle is usually in the form of a centrally located chain ring integrated with two crank arms. The rider pedals the crank arms to rotate the chainrings. The chain links are spaced apart from the rear sprockets but are interconnected by a chain that spans between the chain links and the sprockets. Thereby, the torque applied to the chain ring is transmitted to the rear sprocket, which also rotates. The rear sprocket is fixed to the axle of the rear wheel of the bicycle so that when the rear sprocket rotates, the rear wheel rotates simultaneously.

The drive train of a bicycle typically further includes a drive train to enable a rider to manipulate the rotational force of a chainring that affects the rear wheel. The drive train typically includes a plurality of coaxially mounted rear sprockets of different diameters and a plurality of coaxially mounted chain rings (typically between one and three) of different diameters. By activating the gear mechanism, the rider can move the chain to different sprockets or chain rings, thereby allowing the rider to select the most environmentally appropriate gear ratio.

Current transmission systems are limited in the range of gears they can reach. The bicycle can be set to a larger gear ratio so that the smallest possible gear is not used, or to a smaller "small" gear ratio so that the largest possible gear is not used. Thus, in setting up the bicycle, one of the ranges of the gear ratio subsets must be selected.

A large range of ratios is used for relatively flat terrain, but inevitably leads to undesirable limitations when parts of predominantly flat terrain are uphill at significant slopes, as these cannot be overcome by the preferably small transmission. This in turn can lead to rider fatigue and competitive disadvantages. The pinion gear ratio range is used for relatively steep uphill terrain, but can result in undesirable limitations when riding downhill, as large gear ratios that promote braking at high speeds are not available. This can result in lower than possible speeds and therefore has a competitive disadvantage.

On a practical level, the gear ratio range limitations of prior art chain driven derailleur systems mean that the rider and mechanic must be required to install either a large or small gear ratio range. This not only impairs riding efficiency, but also means that continuous mechanical operations are required to replace and replace the systems on the bicycle between the race days of any circuit event. The same applies to recreational riders who must attempt to replace the drive train according to their desired ride type if they want to efficiently consume ride energy.

While chain driven derailleur systems can efficiently transfer a rider's energy from the crankset to the rear wheel, the efficiency is greatly reduced when the chain is not disposed in a straight line between the plane of the front sprocket and the plane of the rear sprocket, i.e., all three elements are not in the same plane. Due to the inherent limitations of such transmission systems, setting of a linear chain can only be achieved for a small fraction of the transmission range.

When a drive setting is selected that deviates the chain from the straight line between the selected front sprocket ring and the selected rear sprocket, the resulting strain and friction in the chain and between the chain and the sprocket ring and sprocket can cause a significant reduction in power transmission efficiency. This means that up to 20% of the energy provided by the rider to the crankset does not reach the rear wheels. The rider has no choice but to select such an inefficient terrain-sensing transmission setting because forcing the rider's body to adapt to a transmission setting that is too high or too low is less desirable simply because of powertrain efficiency considerations.

A problem with chain driven derailleurs or any split drive systems is that the process of shifting gears results in a temporary loss of power transmission during the repositioning of the chain from one chainring or sprocket to another chain sprocket. Particularly when riding uphill on a steep incline, this results in a significant loss of rider energy, since the loss of momentum created during the shift process requires additional effort to return the bicycle to the speed prior to the shift. This also results in time delays in the chances of responding to the sprint of the other rider during the race, all of which constitute a competitive disadvantage and may make a difference between winning or not winning the road race.

The chain driven derailleur system also has the inherent characteristic of discontinuous transmission when changing chain rings, which results in the need to simultaneously change the sprockets. This exacerbates the momentum loss problem. It also presents a significant challenge to tired riders and often results in ride inefficiency.

Another disadvantage of conventional chain driven derailleur systems is the inability to change gear ratios while stationary. The chain drive system needs to apply a pedaling cadence to facilitate shifting. When the rider unexpectedly has to stop or decelerate, the rider's energy will be lost and eventually the efficiency of the chain drive system will be reduced because the rider must first change from a too large gear ratio to a smaller gear ratio. This consumes a disproportionate amount of energy and the accumulated energy during long distance riding can reduce the endurance of the rider.

Chain and derailleur driven bicycle transmission systems have improved over decades but still have inevitable weight in their components, especially the chain itself, which can only be practically made of heavy steel.

Chain driven derailleur systems are sensitive to physical shock to the bicycle, lack of mechanical alignment quality or other misalignment, component mismatch, and lack of proper rider operation. If either of the above exceeds the limits of its operating design, the chain will fall off the chain ring or sprocket and in the worst case, the chain may break. Chain derailments are common in recreational rides, and even in professional road racing, taking great care even when the equipment is in a high peak condition. Other mechanical failures of conventional chain drives include blockages of certain gear ratios due to dirt ingress or icing.

Conventional chain drive systems, as well as other axle drive systems, require lubrication in order to operate at the highest efficiency possible. These systems are very sensitive to sub-optimal lubrication, resulting in the need for regular maintenance, which is both an operational overhead and a cost. In addition, the new chain becomes effective only after the "break-in" period has elapsed, thereby eliminating the inefficiencies of friction created during the manufacturing process. They then need to be cleaned regularly in a short time, otherwise inefficiencies result.

Chain driven derailleurs and axle planetary transmissions experience high wear rates between the two metal surfaces that interact (i.e., the steel chain and the teeth on the sprocket or chain ring or the planetary gear sprockets in the axle). This reduces the life cycle of the parts, meaning that the entire drive train needs to be replaced periodically to provide efficient power transmission.

The above discussion of the background art is intended to facilitate an understanding of the present invention only. While the discussion focuses on the drive train of a bicycle, it will be readily appreciated that similar problems exist with drive trains used in other applications.

Disclosure of Invention

It is an object of the present invention to provide a pulley and a transmission system including the pulley which ameliorates, alleviates or overcomes at least one disadvantage of the prior art or which will at least provide the public with a useful choice.

While the present invention has been particularly shown and described with reference to bicycles, the present invention is equally applicable to many other applications. For example, the present invention is applicable to most cable/chain/belt/pulley driven systems that currently use different gear ratios to achieve a particular effect. These other applications include, but are not limited to, transmission systems in vehicles, motorcycles, lawn mowers, four-wheel motorcycles, pumps, generators, manufacturing equipment including cnc machines and other industrial mobile equipment and stationary cable/belt driven machinery. These other applications, as well as applications that would be apparent to one skilled in the art, are considered to be within the scope of the invention as defined herein.

Throughout the specification, the term "cable" is used to describe a rope, belt, chain, safety belt or any other rope-like device that may be used to assist in transferring force from a pulley to another object. Further, the term "cable" may refer to a single unitary cable, or a cable made from a number of smaller cables that are twisted together, connected in an end-to-end manner, or otherwise formed to provide a substantially unitary member.

The present invention provides a transmission system including a first pulley and an input spaced therefrom, a cable extending between the first pulley and the input such that movement of the first pulley input causes movement of the first pulley. The first pulley comprises:

a first side assembly spaced apart from a second side assembly, the first side assembly and the second side assembly being rotatably secured together.

A variable annular recess is defined between the first side assembly and the second side assembly, the annular recess adapted to receive a cable.

Each of the first and second side assemblies providing a support surface for supporting the cable, the support surface being laterally movable between a first position and a second position, the first position being spaced outwardly from the second position, the support surfaces of the first and second side assemblies cooperating to engage the cable when the support surface of each side assembly is in the second position whereupon the cable moves from the first diameter to be supported to the second diameter;

at least one actuator for moving each support surface between a first position and a second position;

a movement mechanism including a biasing device that applies a constant or near constant force to each of the at least one actuator, the movement mechanism reacting to the force applied by the cable thereon;

wherein the width of the first pulley remains constant as the support surface moves between the first diameter and the second diameter, and vice versa.

Preferably, the at least one actuator moves radially relative to the first side assembly and the second side assembly.

The at least one actuator may be radially movable relative to the axis of rotation of the first pulley.

The at least one actuator may be variably positioned along a radial direction of the first pulley.

Preferably, the at least one actuator comprises a first actuator connected between the first actuator and a second actuator by a bridge member.

Preferably, the first actuator engages a support surface of the first side assembly and the second actuator simultaneously engages a support surface of the second side assembly to move each support surface between the first and second positions.

The bridge member maintains the first actuator and the second actuator in a fixed relationship. This ensures that each support surface is held in place by the at least one actuator when engaged with the at least one actuator and does not move laterally outward due to the force exerted thereon by the cable.

At least one or both of the first actuator and the second actuator provides a first guide to move the support surface to the second position. The first guide means may comprise a first guide surface which engages the support surface.

At least one or both of the first and second actuators provides a second guiding means to guide the support surface to the first position. The second guide means may comprise a second guide surface which moves the support surface to the first position. The second guide surface may comprise an actuator channel which cooperates with a portion of the support surface to move the support surface to the first position.

The pulley may comprise control means to control the movement of the at least one actuator. The control means may constrain the at least one actuator such that the at least one actuator is constrained to radial movement relative to each side assembly.

The control device may include at least one support channel that engages with the at least one actuator to limit movement thereof along the at least one support channel. The at least one support channel may extend in a radial direction relative to each side assembly such that the at least one actuator is constrained to move radially relative to each side assembly. The at least one actuator may be variably positioned radially.

The control device may include a support housing supporting at least one actuator. The support housing may include a back plate and a movement mechanism. In one embodiment, the back plate may be located at a position between the support surface and the moving mechanism. The back plate may support the support surface and the movement mechanism. The back plate has a central hub adapted to receive a rod or shaft.

The back plate may comprise at least one support channel for limiting the movement of the at least one actuator in the radial direction. The at least one support channel may extend radially outward from the hub. The at least one support channel may be closed at an end proximal to the hub and open at an end distal to the center of the back plate. Alternatively, the at least one support channel may be open at one end near the hub and closed at a distal end of the back plate center. The open end facilitates assembly of the first pulley. The opening may have a closure to prevent the at least one actuator from exiting the at least one support channel.

The moving mechanism may move the at least one actuator in a radial direction.

The movement mechanism may react the force exerted on it by the cable. In this regard, the first pulley will react to ensure that tension in the cable is maintained. If the tension in the cable is to be reduced, the moving mechanism will cause the first pulley to support the cable at a larger diameter. If the tension in the cable is to be increased, the shifting mechanism will cause the first pulley to support the cable at a smaller diameter.

When the cable is not placing tension on the first pulley (or no cable is mounted thereon), the shifting mechanism may place the first pulley in a normal condition, wherein the first pulley is at its maximum diameter. Preferably, the first pulley is biased to its normal condition.

The movement mechanism may bias each of the at least one actuator to the outer position.

Preferably, the biasing means applies a constant or near constant force to each of the at least one actuator regardless of the radial position of the at least one actuator.

The movement mechanism may further comprise a set of lever arms to transfer the force of the biasing means to each of the at least one actuator. The number of lever arms required may depend on the number of at least one actuator. The number of lever arms required may depend on the biasing means selected.

The set of lever arms may include one or more first lever arms and one or more second lever arms.

In another aspect of the invention, the moving mechanism includes a plurality of biasing mechanisms. Preferably, each side assembly has a plurality of biasing mechanisms such that the number of biasing mechanisms on a first side assembly is equal to the number of biasing mechanisms on a second side assembly. Each biasing mechanism comprises at least one biasing means in the form of a spring, and a set of lever arms, preferably comprising a first lever arm and two second lever arms.

The first lever arm may transfer force from the biasing device to the one or more second lever arms. The second lever arm may have a first end rotatably secured to the at least one actuator such that movement of the first end of the second lever arm causes movement of the at least one actuator along the at least one support channel.

The one or more first lever arms may have a first end directly or indirectly connected to the biasing device and a second end directly or indirectly connected to a second end of the one or more second lever arms.

Preferably, the moving mechanism further comprises a ring rotatably fixed to the back plate. The ring may be coaxially positioned near the central hub of the back plate. The second end of the one or more first lever arms is rotatably secured to the ring. The second end of the one or more second lever arms may also be rotatably secured to the ring. Preferably, the second ends of each lever arm are fixed at different angular positions relative to each other.

The biasing means may be in the form of one or more springs. The spring may be a variable force spring. Alternatively, the spring may be a fixed force spring. The spring may be supported around the periphery of the backplate. Each spring may have one end connected to the first end of one of the first lever arms. Preferably, a linkage assembly connects a first end of the first lever arm to an end of the spring.

In alternative embodiments, the biasing means may be provided by one or more magnets, a hydraulic system, or any system/device that will provide a biasing force, as will be appreciated by those skilled in the art.

An end of the at least one actuator may provide a socket to which a first end of the one or more second lever arms is rotatably secured.

In one aspect of the invention, the support surface comprises a plurality of support segments arranged in a circular configuration, wherein the overall appearance of each support segment is that of a truncated segment. The number of support segments may depend on the diameter of the pulley.

Each support section comprises a plurality of support surface units. One or more support surface units define a support surface. Considering a single support section, each support surface unit is stacked one after the other, wherein, in one embodiment, the support surface unit located closest to the rotational axis of the pulley is the smallest internal support surface unit, each support surface unit increasing in length thereafter.

Preferably, each support surface unit is constrained to axial movement relative to an adjacent support surface unit. Each support surface unit may be configured to prevent tangential movement between adjacent support surface units. Each support surface unit may have a spline arrangement between them, wherein the spline arrangement prevents tangential movement between adjacent support surface units.

Each support surface unit may comprise a limiting mechanism to limit axial movement between adjacent support surface units. The limiting mechanism may prevent axial movement of each support surface unit a distance beyond the centre plane of the first pulley. The limiting mechanism may comprise a protrusion incorporated in each support surface unit, wherein the protrusion is adapted to cooperate with a recess in an adjacent support surface unit. The restraining mechanism holds at least the support surface unit in the second position until the at least one actuator allows the support surface unit to move back to the first position.

In another aspect of the invention, each support surface comprises a plurality of support surface units. Each unit is independently movable between a first position and a second position. Each cell is constrained to move between a first position and a second position.

Each support unit is adapted to cooperatively engage at least one actuator, wherein the at least one actuator moves each support unit between a first position and a second position.

Preferably, the at least one actuator engages the support surface unit to move the support surface unit between the first position and the second position when the at least one actuator moves radially outwardly along the at least one support channel. Preferably, the first guide surface of the at least one actuator engages one or more support surface units.

Preferably, the at least one actuator engages one or more support surface units to move the support surface units between the second position and the first position when the at least one actuator moves radially inwardly along the at least one support channel. Preferably, the second guide surface of the at least one actuator engages one or more support surface units.

The present invention also provides a transmission system including a first pulley and an input spaced therefrom, a cable extending between the first pulley and the input such that movement of the input causes the first pulley to rotate, the first pulley comprising:

a first side assembly and a second side assembly spaced apart from each other coaxially mounted and rotatably secured together;

an annular groove between the first side assembly and the second side assembly, the annular groove adapted to receive the cable such that the cable is supported by the first pulley at a first diameter;

each of the first side assembly and the second side assembly includes a support surface including a plurality of independently mounted support surface units adapted to engage the cable, each support surface unit being laterally movable between at least a first position wherein the cable is at the first position. A diameter and a second position, wherein the cable is at the second diameter and the second position is spaced inwardly from the first position;

a movement mechanism including a biasing device that applies a constant or near constant force to each of the plurality of actuators that reacts the force applied by the cable thereon.

The present invention also provides a transmission system including a first pulley and an input spaced therefrom, a cable extending between the first pulley and the input such that movement of the input causes rotation of the first pulley, the first pulley including:

an annular groove between the first side assembly and the second side assembly, the annular groove adapted to receive the cable such that the cable is supported by the first pulley.

Each of the first side assembly and the second side assembly includes a support surface that is laterally movable, the support surface being selectively movable between at least a first position and a second position, the second position being spaced inwardly from the first position, wherein all or any portion of the support surface may be in either the first position or the second position, the support surface being adapted to engage the cable, wherein the cable is supported in one position when the entire support surface of each side assembly is in the first position. A first diameter of the first pulley when the entire support surface of each side assembly is in the second position, the cable being supported at the second diameter when the first portion of the support surface of each side assembly is in the first position, the second portion of the support surface being in the second position, the cable being supported on the first pulley at a third diameter, the third diameter being a diameter between the first diameter and the second diameter;

wherein the first pulley reacts the movement of the support surface of the second pulley and the first pulley comprises a biasing device that biases the support surface of the first pulley to a maximum diameter when the diameter of the cable on the second pulley is minimal or no cable is present. .

The support surface may be selectively positioned such that the third diameter is any size diameter between the first diameter and the second diameter.

The first diameter may be the largest diameter possible for the first pulley.

The second diameter may be the smallest possible diameter of the first pulley.

The movement of the support surface of the first side assembly between the first position and the second position may be immediately subsequent to or prior to the movement of the support surface of the second side assembly between the first position and the second position.

The support surface may comprise a plurality of support surface units, each support surface unit being laterally movable between at least a first position and a second position. The first side assembly may be connected to the second side assembly. The plurality of support surface units may cooperate to provide a support surface whereby selective movement of the support surface units causes the cable to be positioned in transition between different diameters of the first pulley.

The first side assembly and the second side assembly may be coaxially mounted.

Preferably, the cable is supported on a first pulley exhibiting an increasing diameter during the movement of each support surface unit from the first position to the second position.

Preferably, the cable is supported on a first pulley exhibiting a decreasing diameter during the movement of each support surface unit from the second position to the first position.

Preferably, the support surface comprises a plurality of support surface segments, wherein each support surface segment provides one or more support surface units. The support surface segments may take the shape of segments of a circle, such that the combined configuration of the plurality of support surface segments is circular.

Each support surface unit provides at least one contact surface adapted to engage the cable. Each contact surface extends laterally from the support surface unit in a substantially central direction. That is, each contact surface of each support surface unit extends towards a center plane of the first pulley, wherein the center plane is substantially perpendicular to the rotational axis of the pulley.

Preferably, the contact surface of the first side member is offset from the corresponding contact surface of the second side member.

The contact surface of the first side assembly may be offset from the corresponding contact surface of the second side assembly such that the contact surface of the first side assembly is at a different diametrical/radial position than the corresponding contact surface of the second side.

The contact surface of the first side assembly may be offset from a corresponding contact surface of the second side assembly such that when the contact surface of the first side assembly is in the second position and the contact surface of the second side assembly is in the second position, the contact faces overlap.

Preferably, movement of each support surface unit to the second position causes a portion of the contact surface of the first side assembly to be received between radially adjacent contact surfaces of the second side assembly. With this arrangement, the support surface units are effectively meshed together to provide a substantially continuous groove for supporting the cable.

The first pulley may provide a support frame for supporting the cable when the cable is in a position corresponding to the smallest possible diameter of the first pulley.

In one aspect of the invention, the support frame is stationary. The support frame may be in the form of one or more support surface units secured in the second position.

In another aspect of the invention, the support frame may be movable. The support frame may be provided by an innermost support surface unit, wherein the innermost support surface unit is prevented from moving to its first position, rather than between an intermediate position and a second position, the intermediate position being between the first position and the second position. The back plate may further include a stand portion forming a part of the support bracket.

A cable may connect the first pulley and the input. The cable may extend between the first pulley and the input end such that the cable is looped partially around the first pulley and partially around the input end.

The cable may be in the form of a continuous belt that frictionally engages the first pulley. The cross-section of the strip may be V-shaped and may be truncated.

The cable may have a face adapted to be supported by a support surface of each of the first side assembly and the second side assembly, wherein the cross-section of the belt is V-shaped and may be truncated. Preferably, at least 50% of the V-shaped face is supported by the support surface. Preferably, at least 75% of the V-shaped face is supported by the support surface. Preferably, at least 80% of the V-shaped face is supported by the support surface. Preferably, at least 85% of the V-shaped face is supported by the support surface.

The belt may include a plurality of wedge segments depending from the belt portion. Preferably, the cross-sectional profile of the belt varies between a tensioned state, in which the profile represents a narrow V-shape, and a relaxed state, in which the profile represents a wider V-shape. The belt may be placed in tension as it spans between the pulley and the output. The belt may be in a slack condition when the belt is engaged with the pulley and the belt is engaged with the output. The wider V-shaped cross-section has a greater surface area to engage the pulley's annular groove and output end when the belt is in a relaxed condition. In this regard, the V-shape is complementary to the annular groove. When in tension, the narrower V-shape presents a reduced surface area such that the cross-section is narrower than the cross-section of the annular recess. As a result, the belt is not engaged with the pulley until further around the pulley and is disengaged from the pulley earlier than if the belt had only one state. This configuration reduces the frictional losses encountered during the transition between the engagement and disengagement of the pulley with the pulley.

In one aspect of the invention, the frictional force between the belt and the pulley is the same when considered from all directions.

In another aspect of the invention, the ratio of the friction between the belt and the pulley in the belt drive direction to the friction between the belt and the pulley in a direction perpendicular to or close to the drive direction is as high as possible greater than 1: 1, because the friction force in the direction of travel is less than the normal friction force. When the frictional force between the belt and the pulley in the belt driven direction is high and the frictional force between the belt and the pulley in the direction perpendicular to the driven direction is low, power transmission can be performed without occurrence of belt slip. It also improves the shifting of the transmission to overcome non-drive direction friction between the belt and the pulley.

In one aspect of the invention, the surface of the belt and/or the surface of the pulley may include surface irregularities, such as protrusions and/or knurling, to increase friction between the belt and the pulley.

In another aspect of the invention, the surface of the belt and/or the surface of the pulley may include surface irregularities, such as protrusions, knurls, grooves, and/or patterns to help increase the friction ratio between the belts. The pulley is generated in a direction perpendicular or perpendicular to the driving direction in the belt driving direction with respect to a frictional force between the belt and the pulley.

The cable may be in the form of a composite material. The cable may have a core. The core may be formed of a non-yielding material such as an aromatic polyamide or carbon fiber. Although the core is flexible, the length of the core does not yield significantly once the tape is formed. .

Preferably, the input is in the form of a second pulley. The second pulley may be generally larger than the first pulley. However, it should be understood that it may also have a smaller diameter. The second pulley may have similar elements to the first pulley. The second pulley may include a first side assembly and a second side assembly spaced apart from each other, the first side assembly being connected to the second side assembly such that the first side assembly and the second side assembly are coaxially mounted. Preferably, each of the first and second side assemblies of the second pulley comprises a support surface.

In one aspect of the invention, the first pulley includes an actuating device to cause the support surface unit of each side assembly to move between the first position and the second position. Using the actuation device, the first pulley controls the position of the cable, effectively determining the transmission of the transmission system. Preferably, the second pulley reacts the movement of at least one ring of each side assembly of the first pulley. In this regard, the second pulley is a passive pulley.

The first pulley has a biasing device that biases the bearing surface of the first pulley to a maximum diameter when the cable is at a minimum diameter on the second pulley (or when no cable is present).

The biasing means may comprise a plurality of springs which interact with a set of lever arms to move the support surface unit in reaction between the first and second positions.

The biasing means may allow the at least one actuator to move the support surface unit between the first position and the second position. The at least one actuator may include a first actuator head and a second actuator head held in a fixed relationship. Each actuator head may provide at least one guide means.

The at least one guide means may be in the form of a first guide means and a second guide means. The first guide means may move the support surface to the second position. The first guide means may comprise a first guide surface engaging each support surface unit of the support surface.

The second guiding means may guide the support surface to the first position. The second guide means may comprise a second guide surface which moves the support surface to the first position. The second guide surface may comprise an actuator channel which cooperates with a portion of each support surface unit to move the support surface to the first position.

The first pulley may comprise control means to control the movement of the at least one actuator. The control means may constrain the at least one actuator such that the at least one actuator is constrained to radial movement relative to each side assembly.

Preferably, the transmission system is arranged such that when the second pulley is moved from the first diameter to the second diameter, the first pulley is moved from the second diameter to the first diameter. When the belt length is fixed, the belt must move relative to the first pulley to compensate for the movement of the belt relative to the second pulley. Thus, when the belt is positioned to rotate about the larger second diameter of the second pulley, the belt is caused to rotate about the smaller first diameter of the first pulley, and vice versa.

The present invention further provides a transmission system including a first pulley and an input spaced therefrom, a cable extending between the first pulley and the input such that movement of the input causes the first pulley to rotate, the first pulley comprising:

an annular groove between the first side assembly and the second side assembly, the annular groove adapted to receive the cable such that the cable is supported by the first pulley;

each of the first side assembly and the second side assembly includes a support surface provided by a plurality of rings, wherein a diameter of a ring on the first side assembly is different than a diameter of a ring on the second side assembly, and the rings on the second side assembly have offset counterpart rings on the first side assembly, wherein the counterpart rings move between at least a first position and a second position, the second position being spaced inward from the first position, the counterpart rings being adapted to engage a cable, wherein when the counterpart rings are in the second position, the cable is supported by the first pulley at a diameter different than a diameter defined by adjacent counterpart rings, each ring including a plurality of support surface units, each support surface unit of each ring being independently movable by at least one actuator.

The present invention provides a transmission system comprising a first pulley connected to an input by a cable such that movement of the input causes rotation of the first pulley, the first pulley comprising:

an annular groove between a first side of the first pulley and a second side of the first pulley, the annular groove adapted to receive the cable such that the cable is supported by the first pulley;

a pair of support surfaces are located in the annular groove, the pair of support surfaces being movable in a transverse direction relative to the sides of the pulley in a spaced apart condition with the first pulley at a first diameter and the pair of support surfaces having an engaged condition with the first pulley at a second diameter and the pair of support surfaces supporting the cable, the second diameter being greater than the first diameter.

The invention provides a reducing belt pulley, which comprises:

an annular groove for receiving the cable such that the cable is supported by the pulley at a first diameter of the pulley; a pair of support surfaces located in the annular groove, the pair of support surfaces being movable in a transverse direction between a spaced condition in which the pair of support surfaces are not engaged with the cable and an engaged condition in which the pair of support surfaces support the cable at a second diameter of the pulley, the second diameter being greater than the first diameter;

wherein the pulley includes a biasing device to bias the pulley to assume a maximum diameter.

The invention provides a reducing belt pulley, which comprises:

an annular groove for receiving the cable at the first diameter of the pulley;

the annular groove provides a support surface for supporting the cable when received therein, the support surface being movable to have a first diameter and a second diameter.

Wherein the support surface may be positioned to have any diameter between the first diameter and the second diameter; wherein the pulley includes a biasing means to bias the pulley to assume a maximum diameter.

Preferably, the thickness of the pulley remains constant as the pulley moves between the first diameter and the second diameter.

Preferably, the support surface presents a substantially continuous surface to the cable when the support surface is received onto the pulley. The cross-sectional profile of the support surface may be complementary to the cross-sectional shape of the portion of the cable that engages the support surface such that the cable is retained in the annular groove.

Preferably, the cables remain in the same radial plane when supported thereon as the support surface moves between the first diameter and the second diameter.

Preferably, the support surface is formed by a first set of support surface units and a second set of support surface units.

The first set of support surface elements and the second set of support surface elements may be engaged together or overlapped with each other to form a support surface.

The first and second sets of support surface units are movable in a lateral direction between a spaced condition in which the cable is supported at a first diameter of the pulley and the engaged condition in which the cable is supported at a second diameter of the pulley, whereby the cable may be supported on a support surface exhibiting a varying diameter during movement of the sets of support surface units between the conditions.

Circumferentially adjacent support surface elements may define rings. Each ring may not be continuous. Preferably, a gap is defined between adjacent support surface units of the same ring.

Each loop of the first set of support surface elements has a complementary loop of the second set of support surface elements such that the complementary loops are in a staggered relationship to each other to provide a loop pair. The engagement of each ring pair provides a support surface for engaging the cable.

Each ring pair is movable between a first position and a second position.

In the first position, the complementary rings of the ring pair may be spaced apart from each other in the axial/lateral direction. In this position, the pair of rings cannot support the cable.

In the second position, the complementary rings of the ring pair may be in engagement to provide a support surface. In this position, the cable is supported by the loop pairs.

Each ring pair may be movable to a third position between the first position and the second position.

Each ring of the support surface unit may be arranged such that when the ring approaches the second position, its adjacent upper/outer ring starts to move towards the second position.

Each ring of each set of support surface units may be arranged such that as the ring approaches the first position, the adjacent lower/inner ring begins movement towards it towards the first position.

Each support surface unit may be wedge-shaped to provide an inclined contact surface for engagement with the cable.

The pulley may comprise a first side housing for accommodating the first set of support surface units.

The pulley may comprise a second side housing for receiving a second set of support surface units.

The first and second side housings may be coaxially mounted relative to each other to define an annular groove therebetween.

The pulley includes a biasing device to bias the pulley to assume a maximum diameter. In this regard, the biasing force of the biasing means must be overcome before the pulley can be moved to a smaller diameter. Once this force is removed, the pulley will return to its maximum diameter due to the biasing means. In this regard, the pulley is passive/reactive in that it reacts to the forces exerted thereon.

The pulley may include a plurality of actuators. Each actuator is movable about an outer diameter of the pulley between a first position and a second position radially centered on the pulley. Each actuator may have at least one head adapted to cause movement of the support surface unit as each actuator moves between positions. Preferably, each actuator has a first head adapted to cause movement of the support surface unit of the first side assembly and a second head adapted to cause movement of the support surface unit of the second side assembly as each actuator moves between positions. .

The first and second heads may be interconnected by a bridge extending therebetween such that they are held in fixed relation to each other.

Each actuator is supported in a respective channel in the first and second side housings. The plurality of actuators may be radially spaced from one another in a star-mesh arrangement.

When the first and second heads of the actuator move radially outwards from their first position towards their second position, they move the support surface unit successively from its first position to its second position.

Preferably, each support surface unit moves to its second position after the head of each actuator has engaged each support surface unit in succession when moving in the radially outward direction.

Preferably, each support surface unit moves back to its first position after the head of each actuating device has successively passed each support surface unit as the head of each actuator moves in a radially inward direction.

Preferably, the biasing means comprises a plurality of springs interacting with a set of lever arms. Preferably a plurality of springs interact with the lever arms to bias each actuator towards their outermost position such that the pulley assumes a maximum diameter when the biasing force of the biasing means is greater than the force acting on the support surface unit and a smaller diameter when the force exerted thereon is greater than the force of the biasing means.

The present invention provides a transmission system comprising a variable diameter pulley as hereinbefore described connected to an input by a belt.

Brief description of the drawings

In the following description of non-limiting embodiments, other features of the present invention will be described more fully. This description is included for the purpose of illustrating the invention only. It is not intended to be interpreted as a limitation to the broad inventive concept disclosed, or described above. Will be described with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a rear pulley assembly of a transmission system of a bicycle in accordance with a first embodiment of the present invention;

FIG. 2 is a side view of the rear pulley of FIG. 1;

FIGS. 3, 4 and 5 are a series of exploded views of FIG. 1;

FIG. 6 is a cross-sectional end view of FIG. 1 taken along a central plane;

FIG. 7 is a perspective view of the rear pulley of FIG. 1 with the side assembly removed;

FIG. 8 is a side view of FIG. 7;

FIG. 9 is a perspective view of a back plate of the rear pulley shown in FIG. 1;

FIG. 10(a, b, c) are various views of the support surface unit segments of the rear pulley shown in FIG. 1;

FIG. 11 is a side view of a plurality of support surface units having a plurality of actuators of the rear pulley shown in FIG. 1;

FIG. 12 is a perspective view of FIG. 11;

FIG. 13(a, b, c) are various views of one of the support surface units shown in FIGS. 10 to 12;

FIG. 14(a, b) is an enlarged view of one support surface element engaging an adjacent support surface element;

FIG. 15 (a-d) are various views of one of the support surface units according to the alternative embodiment shown in FIG. 13;

fig. 16(a, b) are views of the actuator;

FIG. 17 is a perspective view of a portion of the biasing device of the rear wheel illustrated in FIG. 1;

FIG. 18 is a view similar to FIG. 17 with a back plate;

FIG. 19 is a perspective view of a different portion of the biasing apparatus of the rear wheel of FIG. 1 having a backing plate;

FIG. 20 is a perspective view of a different portion of the biasing apparatus of the rear wheel shown in FIG. 1 having a backing plate;

FIG. 21 is a perspective view of the biasing device of the rear pulley shown in FIG. 1 interacting with a plurality of actuators;

FIG. 22 is a view similar to FIG. 21 with a backing plate;

FIG. 23 is a side perspective view of the rear pulley of FIG. 1 with the biasing device oriented in relation to the maximum diameter of the pulley;

FIG. 24 is a view similar to FIG. 23 showing a portion of the biasing apparatus with a back plate;

FIG. 25 is a side perspective view of the rear pulley of FIG. 1 with the biasing device oriented in relation to the diameter of the pulley between its maximum and minimum diameters;

FIG. 26 is a view similar to FIG. 25, showing a portion of the biasing apparatus with a back plate;

FIG. 27 is a side perspective view of the rear pulley of FIG. 1 with the biasing device oriented in relation to the minimum diameter of the pulley;

FIG. 28 is a view similar to FIG. 27 showing a portion of the biasing apparatus with a back plate;

FIG. 29 is a cross-sectional perspective view of the rear pulley of FIG. 1 with no biasing device taken through a vertical plane, the rear pulley having a minimum diameter;

FIG. 30 is a schematic view of the upper portion of FIG. 29, showing the actuator;

FIG. 31 is a view similar to FIG. 30, but partially showing the actuator;

FIG. 32 is a schematic illustration of the transmission system of the first embodiment at a minimum/lowest gear ratio (with one side of each pulley removed for purposes of illustration);

FIG. 33 is a schematic view of a portion of the rear pulley showing the location of a plurality of support surface units of the pulley of FIG. 1 when supporting the cable in its lowest position, i.e., minimum diameter;

34-38 are schematic views of a portion of the rear pulley illustrating the change in position of the plurality of support surface units as the actuator moves outwardly relative to the central region of the first pulley; and

fig. 39 and 40 are schematic views of the transmission system (one side of each pulley is removed for illustration purposes-fig. 39), with a portion of the first pulley (fig. 40) showing the change in position of the plurality of supports when the actuator is in the outermost position relative to the central region of the rear pulley, these portions representing the maximum diameter.

FIG. 41 is a perspective view of a back plate according to an alternative embodiment;

FIG. 42 is a close-up view of a portion of FIG. 41; and

FIG. 43 is a cross-sectional view of a support surface unit interacting with the back plate shown in FIG. 41.

As shown, the invention according to a first embodiment of the invention is in the form of a transmission system 12, which transmission system 12 comprises a first pulley in the form of a rear variable diameter pulley 11. The pulley 11 is particularly suitable for use with a transmission system which functions similarly/identically to a Continuously Variable Transmission (CVT).

As will be emphasized in the discussion that follows, the difference between the present invention and prior art CVTs is that the pulleys of the present invention are configured to maintain relatively narrow specifications. This enables the pulley and the transmission system associated therewith to be applied in transmission systems with minimal space, such as bicycles, including conventional bicycles, electric bicycles and intelligent electric vehicles.

Existing CVTs include relatively thick front and/or rear pulley arrangements, which are not easily used in applications having limited space to accommodate the pulley arrangements. For example, prior art CVTs cannot be applied to bicycles because they would impede pedal action and/or require a wide rear axle, do not provide a sufficient gear ratio range, impose significant stress on the chain and/or are too heavy. The relatively narrow pulley of the present invention provides a practical and effective drive train geometry for the drive train. When applied to a bicycle, the thickness of the pulley of the present invention is similar to or less than the thickness of a rear wheel case or a hub gear system of a sprocket of a conventional gear type bicycle.

The present invention also allows the diameter of the pulley to be increased with minimal or no change in pulley width. This provides a wide range of gear ratios. Further enhancing the broad applicability of the present invention.

The following embodiments discuss the present invention as applied to a bicycle. However, there are many more applications in other types of drive devices. These include applications in vehicles, lawn mowers, electric scooters, four-wheel motorcycles, snowmobiles, mobile or industrial equipment (e.g., generators, pumps, conveyors and chain saws). Other applications as would be understood by one skilled in the art are considered to be within the scope of the present invention.

In this embodiment, the pulley 11 is adapted to be positioned on the rear wheel of a bicycle. The rear pulley 11 has a central hub 13. As best shown in fig. 1, the central hub 13 has a plurality of ribs 15. As shown in fig. 2, the hub 13 receives an axle 21 (not shown) of the bicycle, wherein the axle is shown in fig. 21, and the rear wheel has a set of complementary ribs that are complementary in the hub 13 so that the rear wheel is rotatably fixed relative to the bicycle when mounted thereto.

The pulley 11 includes a first side assembly 17 and a second side assembly 19. The first side assembly 17 and the second side assembly 19 are coaxially mounted.

The first side member 17 and the second side member 19 are spaced a distance apart from each other such that when the pulley 11 is assembled, the first side member 17 and the second side member 19 define an annular groove 25 therebetween. The annular groove 25 is adapted to receive a cable in the form of a V-belt 40, as shown in fig. 33.

Each

side module

17, 19 includes a back plate 29 and a support surface 31. Since the configuration of the second side assembly 19 is largely the same as that of the first side assembly 17, only one side assembly will be described below. For ease of reference, similar parts of the side assembly are suffixed with an "a" when associated with the first side assembly 17 and a "b" when associated with the second side assembly 19.

As best shown in fig. 6, the annular groove 25 is defined by the first side member 17, the second side member 19 and the support surface 31. The support surface 31 is movable in the transverse direction between a first/spaced state (in which the support surface 31 is not engaged with the belt 40) and a second/engaged state (in which the support surface 31 supports the belt 40). .

Each support surface 31 comprises a plurality of support surface units 33. When arranged, the support surface unit 33 is of a circular configuration, divided into a plurality of support surface segments 35. Each support surface section 35 has a gap 37 for its reason. This will be described below.

As shown in fig. 10, each support surface section 35 comprises a set of a plurality of support surface units 33 arranged one on top of the other. In this embodiment, each support surface section 35 comprises one support surface unit 33 stacked on another support surface unit 33. In other embodiments, each support surface segment 35 may have two or more support surface units 33 in a side-by-side relationship, with one or more support surface segments 35 stacked thereon.

Each support surface unit 33 provides a contact surface 39, which contact surface 39, when in place, extends in an oblique direction towards the centre plane of the pulley. The contact surface 39 cooperates with contact surfaces 39 of other support surface units 33 to provide a support surface 31, which support surface 31 directly engages and supports a cable in the form of a V-belt 40, as will be described in further detail below.

The upper surface 41 of each support surface unit 33 is shaped to engage with a complementary shape in the lower surface 43 of an adjacent support surface unit 33. As shown in fig. 13 and 14, the upper surface 41 and the complementary shaped adjacent lower surface 43 of the surface provide a spline type arrangement 45 whereby movement of adjacent support surface units 33 is constrained by the spline arrangement 45 to move laterally relative to each other as shown by arrow "a" in fig. 10 (b).

In one arrangement, the lower surface 43 of each innermost support surface unit 33c also engages the back plates 29a, 29b in the spline arrangement 45 to limit lateral movement therebetween. Similarly, the upper surface 41 of each outermost support surface unit 33d engages the back plate 29 in a spline arrangement 45 to limit lateral movement relative to each other. (splines on back plate 29 are not shown).

In another arrangement, as shown in fig. 41, 42 and 43, the support channels 183 in the back plate 129 are closed at the outermost end and open at the innermost end. A rib 130 is provided on a portion of the back plate 129 between each of the support channels 183. Each rib 130 cooperates with a notch 134 on the rear of each support surface unit 33. As shown in fig. 43, a rib 130 is received in each notch 134 to prevent lateral movement of the support surface unit 33 relative to the back plate 129.

In this embodiment, the back plate 129 further comprises an annular spacer (not shown) adapted to fit between the inner surface 138 of the periphery 140 of the back plate 129 and the upper surface 41 of the outermost support surface unit 33 d. The spacers are adapted to adjustably mate with a plurality of holes 136 in the outer periphery of the back plate 129, such as with screws, to adjust the distance between the spacers and the inner surface 138 of the outer periphery 140. The support surface unit 33 is held firmly in place relative to the back plate 129.

The cooperation of the projection 47 and the recess 49 limits the lateral movement of the lower support surface unit 33 such that the lower adjacent support surface unit 33 cannot return to the first position. The upper adjacent support surface unit 33 must first be returned to the first position before the support surface unit 33 can be returned to the first position.

Each support surface unit 33 has a pin 51 at each end. The pin 51 is used to move the support surface unit 33 between a first position and a second position as described below.

Each support surface unit 33 also has a guide surface 53 at each end. The guide surface 53 is located between the pin 51 and the contact surface 39. In this embodiment, the guide surface 53 is parallel to the contact surface 39.

Each support surface element 33 is arc-shaped so that support surface elements 33 of the same diameter in adjacent support surface sections 35 define a ring which is discontinuous due to the gap 37.

The pin 51 is used to move the support surface unit 33 between a first position and a second position as described below.

The guide surface 53 is used to move the support surface unit 33 between a first position and a second position, as described below.

Fig. 15 shows an alternative support surface unit 133 shown in fig. 10 to 14. The alternative support surface unit 133 still has a spline arrangement 145, but has fewer splines in its upper surface 141, so fewer spline receiving grooves are required. The alternating support surface units 133 also include two protrusions 147 in their upper surface 141 and corresponding recesses 149 in their lower surface 143. As mentioned above, these provide the same limits for lateral movement as the support surface unit 33.

Pulley 11 also includes a shifting mechanism that provides a biasing force to first pulley 11 such that bearing surface 31 is biased or directed toward the maximum diameter.

First pulley 11 also includes a plurality of actuators 59 and a control device to control the movement of each actuator 59. Each actuator 59 is movable in a radial direction relative to pulley 11. In fig. 59, the support surface 31 is moved from the first position to the second position when moved radially outward. As each actuator 59 moves radially inward, the support surface 31 is moved from the second position to the first position. The position of the actuator 59 depends on the force exerted by the belt on the first pulley 11. The moving mechanism maintains each of the at least one device 59 in an outermost position relative to the back plate 29a, 29b if the force is less than the force provided by the moving mechanism. In this position, the first pulley 11 has its largest diameter.

When the force exerted on the first pulley 11 is greater than the force of the moving mechanism, each of the at least one devices 59 moves inwardly. As this occurs, the diameter of the first pulley 11 decreases. The extent to which each of the at least one devices 59 travels to its most inward position, and hence the extent to which the diameter reduction of the first pulley occurs, will depend on the amount of force exerted on the first pulley 11 by the belt 40.

As best shown in fig. 16, each actuator 59 includes a first head 61a and a second head 61b, the first head 61a and the second head 61b being maintained in a spaced apart relationship by a bridge 63 extending therebetween.

Each head 61a, 61b provides first guiding means 65 to move the support surface unit 33 to the second position. The first guide means 65 comprises a first guide surface 67, which first guide surface 67 is adapted to slidingly engage the guide surface 53 of each support surface unit 33.

Each head 61a, 61b also provides second guiding means 69 to guide the support surface 31 to the first position. The second guide means 69 comprises a second guide surface 71 on each side of the head 61a, 61b, which second guide surface 71 engages the pin 51 of each support surface unit 33 to move it to the first position. The second guide surface 71 is in the form of an actuator channel 73, which actuator channel 73 receives and cooperates with the pin 51 of the support surface unit 33 to move the support surface 31 to the first position.

The actuator channel 73 has a first opening 75 in the upper portion of the head 61a, 61b that is wide enough to receive the pin 51. As each actuator 59 moves radially outward, the pin 51 support surface units 33 on each side of the pin 51 are received in the respective first openings 75. Further outward movement of the actuator 59 causes the first guide surface 67 of the actuator 59 to engage the guide surface 53 of each support surface unit 33. The support surface unit 33 is moved towards its second position. When the support surface unit 33 starts to move towards its second position, the pin 51 is routed along a second guide surface 71, which in this embodiment is in the form of an inclined wall.

To move the support surface unit 33 from the second position to the first position, the actuator 59 is moved radially downwards. When the actuator 59 approaches the support surface unit 33, the pin 51 is received in the second opening 77. Further downward movement of the actuator 59 causes the pin to engage the inclined wall of the second guide surface 71. This forces the support surface unit 33 to move from the second position to the first position. Once the actuator 59 has moved sufficiently downwards to bring the support surface unit 33 into the first position, the pin 51 leaves the actuator channel 53 through the first opening 75.

The control device also includes a plurality of support channels 83 that limit the movement of the plurality of actuators 59 to movement in a radial direction. As shown in fig. 9, a plurality of support channels 83 are formed in each back plate 29a, 29 b. Each end of each actuator 59 is positioned in its respective support channel 83 such that the back plate 29 is received between the sides of the actuator head 61 and the

lever arms

115, 117.

In the present embodiment, the moving mechanism includes a plurality of biasing mechanisms 111. In this embodiment, each

side assembly

17, 19 has three biasing mechanisms 111, as shown in fig. 1-5. The number of biasing mechanisms 111 required depends on the size of the pulley and the force to be applied thereto.

Each biasing mechanism 111 comprises a biasing means in the form of a spring 113, a linkage assembly 114 and a set of lever arms. The set of lever arms includes a first lever arm 115 and two second lever arms 117.

The spring 113 is a variable force spring, and is supported on the periphery of the back plate 29. The spring 113 is connected at one end to the linkage assembly 114 and at the other end to a post 121 extending from the back plate 29. Link assembly 114 is also rotatably coupled to a first end 119 of first lever arm 115. The linkage assembly 114 transfers the movement of the spring 113 to the first lever arm 115 and vice versa.

The moving mechanism further comprises a ring 123 mounted coaxially with respect to the back plate 29 such that the ring 123 moves rotatably with respect to the back plate 29.

As shown in fig. 17 and 18, the first lever arm has a second end 120 rotatably secured to a ring 123.

As shown in fig. 21, each second lever arm 117 has a first end 125 rotatably secured to one of the plurality of actuators 59. Each second lever arm 117 also has a second end 126 rotatably secured to the ring 123.

In operation, the force of the spring acts on the set of lever arms to affect the position of each actuator 59 and thus the position of support surface 31 and the diameter of first pulley 11.

When the force exerted on the first pulley 11 is equal to or less than the force of the moving mechanism provided by the spring 113, the pulley assumes the maximum diameter. This configuration can be considered as a normal state of the first pulley 11, and is a state that the pulley 11 assumes when no force is exerted thereon.

In this state, the set of lever arms holds each actuator 59 in their most outward position relative to the back plate 29, as best shown in fig. 23 and 24.

When the force exerted by belt 40 on pulley 11 is greater than the biasing force of the shifting mechanism, belt 40 causes the diameter of support surface 31 to decrease. In particular, the belt forces the support surface unit 33 to move outwardly away from the center plane of the pulley 11. This causes each actuator 59 to move radially inward toward central hub 13 of pulley 11.

As shown in fig. 26 and 27, inward movement of the actuator 59 rotates the ring 123 through the transfer of movement of each second lever arm 117. Rotation of the ring 123 moves the first lever arm 115. The spring 113 is expanded by the link assembly 114.

If the force exerted on the first pulley reaches a point equal to the biasing force of the moving mechanism, the diameter of the support will be maintained.

If the force exerted on the first pulley remains greater than the biasing force of the moving mechanism, the diameter of the support surface 31 will continue to decrease. If the applied force remains greater, the diameter of the support surface 31 will continue to decrease until the minimum diameter is reached, as shown in FIGS. 27 and 28. In this arrangement, actuator 59 is in its innermost position and, in addition, each spring 113 is at its maximum expansion, taking into account the structural constraints of pulley 11.

When the force exerted by the belt on the pulley is reduced, a reverse movement occurs, causing the diameter of the support surface to increase. When this occurs, the spring 113 of the moving mechanism contracts, moving the set of levers in a manner that returns each of the actuating devices 59 toward their outermost position. This causes the support surface units 33 to move sequentially towards their innermost positions.

When considering a plurality of support surface units 33 arranged adjacent to each other in the circumferential direction, the adjacent support surface units 33 have a circular structure with a gap 37 therebetween. Each support surface unit 33 is movable in a transverse direction relative to its

side assemblies

17, 19 between a first position, in which the support surface unit 33 is adjacent the back plates 29a, 29b, and a second position, in which the support surface unit 33 is spaced from the back plates 29a, 29 b.

The support surface units 33 are arranged such that the support surface unit 33a on one side is offset with respect to the corresponding support surface unit 33b on the other side. In this arrangement, when in the second position, the support surface units overlap to provide a support surface 31 to support at least about 75% of the belt 40.

As shown in fig. 31, first pulley 11 includes a support bracket 95 for supporting belt 40 when belt 40 is in a position corresponding to the smallest possible diameter of first pulley 11. The support surface unit 33c closest to the center axis of the pulley 11 and the bracket portion 101 of the pad. When the belt 40 is supported by the support bracket 95, the remaining support surface units are in their first position and the belt 40 is supported by the pulley 11 at the system minimum diameter.

The belt 40 may be supported by the pulley at any diameter between the minimum and maximum diameters and, depending on the force exerted on the pulley, determines the position of the actuator 59.

The first variable-diameter pulley 11 may be combined with the second variable-diameter pulley 211 to constitute the transmission system 12. As can be noted in the figures, the belt 40, as a continuous loop, extends between the two

pulleys

11, 211 to transmit motion between the

pulleys

11, 211.

The first pulley 11 acts as a driven pulley, whereby it reacts to the change of the second pulley 211. In this embodiment, the second pulley 211 is a larger version of the first pulley 11.

Due to the configuration of the plurality of support surface units 33, the pulleys provide a substantially continuous support surface for belt 40 as belt 40 moves between a minimum diameter and a maximum diameter relative to pulley 11. In this embodiment, approximately 75% of the belt 40 is supported on the plurality of support surface units 33 at any one time.

Fig. 32 to 40 show various schematic views of the transmission system. The transmission system 12 includes a first variable diameter pulley 11 and a second variable diameter 211 interconnected by a belt 40. The various views show various positions of the belt 40 in the transmission system 12, wherein the various positions correspond to various gear positions of a derailleur in a conventional bicycle chain driven derailleur system.

With reference to fig. 32 to 34, the transmission system 12 is shown in a position associated with a maximum/highest transmission ratio, wherein the actuator 59 is located in its innermost position, whereby the first guide surface 67, 61b of each actuator head 61a engages with the guide surface 53 of the support surface unit 33. In this position, the innermost support surface element 33a of the first side assembly 17 of the first pulley 11 and the innermost support surface element 33b of the second side assembly 19 of the first pulley 11. The pulleys 11 are in their second positions, respectively. When in this position, the remaining support surface unit 33 of the first pulley 11 is in its first position.

When the belt 40 is supported by the minimum diameter of the first pulley 11, the belt 40 is supported by the maximum diameter of the second pulley 211. In this position, the outermost support surface unit 33 of the first side assembly 17 of the second pulley 211 and the outermost support surface unit 33 of the second side assembly 19 of the second pulley 211, respectively, are in a second position, the remaining support surface units 33 also being in their second position.

When the heads 61a, 61b of the actuator 59 of the first pulley 11 move outwardly, the pin 51 of the next adjacent bearing surface unit 33 enters the first opening 75 of the actuator channel 73. Further outward movement causes the surface 67 of the first guide head 61a, 61b to engage the guide surface 53 of the support surface unit 33. At this point, the support surface unit 33 starts to move towards its second position. Further outward movement of the actuator 59 will cause the support surface unit 33 to reach its second position. Once in this position, pin 51 is aligned with second opening 77 of actuator channel 73 and can clear second opening 77 of actuator channel 73, allowing actuator 59 to continue its outward movement.

When the actuator 59 is moved further outwards, the sequence continues for the subsequent adjacent support surface unit 33.

Once the actuator 59 has passed the support surface unit so that the support surface unit 33 is in its second position, the projection 47 in the lower surface 43 of the support surface unit is aligned with the recess 49 and received in the recess 49 in the upper surface 41 of the lower adjacent support surface unit. This holds the lower adjacent support surface unit in the second position until the actuator 59 returns inwardly and returns the upper adjacent support surface unit to its first position. This cooperation ensures that the support surface units remain in their second position and are not accidentally returned to their first position by the actuator 59.

Referring to fig. 35 and 36, the transport system 12 is shown in a first intermediate position. In these figures, the actuator 59 has begun to move in a radially outward direction. The right-hand support surface unit 33c is allowed to move to its second position, while the left-hand support surface unit 33c has moved further to its second position. This causes the support surface 31 to move outwardly to a larger diameter, thereby continuing to support the belt 40 as the applied force is reduced.

Referring to fig. 37, the transport system 12 is shown in a second intermediate position. Referring to fig. 38, the transport system 12 is shown in a third intermediate position. In these sets of maps, drive train 12 is moving away from the maximum/highest gear ratio. This occurs when the force exerted by the belt on the pulley is reduced, which allows the moving mechanism 85 to move the actuators 59 outwardly toward their outermost positions.

Referring to fig. 39 and 40, the drive system 12 is shown in a position associated with a minimum/lowest gear ratio with each actuator head 61a, 61b in its outermost position. This is also represented by fig. 6, which shows the outermost portion of each actuator 59. In this position, the first guide surface 67 of each actuator head 61a, 61b engages the guide surface 53 of the outermost support surface unit 33d of each

side assembly

17, 19. In this position all support surface units 33 are in their second position, supporting the belt 40 at its maximum diameter.

When belt 40 is supported by first pulley 11 at its maximum diameter, the configuration of the pulleys ensures that belt-receiving recess 25 limits the ability of belt 40 to disengage from pulley 11.

When the belt 40 is supported by the first pulley 11 of the largest diameter, the belt 40 is supported by the second pulley 211 of the smallest diameter, as shown in fig. 39.

In this embodiment, the second pulley 211 is a driving pulley, actively moved to a new operating position. Any resulting change in tension in the belt 40 will cause the first pulley 11 to react to support the belt 40 in a new position.

In the reverse operation, the support surface unit 33 of the first pulley 11 is returned to its first position. When the heads 61a, 61b of the actuator 59 move inwardly, the pins 51 of the underlying adjacent support surface unit 33 enter the second openings 77 of the actuator channels 73. Further inward movement causes the pin 51 to engage the second guide surface 71. With further inward movement, the inclined surface of the second guide surface 71 acts on the pin 51 to return the support surface unit 33 to its first position. When the support surface unit 33 is in the first position, the pin 51 aligns with the first opening 75 of the actuator channel 73 before exiting the actuator channel 73, allowing the actuator 59 to continue its inward movement.

When the actuator 59 is moved further inwards, the sequence continues for the subsequent support surface unit 33.

Similarly, the supporting surface unit of the second pulley 211 is moved to support the belt 40 with a larger diameter.

It can be seen from the operation of this embodiment that the transmission system 12 presents a substantially continuous bearing surface on both the first pulley 11 and the second pulley 211 as the transmission system moves between a maximum/maximum transmission ratio and a minimum/minimum transmission ratio. Minimum/lowest gear ratio. Further, the biasing means operate such that the actuators 59 can be positioned between their lowermost and outermost positions (including the end points) and can be held in that position. Thus, the surface of the support belt may be any diameter between the maximum diameter and the minimum diameter.

In view of the bicycle, prior art chain driven derailleur systems are prone to mechanical failure or even malfunction. Including when the bicycle is subjected to an impact (e.g., a rider passing through a hole in the road or over an edge) or an overly aggressive shifting event, the chain falls off of the sprocket or chainring. At best, these failures can cause significant inconvenience, result in game loss, or at worst, result in injury to the rider.

The reason that such a failure or malfunction may occur is because the design and construction of the prior art cassette and chain loop system driven by the transmission does not physically force the chain to remain in place. The present invention is designed such that the belt is relatively unlikely to fall off the front or rear pulleys because no riding wheels are used and the edges of the pulleys physically restrain the belt under any load, including impacts caused by road conditions. This increases the safety of riding and improves competitiveness in the race.

The present invention mitigates power losses during gear ratio changes because continuous power transfer is provided during those gear ratio changes. This does not apply to the derailleur system of the prior art bicycle or any other discrete transmission system that suffers from a loss of momentum during a gear shift (chainring or sprocket).

The loss of momentum is particularly important in prior art derailleurs when changing between chain rings that simultaneously require the replacement of an associated plurality of sprockets (typically 3-4) in the cassette to avoid excessive gear ratio adjustments from the current setting.

This embodiment can be activated by a single trigger up or down shift (using existing or dedicated handlebar mounted shifter hardware) on the front crankset. The rear wheel drive will automatically adjust to the crank setting. Prior art derailleur transmission systems require the rider to coordinate the shifting of the rear sprockets and front chainrings separately to achieve continuous shifting during upshifts or downshifts, which is not only inefficient, but also results in loss of momentum as the chainrings must be changed between 3 to 4 shifts are traversed, but also stresses the rider in the event of fatigue or a need to warn against racing conditions.

This embodiment eliminates the need for manual coordination of rear (tape cassette) and front (chain link) changes, making shifting simpler. This is particularly desirable when the rider is tired. This embodiment also eliminates the ratio duplication found in all prior art chain loop and cassette combinations, thereby further simplifying the system.

This embodiment eliminates the need for driveline lubrication, which reduces maintenance and does not compromise drive efficiency. [00239] The present embodiment also extends over the maximum and minimum gear ratios available with prior art derailleur systems.

Since the present embodiment is continuously variable, the rider is no longer forced to use the relatively energy-consuming gear stages inherent in prior art powertrains.

The efficiency of this embodiment is superior to that of prior art systems because the conventional system is inefficient when using the smallest sprocket and using a cross-sprocket arrangement. The efficiency of the present embodiment ensures that more rider energy input at the crank set is transferred to the rear wheels.

In other applications/embodiments of the invention, many of the above-described advantages of this embodiment are also achieved in one form or another. For example, as the gears change, the shift between gears is no longer associated with a loss/drop in power. The present invention allows for smooth transitions between gear ratios, thereby maintaining power transfer at all times. It also allows shifting under load.

The present invention provides a transmission system having a relatively narrow, fixed width pulley that can be designed with an almost infinite transmission ratio. This is in contrast to current variable diameter pulley systems, which must increase in width as the transmission ratio increases.

Example embodiments are provided so that this disclosure will be thorough and will fully convey the scope of the invention to those skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," "has," "having," or any variation thereof, are intended to cover a non-exclusive inclusion, such that the presence of the stated features, integers, steps, operations, elements, and/or components is/are specified, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

When an element or layer is referred to as being "on," "engaged to," "connected to" or "coupled to" another element or layer, it can be directly on, engaged, connected or coupled to the other element or layer. Elements or layers or intermediate elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to" or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements (e.g., "between" and "directly between," "adjacent" and "directly adjacent," etc.) should be interpreted in a similar manner. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first," "second," and other numerical terms used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

For convenience in description, this is used herein to describe one element or feature's relationship to another element or features as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the example term "below … …" can include both an orientation above … … and below … …. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Claims

1. A transmission system including a first pulley and an input spaced therefrom, a cable extending between the first pulley and the input such that movement of the input causes movement of the first pulley, the first pulley comprising:

a first side assembly spaced apart from a second side assembly, the first side assembly and the second side assembly rotatably secured together;

2. A transmission system according to claim 1, wherein the at least one actuator is variably positionable along a radial extent of the first pulley.

3. A transmission system according to claim 1 or claim 2, wherein the at least one actuator includes first and second actuators connected therebetween by a bridge member.

4. A transmission system according to claim 3, wherein the bridge member holds the first and second actuators in a fixed relationship.

5. A transmission system according to claim 3 or 4, wherein the first actuator cooperates with a support surface of the first side assembly and the second actuator cooperates with a support surface of the second side assembly simultaneously to bring each support surface into two first and second positions.

6. A transmission system according to claim 3, 4 or 5, wherein at least one or both of the first and second actuators provides first guide means to move the support surface to the second position, the first guide means may comprise: a first guide surface engaged with the support surface.

7. A transmission system according to any one of claims 3 to 6, wherein at least one or both of the first and second actuators provides second guide means to guide the support surface to the first position, the second guide means including a second guide surface to move the support surface to the first position.

8. The transmission system according to claim 7 wherein the second guide surface includes an actuator channel that cooperates with a portion of the support surface to move the support surface to the first position.

9. A transmission system according to any one of claims 1 to 8, wherein the pulley includes control means to control movement of the at least one actuator, wherein the control means constrains the at least one actuator such that it is constrained to radial movement relative to each side assembly.

10. A transmission system according to claim 9, wherein the control means includes at least one support channel which engages with the at least one actuator to limit movement along the at least one support channel, the at least one support channel extending relative to a radial direction; at least one actuator is limited relative to each side assembly to radial movement relative to each side assembly, the at least one actuator being variably positionable along a radial extent.

11. A transmission system according to claim 9 or claim 10, wherein the control means includes a support housing supporting the at least one actuator, the support housing including a back plate and the movement mechanism, the back plate being located at a position between the support surface and the movement mechanism, the back plate supporting the support surface and the movement mechanism.

12. A transmission system according to claim 11, wherein the back plate has a central hub adapted to receive a rod or shaft.

13. A transmission system according to claim 11 or 12, wherein the backplate incorporates the at least one support passage for limiting movement of the at least one actuator in a radial direction, the at least one support passage extending radially outwardly from the hub.

14. The transmission system according to claim 13 wherein the at least one support channel is closed at one end proximate the hub and open at an end distal from the center of the back plate.

15. The transmission system according to claim 13 wherein the at least one support channel is open at one end proximate the hub and open at an end distal from a center of the back plate.

16. A transmission system according to claim 14 or 15, wherein the opening has a closure to prevent the at least one actuator from exiting the at least one support channel.

17. A transmission system according to any one of claims 11 to 16, wherein the movement mechanism moves the at least one actuator along the radial range, the movement mechanism reacting to forces exerted thereon by the cable.

18. A transmission system according to any one of claims 1 to 17, wherein the first pulley is biased to its normal condition.

19. A transmission system according to any one of claims 11 to 18, wherein the movement mechanism biases each of the at least one actuator to an outer position.

20. A transmission system according to claim 19, wherein the biasing means applies a constant or near constant force to each of the at least one actuator regardless of the radial position of the at least one actuator.

21. The transmission system according to claim 20 wherein the movement mechanism further includes a set of lever arms to transfer the force of the biasing device to each of the at least one actuator.

22. The transmission system according to claim 21 wherein the set of lever arms includes one or more first lever arms and one or more second lever arms.

23. A transmission system according to claim 19, wherein the movement mechanism includes a plurality of biasing mechanisms.

24. The transmission system of claim 23, wherein each side assembly has a plurality of biasing mechanisms such that the number of biasing mechanisms on the first side assembly is equal to the number of biasing mechanisms on the second side assembly.

25. A transmission system according to claim 24, wherein each biasing mechanism includes: at least one biasing means in the form of a spring; and a set of lever arms comprising a first lever arm and two second lever arms.

26. A transmission system according to claim 25, wherein the first lever arm transfers the force from the biasing means to one or more second lever arms.

27. A transmission system according to claim 25 or 26, wherein the second lever arm has a first end rotatably secured to the at least one actuator such that movement of the first end of the second lever arm causes movement of the at least one actuator along the at least one support channel.

28. A transmission system according to claim 25, 26 or 27, wherein the one or more first lever arms have a first end connected directly or indirectly to the biasing means and a second end connected directly or indirectly to a second end of the one or more second lever arms.

29. A transmission system according to any one of claims 11 to 28, wherein the movement mechanism further includes a ring rotatably fixed to the backplate, the ring being positioned coaxially about a central hub of the backplate, the second end being located centrally of the backplate. The one or more first lever arms are rotatably secured to the ring and the second ends of the one or more second lever arms are rotatably secured to the ring.

30. A transmission system according to claim 28 or 29, wherein the second ends of each lever arm are fixed at different angular positions relative to one another.

31. A transmission system according to any one of claims 25 to 30, wherein the biasing means is in the form of one or more springs supported around the periphery of the backplate, each spring having one end connected to the first end of one of the first lever arms.

32. The transmission system according to claim 31, wherein a linkage assembly connects a first end of the first lever arm to an end of the spring.

33. A transmission system according to any one of claims 1 to 32, wherein the support surface includes a plurality of support segments arranged in a circular configuration, wherein the overall appearance of each support segment is that of a truncated sector.

34. A transmission system according to claim 33, wherein each support section comprises a plurality of support surface units, whereby one or more support surface units define the support surface.

35. A transmission system according to claim 34, wherein each individual support section has each support surface unit stacked on top of one another, wherein each support surface unit is constrained to axial movement relative to an adjacent support surface unit and is configured to prevent tangential movement of adjacent support surface units relative to one another.

36. A transmission system according to claim 34 or 35, wherein the support surface units include a limiting mechanism to limit axial movement between adjacent support surface units. The limiting mechanism may prevent axial movement of each support surface unit a distance beyond the centre plane of the first pulley; the restraining means may comprise a protrusion incorporated in each support surface unit, wherein the protrusion is adapted to cooperate with a recess in an adjacent support surface unit; the restraining mechanism holds at least the support surface unit in the second position until the at least one actuator allows the support surface unit to move back to the first position.

37. A transmission system according to any one of claims 1 to 32, wherein each support surface includes a plurality of support surface units, each unit being independently movable between the first and second positions, each unit being constrained to move between the first and second positions. In the second position, each support unit is adapted to matingly engage with at least one actuator, wherein the at least one actuator moves each support unit between the first position and the second position.

38. A transmission system according to claim 37, wherein the at least one actuator engages the support surface unit when the at least one actuator moves radially outwardly to move the support surface unit outwardly along at least one prop channel between the first and second positions.

39. A transmission system according to claim 34 or 37, wherein the at least one actuator engages one or more support surface units when the at least one actuator is moved radially to move the support surface units inwardly along at least one support channel between the second position and the first position.

40. A transmission system including a first pulley and an input spaced therefrom, a cable extending between the first pulley and the input such that movement of the input causes the first pulley to rotate, the first pulley comprising:

41. A transmission system including a first pulley and an input spaced therefrom, a cable extending between the first pulley and the input such that movement of the input causes rotation of the first pulley, the first pulley comprising:

wherein the first pulley reacts the movement of the support surface of the second pulley and the first pulley comprises a biasing device that biases the support surface of the first pulley to a maximum diameter when the diameter of the cable on the second pulley is minimal or no cable is present.

42. A transmission system according to claim 40 or 41, wherein the support surfaces are selectively positioned such that the third diameter is any size diameter between the first and second diameters.

43. A transmission system according to claim 40, 41 or 42, wherein the support surface may comprise a plurality of support surface units, each support surface unit being laterally movable between at least a first position and a second position. The first side assembly may be connected to the second side assembly; the plurality of support surface units may cooperate to provide a support surface whereby selective movement of the support surface units causes the cable to be positioned in transition between different diameters of the first pulley.

44. The transmission system according to claim 40, 41 or 42, wherein the support surface comprises a plurality of support surface portions, wherein each support surface portion provides one or more support surface units, wherein each support surface unit provides at least one cable-engaging contact surface, each contact surface extending transversely from the support surface unit in a substantially central direction, the contact surface of the first side assembly being offset from the corresponding contact surface of the second side assembly such that the contact surface of the first side assembly may be at a different diametrical/radial position than the corresponding contact surface of the second side assembly, wherein when the contact surfaces of the first side assembly are in the second position and the contact surfaces of the second side assembly are in the second position, the contact surfaces overlap.

45. The transmission system according to claim 44, wherein movement of each support surface unit to the second position causes a portion of the contact surface of the first side assembly to be received between radially adjacent contact surfaces of the second side assembly.

46. A transmission system according to any one of claims 1 to 45, wherein the cable extends between the first pulley and the input device such that the cable is looped partially around the first pulley and partially around the input device.

47. A transmission system according to any one of the preceding claims, wherein the input is in the form of a second pulley comprising first and second side members spaced apart from one another, the first side member being connected to the second side member, the first and second side members being coaxially mounted, the first and second side members of the second pulley each comprising a support surface.

48. A transmission system according to claim 47, wherein the second pulley includes an actuating arrangement to move the support surface unit of each side assembly between the first and second positions.

49. A transmission system according to any one of claims 41 to 48, wherein the biasing means includes a plurality of springs which interact with a set of lever arms to move the support surface unit in reaction between the first and second positions.

50. A transmission system according to claim 49, wherein the biasing arrangement allows at least one actuator to move the support surface unit between the first and second positions.

51. The transmission system according to claim 50 wherein said at least one actuator includes first and second actuator heads held in fixed relation, each actuator head providing said at least one guide means, said at least one guide means being located therein. The first guide means moves the support surface to the second position in the form of first guide means comprising a first guide surface engaging each support surface element of the guide surface and second guide means guiding the support surface to the first position, the second guide means may comprise a second guide surface moving the support surface to the first position.

52. A transmission system according to claim 51, wherein the second guide surface includes an actuator channel which cooperates with a portion of each support surface unit to move the support surface to the first position.

53. A transmission system according to any one of claims 40 to 52, wherein the first pulley includes control means to control movement of the at least one actuator, the control means constraining the at least one actuator such that the at least one actuator is constrained to radial movement relative to each side assembly.

54. A transmission system according to any one of claims 47 to 51, wherein the transmission system is arranged such that the first pulley moves from the second diameter to the first diameter when the second pulley moves from the first diameter to the second diameter.

55. A transmission system including a first pulley and an input spaced therefrom, a cable extending between the first pulley and the input such that movement of the input causes the first pulley to rotate, the first pulley comprising:

56. A transmission system including a first pulley connected to an input by a cable such that movement of the input causes rotation of the first pulley, the first pulley comprising:

57. A variable diameter pulley comprising:

the method comprises the following steps:

an annular groove for receiving the cable such that the cable is supported by the pulley at a first diameter of the pulley;

a pair of support surfaces located in the annular groove, the pair of support surfaces being movable in a transverse direction between a spaced condition in which the pair of support surfaces are not engaged with the cable and an engaged condition in which the pair of support surfaces support the cable at a second diameter of the pulley, the second diameter being greater than the first diameter;

58. A variable diameter pulley comprising:

an annular groove for receiving the cable at the first diameter of the pulley;

Wherein the support surface may be positioned to have any diameter between the first diameter and the second diameter;

Wherein the thickness of the pulley remains constant as the pulley moves between the first diameter and the second diameter.

59. A pulley as claimed in claim 57 or 58 in which the support surface presents a substantially continuous surface to the cable when received on the pulley.

60. A pulley as claimed in claim 57, 58 or 59 in which the support surface is formed by a plurality of support surface units including a first set of support surface units and a second set of support surface units, in which the first and second sets of support surface units engage and/or overlap one another to form a support surface.

61. The transport system of any of claims 57-60, wherein the first and second sets of support surface units are movable in a lateral direction between spaced apart states, wherein the cable is supported at the first diameter. Wherein the cable is supported at the second diameter of the pulley whereby the cable is supported on a support surface exhibiting a varying diameter during movement of the set of support surface units between the states.

62. A transmission system according to claim 60 or 61, wherein circumferentially adjacent support surface elements define discontinuous rings.

63. A transmission system according to claim 62, wherein a gap is defined between adjacent support surface units of the same ring.

64. A transmission system according to claim 62 or 63, wherein each ring of the first set of support surface units has a complementary ring of the second set of support surface units, whereby the complementary rings are in staggered relationship to one another to provide a ring pair.

65. The transfer system of claim 64 wherein each pair of rings is movable between a first position in which the complementary rings of the pair are spaced apart from each other in the axial/transverse direction, wherein the cable cannot be supported by the pair of rings, and a second position in which the complementary rings of the pair of rings are in engagement to provide a support surface in which the cable is supported by the pair of rings.

66. A transmission system according to any one of claims 57 to 65, wherein the pulley includes a plurality of actuators, each actuator being movable in a radial direction between a first position at the centre of the pulley and a second position adjacent the outer portion. Each actuator has at least one head on a diameter of the pulley adapted to cause movement of the support surface unit as each actuator moves between positions.

67. The pulley of claim 66, wherein each actuator has a first head adapted to move the support surface unit of the first side assembly and a second head adapted to move the support surface unit of the second side. When each actuator is moved between positions, the first and second heads are interconnected by a bridge extending therebetween such that they are maintained in a fixed relationship to each other when the first and second assemblies are assembled.

68. A pulley as claimed in any one of claims 66 to 67 in which the biasing means comprises a plurality of springs which interact with a set of lever arms to bias each actuator towards its outermost extent. The location is such that the pulley assumes a maximum diameter when the biasing force of the biasing means is greater than the force acting on the support surface unit and a smaller diameter when the force exerted thereon is greater than the force of the biasing means.

69. A transmission system including a variable diameter pulley according to any one of claims 57 to 68 connected to an input end by a cable.