WO2005119097A1

WO2005119097A1 - Continuously variable transmission

Info

Publication number: WO2005119097A1
Application number: PCT/NZ2005/000111
Authority: WO
Inventors: Muthuvetpillai Jegatheeson
Original assignee: Muthuvetpillai Jegatheeson
Priority date: 2004-06-04
Filing date: 2005-06-03
Publication date: 2005-12-15

Abstract

A transmission has a fixed housing 103, a rotatable or reciprocable input member, a torque shaft 109, and a rotatable linkage arrangement. A gyroscopic rotor mounted on the linkage arrangement has a spin axis which is cyclically angularly deflected to generate gyroscopic reaction forces which are applied to the torque shaft as positive and negative torque. A first one-way clutch 131a and a second one-way clutch of opposite sense are operatively connected to the torque shaft 109. An output 134 is selectively or permanently operatively connected to the first one-way clutch 131a. The transmission has a forward operating configuration in which the output 134 is driven by the input member in one direction and a reverse operating configuration in which the output 134 is driven by the input member in the opposte direction. The transmission is preferably capable of engine braking.

Description

CONTINUOUSLY VARIABLE TRANSMISSION

FIELD OF THE INVENTION

The present invention relates to a continuously variable transmission. More particularly, the invention relates to a continuously variable transmission which includes a gyroscopic rotor having a spin axis which is precessed in response to input motion, to generate gyroscopic reaction forces.

BACKGROUND OF THE INVENTION

A gyroscopic continuously variable transmission (GVT) unit includes a rotor mounted on a linkage arrangement, and uses the precession of the rotor spin axis to generate gyroscopic reactions forces which are delivered to a torque shaft as positive and negative toque. That torque is then fully or partially rectified, such that torque is transmitted to a transmission output. Such transmissions are described in US Patent No. 6,640,659 and PCT Publication Number WO 00/45068, the disclosures of which are incorporated herein by reference.

Figures la and lb show examples of gyroscopic continuously variable transmission (GVT) units. GVT units generally have at least: a fixed housing or support; an input member which is either rotatable about an axis of rotation relative to said fixed housing or support or reciprocable along an axis relative to said fixed housing or support; a torque shaft; and an output member arranged to be rotated about an axis of rotation by the torque shaft; a first one-way clutch between the torque shaft and output member; a linkage arrangement rotatable about the axis of the input member under the influence of said input member; and a gyroscopic rotor mounted on the linkage arrangement and having a spin axis which is cyclically angularly deflected in response to the input member to generate gyroscopic reaction forces, the reaction forces generated by the rotor as its axis is cyclically deflected being applied to the torque shaft as positive and negative torque; the first-one way clutch being configured to apply the positive torque to the output member; and the torque shaft being connected over a second one-way clutch of opposite sense to the first one-way clutch either to said housing or support to apply the negative torque to the housing or support, or alternatively to the output member over a rotation reversal system to apply the negative torque to the output member as positive torque. The torque shaft may be part of the linkage arrangement or may be separate to the linkage arrangement.

By using engine braking, advantages such as a reduction in brake wear and safer braking can be achieved. Engine braking occurs when energy is transferred from the wheels, back through the transmission unit to the engine, to slow the vehicle. That cannot be achieved with an unmodified GVT unit having the above configuration.

Further, in certain applications, such as ride on lawnmowers, it is desirable that the option is available whereby a reverse gear or motion can be selected while the mower is still moving forwards. Again that cannot be achieved with an unmodified GVT unit having the above configuration.

It is an object of at least preferred embodiments of the present invention to provide an alternative gyroscopic continuously variable transmission which addresses at least one of the above mentioned disadvantages, and/or which at least provides the public with a useful alternative.

SUMMARY OF THE INVENTION

Broadly, the invention consists in alternative gyroscopic continuously variable transmission units having clutch and gear arrangements which provide for a reversible output motion. In preferred embodiments, the transmission is capable of a reversible power flow through the transmission to provide engine braking.

The term 'comprising' as used in this specification and claims means 'consisting at least in part of, that is to say when interpreting statements in this specification and claims which include that term, the features prefaced by that term in each statement all need to be present but other features can also be present. In accordance with a first aspect of the present invention, there is provided a transmission comprising: a fixed housing or support; an input member which is either rotatable about an axis of rotation relative to said fixed housing or support or reciprocable along an axis relative to said fixed housing or support; a torque shaft; a linkage arrangement rotatable about the axis of the input member under the influence of said input member; and a gyroscopic rotor mounted on the linkage arrangement and having a spin axis which is cyclically angularly deflected in response to the input member to generate gyroscopic reaction forces, the reaction forces generated by the rotor as its axis is cyclically deflected being applied to the torque shaft as positive and negative torque; a first one-way clutch operatively connected to the torque shaft; a second one-way clutch of opposite sense to the first one-way clutch and operatively connected to the torque shaft; and an output which is selectively or permanently operatively connected to the first one-way clutch; wherein the transmission has a forward operating configuration in which the output is driven by the input member in one direction and a reverse operating configuration in which the output is driven in the opposite direction by the input member.

The torque shaft may be part of the linkage arrangement.

Preferably, the transmission has an engine braking configuration which provides a net flow of energy from the output to the input member and to a source of motive power which is operatively connected to the input member, to thereby slow the output.

In a preferred embodiment, the output is selectively operatively connectable to the first one-way clutch or the second one-way clutch, and the transmission is in the forward operating configuration when the output is operatively connected to the first one-way clutch and is in the reverse operating configuration when the output is operatively connected to the second one-way clutch. Suitably, the first one-way clutch can be selectively coupled to or decoupled from the fixed housing or support; the second one- way clutch can be selectively coupled to or decoupled from the fixed housing or support; the transmission has a forward operating configuration in which the second one-way clutch is coupled to the fixed housing or support, the first one-way clutch is decoupled from the fixed housing or support, and the output is operatively connected to the first one-way clutch such that positive torque from the torque shaft is applied to the output by the first one-way clutch and negative torque from the torque shaft is applied to the fixed housing or support by the second one-way clutch; and the transmission has a reverse operating configuration in which the second one-way clutch is decoupled from the fixed housing or support, the first one-way clutch is coupled to the fixed housing or support, and the output is operatively connected to the second one-way clutch such that negative torque from the torque shaft is applied to the output by the second one-way clutch and positive torque from the torque shaft is applied to fixed housing or support by the first one-way clutch. Preferably, the transmission has an engine braking configuration in which the second one-way clutch is decoupled from the fixed housing or support, the first one-way clutch is partially coupled to the fixed housing or support, and the output is operatively connected to the second one-way clutch to provide a net flow of energy from the output to the input member and to a source of motive power which is operatively connected to the input member, to thereby slow the output.

A clutch is "decoupled" when torque cannot be transmitted by the clutch from the torque shaft to the fixed housing or support, and is "coupled" when at least a substantial part of the torque of the relevant sense can be transmitted by the clutch from the torque shaft to the fixed housing or support.

A clutch is "partially coupled" when more than zero but less than a substantial part of the torque of the relevant sense from the torque shaft can be applied by the clutch from the torque shaft to the fixed housing or support.

Advantageously, the output comprises an output gear, and further comprising a dog gear assembly having a gear which is operatively connected to the output gear, wherein the dog gear assembly is selectively operatively connectable to one of the first and second one-way clutches. Each of the first and second one-way clutches may be mounted in a respective housing which is selectively engageable with the gear of the dog gear assembly. Each of the first and second one-way clutches may be mounted in a respective housing which is integral with or connected to a brake disc, and the transmission may comprise a brake caliper associated with each brake disc and configured such that when the disc is released by the caliper the respective clutch is decoupled, when the disc is partially braked by the caliper the clutch is partially coupled, and when the disc is at least substantially braked by the caliper the clutch is coupled.

Preferably, in the forward operating configuration, positive torque from the torque shaft is delivered to the output by the first one-way clutch and negative torque from the torque shaft is delivered to the output by the second one-way clutch over a rotation reversal system. Preferably, in the reverse operating configuration, negative torque from the torque shaft is delivered to the output by the second one-way clutch and positive torque from the torque shaft is delivered to the output by the first one-way clutch over a rotation reversal system.

Advantageously, the first one-way clutch is selectively operatively connectable to a first gear which is operatively connected to the output or to a second gear which is operatively connected to the output over a rotation reversal system, and the second oneway clutch is selectively operatively connectable to a third gear which is operatively connected to the output over a rotation reversal system or to a fourth gear which is operatively connected to the output, the configuration being such that when the first one-way clutch is operatively connected to the first gear the second one-way clutch is operatively connected to the third gear, and when the first one-way clutch is operatively connected to the second gear the second one-way clutch is operatively connected to the fourth gear. Each of the first, second, third, and fourth gears may form part of a dog gear assembly, with each of the first and second one-way clutches mounted in a housing which is selectively engageable with the respective gears of the dog gear assembly.

In one embodiment, the gears of the dog gear assembly are rotatable relative to the torque shaft and are axially movable relative to the torque shaft to engage with the respective one-way clutches. Preferably, the transmission comprises an actuator to concurrently axially move the gears of the dog gear assembly. In another embodiment, the gears of the dog gear assembly are rotatable relative to the torque shaft, and wherein the first and second one-way clutches are axially movable relative to the torque shaft to engage with the respective gears of the dog gear assembly. Preferably, the transmission includes an actuator to concurrently axially move the first and second one-way clutches.

Preferably, the transmission comprises a reversible gear arrangement which has a forward operating configuration in which positive torque is transferred from the torque shaft, by the first one-way clutch, to the output, and a reverse operating configuration in which positive torque is transferred from the torque shaft, by the first one-way clutch, to the output over a rotation reversal system. The second one-way clutch may be configured to transfer negative torque from the torque shaft to the reversible gear arrangement, over a rotation reversal system. Preferably, the second one-way clutch can be selectively coupled to or decoupled from the fixed housing or support to apply the negative torque from the torque shaft to the fixed housing or support when coupled thereto, the transmission having a forward operating configuration in which the second one-way clutch is coupled to the fixed housing or support and the reversible gear arrangement is in a forward configuration, the transmission further having a reverse operating configuration in which the second one-way clutch is coupled to the fixed housing or support and the reversible gear arrangement is in a reverse configuration. More preferably, the transmission has an engine braking configuration in which the second one-way clutch is partially coupled to the fixed housing or support and the reversible gear arrangement is in the reverse configuration, to provide a net flow of energy from the output to the input member and to a source of motive power which is operatively connected to the input member, to thereby slow the output.

The second one-way clutch may be mounted in a respective housing which is integral with or connected to a brake disc, and the transmission may comprise a brake caliper associated with the brake disc and configured such that when the disc is released by the caliper the respective clutch is decoupled, when the disc is partially braked by the caliper the clutch is partially coupled, and when the disc is at least substantially braked by the caliper the clutch is coupled.

Preferably, the reversible gear arrangement comprises a shaft which is rotated as a result of torque delivered from the first one-way clutch, and first and second dog gears rotatably mounted on the shaft, with the first dog gear operatively connected to the output and the second dog gear operatively connected to the output over a rotation reversal system, the reversible gear arrangement further including a dog member which is configured for rotation with the shaft and axially moveable relative to the shaft to selectively engage the first and second dog gears. The transmission preferably includes an actuator to axially move the dog member relative to the shaft.

The transmission preferably comprises an arrangement to decouple the torque shaft of the transmission to enable the transmission to be changed from the forward operating configuration to the reverse operating configuration, more preferably when the output is moving. The torque shaft is "decoupled" when torque cannot be transmitted between the transmission input and transmission output.

The arrangement to decouple may comprise an arrangement to increase the inertia of the torque shaft. The arrangement to increase the inertia of the torque shaft may comprise a fly-ball arrangement or flywheel arrangement.

The arrangement to decouple may comprise an arrangement to brake movement of the torque shaft.

Alternatively or in addition, the arrangement to decouple may comprise a speed controller of the gyroscopic rotor, wherein the transmission is configured such that when the rotor is not spinning on its spin axis, the torque shaft is decoupled.

As used herein, a one-way clutch as a device which allows substantially free relative movement (free-wheeling) of a given component in relation to the other component when the relative speed between the components is, say, positive but does not allow relative movement when the relative speed is zero and tending to become negative. In other words the one-way clutch is a device which locks or engages the two components when there is tendency for the relative speed to become negative from zero. Another term for a one-way clutch is "overrunning clutch". The clutches may be conventional mechanical one-way clutches or the particular embodiment clutches described herein, but the term also covers other alternatives such as brakes which are controlled to allow rotational movement in one direction but not the other and fluid based systems for example.

In accordance with a second aspect of the present invention, there is provided a transmission comprising: a fixed housing or support; an input member which is either rotatable about an axis of rotation relative to said fixed housing or support or reciprocable along an axis relative to said fixed housing or support; a torque shaft; a linkage arrangement rotatable about the axis of the input member under the influence of said input member; and a gyroscopic rotor mounted on the linkage arrangement and having a spin axis which is cyclically angularly deflected in response to the input member to generate gyroscopic reaction forces, the reaction forces generated by the rotor as its axis is cyclically deflected being applied to the torque shaft as positive and negative torque; a first one-way clutch operatively connected to the torque shaft and which can be selectively coupled to or decoupled from the fixed housing or support; a second one-way clutch of opposite sense to the first one-way clutch and operatively connected to the torque shaft and which can be selectively coupled to or decoupled from the fixed housing or support; and an output which can be selectively operatively connected to the first one-way clutch or the second one-way clutch; the transmission having a forward operating configuration in which the second one-way clutch is coupled to the fixed housing or support, the first one-way clutch is decoupled from the fixed housing or support, and the output is operatively connected to the first one-way clutch such that positive torque from the torque shaft is applied to the output by the first oneway clutch and negative torque from the torque shaft is applied to the fixed housing or support by the first one-way clutch; the transmission further having a reverse operating configuration in which the second one-way clutch is decoupled from the fixed housing or support, the first one-way clutch is coupled to the fixed housing or support, and the output is operatively connected to the second one-way clutch such that negative torque from the torque shaft is applied to the output by the second one-way clutch and positive torque from the torque shaft is applied to fixed housing or support by the first one-way clutch.

In accordance with a third aspect of the present invention, there is provided a transmission comprising: a fixed housing or support; an input member which is either rotatable about an axis of rotation relative to said fixed housing or support or reciprocable along an axis relative to said fixed housing or support; a torque shaft; a linkage arrangement rotatable about the axis of the input member under the influence of said input member; and a gyroscopic rotor mounted on the linkage arrangement and having a spin axis which is cyclically angularly deflected in response to the input member to generate gyroscopic reaction forces, the reaction forces generated by the rotor as its axis is cyclically deflected being applied to the torque shaft as positive and negative torque; a first one-way clutch operatively connected to the torque shaft; a second one-way clutch of opposite sense to the first one-way clutch and operatively connected to the torque shaft; and an output; wherein the transmission has a forward operating configuration in which positive torque from the torque shaft is delivered to the output by the first one-way clutch and negative torque from the torque shaft is delivered to the output by the second one-way clutch over a rotation reversal system, to drive the output in one direction; the transmission further having a reverse operating configuration in which the output is driven in the opposite direction.

In accordance with a fourth aspect of the present invention, there is provided a transmission comprising: a fixed housing or support; an input member which is either rotatable about an axis of rotation relative to said fixed housing or support or reciprocable along an axis relative to said fixed housing or support; a torque shaft; an output; a first one-way clutch connected between the torque shaft and a reversible gear arrangement having a forward configuration and reverse configuration; a linkage arrangement rotatable about the axis of the input member under the influence of said input member; and a gyroscopic rotor mounted on the linkage arrangement and having a spin axis which is cyclically angularly deflected in response to the input member to generate gyroscopic reaction forces, the reaction forces generated by the rotor as its axis is cyclically deflected being applied to the torque shaft as positive and negative torque; the first-one way clutch configured to apply the positive torque to the output member over the reversible gear arrangement; and a second one-way clutch of opposite sense to the first one-way clutch and which can be selectively coupled to or decoupled from the fixed housing or support to apply the negative torque from the torque shaft to the fixed housing or support when coupled thereto; the transmission having a forward operating configuration in which the second one-way clutch is coupled to the fixed housing or support and the gear arrangement is in a forward configuration; the transmission further having a reverse operating configuration in which the second one-way clutch is coupled to the fixed housing or support and the gear arrangement is in a reverse configuration.

Preferably, the transmission has an engine braking configuration in which the second one-way clutch is partially coupled to the fixed housing or support, and the gear arrangement is in a reverse configuration to provide a net flow of energy from the output to the transmission input and to a source of motive power which is operatively connected to the transmission input, to thereby slow the output.

The transmission of the second to fourth aspects may have any one or more of the features outlined in respect of the first aspect above.

In accordance with a fifth aspect of the present invention, there is provided a method of operating a transmission having a fixed housing or support; an input member which is either rotatable about an axis of rotation relative to said fixed housing or support or reciprocable along an axis relative to said fixed housing or support; a torque shaft; an output; a linkage arrangement rotatable about the axis of the input member under the influence of said input member; and a gyroscopic rotor mounted on the linkage arrangement and having a spin axis which is cyclically angularly deflected in response to the input member to generate gyroscopic reaction forces, the reaction forces generated by the rotor as its axis is cyclically deflected being applied to the torque shaft as positive and negative torque; the method comprising: decoupling the torque shaft so that torque cannot be transferred from the input member to the output, and selecting a reverse operating configuration.

The method may comprise selecting the reverse operating configuration while the output member is moving.

The method may further comprise following selecting a reverse operating configuration, partially restraining the torque shaft to provide a net flow of energy from the output to the input member and to a source of motive power which is operatively connected to the input member, to thereby slow the output.

The invention consists in the foregoing and also envisages constructions of which the following gives examples only.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings in which: Figure la (prior art) schematically shows a differential-type gyroscopic continuously variable transmission unit; Figure lb (prior art) schematically shows a reciprocating-type gyroscopic continuously variable transmission unit; Figure lc schematically shows a crank and connecting rod arrangement for transferring motion from a rotating shaft to the reciprocable input of the gyroscopic variable transmission unit of Figure lb; Figure 2a schematically shows a gear and clutch arrangement of a first preferred embodiment reversible gyroscopic continuously variable transmission unit; Figure 2b schematically shows detail B of Figure 2a; Figures 3a and 3b show details of suitable arrangements for adjusting the effective inertia of the torque shaft of the preferred embodiment gyroscopic continuously variable transmission units of Figure 2, to selectively decouple the torque shaft; Figure 3 c schematically shows an alternative arrangement for selectively decoupling the torque shaft of the preferred continuously variable transmission units of Figure 2; Figure 4 schematically shows a gear and clutch arrangement of a second preferred embodiment reversible gyroscopic continuously variable transmission unit; Figure 5 schematically shows a gear and clutch arrangement of a third preferred embodiment reversible gyroscopic continuously variable transmission unit; Figure 6 schematically shows a gear and clutch arrangement of a fourth preferred embodiment gyroscopic continuously variable transmission unit; and Figure 7 schematically shows a gear and clutch arrangement of a fifth preferred embodiment gyroscopic continuously variable transmission unit.

DETAILED DESCRIPTION OF PREFERRED FORMS

An example of a differential-type GVT unit is shown in Figure la. That GVT unit includes an input member 1 which is rotatable relative to a fixed housing or support 3 and would generally be operatively connected to a source of motive power, such as the crankshaft of an internal combustion engine M for example. Other sources of motive power can be used such as a spark ignition engine or an electric motor could be used.

A gimbal arrangement has a main outer frame 5 which is fixed for rotation with the input member 1. A shaft 107 is rotatably mounted on the main frame 5, and a torque shaft 9 is coupled to the shaft 7 differentially through a gear train having gears 11, 13, 15, and 17. A shaft 19 is rotatably mounted on the main frame 5 and the gears 13, 15 are attached to the shaft. Shaft 7 is coaxial with shaft 21 which is also rotatably mounted on the main frame, and an inner sub-frame 23 of the gimbal is attached to the shafts 7, 21.

A gyroscopic rotor 25 is rotatably mounted on the sub-frame 23, preferably via a shaft 27. Rotation of the rotor 25 may be driven by a motor 29 (for example, an electric motor), or could be driven as a result of input/output motions via a gear system for example. The torque shaft 9 is connected via a first one-way clutch 31 to an output member 33 and via a second opposite one-way clutch 35 of opposite sense to the first one-way clutch, to the fixed housing or support.

During operation of the transmission, the input motion of the input member 1 causes precession of the spin axis and thereby the spin vector of the rotor 25. As the spin vector is precessed continuously, a cyclical gyroscopic reaction is generated from the spin vector. The cyclical reaction is rectified by the one-way clutches 31, 35 so that the rectified (positive) component is applied to the output member 33 of the transmission. In the embodiment shown, the other (negative) component is transmitted to the fixed housing or support via one-way clutch 35.

The above-mentioned cyclical reaction is affected by the output rotation as well. When the output rotation is zero the cyclical reaction has no component acting on the input and hence no power is drawn from the input. However when the output rotation is present a corresponding reaction component on the input occurs to match the energy output. Thus, such a GVT is inherently able to match the input and the output energy without any external controls, and by utilising good bearing technology and practices advantageously features high efficiency / low loss at all times. Feedback control is only required to achieve desired operating point and it is achieved by stroke control of the input (if a reciprocating input GVT is used), rotor speed control and/or control of the inertia of the torque shaft.

When the torque shaft 9 of the transmission receives the positive (or output) torque, the torque shaft is accelerated to synchronise with the transmission output member 33 at which point the first one-way clutch 31 transmits torque to the output member, transmitting power. During the negative (or reaction) torque part of the cycle, the torque shaft 9 is decelerated until its rotational speed is zero at which point it is synchronised with the fixed housing or support 3 and the second one-way clutch 35 transmits the negative torque to the housing.

The theory behind the gyroscopic reactions in the operation of the transmission is described in more detail in WO 00/45068. Figure lb shows an example of a reciprocating-type GVT unit. The transmission has an input member 1 ' which is reciprocable along an axis relative to a fixed housing or support 3'.

An output member 33' is rotatable relative to the fixed housing or support 3', and is connected to a gear 33a' which engages a gear 3 la' on a first one-way clutch 31', which is mounted between the gear 31a' and the torque shaft 9'. The torque shaft 9' is rotatable relative to the fixed housing or support 3'. A second one-way clutch 35' of opposite sense to the first one-way clutch is mounted between the torque shaft 12' and the fixed housing or support 3'. A fork 43' is attached to the torque shaft 9'. A rotor shaft 27' of the gyroscopic rotor 25' is rotatably mounted on a frame member 47'. The frame member 47' is rotatably mounted on the fork 43' by means of co-axial shafts 48' which extend from the frame member 47'.

A thrust bearing arrangement 18' connects the input member 1' to an outer frame member 40' which forms a rack of a rack and pinion arrangement. Pinions 42' are attached to the shafts 48', such that reciprocating motion of the input member 1' is translated into oscillation of the rotor shaft 27' about the axis of the shafts 48' thereby creating an output torque and reaction torque on the torque shaft 9'.

In the configuration of Figure lb, the input motion also spins the rotor. A bevel gear 44' is rotatably mounted to one of the forks 43' concentrically with the shafts 48'. A compound gear 45' is rotatably mounted on the frame member 47'. The bevel gear ring of bevel gear 45' engages the gear 44', while the spur gear ring of bevel gear 45' engages gear 46' which is coupled to the rotor shaft 27' through a one-way clutch (not shown).

The operation of this type of gyroscopic transmission is described in WO 00/45068, however to summarise reciprocating motion of the input member 1 ' results in reciprocating motion of the rack 40', which in turn causes oscillation of the rotor shaft

27' about the axis of the shafts 48' due to movement of the pinions 48', and also rotation of the rotor 25' relative to the frame member 47' via the gears 44', 45', and 46'. That results in the formation of gyroscopic forces which rotate the fork 43' about the axis of the torque shaft 9', and the delivery of an output torque and reaction torque on the torque shaft 9'. In the same manner as described above, positive or output torque from the torque shaft is applied to the output member 33' via the first one-way clutch 31' and gears 31a' and 33a', while negative or reaction torque from the torque shaft is applied to the fixed housing or support 3' by the second one-way clutch 35'.

It will likely be necessary to create a reciprocating motion of the input member 1 ' from rotation of the crankshaft of the engine. That can be achieved using a convertor C such as a crank and connecting rod, a wobble plate, or a cam or similar arrangement. It is preferred that reciprocating type GVT units are used, as they have higher possible speed ratios.

Figure lc schematically shows a suitable crank and connecting rod arrangement 8 for creating a reciprocating motion of the input member 1 ' from rotation of another shaft, such as the crankshaft S of the engine. A crank 8a is cantilevered from the crankshaft S, is configured to rotate with rotation of the drive shaft. A connecting rod 8b is pivoted to the crank 8a at pivot 8c. A slider 8d is pivoted to the connecting rod at pivot 8d. The slider is arranged to move within a part of the fixed housing or support 3' which acts as a guide for the slider, and is operatively connected to the input member 1 ' of the GVT unit. As the drive shaft S rotates, the crank and connecting rod arrangement 8 causes the input member 1 ' to reciprocate in the guide.

The systems of the present invention are based on GVT transmissions as described in WO 00/45068, such as those outlined above by way of example. Generally, the preferred embodiment systems described below can be considered to have the same or equivalent features as described in WO 00/45068 between the input and the torque shaft, but are provided with different clutch and gear arrangements 100, 500, 600, 1000, 1500 described below. This is indicated schematically by boxes T in Figures la and lb, where the preferred embodiment transmission can be considered to include the features included in boxes T of Figures la and lb for example, but the clutch and gear arrangements are as described below. That is, the preferred embodiments can be considered to have at least: a fixed housing or support; an input member which is either rotatable about an axis of rotation relative to said fixed housing or support or reciprocable along an axis relative to said fixed housing or support; a torque shaft; a linkage arrangement rotatable about the axis of the input member under the influence of said input member; a gyroscopic rotor mounted on the linkage arrangement and having a spin axis which is cyclically angularly deflected in response to the input member to generate gyroscopic reaction forces, the reaction forces generated by the rotor as its axis is cyclically deflected being applied to the torque shaft as positive and negative torque, as well as one of the clutch and gear arrangements described below. The torque shaft may be part of the linkage arrangement or may be separate from the linkage arrangement.

Turning now to Figure 2a, the torque shaft (corresponding to torque shaft 9 of Figure 1 a or torque shaft 9a of Figure lb) is indicated by reference numeral 109, and receives positive and negative (or output and reaction) torque as a result of precession of the spin axis of the gyroscopic rotor. The transmission input will be operatively connected to a source of motive power M, such as the crank shaft of an internal combustion engine.

The first preferred embodiment clutch and gear arrangement 100 includes a first oneway clutch 131a connected to the torque shaft 109 and a clutch housing/dog clutch plate 131b, which is in turn connected to or integral with a brake disc 131c, so that the torque shaft 109 can rotate in one direction relative to the transmission housing but not in the opposite direction when the brake disc is held fixed relative to the transmission housing. Other suitable configurations could also be used.

The clutch housing/dog clutch plate 131b and brake disc 131c are rotatable relative to the fixed housing or support 103 of the transmission unit. The brake arrangement includes a caliper 130a and an actuator 130b which are fixed relative to the fixed housing or support 103 of the transmission unit. The caliper 130a can be released so that the brake disc is rotatable relative to the fixed housing or support 103 (the clutch is decoupled from the housing), or can engage the brake disc 13 lc so that the brake disc is partially restrained (the clutch is partially coupled to the housing), or is fully restrained (the clutch is coupled to the housing), by the fixed housing or support 103.

The clutch housing/dog clutch plate 131b includes dog teeth 13 Id or apertures or slots to engage a dog gear assembly as will be described below.

A second one-way clutch 135a of opposite sense to the first one-way clutch 131 is connected to the torque shaft 109 and a clutch housing/dog clutch plate 135b is in turn connected to or integral with a brake disc 135c, so that the torque shaft 109 can rotate in one direction relative to the transmission housing but not in the opposite direction when the brake disc is held fixed relative to the transmission housing. Other suitable configurations could also be used.

The clutch housing/dog clutch plate 135b and brake disc 135c are rotatable relative to the fixed housing or support 103 of the transmission unit. The brake arrangement includes a caliper 136a and an actuator 136b which are fixed relative to the fixed housing or support 103 of the transmission unit. The caliper 136a can be released so that the brake disc 135c is rotatable relative to the fixed housing or support 103 (the clutch is decoupled from the housing), or can engage the brake disc 135c so that the brake disc is partially restrained (the clutch is partially coupled to the housing), or is fully restrained (the clutch is coupled to the housing), by the fixed housing or support 103.

The clutch housing/dog clutch plate 135b includes dog teeth 135d or apertures or slots to engage a dog gear assembly as will be described below.

A dog gear unit 132 is shown in Figure 2b and is slidable relative to the torque shaft 109. The dog gear assembly 132 includes a dog gear 132a which engages an output gear 133 of the transmission which is connected to an output member 134. The output member 134 is operatively connected to drive wheel(s) of the vehicle. A unit having a dog gear/dog clutch plate 132a, a sleeve or collar 132b, and a dog clutch plate 132c is slidably and rotatably mounted on the torque shaft 109, and this unit is rotatable relative to the torque shaft 109 and relative to a selection fork 132d. The selection fork 132d and actuating link 132e which preferably runs generally parallel to the torque shaft 109 are actuated by an actuator 132f. For example, moving the selection fork 132d to the left moves the dog gear unit to the left relative to the torque shaft and engages the dog clutch plate 132c to the clutch housing/dog clutch plate 135b of one-way clutch 135a, while moving the selection fork 132c to the right moves the dog gear unit 132 to the right relative to the torque shaft and engages the dog gear/dog clutch plate 132a to the clutch housing/dog clutch plate 131b of one-way clutch 131a. 132g, 132h are dog teeth or apertures or slots to engage with dog teeth 131d, 135d or apertures or slots on clutch housings/dog clutch plates 131b, 135b.

It will be appreciated that the gear teeth on perimeter of the dog gear 132a and output gear 133 are of sufficient length to remain engaged in either of the extreme left or right positions of the dog gear unit.

During normal forward driving operation of the transmission, power from a source of motive power such as a vehicle engine is transmitted to the torque shaft 109 as positive and negative torque as a result of gyroscopic reactions from the rotor in the transmission T. The dog assembly will for example be in the right most position such that the dog gear/dog clutch plate 132a is engaged with the first one-way clutch 131a. The brake caliper 130a is released so that the clutch housing or dog plate 131b of the first one-way clutch is rotatable relative to the fixed housing or support 103, and the other brake caliper 136a frictionally restrains the disc 135c of the second one-way clutch 135 so that the clutch housing/dog clutch plate 135b cannot move relative to the fixed housing or support 103. Positive or output torque from the torque shaft is transmitted by the first one-way clutch 131a, dog teeth 131d, 132g, and dog gear 132a, to the output gear 133 and output member 134. Negative or reaction torque from the torque shaft is applied to the fixed housing or support by the second one-way clutch 135a. When it is desired to slow the vehicle, power from the source of motive power is cut off such that the crank shaft of the source of motive power is in an idling mode, and the brake 136a is released to free the clutch housing/dog clutch plate or clutch housing 135b so it is rotatable relative to the fixed housing or support 103. The torque shaft is decoupled so that torque cannot be transmitted to the output gear 133 from the transmission input 1 , such as by reducing the spin speed of the gyroscopic rotor to zero and/or by increasing the effective inertia of the torque shaft (as will be described below with reference to Figures 3a and 3b). The dog assembly 132 is then moved to the left so that the dog clutch plate 132c engages with the clutch housing/dog clutch plate 135b of the second one-way clutch 135a. The torque shaft is then recoupled so that torque can be transmitted between transmission input and the output by bringing the rotor back up to speed or by reducing the effective inertia of the torque shaft. The brake 130a is gradually applied to the disc 131c to partially restrain the disc 131c relative to the fixed housing or support 103. The partial braking of the disc and thereby the clutch housing/dog clutch plate 131b will result in a net flow of energy from the output 134 back to the source of motive power M (engine braking) until the speed of the output member 134 is zero. Following that, when power is applied to the transmission by the source of motive power and the dog plate or clutch housing 131b is fully braked via disc 131c, the output (gear 133 and thereby the output member 134 will be driven in the opposite direction to previously, ie in reverse. This arrangement effectively allows reverse to be selected while the vehicle is in forward motion.

During the engine braking procedure described above, when the brake 136a is released and the dog assembly 132 is brought into engagement with the clutch housing/dog clutch plate 135b of the second one-way clutch 135a, as a result of the output speed being transferred the clutch 135a will try and rotate faster in the positive direction than the torque shaft 109, meaning the clutch 135a will lock to the torque shaft 109. As the rotor is brought back up to speed, the fluctuating torque applied to the torque shaft will be increased. The negative portion of the torque will result in the engine braking, whereas the positive portion of the torque will attempt to free the torque shaft 109 from engagement with second one-way clutch 135a. If the first one-way clutch 131a was unrestrained, the torque shaft 109 would possibly not re-engage with the second one- way clutch 135a. By partially restraining the first one-way clutch 131a, the torque shaft 109 can continue to engage with the second one-way clutch, thereby continuing the engine braking.

If the brake 132a is applied forcefully, that will more forcefully brake the output and thereby the vehicle. However, it may be desirable to do that using conventional wheel brakes.

To reselect the forward movement of the output while the vehicle is moving in reverse, power from the source of motive power is cut off and the brake 130a is released to free the brake disc 131c and thereby the dog plate or clutch housing 131b so it is rotatable relative to the fixed housing or support 103. The torque shaft is decoupled so that torque cannot be transmitted between the transmission input and transmission output, such as by reducing the spin speed of the gyroscopic rotor to zero or by increasing the effective inertia of the torque shaft. The dog unit 132 is moved back to the right so that the dog gear/dog clutch plate 132a engages with the clutch housing/dog clutch plate 131b of the first one-way clutch 131a. The torque shaft is then recoupled so that torque can be transmitted between the transmission input and transmission output by bringing the rotor back up to speed or by reducing the effective inertia of the torque shaft. The brake 136a is gradually applied to the brake disc 135c to partially restrain the brake disc 135c and thereby the clutch housing/dog clutch plate 135b relative to the fixed housing or support 103. The partial braking of the brake disc will result in a net flow of energy from the output 134 back to the source of motive power M (engine braking) until the speed of the output member 134 is zero. Following that, when more power is applied to the transmission by the source of motive power and the brake disc 135c and thereby the clutch housing/dog clutch plate 135b is fully braked, the output gear 133 and thereby the output member 134 will be driven in the forwards direction.

It can be seen from the above description that the transmission is capable of engine braking when the vehicle is traveling in a forward or reverse direction. If the output is stationary, changing between forward and reverse can be achieved without the partial braking of the clutch housings. Rather, it is simply necessary to decouple the torque shaft, unbrake one clutch housing, change the dog assembly between the clutches, recouple the torque shaft, and fully apply the brake to the other clutch housing.

It will be appreciated that if the transmission is in the reverse operating configuration when the vehicle, and thereby the output, is stationary, when power from the source of motive power is applied to the transmission the output and thereby the vehicle will be driven in a reverse direction.

In the above embodiment, the torque shaft will not change direction when engine braking occurs, but will change direction when the vehicle is being reversed.

One suitable way of decoupling the torque shaft is to slow the rotor speed to zero rpm, so that no torque is transmitted to the transmission output. In that embodiment, the mechanism to decouple the transmission will comprise the speed controller for the rotor.

Another alternative is to adjust the effective inertia of the torque shaft. A flyball type arrangement is shown in Figure 3a. In that embodiment, the torque shaft 109 extends beyond the first one-way clutch 131 and terminates in a member 200. A pair of elbow linkages 201 are hinged at 203, 205 and 207. Masses 209 are carried by the elbow linkages. A thrust bearing 211 is provided between a shoulder 213 on a shaft 215 and the elbow linkages 201, so that when the torque shaft rotates 109 the elbow linkages can also rotate but the shaft 215 can remain stationary. A gear 217 is mounted on a screw thread on the shaft 215 and engages with a gear 219 which is driven by a servomotor 221.

During operation, the effective inertia of the torque shaft 109 is altered by rotation of the gear 217, which as a result of the screw thread moves the shaft 215 linearly along the axis of the torque shaft causing the masses to move radially. When the masses 209 are at their outermost positions, the torque shaft inertia 109 will be at a maximum, thereby effectively decoupling the transmission by preventing the torque shaft from reaching the output speed. When the masses 209 are at their inner positions, the torque shaft inertia will be at a minimum, such that the transmission is coupled. This method of decoupling is possible only if the output speed is significant, as the decoupling is achieved when the torque shaft can not reach the output speed.

Another alternative is shown in Figure 3b. A flywheel 231 is mounted on bearings 233 on a linkage member 235 which is pivotally connected at pivots 237 to linkage members 239, 241. One linkage member 239 is pivotally connected to an end of the torque shaft 109 extends beyond the first one-way clutch 131 and is mounted in a double thrust bearing 243 in the fixed housing or support. The other linkage member 241 is pivotally connected to a shaft 245 which is mounted for rotation in a double thrust bearing 247 in a housing 249. The angle of the linkage member 235 upon which the flywheel 231 is rotatably mounted is adjustable by axial movement of the housing 249 and thereby the shaft 245. In the position shown, the contribution of the flywheel to torque shaft inertia is at a maximum, and the transmission is decoupled by preventing the torque shaft from reaching the output speed. When the axis of the linkage member 235 coincides with the axis of the torque shaft 109, the contribution of flywheel inertia to the torque shaft is zero, and the transmission of torque is at a maximum.

Another alternative is shown in Figure 3c. In this alternative a gear 151 is mounted on the torque shaft 109 of the transmission, and meshes with a further gear 153. A linkage

155 is pivotally connected to the gear 153 via an eccentrically positioned pin 157, and is pivotally mounted at its other end to a shaft 159 of a piston 161 which is reciprocally movable in a hydraulic cylinder 163 as indicated by arrow A. This is a crank/connecting rod arrangement. During normal operation, when the transmission unit is coupled, as the torque shaft rotates the gear 151 also rotates as does gear 153, and via linkage 155 the piston 161 reciprocates in the cylinder 163. As the piston 161 reciprocates, the hydraulic fluid travels from end to end via the bypass line 165 through open control valve 169. When it is desired to decouple the transmission unit, the control valve 169 is closed. That will prevent the piston from moving within the cylinder 163, as the hydraulic fluid will be substantially incompressible. That, in turn, will prevent the gear 153 from turning, which will also prevent the gear 151 and thereby the attached torque shaft 109 from rotating. An air pocket 167 is provided in the bypass line to prevent sudden stoppage and therefore shock as the valve 169 is quickly closed. As the torque shaft cannot rotate, the transmission unit is decoupled, because positive and negative torque are both applied to the transmission housing and the input and output members are free to rotate without affecting one another. This mechanism effectively "brakes" the torque shaft.

Figure 4 shows a second preferred embodiment clutch and gear arrangement having features similar to Figure 2, however in this arrangement the torque from the torque shaft is fully rectified, i.e. both positive and negative torque from the torque shaft are applied to the output, with the negative torque being first converted to positive torque over a rotation reversal system. The torque shaft (corresponding to torque shaft 9 of Figure la or torque shaft 9a of Figure lb) is indicated by reference numeral 509, and receives positive and negative (or output and reaction) torque as a result of precession of the spin axis of the gyroscopic rotor. The transmission input will be operatively connected to a source of motive power M, such as the crank shaft of an internal combustion engine.

The second preferred embodiment clutch and gear arrangement 500 includes a first oneway clutch 531a connected to the torque shaft 109 mounted in a clutch housing/dog clutch plate 531b so that the torque shaft 109 can rotate in one direction relative to the clutch housing/dog clutch plate 531b but not in the opposite direction. Other suitable configurations could also be used.

The clutch housing/dog clutch plate 531b includes dog teeth 53 Id and apertures to engage dog gears as will be described below.

A second one-way clutch 535a of opposite sense to the first one-way clutch 531a is connected to the torque shaft 109 and mounted in a clutch housing/dog clutch plate 535b so that the torque shaft 109 can rotate in one direction relative to the clutch housing/dog clutch plate 535b but not in the opposite direction. Other suitable configurations could also be used. A dog gear assembly includes four dog gears 532a, 532b, 532c, 532d which are rotatable and slidable relative to the torque shaft 109. Each of the dog gears 532a-532d includes dog teeth 532e and slots to engage the dog teeth and slots on the clutch housings or dog clutch plates 531b, 535b. The dog gears 532a-532d are rotatable relative to selecting forks or linkages 532f. The selecting forks or linkages 532f and actuating link 532g are actuated by an actuator 532h. For example, moving the selection forks 532f to the left moves the dog gears to the left relative to the torque shaft and engages the clutch housing/dog clutch plate 531b to gear 532d and clutch housing/dog clutch plate 535b to gear 532b, while moving the selection forks 532f to the right moves the dog gears to the right relative to the torque shaft and engages the clutch housing/dog clutch plate 531b to gear 532c and clutch housing/dog clutch plate 535b to gear 532a.

An output gear arrangement is mounted on an output shaft 534 and includes four gears 534a, 534b, 534c and 534d, all of which are fixed on the shaft. Gear 532a engages with gear 534a, gear 532b engages with an idler gear 534e which engages with gear 534b, gear 534c engages with idler gear 534f which engages with gear 534c, and gear 532d engages with gear 534d. It will be appreciated that the gear teeth 532a-d and 534a, 534e, 534f, and 534d are of sufficient length to remain engaged when the dog gears are moved by the selecting forks or linkages 532f.

For, say, a normal forward driving operation of the transmission, power from a source of motive power such as a vehicle engine is transmitted to the torque shaft 509 as positive and negative torque as a result of gyroscopic reactions from the rotor in the transmission T. The actuating link will be at the leftmost position so that clutch housing/dog clutch plate 53 lb is engaged with teeth 532e of gear 532d. Positive torque from the torque shaft is transmitted by the first one-way clutch 531a, clutch housing/dog clutch plate 531b, dog teeth 531c, 532e, dog gear 532d, and output gear 534d to the output shaft 534. Negative torque from the torque shaft is transmitted by the second one-way clutch 535a, clutch housing/dog clutch plate 535b, dog teeth 531c, 532b, dog gear 532c, idler gear 534e, and gear 534b, to the output shaft 534. When the transmission output shaft 534 is not moving, it is possible to change the transmission from a forward driving configuration to a reverse driving configuration. To achieve that, the torque shaft is decoupled from the output by reducing the rotor speed to zero for example, and the dog gears are moved to the right relative to the torque shaft. In that configuration, the clutch housing/dog clutch plate 53 lb and thereby the first one-way clutch 531a is engaged with the dog gear 532c, and the clutch housing/dog clutch plate 535b and thereby the second one-way clutch 535a is engaged with the dog gear 532a. The torque shaft is then recoupled to the output by increasing the rotor speed. In that configuration, positive torque from the torque shaft is transmitted by the first one-way clutch 531a, clutch housing/dog clutch plate 531b, dog teeth 531c, 532e, dog gear 532c, idler gear 534f, and output gear 534c to the output shaft 534. Negative torque from the torque shaft is transmitted by the second one-way clutch 535a, clutch housing/dog clutch plate 535b, dog teeth 535c, 532e, dog gear 532a, and output gear 534a, to the output shaft 534.

When the transmission output shaft 534 is not moving, it is possible to change the transmission from the reverse driving configuration back to the forward driving configuration, by decoupling the torque shaft, moving the dog gears to the right, and recoupling the torque shaft.

Figure 5 shows a third embodiment clutch and gear arrangement, which is similar to that of Figure 4. Like reference numerals are used to indicate like parts, with the addition of 100.

Again, the torque from the torque shaft is fully rectified, i.e. both positive and negative torque from the torque shaft are applied to the output, with the negative torque being first converted to positive torque over a rotation reversal system. The torque shaft (corresponding to torque shaft 9 of Figure la or torque shaft 9a of Figure lb) is indicated by reference numeral 609, and receives positive and negative (or output and reaction) torque as a result of precession of the spin axis of the gyroscopic rotor. The transmission input will be operatively connected to a source of motive power M, such as the crank shaft of an internal combustion engine. The second preferred embodiment clutch and gear arrangement 600 includes a first oneway clutch 631a which has internal splines (not shown) which engage with a splined portion 609a of the torque shaft 109. As such, the first one-way clutch 631a is slidable along part of the torque shaft, but cannot rotate relative to the torque shaft. The first one-way clutch 631a is mounted in a clutch housing/dog clutch plate 631b so that the torque shaft 109 can rotate in one direction relative to the clutch housing/dog clutch plate 631b but not in the opposite direction. Other suitable configurations could also be used.

The clutch housing/dog clutch plate 631b includes dog teeth 63 Id and apertures to engage dog gears as will be described below.

A second one-way clutch 635a of opposite sense to the first one-way clutch has internal splines (not shown) which engage with a splined portion 609b of the torque shaft 109. As such, the second one-way clutch 635a is slidable along part of the torque shaft, but cannot rotate relative to the torque shaft. The second one-way clutch 635a is mounted in a clutch housing/dog clutch plate 635b so that the torque shaft 109 can rotate in one direction relative to the clutch housing/dog clutch plate 635b but not in the opposite direction. Other suitable configurations could also be used.

A dog gear assembly includes four dog gears 632a, 632b, 632c, 632d which are rotatable and axially slidable relative to the torque shaft 109. Each of the dog gears 632a-632d includes dog teeth 632e and slots to engage the dog teeth and slots on the clutch housings or dog clutch plates 631b, 635b. Each of the dog gears 632a-632d can rotate relative to the torque shaft, but will be substantially immovable axially along the torque shaft.

The clutch housings or dog clutch plates 635b are rotatable relative to selecting forks or linkages 632f. The selecting forks or linkages 632f and actuating link 632g are actuated by an actuator 632h. For example, moving the selection forks 632f to the left moves the first and second one-way clutches to the left relative to the torque shaft and engages the clutch housing/dog clutch plate 631b to gear 632c and clutch housing/dog clutch plate 635b to gear 632a, while moving the selection forks 632f to the right moves the first and second one-way clutches to the right relative to the torque shaft and engages the clutch housing/dog clutch plate 631b to gear 632d and clutch housing/dog clutch plate 635b to gear 632b.

An output gear arrangement is mounted on an output shaft 634 and includes four gears 634a, 634b, 634c and 634d, all of which are fixed on the shaft. Gear 632a engages with gear 634a, gear 632b engages with an idler gear 634e which engages with gear 634b, gear 634c engages with idler gear 634f which engages with gear 634c, and gear 632d engages with gear 634d.

For, say, a normal forward driving operation of the transmission, power from a source of motive power such as a vehicle engine is transmitted to the torque shaft 609 as positive and negative torque as a result of gyroscopic reactions from the rotor in the transmission T. The actuating link will be at the rightmost position so that clutch housing/dog clutch plate 631b is engaged with teeth 632e of gear 632d and clutch housing/dog clutch plate 635b is engaged with teeth 632e of gear 632b. Positive torque from the torque shaft is transmitted by the first one-way clutch 631 a, clutch housing/dog clutch plate 631b, dog teeth 631c, 632e, dog gear 632d, and output gear 634d to the output shaft 634. Negative torque from the torque shaft is transmitted by the second one-way clutch 635a, clutch housing/dog clutch plate 635b, dog teeth 635c, 632e, dog gear 632b, idler gear 634e, and gear 634b, to the output shaft 634 as positive torque.

When the transmission output shaft 634 is not moving, it is possible to change the transmission from a forward driving configuration to a reverse driving configuration. To achieve that, the torque shaft is decoupled from the output by reducing the rotor speed to zero, and the first and second one-way clutches are moved to the left relative to the torque shaft. In that configuration, the clutch housing/dog clutch plate 631b and thereby the first one-way clutch 631a is engaged with the dog gear 632c, and the clutch housing/dog clutch plate 635b and thereby the second one-way clutch is engaged with the dog gear 632a. The torque shaft is then recoupled to the output by increasing the rotor speed. In that configuration, positive torque from the torque shaft is transmitted by the first one-way clutch 631a, clutch housing/dog clutch plate 631b, dog teeth 631c, 632e, dog gear 632c, idler gear 634f, and output gear 634c to the output shaft 634. Negative torque from the torque shaft is transmitted by the second one-way clutch 635a, clutch housing/dog clutch plate 635b, dog teeth 635c, 632e, dog gear 632a, and output gear 634a, to the output shaft 634.

When the transmission output shaft 634 is not moving, it is possible to change the transmission from the reverse driving configuration back to the forward driving configuration, by decoupling the torque shaft, moving the first and second one-way clutches to the left, and recoupling the torque shaft.

Turning now to Figure 6, which shows a fourth embodiment clutch and gear arrangement, the torque shaft (corresponding to torque shaft 9 of Figure la or 9' of Figure lb) is indicated by reference numeral 1009, and receives positive and negative (or output and reaction) torque as a result of precession of the spin axis of the gyroscopic rotor. The transmission input will be operatively connected to a source of motive power M, such as the crank shaft of an internal combustion engine.

The fourth preferred embodiment clutch and gear arrangement 1000 includes a first oneway clutch 1031a connected to the torque shaft and mounted in a clutch housing 1031b, so that the torque shaft 1009 can rotate in one direction relative to the clutch housing but not in the opposite direction. Other suitable configurations could be used.

The periphery of the clutch housing 1031b carries or is in the form of a gear 1031c.

A second one-way clutch 1035a of opposite sense to the first one-way clutch 1031 is connected to the torque shaft and is mounted in a clutch housing 1035b which is connected to or integral with a brake disc 1035 c, so that the torque shaft 1009 can rotate in one direction relative to the transmission housing but not in the opposite direction when the brake disc is held fixed relative to the transmission housing. Other suitable configurations could be used. The clutch housing 1035b is rotatable relative to the main fixed housing or support 1003 of the transmission unit. The brake arrangement includes a caliper 1036a and an actuator 1036b which are fixed relative to the fixed housing or support 1003 of the transmission unit. The caliper 1036a can be released as shown so that the brake disc 1035c and thereby the clutch housing 1035b is rotatable relative to the fixed housing or support 1003 (the clutch is decoupled from the housing), or can engage the brake disc 1035c such that the brake disc and thereby the clutch housing 1035b is at least partially restrained (the clutch is partially coupled to the housing), or is fully restrained (the clutch is coupled to the housing), by the fixed housing or support 1003.

The gear 1031c is meshed with a gear 1032a of an output gear arrangement. The gear 1032a is fixed relative to a shaft 1032b, a portion 1032c of which is splined. The shaft 1032b is arranged for rotation relative to the fixed main housing or support 1003. A dog unit 1032d including a collar or sleeve 1032e and dog members or dog clutch plates 1032f, is slidably mounted on the splined portion 1032c. The dog clutch plates 1032f and collar 1032e are configured, via splines, to rotate with the shaft 1032b. The dog clutch plates 1032f and collar or sleeve 1032e are preferably an integral member.

The dog clutch plates 1032f have outwardly facing dog teeth 1032g or apertures or slots. The dog unit 1032d is rotatable relative to a selection fork 1032h. The selection fork 1032h and actuating link 1032i which preferably runs generally parallel to the torque shaft 1009 are actuated by an actuator 1032j. Moving the selection fork 1032h to the left moves the dog unit 1032d to the left relative to the shaft 1032b. Moving the selection fork 1032h to the right moves the dog unit 1032d to the right relative to the shaft 1032b.

A gear 1032k is rotatably mounted on the shaft the left side of the dog unit 1032d and a further gear 10321 is rotatably mounted on the right side of the dog unit 1032d. The gears 1032k, 10321 are axially restrained so they cannot axially move on the shaft 1032b. Each of the gears includes dog teeth 1032m, apertures, or slots to engage the apertures, slots, or teeth 1032g on the dog clutch plates 1032f. In the right most position of the dog unit 1032d, the unit engages gear 10321. In the left most position of the dog unit 1032d, the unit engages gear 1032k.

A rotatable output shaft 1034a carries two gears 1034b, 1034c. Gear 1034b engages with gear 1032k, and gear 1034c is operatively connected with gear 10321 via a reversing gear 1034d.

During normal forward driving operation of the transmission, power from a source of motive power such as a vehicle engine is transmitted to the torque shaft 1009 as positive and negative (or output and reaction) torque as a result of gyroscopic reactions of the rotor of transmission T. The brake caliper 1036b is engaged with the disc 1035c so that the disc 1035c is fixed relative to the fixed housing or support 1003. The dog unit 1032d engages with gear 1032k. Positive torque from the torque shaft 1009 is transmitted via the clutch 1031a, gear 1031c, gear 1032a, shaft 1032b, splines 1032c, left dog clutch plate 1032f, gear 1032k, and gear 1034b to the output member 1034a. Negative torque from the torque shaft is transmitted via clutch 1035 a, clutch housing 1035b, disc 1035c, and brake caliper 1036b to the fixed housing or support 1003.

When it is desired to slow the vehicle, power from the source of motive power is cut off such that the crank shaft is in an idling mode, and the brake 1036a is released to free the brake disc 1035c and thereby the clutch housing 1035b so it is rotatable relative to the fixed housing or support 1003. The torque shaft is decoupled so that it cannot transmit torque between the transmission input and transmission output, such as by reducing the spin speed of the gyroscopic rotor for example. In this design, as the clutch 1035 does not transmit torque to the output, it is possible to make the clutch housing 1035b and/or disc 1035c sufficiently large and/or heavy that it has sufficiently high inertia to decouple the torque shaft when the clutch is released.

The dog unit 1032d is then moved to the right to engage the gear 10321. In that configuration, the torque shaft 1009 will be driven as a result of movement of the output shaft 1034a, via gears 1034c, 1034d and 10321, shaft 1032b, gears 1032a and 1031c, and clutch 103 la. With the brake released, there is no net coupling between the input of the transmission and the output shaft 1034a. By partially reapplying the brake caliper 1036b to brake disc 1035c, there will be a net flow of energy from the output to the input of the transmission and to the source of motive power so that engine braking of the output 1034a occurs until the speed of output 1034a reaches zero. Following that, when power is applied to the transmission by the source of motive power and the disc brake 1035c and thereby the clutch housing 1035b is fully braked, the output member 1034a will be driven in reverse by clutch 1031a, gears 1031c and 1032a, shaft 1032b, spline 1032c, dog unit 1032d, gears 10321, 1034d, and 1034c. This arrangement effectively allows reverse motion to be selected while the vehicle is in forward motion.

If the brake 1036b is applied forcefully, that will more forcefully brake the output and thereby the vehicle. However, it may be desirable to do that using conventional wheel brakes.

To reselect the forward movement of the output when the vehicle is moving in reverse, power from the source of motive power is cut off. The clutch 1035a is decoupled by releasing the brake 1036b, and the torque shaft is decoupled so that it cannot transmit torque between the transmission input and transmission output, such as reducing the spin speed of the gyroscopic rotor if necessary. The dog unit 1032d is moved back to the left to engage the gear 1032k. The torque shaft is then recoupled so that torque can be transmitted between the transmission input and transmission output, by bringing the rotor back up to speed if applicable. If a high inertia brake disc or clutch housing is used to decouple the torque shaft, the recoupling can be achieved by gradually applying the brake to the brake disc. The brake 1036a is gradually applied to the brake disc 1035c to partially restrain the brake disc 1035c and thereby the clutch housing 1035b relative to the fixed housing or support 103. The partial braking of the clutch housing 1035b will result in a net flow of energy from the output member 1034a to the transmission input and back to the source of motive power (engine braking) until the speed of the output member 1034a is zero. Following that, when power is applied to the transmission by the source of motive power and the brake disc 1035c and thereby the clutch housing 1035b is fully braked, the output member 1034a will be driven in the forwards direction. It can be seen from the above description that the transmission is capable of engine braking when the vehicle is traveling in a forward or reverse direction.

If the output is stationary, changing between forward and reverse can be achieved without the partial braking of the clutch housing. Rather, it is simply necessary to release the brake 1036b, decouple the torque shaft (which may be achieved by releasing the brake), move the dog assembly between gears, recouple the torque shaft (which may occur by rebraking the disc 1035c), and fully rebrake the brake disc 1035c.

In this embodiment, the torque shaft will change direction when engine braking occurs, but will go back to the original direction when the vehicle is being reversed.

The embodiment of Figure 6 has the benefit over Figures 2a and 2b that only a single clutch brake is required. Further, if a high inertia brake disc or clutch housing is used, little or no rotor speed control is required for decoupling of the torque shaft. A disadvantage over the system of Figures 2a and 2b is that a reversing gear set is required. A further benefit of this system as only a single control point is necessary when a number of preferred transmissions are coupled in parallel to increase the overall power transmitted by the transmission. Each transmission could have a torque shaft 1009 and a clutch 1031 with the gear 1031c, and each of those gears 1031c could engage with the single gear 1032a on the shaft 1032b. Only a single selector fork would be required to change from forward to reverse output movement.

Figure 7 shows a fifth preferred embodiment clutch and gear arrangement having features similar to Figure 6, however in this arrangement the torque from the torque shaft is fully rectified, i.e. both positive and negative torque from the torque shaft are applied to the output, with the negative torque first being converted to positive torque over a rotation reversal system.

The torque shaft (corresponding to torque shaft 9 of Figure la or 9' of Figure lb) is indicated by reference numeral 1509, and receives positive and negative (or output and reaction) torque as a result of precession of the spin axis of the gyroscopic rotor. The transmission input will be operatively connected to a source of motive power M, such as the crank shaft of an internal combustion engine.

The fifth preferred embodiment clutch and gear arrangement 1500 includes a first oneway clutch 1531a connected to the torque shaft and mounted in a clutch housing 1531b, so that the torque shaft 1509 can rotate in one direction relative to the clutch housing but not in the opposite direction. Other suitable configurations could be used. The periphery of the clutch housing 1531b carries or is in the form of a gear 1531c.

A second one-way clutch 1535a of opposite sense to the first one-way clutch 1531a is connected to the torque shaft and mounted in a clutch housing 1535b, so that the torque shaft 1509 can rotate in one direction relative to the clutch housing but not in the other direction. Other suitable configurations could be used. The periphery of the clutch housing 1535b carries or is in the form of a gear 1535c.

The gear 1531c engages a gear 1532a of an output gear arrangement. The gear 1535c engages an idler gear 1532b which engages a gear 1532c of the output gear arrangement. The gears 1532a, 1532b are fixed relative to a shaft 1532d, a portion 1532e of which is splined. The shaft 1532d is arranged for rotation relative to the fixed main housing or support. A dog unit 1532f including a collar or sleeve 1532g and dog members or dog clutch plates 1532h, is slidably mounted on the splined portion 1532e. The dog clutch plates 1532h and collar or sleeve 1532g are configured, via splines, to rotate with the shaft 1532d. The dog clutch plates 1532h and collar or sleeve 1032g are preferably an integral member. The dog clutch plates 1532h have outwardly facing dog teeth 1532i and slots. The dog unit 1532f is rotatable relative to a selection fork 1532j. The selection fork 1532j and actuating link 1532k which preferably runs generally parallel to the shaft 1532d are actuated by an actuator 15321. Moving the selection fork 1532j to the left moves the dog unit 1532f to the left relative to the shaft 1532d. Moving the selection fork 1532j to the right moves the dog unit 1532f to the right relative to the shaft.

A gear 1532m is rotatably mounted on the shaft the left side of the dog unit 1532f and a further gear 1532n is rotatably mounted on the shaft on the right side of the dog unit 1532f. The gears 1532m, 1532n are axially restrained so they cannot axially move on the shaft 1532d. Each of the gears includes dog teeth 1532o and slots to engage the dog member teeth 15321 and slots on the dog clutch plates 1532h. In the right most position of the dog unit 1532f, the unit engages gear 1532n. In the left most position of the dog unitl532f, the unit engages gear 1532m.

Two gears 1534b, 1534c are mounted on a rotatable output shaft 1534a. Gear 1534b engages gear 1532m, and gear 1534c is operatively connected with gear 1532n via a reversing gear 1534d.

During normal forward driving operation of the transmission, power from a source of motive power such as a vehicle engine is transmitted to the torque shaft 1509 as positive and negative (or output and reaction) torque as a result of gyroscopic reactions of the rotor of transmission T. The dog unit 1532f engages with gear 1532m. Positive torque from the torque shaft 1509 is transmitted via the clutch 1531a, gear 1531c, gear 1532a, shaft 1532d, splines 1532e, left dog clutch plate, gear 1532m, and gear 1534b to the output member 1534a as positive torque. Negative torque from the torque shaft is transmitted via the clutch 1535a, gear 1535c, idler gear 1532b, gear 1532c, shaft 1532d, splines 1532e, left dog clutch plate, gear 1532m, and gear 1534b to the output member 1534 as positive torque.

When the transmission output "1534a is not moving, it is possible to change the transmission from a forward driving configuration to a reverse driving configuration. To achieve that, the torque shaft is decoupled from the output by reducing the rotor speed to zero for example, and the dog unit 1532f is moved to the right relative to the shaft 1532d. The torque shaft is then recoupled to the output by increasing the rotor speed. Power from a source of motive power such as a vehicle engine is transmitted to the torque shaft 1509 as positive and negative (or output and reaction) torque as a result of gyroscopic reactions of the rotor of transmission T. The dog unit 1532f engages with gear 1532n. Positive torque from the torque shaft 1509 is transmitted via the clutch 1531a, gear 1531c, gear 1532a, shaft 1532d, splines 1532e, right dog clutch plate, gear 1532n, idler gear 1534d, and gear 1534c to the output member 1534a as negative torque. Negative torque from the torque shaft is transmitted via the clutch 1535a, gear 1535c, idler gear 1532b, gear 1532c, shaft 1532d, splines 1532e, right dog clutch plate, gear 1532n, idler gear 1534d, and gear 1534c to the output member 1534 as negative torque.

When the transmission output shaft 1534 is not moving, it is possible to change the transmission from the reverse driving configuration back to the forward driving configuration, by decoupling the torque shaft, moving the dog unit to the left, and recoupling the torque shaft.

In the above systems, one or more control systems will be provided to control the decoupling mechanism for the torque shaft, the clutch brake(s), and the operation of the GVT's (for example the spin speed of the GVT rotor).

It should be understood that the above describes preferred forms of the invention and modifications made thereto without departing from the scope of the invention as defined by the following claims.

For example, for most embodiments above, reducing the rotor speed to zero is described as the preferred method of decoupling the torque shaft. Alternatively or in addition, one of the mechanisms shown in Figures 3a to 3c could be used. Decoupling one of the clutches may also be sufficient, as described above with reference to Figure 6. When engine braking is being used, it is desirable to reduce the rotor speed, but when only swapping between the forward operating configuration and the reverse operating configuration without engine braking, one of the methods shown in Figures 3a to 3c may alone be sufficient.

Claims

CLAIMS:

1. A transmission comprising: a fixed housing or support; an input member which is either rotatable about an axis of rotation relative to said fixed housing or support or reciprocable along an axis relative to said fixed housing or support; a torque shaft; a linkage arrangement rotatable about the axis of the input member under the influence of said input member; and a gyroscopic rotor mounted on the linkage arrangement and having a spin axis which is cyclically angularly deflected in response to the input member to generate gyroscopic reaction forces, the reaction forces generated by the rotor as its axis is cyclically deflected being applied to the torque shaft as positive and negative torque; a first one-way clutch operatively connected to the torque shaft; a second one-way clutch of opposite sense to the first one-way clutch and operatively connected to the torque shaft; and an output which is selectively or permanently operatively connected to the first one-way clutch; wherein the transmission has a forward operating configuration in which the output is driven by the input member in one direction and a reverse operating configuration in which the output is driven in the opposite direction by the input member.

2. A transmission as claimed in claim 1, wherein the torque shaft is part of the linkage arrangement.

3. A transmission as claimed in claim 1 or 2, wherein the transmission has an engine braking configuration which provides a net flow of energy from the output to the input member and to a source of motive power which is operatively connected to the input member, to thereby slow the output.

4. A transmission as claimed in any one of claims 1 to 3, wherein the output is selectively operatively connectable to the first one-way clutch or the second one-way clutch, and wherein the transmission is in the forward operating configuration when the output is operatively connected to the first one-way clutch and is in the reverse operating configuration when the output is operatively connected to the second one-way clutch.

5. A transmission as claimed in claim 4, wherein the first one-way clutch can be selectively coupled to or decoupled from the fixed housing or support; the second oneway clutch can be selectively coupled to or decoupled from the fixed housing or support; the transmission has a forward operating configuration in which the second one-way clutch is coupled to the fixed housing or support, the first one-way clutch is decoupled from the fixed housing or support, and the output is operatively connected to the first one-way clutch such that positive torque from the torque shaft is applied to the output by the first one-way clutch and negative torque from the torque shaft is applied to the fixed housing or support by the second one-way clutch; and the transmission has a reverse operating configuration in which the second one-way clutch is decoupled from the fixed housing or support, the first one-way clutch is coupled to the fixed housing or support, and the output is operatively connected to the second one-way clutch such that negative torque from the torque shaft is applied to the output by the second one-way clutch and positive torque from the torque shaft is applied to fixed housing or support by the first one-way clutch.

6. A transmission as claimed in claim 5, wherein the transmission has an engine braking configuration in which the second one-way clutch is decoupled from the fixed housing or support, the first one-way clutch is partially coupled to the fixed housing or support, and the output is operatively connected to the second one-way clutch to provide a net flow of energy from the output to the input member and to a source of motive power which is operatively connected to the input member, to thereby slow the output.

7. A transmission as claimed in claim 5 or 6, wherein the output comprises an output gear, and further comprising a dog gear assembly having a gear which is operatively connected to the output gear, wherein the dog gear assembly is selectively operatively connectable to one of the first and second one-way clutches.

8. A transmission as claimed in claim 7, wherein each of the first and second oneway clutches is mounted in a respective housing which is selectively engageable with the gear of the dog gear assembly.

9. A transmission as claimed in any one of claims 5 to 8, wherein each of the first and second one-way clutches is mounted in a respective housing which is integral with or connected to a brake disc, and the transmission comprises a brake caliper associated with each brake disc and configured such that when the disc is released by the caliper the respective clutch is decoupled, when the disc is partially braked by the caliper the clutch is partially coupled, and when the disc is at least substantially braked by the caliper the clutch is coupled.

10. A transmission as claimed in claim 1 or 2, wherein in the forward operating configuration, positive torque from the torque shaft is delivered to the output by the first one-way clutch and negative torque from the torque shaft is delivered to the output by the second one-way clutch over a rotation reversal system.

11. A transmission as claimed in claim 10, wherein in the reverse operating configuration, negative torque from the torque shaft is delivered to the output by the second one-way clutch and positive torque from the torque shaft is delivered to the output by the first one-way clutch over a rotation reversal system.

12. A transmission as claimed in claim 10 or 11, wherein the first one-way clutch is selectively operatively connectable to a first gear which is operatively connected to the output or to a second gear which is operatively connected to the output over a rotation reversal system, and wherein the second one-way clutch is selectively operatively connectable to a third gear which is operatively connected to the output over a rotation reversal system or to a fourth gear which is operatively connected to the output, the configuration being such that when the first one-way clutch is operatively connected to the first gear the second one-way clutch is operatively connected to the third gear, and when the first one-way clutch is operatively connected to the second gear the second one-way clutch is operatively connected to the fourth gear.

13. A transmission as claimed in claim 12, wherein each of the first, second, third, and fourth gears form part of a dog gear assembly, and wherein each of the first and second one-way clutches is mounted in a housing which is selectively engageable with the respective gears of the dog gear assembly.

14. A transmission as claimed in claim 13, wherein the gears of the dog gear assembly are rotatable relative to the torque shaft and are axially movable relative to the torque shaft to engage with the respective one-way clutches.

15. A transmission as claimed in claim 14, comprising an actuator to concurrently axially move the gears of the dog gear assembly.

16. A transmission as claimed in claim 13, wherein the gears of the dog gear assembly are rotatable relative to the torque shaft, and wherein the first and second oneway clutches are axially movable relative to the torque shaft to engage with the respective gears of the dog gear assembly.

17. A transmission as claimed in claim 16, including an actuator to concurrently axially move the first and second one-way clutches.

18. A transmission as claimed in any one of claims 1 to 3, comprising a reversible gear arrangement which has a forward operating configuration in which positive torque is transferred from the torque shaft, by the first one-way clutch, to the output, and a reverse operating configuration in which positive torque is transferred from the torque shaft, by the first one-way clutch, to the output over a rotation reversal system.

19. A transmission as claimed in claim 18, wherein the second one-way clutch is configured to transfer negative torque from the torque shaft to the reversible gear arrangement, over a rotation reversal system.

20. A transmission as claimed in claim 18, wherein the second one-way clutch can be selectively coupled to or decoupled from the fixed housing or support to apply the negative torque from the torque shaft to the fixed housing or support when coupled thereto, the transmission having a forward operating configuration in which the second one-way clutch is coupled to the fixed housing or support and the reversible gear arrangement is in a forward configuration, the transmission further having a reverse operating configuration in which the second one-way clutch is coupled to the fixed housing or support and the reversible gear arrangement is in a reverse configuration.

21. A transmission as claimed in claim 20, wherein the transmission has an engine braking configuration in which the second one-way clutch is partially coupled to the fixed housing or support and the reversible gear arrangement is in the reverse configuration, to provide a net flow of energy from the output to the input member and to a source of motive power which is operatively connected to the input member, to thereby slow the output.

22. A transmission as claimed in claim 20 or 21, wherein the second one-way clutch is mounted in a respective housing which is integral with or connected to a brake disc, and the transmission comprises a brake caliper associated with the brake disc and configured such that when the disc is released by the caliper the respective clutch is decoupled, when the disc is partially braked by the caliper the clutch is partially coupled, and when the disc is at least substantially braked by the caliper the clutch is coupled.

23. A transmission as claimed in any one of claims 18 to 22, wherein the reversible gear arrangement comprises a shaft which is rotated as a result of torque delivered from the first one-way clutch, and first and second dog gears rotatably mounted on the shaft, with the first dog gear operatively connected to the output and the second dog gear operatively connected to the output over a rotation reversal system, the reversible gear arrangement further including a dog member which is configured for rotation with the shaft and axially moveable relative to the shaft to selectively engage the first and second dog gears.

24. A transmission as claimed in claim 23, including an actuator to axially move the dog member relative to the shaft.

25. A transmission as claimed in any one of the preceding claims, comprising an arrangement to decouple the torque shaft of the transmission to enable the transmission to be changed from the forward operating configuration to the reverse operating configuration.

26. A transmission as claimed in claim 25, wherein the arrangement to decouple comprises an arrangement to increase the inertia of the torque shaft.

27. A transmission as claimed in claim 26, wherein the arrangement to increase the inertia of the torque shaft comprises a fly-ball arrangement or flywheel arrangement.

28. A transmission as claimed in claim 25, wherein the arrangement to decouple comprises an arrangement to brake movement of the torque shaft.

29. A transmission as claimed in any one of claims 25 to 28, wherein the arrangement to decouple comprises a speed controller of the gyroscopic rotor, and wherein the transmission is configured such that when the rotor is not spinning on its spin axis, the torque shaft is decoupled.

30. A transmission comprising: a fixed housing or support; an input member which is either rotatable about an axis of rotation relative to said fixed housing or support or reciprocable along an axis relative to said fixed housing or support; a torque shaft; a linkage arrangement rotatable about the axis of the input member under the influence of said input member; and a gyroscopic rotor mounted on the linkage arrangement and having a spin axis which is cyclically angularly deflected in response to the input member to generate gyroscopic reaction forces, the reaction forces generated by the rotor as its axis is cyclically deflected being applied to the torque shaft as positive and negative torque; a first one-way clutch operatively connected to the torque shaft and which can be selectively coupled to or decoupled from the fixed housing or support; a second one-way clutch of opposite sense to the first one-way clutch and operatively connected to the torque shaft and which can be selectively coupled to or decoupled from the fixed housing or support; and an output which can be selectively operatively connected to the first one-way clutch or the second one-way clutch; the transmission having a forward operating configuration in which the second one-way clutch is coupled to the fixed housing or support, the first one-way clutch is decoupled from the fixed housing or support, and the output is operatively connected to the first one-way clutch such that positive torque from the torque shaft is applied to the output by the first oneway clutch and negative torque from the torque shaft is applied to the fixed housing or support by the first one-way clutch; the transmission further having a reverse operating configuration in which the second one-way clutch is decoupled from the fixed housing or support, the first one-way clutch is coupled to the fixed housing or support, and the output is operatively connected to the second one-way clutch such that negative torque from the torque shaft is applied to the output by the second one-way clutch and positive torque from the torque shaft is applied to fixed housing or support by the first one-way clutch.

31. A transmission comprising: a fixed housing or support; an input member which is either rotatable about an axis of rotation relative to said fixed housing or support or reciprocable along an axis relative to said fixed housing or support; a torque shaft; a linkage arrangement rotatable about the axis of the input member under the influence of said input member; and a gyroscopic rotor mounted on the linkage arrangement and having a spin axis which is cyclically angularly deflected in response to the input member to generate gyroscopic reaction forces, the reaction forces generated by the rotor as its axis is cyclically deflected being applied to the torque shaft as positive and negative torque; a first one-way clutch operatively connected to the torque shaft; a second one-way clutch of opposite sense to the first one-way clutch and operatively connected to the torque shaft; and an output; wherein the transmission has a forward operating configuration in which positive torque from the torque shaft is delivered to the output by the first one-way clutch and negative torque from the torque shaft is delivered to the output by the second one-way clutch over a rotation reversal system, to drive the output in one direction; the transmission further having a reverse operating configuration in which the output is driven in the opposite direction.

32. A transmission comprising: a fixed housing or support; an input member which is either rotatable about an axis of rotation relative to said fixed housing or support or reciprocable along an axis relative to said fixed housing or support; a torque shaft; an output; a first one-way clutch connected between the torque shaft and a reversible gear arrangement having a forward configuration and reverse configuration; a linkage arrangement rotatable about the axis of the input member under the influence of said input member; and a gyroscopic rotor mounted on the linkage arrangement and having a spin axis which is cyclically angularly deflected in response to the input member to generate gyroscopic reaction forces, the reaction forces generated by the rotor as its axis is cyclically deflected being applied to the torque shaft as positive and negative torque; the first-one way clutch configured to apply the positive torque to the output member over the reversible gear arrangement; and a second one-way clutch of opposite sense to the first one-way clutch and which can be selectively coupled to or decoupled from the fixed housing or support to apply the negative torque from the torque shaft to the fixed housing or support when coupled thereto; the transmission having a forward operating configuration in which the second one-way clutch is coupled to the fixed housing or support and the gear arrangement is in a forward configuration; the transmission further having a reverse operating configuration in which the second one-way clutch is coupled to the fixed housing or support and the gear arrangement is in a reverse configuration.

33. A transmission as claimed in claim 32, wherein the transmission has an engine braking configuration in which the second one-way clutch is partially coupled to the fixed housing or support, and the gear arrangement is in a reverse configuration so as to provide a net flow of energy from the output to the input member and to a source of motive power which is operatively connected to the input member, to thereby slow the output.

34. A method of operating a transmission having a fixed housing or support; an input member which is either rotatable about an axis of rotation relative to said fixed housing or support or reciprocable along an axis relative to said fixed housing or support; a torque shaft; an output; a linkage arrangement rotatable about the axis of the input member under the influence of said input member; and a gyroscopic rotor mounted on the linkage arrangement and having a spin axis which is cyclically angularly deflected in response to the input member to generate gyroscopic reaction forces, the reaction forces generated by the rotor as its axis is cyclically deflected being applied to the torque shaft as positive and negative torque; the method comprising: decoupling the torque shaft so that torque cannot be transferred from the input member to the output, and selecting a reverse operating configuration.

35. A method as claimed in claim 34, wherein the method comprises selecting the reverse operating configuration while the output is moving.

36. A method as claimed in claim 34 or 35, wherein the method further comprises following selecting a reverse operating configuration, partially restraining the torque shaft to provide a net flow of energy from the output to the input member and to a source of motive power which is operatively connected to the input member, to thereby slow the output.