AU2017100497A4 - Platform lifting arrangement - Google Patents

Abstract

A platform lifting arrangement 10, including a lifting platform 16 for lifting a load from a lower level to an upper level and a plurality of lifting mechanisms 26. Each lifting mechanism 26 is connected to a respective lifting point 34 on the lifting platform 16. Each lifting mechanism 26 includes an articulated lifting arm 36 connected to the respective lifting point 34 and being extendable from a retracted position to an extended position to lift the platform 16 from the lower level to the upper level, an upright guide member 38 extending between the lower and upper levels and in guided connection with the lifting arm 36 for guiding extension of the lifting arm 36 between the retracted and extended positions, and an actuator 40 pivotally connected to the lifting arm 36 for actuating extension of the lifting arm 36. ( 18 FIGURE 1 12 - -- 18 33 34 FIGURE 2 30 16

Description

1 2017100497 05 May 2017

Title of Invention

Platform lifting arrangement Technical Field [0001] The present invention relates to a lifting arrangement and, in particular, a platform lifting arrangement for lifting a platform and a load supported on a platform. The present invention has been particularly developed as an automobile lifting device for use in a multi-vehicle transportation trailer and it will be convenient to hereinafter describe the invention in the context of this exemplary application. However, it is to be appreciated that the invention is not limited to this particular application and may be applied in any number of alternative lifting applications.

Background of Invention [0002] The following discussion of the background to the invention is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of the application.

[0003] Automobile transport trailers known as ‘car carriers’ are used to concurrently transport multiple vehicles between locations. Car carriers may be used, for example to transport a number of new vehicles from their place of manufacture to a vehicle showroom, or to a testing facility, or from a testing facility to a vehicle showroom. Large car carriers are capable of transporting seven vehicles in one trailer and multiple car carrier trailers may be hitched together to transport an even larger amount of vehicles behind a single prime mover and with a single driver. By way of example, a single prime mover may tow a pair of 6-vehicle car carrying trailers and a thirteenth vehicle can be positioned on a support platform mounted atop the cabin of the prime mover.

[0004] To improve transport efficiency it is desirable to maximise the amount of vehicles capable of being transported in each car-carrying trailer. This is achieved by 2 2017100497 05 May 2017 providing car carriers having multiple tiers or levels allowing an upper tier of vehicles to be positioned above a lower tier of vehicles and thereby increasing car-carrying capacity. Multi-tiered car carriers require one or more lifting mechanisms capable of moving vehicles between the upper and lower tiers. It is necessary for the lifting mechanisms to be reliable and safe for operators to use. It is often also necessary for the lifting mechanisms to be sufficiently robust to support the mass of one or more vehicles, particularly during transport, as the lifting mechanisms often also form a support for the last vehicle or vehicles that is lifted to the upper tier.

[0005] The lifting mechanisms of typical car carriers include rope and pulley configurations actuated by a series of hydraulic actuators to raise or lower a vehicle platform. However these designs suffer from the drawback of the ropes requiring periodic replacement, contributing significantly to maintenance costs. Alternative designs utilise various methods to raise and lower the vehicle platforms. However it is challenging to configure multiple hydraulic systems to operate in synchronisation which is necessary to obtain even movement of the vehicle platform as is necessary to ensure safe lifting of a vehicle. Addressing this drawback requires expensive hydraulic control systems which contribute significantly to the capital cost of hydraulic lifting mechanisms.

[0006] In view of the above, it is desirable to provide an alternative lifting arrangement which addresses one or more of the above drawbacks.

Summary of Invention [0007] According to the present invention, there is provided a platform lifting arrangement including: a lifting platform for lifting a load from a lower level to an upper level; and a plurality of lifting mechanisms, each lifting mechanism connected to a respective lifting point on the lifting platform and each lifting mechanism including: an articulated lifting arm connected to the respective lifting point and being extendable from a retracted position to an extended position to lift the platform from the lower level to the upper level; an upright guide member extending between the lower and upper levels and in guided connection with the lifting arm for guiding extension of the lifting arm between the retracted and extended positions; and an actuator pivotally connected to the lifting arm for actuating extension of the lifting arm. 3 2017100497 05 May 2017 [0008] Advantageously, the lifting mechanisms of the present invention obviate the rope and pulley componentry in existing car-carrier lifting systems therefore providing a more reliable lifting arrangement which minimises periodic part replacement. As well as reducing ongoing maintenance costs, the present invention reduces maintenance downtime in which a car-carrier is unavailable for use.

[0009] The lifting mechanisms of the present invention are capable of operation with significantly fewer components than existing rope/pulley systems or existing hydraulic systems providing a desirable improvement in reliability. In particular, each lifting mechanism advantageously utilises a guide member to guide movement of the lifting arm and thereby regulate or control the movement of the lifting platform between the lower and upper levels. This arrangement is relatively simple and provides a robust system which does not rely on ropes or cables and does not require complicated hydraulic arrangements to control and regulate movement of the lifting platform.

[0010] The present invention can include two, three, four or more lifting mechanisms, each connected to a respective lifting point on the lifting platform. Each lifting mechanism includes a lifting arm which can connect to the respective lifting point at a variety of points along the length of the lifting arm. This allows for adjustment in the height of the platform in both the lowered and elevated positions. However, in a particular form of the invention each lifting arm is connected to the respective lifting point at or adjacent a free end of the lifting arm. Similarly, the guided connection between the guide member and the lifting arm may comprise a variety of configurations occurring at a variety of locales on the lifting arm however, in an exemplary embodiment, each guide member is in guided connection with the free end of the respective lifting arm. In this regard, each articulated lifting arm can include a stationary end and a free end, opposite to the stationary end, at which each articulated arm connects to the respective lifting point and to the respective guide member. It will be appreciated that movement of the free end of the lifting arm is regulated by the guided connection to the guide member and therefore is not free to move (or is restrained against movement) in all directions. However, in this form of the invention, the free end is free to move along the guide member between the upper and lower levels and the term ‘free end’ will be construed in this context. 4 2017100497 05 May 2017 [0011] The articulated lifting arm can comprise any number of arm sections or segments pivotally or hingedly connected together. In a particular form of the invention, each articulated lifting arm includes a primary arm pivotally connected to a secondary arm and the secondary arm being connected to the respective lifting point. The secondary arm can include a first end pivotally connected to the primary arm and a second end connected to the lifting point. In a particular form of the invention, the actuators are pivotally connected to a point on the secondary arm intermediate of the first and second ends. In an alternative embodiment of the invention, the actuators are connected to the second ends of the secondary arms, that is, each of the actuator, lifting point and guide member can all be associated with the second end of each secondary arm. It will be appreciated that the second end of each secondary arm may therefore correspond to the above-noted ‘free end’ of each articulated arm.

[0012] The shape or profile of the primary and secondary arms may vary. In a particular form of the present invention, the secondary arms are generally S-shaped. According to a particular embodiment of the present invention, the secondary arm includes first and second bent portions cooperatively providing a generally S-shaped secondary arm. In alternative forms of the invention the secondary arms may be, for example, linear, arcuate or L-shaped. Similarly, the primary arms may be L-shaped, arcuate, curvilinear or S-shaped. However, in exemplary embodiment of the invention, the primary arms are linear.

[0013] As noted above, each lifting mechanism includes an articulated lifting arm which can include a primary arm pivotally connected to a first end of secondary arm and a second end of the secondary arm (i.e. the “free end” of the articulated lifting arm) can be connected to the respective lifting point and the respective guide member that are associated with the lifting mechanism. The opposite end of the articulated lifting arm from the free end can comprise a stationary end mounted to a static portion of the lifting arrangement or to a mounting surface which is static, relative to the guide member. In a particular embodiment of the invention, each lifting mechanism includes a joint pivotally connecting the primary arm to an arm mounting point.

[0014] In one form of the invention, each actuator is pivotally mounted to an actuator mounting point. Each of the actuator mounting point and the arm mounting 5 2017100497 05 May 2017 point may be located at a variety of positions on the lifting arrangement. In one form of the invention, the actuator mounting point and the arm mounting point are located at the lower level. In forms of the invention where the arm mounting point is located at the lower level, placement of the lifting platform at the lower level may correspond to the lifting arms being in the retracted position. In other words, extension of the lifting arm from the retracted position to the extended position will actuate upward movement of the lifting platform towards the upper level.

[0015] In an alternative form of the invention, each of the actuator mounting points and the arm mounting point are located at the upper level. In forms of the invention where the arm mounting point is located at the upper level, placement of the lifting platform at the lower level may correspond to the lifting arms being in the extended position. In other words, extension of the lifting arm will lower the lifting platform from the upper level to the lower level.

[0016] In either of the above configurations, the actuator mounting point may be located at the upper level, the lower level, at a position intermediate of the upper and lower levels or at a position above the upper level or below the lower level. However, as noted above, an exemplary embodiment of the invention provides that the actuator mounting point and arm mounting point are positioned at the same level. As noted above, some forms of the invention include a joint connecting the primary arm of the articulated lifting arm to an arm mounting point. In a particular form of the invention, the actuator mounting point and the arm mounting point are located at the same point or are in close proximity, or are adjacent each other. By way of example, the primary arm and the actuator may each be pivotally connected to a pivot plate and the pivot plate is connected to a single mounting point. According to a particular embodiment of the invention, the lifting arrangement includes a base and each arm and its associated actuator are mounted to a portion of the base, for example a bracket. As noted above, the mounting points of an arm and its associated actuator may be located at the same point or may be adjacent one another i.e. the same point of a bracket or adjacent to one another on the same bracket.

[0017] The guided connection between each lifting arm and the respective lifting member can be achieved in a variety of configurations. In some forms of the invention 6 2017100497 05 May 2017 the lifting arm can be directly connected to the guide member, that is, a connection without an intermediary component. In alternative forms of the invention, the lifting arm can be connected to the guide member indirectly and via an intermediary component. For example, in a particular form of the invention, each lifting mechanism includes a sliding member connecting the lifting arm to the guide member. The sliding member can comprise a carriage pivotally connected to the lifting arm and configured to slide along or within the guide member to facilitate movement of the carriage along the guide member between the lower and upper levels. The connection between the guide member and the carriage may include a track or guide channel mounted to or formed in the guide member with which the carriage is engaged. The carriage may be connected to the second end of the secondary arm i.e. the “free end” or “lifting end” of the articulated lifting arm. Alternatively the carriage may be pivotally connected to the secondary arm at the position intermediate of the first and second ends of the secondary arm. The carriage may be directly connected to the second end of the secondary arm or may be connected indirectly such as by a bracket or plate.

[0018] It will be appreciated that even and steady lifting movement is highly desirable when moving the lifting platform between the lower and upper levels and, in particular, when transporting heavy and expensive cargo such as new automobiles. In forms of the invention where each lifting mechanism in the lifting arrangement is associated with a separate lifting point on the lifting platform it is desirable for movement of the respective lifting mechanisms to be synchronised in order to ensure even movement of the respective lifting points on the lifting platform. As noted in the foregoing, existing hydraulic systems typically require the use of complicated and expensive hydraulic control systems to synchronise movement of various hydraulic components.

[0019] According to a particularly advantageous form of the invention the plurality of lifting mechanisms includes a pair of lifting mechanisms and the lifting arrangement further includes a synchronisation linkage connecting the pair of lifting mechanisms. The synchronisation linkage therefore facilitates synchronised movement of each lifting arm along the respective guide members, substantially preventing one of the lifting arms in the pair of lifting arms from becoming more or less extended than the other lifting arm. The expression “substantially preventing” is intended to allow for 7 2017100497 05 May 2017 slight differences in extension between the lifting arms of the pair of lifting arms, so that exact synchronisation is not essential for proper operation of the invention. What is required is that the lifting arms generally extend or retract at about the same rate. In some forms of the invention, the pair of lifting mechanisms are on opposing sides of the lifting platform. In this instance, the synchronisation linkage can extend between the opposing sides of the lifting platform.

[0020] In a particular embodiment of the invention the guide members include a guide channel and the synchronisation linkage comprises a torsion bar extending between opposing lengthwise sides of the lifting platform, each opposing end of the torsion bar being rigidly connected to a respective lifting mechanism and, in some forms of the invention, to the second end of the secondary arm and again in some forms of the invention, to the carriage at the second end of the secondary arm of each lifting mechanism. In this latter form of the invention, the carriages at the opposing ends of the torsion bar are tracked within the guide channel for upward and downward movement, thus permitting upward and downward movement of the torsion bar (and the lifting arm connected thereto) along the axis of the guide member. The rigid connection of the torsion bar to the secondary arms of the lifting mechanism means that greater movement of a first of the lifting arms relative to a second of the lifting arms causes a torsional load on the torsion bar that translates to the second lifting arm and tends to correct the imbalance by increasing or decreasing the movement of one of the first and second lifting arms. This is a simple but very effective correction mechanism. The guide channel could be formed integrally within the guide member or, alternatively, could be mounted to the guide members as a separate component.

[0021] In a particular form of the invention the torsion bar extends through bushings or bearings mounted within the lifting platform to permit relative rotation of the torsion bar with respect to the lifting platform. Rotation of the torsion bar relative to the carriage can be regulated or prevented to thereby impose a torsional or bending load upon the torsion bar in the event that an end of the torsion bar is lifted or lowered out of synchronisation with the opposite end. In this manner, the torsion bar can retain the pair of lifting mechanisms connected to the torsion bar’s opposing ends in synchronised movement between the lower and upper levels. 8 2017100497 05 May 2017 [0022] The lifting platform may comprise any desirable shape as dictated by the intended lifting application. For example, when used to lift vehicles in a car-carrying trailer, the lifting platform may be generally rectangular, its length and width generally corresponding to the dimensions of a large car. In a particular form of the invention, the lifting platform is rectangular and includes a pair of lengthwise side edges extending between a pair of end edges. In this regard, the lifting arrangement can include four lifting mechanisms associated with four respective lifting points, the four lifting points comprising two lifting points on each of the lengthwise sides. Each of the four lifting points can be adjacent to an outer end of one of the lengthwise sides. In this regard, the four lifting points are each proximate to one of the four corners of the rectangular lifting platform. This arrangement is a desirably stable configuration insofar as each of the corners of the lifting platform is supported by an associated lifting point.

[0023] The actuators in the lifting mechanisms may be comprised of any appropriate actuating device, for example, a pneumatic actuator, electric actuator or screw drive actuator (a ball screw actuator for example). In a particular form of the invention the actuators are hydraulic cylinders. As noted above, the present invention is advantageously suitable for the use with relatively simple hydraulic cylinders as opposed to the complex hydraulic synchronisation systems required to achieve synchronised hydraulic movement in certain prior art lifting arrangements.

[0024] According to a particular embodiment of the invention each lifting mechanism includes a locking mechanism for locking the lifting platform at a position along the guide members. The locking mechanism may include a ratcheting arrangement. In particular, the locking mechanism may include a ratcheting arrangement including at least one toothed rack mounted to each of the guide members. Advantageously, the toothed rack may engage with a pawl connected to the carriage, lifting arm or lifting platform which locks the lifting platform against undesirable movement, typically downward movement, more particularly violent downward movement. Engagement of the locking mechanism may be configured to occur, for example, when the actuators are deactivated. Upon activation of the actuators, i.e. when movement of the lifting platform is desired, the locking mechanism can disengage to permit movement of the lifting platform along the guide 9 2017100497 05 May 2017 members. Disengagement might require slight upward movement to relieve any locking load.

[0025] According to a particular form of the invention, the guide members include a guide channel and the carriages include a locking mechanism which tracks within the guide channel facilitating the guided connection between the lifting arm and also providing the above noted locking functionality. The guide members can include a toothed rack extending along the length of the guide member and the locking mechanism can include a movable or an expandable locking projection for engaging the toothed rack during activation of the locking mechanism. In this manner, expansion of the locking projection to engage with the toothed rack prevents the locking mechanism from downward movement of the lifting platform in the event of a mechanical failure in the lifting arms or the associated actuators.

[0026] According to a particular form of the invention, the locking mechanism includes at least one normally-expanded pawl configured to engage with a toothed rack in the guide channel to provide a ratcheting system permitting upward movement of the locking mechanism along the toothed rack whilst resisting downward movement. The normally-expanded pawl can be hinged to the locking mechanism and biased to an outward position. The locking mechanism can further include a retraction mechanism to retract the pawl in order to facilitate downward movement of the locking mechanism along the guide member. Retraction might be accompanied by a slight upward movement of the pawl.

[0027] The guide member of each lifting arrangement can, in some embodiments of the invention, comprise a guide post. Alternatively, the guide member can be a guide rack secured to a surface such as a wall. In still further alternatives, the guide member can comprise a wall with an integrated guide formation such as an integrated guide channel or integrated guide rail. It will be appreciated that the guide member regulates movement of the lifting platform in a single axis extending between the lower and upper levels and that the particular configuration of the guide member suitable for achieving this function can vary depending on the application of the invention. 10 2017100497 05 May 2017 [0028] The lifting platform of the present invention may be used to lift a variety of different loads. As will be appreciated from the above discussion, the lifting platform may be a vehicle-lifting platform however, in alternative forms of the invention, the lifting platform may be used, for example, to raise and lower cargo onto trucks or ships or to facilitate access to elevated areas. Whereas the above discussion relates to use of the present invention as a lifting device, the present invention may also be utilised as a ‘push/pull’ device. That is, the lifting arrangement may be reorientated 90°such that the guide members are generally horizontal and the lifting platform may therefore function as a pushing or pulling member. The arrangement could be orientated at any desired angle to apply an actuating load in any directed direction. It will be appreciated that this form of the invention may provide a variety of alternative applications such as compacting rubbish or pushing cargo from one location to another.

[0029] In this regard, a second aspect of the present invention provides an actuating arrangement including: a drive member for pushing or pulling a load between a first position and a second position; and a plurality of actuating mechanisms, each actuating mechanism connected to a respective connection point on the drive member and each actuating mechanism including: an articulated arm connected to the respective connection point and being extendable from a retracted position to an extended position to actuate the drive member from the first position to the second position; a guide member extending between the first and second positions and in guided connection with the articulated arm for guiding extension of the arm between the retracted and extended positions; and an actuator pivotally connected to the arm for actuating extension of the arm.

[0030] The second aspect of the present invention is suitable for actuating the drive member in an orientation other than vertical, such as in a generally horizontal axis as opposed to the generally upright movement axis of the lifting platform in the first aspect of the present invention. The drive member of the second aspect can comprise any suitable beam, sheet, piston, ram, or other member suitable for applying a horizontal or lateral pushing or pulling force to actuate movement of the load. In some embodiments, the second aspect of the present invention is equivalent to the first aspect of the present invention albeit rotated 90° such that the lifting 2017100497 05 May 2017 11 platform defines a generally vertical surface suitable for pushing or pulling a load along a generally horizontal plane.

[0031] The actuating arrangement according to the second aspect of the present invention may be used to provide pushing/pulling or lifting/lowering functionality in directions other than vertical or horizontal and may be configured to operate at any desired angle. For example 20° 45°or 60°to horiz ontal. It will be appreciated that the desired angle of operation may be achieved by angular alignment of the guide members. Applications of the second aspect of the present invention include garbage compaction, or rotated 180°(i.e. inverted) for use in grain compaction or rotated 90° (i.e. horizontal movement) for use in actuating movement of cargo. One or more actuating arrangements according to the second aspect of the present invention may also be used as a clamping device to clamp an object in a desired location. It should be appreciated that all the features discussed in relation to the first aspect of the present invention are equally applicable to the second aspect of the present invention.

Brief Description of Drawings [0032] For a better understanding of the invention and to show how it may be performed, embodiments thereof will now be described, by way of non-limiting example only, with reference to the accompanying drawings.

[0033] Figure 1 is a side perspective of a lifting arrangement according to the present invention mounted to the chassis of a car-carrying truck.

[0034] Figures 2 to 6 are perspective views of a lifting arrangement according to the present invention showing sequential movement of a lifting platform between the lower and upper levels.

[0035] Figure 7 is a perspective view of a pair of the lifting arms in Figures 1 to 6 with the lifting platform and guide posts removed for illustrate purposes.

[0036] Figure 8 is a perspective view of the lifting arms illustrated in Figure 7 with guide posts illustrated. 12 2017100497 05 May 2017 [0037] Figure 9 is a side perspective of a carriage locking mechanism illustrated in Figure 7, in a locked position.

[0038] Figure 10 is a side perspective of the carriage locking mechanism in Figure 9 in an unlocked position.

[0039] Figure 11 is an exploded perspective of the torsion bar, carriage and lifting arm assembly illustrated in Figures 7 and 8.

Detailed Description [0040] Figure 1 illustrates a platform lifting arrangement 10 mounted to a chassis 12 of a car-carrying truck 14. Lifting arrangement 10 includes a rectangular lifting platform 16 for lifting a vehicle between a lower level 18 and an upper level 20. As illustrated in Figure 1, platform 16 is used to elevate a first vehicle 22 above the lower level 18 so as to permit a second vehicle 24 to be stowed beneath the first vehicle thereby increasing the car-carrying capacity of truck 14.

[0041] Figure 2 provides a perspective view of lifting arrangement 10 which includes four lifting mechanisms 26 located at each of the four corners of the rectangular lifting platform 16. Lifting platform 16 includes a pair of opposing lengthwise side edges 30 extending between a pair of opposing end edges comprising a first end edge 32 and a second end edge 33. Each lifting mechanism 26 is connected to respective lifting points on lifting platform 16 located at the outer ends of each of the lengthwise side edges 30. In this regard, each of the end edges 32, 33 is associated with a pair of lifting mechanisms 26. Figure 2 illustrates the lifting platform 16 positioned at the lower level 18 to facilitate vehicle access onto the lifting platform 16 via a ramp 28 connected to the first end edge 32.

[0042] Referring briefly to Figures 2 to 6 in sequence, the operation of lifting arrangement 10 will be generally appreciated. For illustrative purposes, the operation of lifting arrangement 10 will be illustrated without a load on lifting platform 16. Figure 2 illustrates lifting platform 16 in a lowered positioned whereupon a vehicle can be driven or reversed onto lifting platform 16. Once the vehicle is parked and secured in position, a first stage of the lifting sequence consists of first end edge 32 being lifted upwards to a position intermediate of the lower and upper levels 18, 20 by activating 13 2017100497 05 May 2017 the pair of lifting mechanisms 26 associated with the first end edge 32. Figure 3 illustrates the end of the first stage of the lifting sequence at which the lifting platform 16 is at an incline with first end edge 32 being raised above base 50 and second end edge 33 at its original lowered position.

[0043] Figures 4 and 5 illustrate the second stage of the lifting sequence, in which the pair of lifting mechanisms 26 associated with second end edge 33 are activated to return the lifting platform 16 to a generally horizontal position and then continue to raise second end edge 33 to upper level 20. In a third and final stage of the lifting sequence, first end edge 32 is lifted to the upper level 20 thereby returning the lifting platform 16 to the generally horizontal orientation illustrated in Figure 6. In this position, a second vehicle may be driven onto base 50 beneath the elevated lifting platform 16. In some applications of the invention it may not be necessary for the lifting platform 16 to be fully raised to permit entry of the second vehicle. For example, Figure 1 illustrates a second vehicle positioned beneath an inclined lifting platform 16 with first end edge 32 positioned intermediate of the lower and upper levels 18, 20. As will be appreciated by a person skilled in the art, the incline of lifting platform 16 illustrated in Figure 1 advantageously lowers the car-carrier’s centre of gravity as well as improving aerodynamic efficiency. To these ends, the present invention advantageously facilitates vehicles to be stacked and transported at an incline, as illustrated in Figure 1.

[0044] In an alternative lifting sequence to that which is illustrated in Figures 2 to 6 and described above, all four lifting mechanisms 26 can be concurrently operated such that the lifting platform 16 is lifted at all four lifting points 34 simultaneously and the lifting platform 16 is lifted substantially horizontally. Clearly other lifting sequences are possible and within the scope of the present invention.

[0045] Turning to Figure 3, the lifting mechanisms 26 will now be described in further detail. Each lifting mechanism 26 includes an articulated lifting arm 36, a guide member comprising an upright guide post 38 and a hydraulic lifting actuator 40. Each lifting arm 36 is connected to the respective lifting point 34 via a carriage 43 (see Figure 7) connected to a free end of the lifting arm 36. Lifting arms 36 are configured for movement between a retracted position and an extended position to lift the lifting 2017100497 05 May 2017 14 platform 16 from the lower level 18 to the upper level 20 or to an intermediate position therebetween. As will be discussed in further detail below, carriages 43 are in guided connection with the respective guide post 38. In this regard, this means that the free end of each lifting arm is in guided connection with the respective guide post 38. The upper ends of guide posts 38 are connected via an upper framework comprising a pair of lengthwise frame members 46 and an end frame member 48 which provide rigidity and which secure guide posts 38 in their upright orientation. Base 50 provides a mounting surface for lifting mechanisms 26 and a support surface for lifting platform 16 when positioned at the lower level 18. As illustrated in Figure 4, each articulated lifting arm 36 is pivotally mounted to an arm mounting point comprising a bracket 60 on base 50.

[0046] A closer perspective of lifting arms 36 is provided in Figure 7 in which the guide posts and lifting platform have been removed for illustrative purposes. Each lifting arm 36 includes a primary arm 52 and a secondary arm 54 pivotally connected at a first joint 56. Primary arm 52 includes a static end 58 pivotally mounted to bracket 60 and a mobile end 62, opposite to the static end 58. Secondary arm 54 includes a pair of first and second opposite ends 64, 66. The first end 64 of secondary arm 54 is pivotally connected at first joint 56 to the mobile end 62 of primary arm 54. As will be discussed in further detail below with respect to Figure 11, the second end 66 of secondary arm 54 is rotatably connected to carriage 43.

[0047] Primary arms 52 comprise an elongate tubular member. Secondary arms 54 comprise first, second and third members 68, 70, 71 rigidly connected to one another and generally defining an S-shape profile. The S-shape profile of the secondary arms is provided by a pair of first and second bent portions. The first bent portion occurs at the intersection of first member 68 and second member 70 which are angled with respect to each other. The second bent portion of each secondary arm occurs in third member 71 which, as illustrated in Figure 7, bends generally upwardly from the axis defined by the second member 70. It will be appreciated that the second end 66 of secondary arm 54 is located at the outer end of the third member 71. 15 2017100497 05 May 2017 [0048] Third members 71 are formed from a planar sheet whereas first and second members 68, 70 have a generally quadrilateral profile. As illustrated in Figure 8, guide post 38 includes a guide channel 78 having an opening 79 extending along the length of guide post 38. Carriages 43 are positioned within guide channels 78 with three sides of the carriages 43 generally enclosed by walls of the guide channel 78. A portion of the fourth side of the carriages 43 is exposed via the opening 79 of the guide channel 78. Referring again to Figure 7, the planar form of each third member 71 permits connection with the carriage 43 on the portion facing outwardly from guide channel opening 79. Of course, it will be appreciated that the profile of the first, second and third members may vary depending on the particular application of the lifting arm. For example, in applications where intended loads are relatively light, all three members may be provided by a planar sheet. Alternatively, in applications where particularly heavy lifting is required, the planar third member may be substituted with a thicker non-planar member if necessary to support the intended load.

[0049] Secondary arms 54 further include a pair of opposing flanges 72 extending from the first 68 and second 70 members. The first joint 56 comprises mobile end 62 of the primary arm 52 located between and pivotally connected to opposing flanges 72. An upper end of lifting actuator 40 is located between and pivotally connected to opposing flanges 72 at a second joint 57 generally intermediate of the first and second ends 64, 66. A lower end of each lifting actuator 40 is pivotally connected to bracket 60. It will be appreciated that the location of the second joint 57 affects the leverage ratio between extension movement of lifting actuator 40 and movement of the second end 66 of the secondary arm 54. That is, the closer the second joint 57 is to the first end 64 of the secondary arm 54, the higher the ratio of actuator-to-arm movement. Accordingly, moving the second joint 57 toward the second end 66 of the secondary arm 54 (i.e. the closer to the guide post) would require longer extension of the lifting actuators 40 in order to achieve the same amount of lifting movement. It will be appreciated that this ratio may be varied, as necessary, depending upon particular application parameters such as the desired height of the upper level, the dimensions and capacity of the actuators and the dimensions of the lifting arms being used. 16 2017100497 05 May 2017 [0050] Still referring to Figure 7, each carriage 43 includes a locking mechanism 74. Locking mechanisms 74 are located within the guide channel 78 formed in each guide post 38 and illustrated in Figure 8. Carriages 43 and locking mechanisms 74 are permitted to slide upwardly and downwardly within guide channels 78 thereby providing the guided connection between the carriage 43 and guide posts 38 and thus the guided connection between lifting arms 36 and guide posts 38. As best illustrated in Figures 9 and 10, each locking arrangement 74 includes a pair of expandable pawls 76 for engaging with a pair of toothed racks 80 mounted to opposing walls within guide channels 78.

[0051] Figure 9 illustrates locking mechanisms 74 in the locked position whereby pawls 76 are expanded to contact and engage with the teeth of toothed racks 80. In the locked position, locking mechanism 74 (and the loading platform connected thereto) is locked against downward movement. Pawls 76 are hinged with respect to the carriage and are biased towards the locked position illustrated in Figure 9 by an actuator 45. In this regard, locking mechanism 74 is biased towards a normally locked configuration and advantageously prevents downward movement of the lifting platform in the event of a hydraulic or other mechanical failure. Pawls 76 are connected to a movable linkage 47 which is configured for movement in the axis of the guide posts and is actuated by pneumatic locking actuator 45. Locking actuator 45 is pneumatic and is also spring loaded to be biased to an extended position in which pawls 76 are maintained in their locked position. In the locked position, illustrated in Figure 9, linkage 47 is urged downwardly by actuator 45. Locking actuator 45 thereby maintains locking mechanism 74 in a ‘normally locked’ configuration via both pneumatic and spring biases. In this manner, pawls 76 would be urged towards their locked position by the spring system within locking actuator 45, even in the event of a pneumatic failure in locking actuator 45.

[0052] During upward/lifting movement, the upward load applied by the lifting arms to the carriage and to the locking mechanism 74 causes pawls 76 to slide upwardly along toothed rack 80. The teeth of rack 80 include a ramp surface 83 inclined with respect to the direction of movement and a locking surface 81 orientated perpendicularly to the direction of movement. When locking mechanism 74 is stationary, pawls 76 are seated, in their expanded position, upon locking surface 81 17 2017100497 05 May 2017 such that the weight of lifting platform is supported by racks 80 in the event that the lifting arms were unable to do so (for example, in the event of a hydraulic failure). During upward movement, the lifting load applied by the lifting arms overcomes the pneumatic and spring biases urging pawls 76 to their expanded position such that pawls 76 slide upward along the ramp surface 76 of each tooth, causing pawls 76 to temporarily hinge inward as each tooth in rack 80 is surmounted. In this manner, upward movement of pawls 76 along rack 80 is a ratcheting movement in which upward movement is permitted whilst downward movement is resisted.

[0053] Figure 10 illustrates the operation of locking mechanism 74 when downward/lowering movement is required. To facilitate downward movement, the pneumatic system within locking actuator 45 reverses direction to urge linkage 47 upwardly. The pneumatic retracting force within locking actuator 45 overcomes the spring expansion force such that linkage 47 is actuated upwardly causing pawls 76 to hinge inwardly toward an unlocked position in which they are disengaged from toothed rack 80. Locking actuator 45 maintain pawls 76 in the unlocked position illustrated in Figure 10 throughout the downward movement until the lifting platform is lowered to the desired height.

[0054] In particular embodiments of the present invention, locking mechanism 74 can be configured to automatically expand pawls 76 in the event of a mechanical failure during the lowering movement. For example, locking actuators 45 can be connected to sensors associated with the lifting arm 36 and/or lifting actuator 40 so as to automatically expand pawls 76 in the event of a failure in lifting actuator 40 or in the event of an unexpected downward acceleration which could signifying a possible failure in the lifting arms 36 or lifting actuators 40.

[0055] Whilst the locking actuators 45 in the illustrated embodiment are pneumatic, it will be appreciated that a variety of alternative actuators may be suitable for use with the present invention for example, hydraulic or electric actuators. The use of pneumatic locking actuators in the illustrated embodiment is particular advantageous insofar as it permits the locking bias applied to the pawls 76 to be overcome by the stronger hydraulic lifting force applied by hydraulic lifting actuator 40 during lifting movement. However it is envisioned that this operation could be 18 2017100497 05 May 2017 achieved in a variety of alternative configurations or alternative actuator types, each of which being within the scope of the present invention.

[0056] During operation of the lifting mechanisms 26, lifting actuators 40 are hydraulically driven to expand in length thereby actuating movement of the lifting arms 36 from the retracted position illustrated in Figure 2 to the expanded position illustrated in Figure 6, or to a position intermediate position as illustrated in Figure 4. In the closing sequence, lifting actuators 40 contract in length causing the lifting arms 36 to move toward the retracted position and thereby lowering carriages 43 and lifting platform 16 connected thereto toward the lower level.

[0057] As illustrated in Figures 7 and 8, a synchronisation linkage comprising a torsion bar 82 extends between the pair of carriages 43 associated with the lifting platform end edges 32, 33. The function of torsion bar 82 is to help synchronise movement between lifting mechanisms on opposing sides of the lifting platform. Turning to Figure 11, the configuration and operation of the torsion bar 82 will be discussed in greater detail. Torsion bar 82 extends across the width of the lifting platform and is bolted at each end to shafts 84 welded to the free ends of the lifting arm third members 71 i.e. the second ends 66 of the secondary lifting arm. As illustrated in Figure 11, shafts 84 include a cylindrical projection 85 including a pair of bores 90 extending between opposing sides of the projection 85 and the hollow ends of torsion bar 82 include openings 92 on opposing sides of torsion bar 82. The hollow ends of torsion bar 82 are sleeved over cylindrical projections 85. Thereafter, plate washers 96 are tack welded onto torsion bar 82. Plate washers 96 include openings aligning with openings 92 and 90. Bolts 88 are inserted through the plate washer openings, through openings 92 and through openings 90. The ends of bolts 88 protrude from the opposite side of torsion bar 82 and nuts 93 are secured to the ends of bolts 88. Torsion bar 82 is thereby secured, at each end, to shafts 84 which are welded to the second end 66 of the secondary lifting arm.

[0058] As will be appreciated from Figure 11, the torsion bar 82 extends between inner sides of the lifting arm third members 71. On the opposing sides, i.e. the ‘outer’ side of third members 71, a boss 94 extends outwardly from the third members 71 and is received within an aperture 86 in the associated carriage 43. Apertures 86 19 2017100497 05 May 2017 include a nylon bushing such that bosses 94 are permitted to rotate within apertures 86 relative to carriages 83 during lifting or lowering movement whilst restricting translational movement of the torsion bar 82 and the second ends 66 of the secondary lifting arms to the vertical axis of the associated guide post. Carriages 43 thereby guide movement of torsion bar 82 and consequently guide movement of the lifting arms which are also in guided connection with the guide posts through sleeves 84, torsion bar 82 and carriages 43.

[0059] Lifting platform 16 includes openings (not shown) in each of the lengthwise side edges 30 through which shafts 84 extend. A bushing or bearing (not shown) is located on shaft 84 to reduce friction between the lifting platform 16 and shaft 84 and to facilitate relative rotation between the shaft 84 and the lifting platform. The lifting platform 16 is thereby supported by the lifting mechanism at shafts 84. The openings in lifting platform 16 may be annular or may be elongate slots. In a particular embodiment of the invention, the pair of openings located adjacent to the second end edge 33 (see Figure 2) are annular openings corresponding to the diameter of the shaft 84 and the pair of openings located adjacent to the first end edge 32 are elongate slots. The shafts 84 extending through the elongate slots adjacent the first end edge 32 are allowed a degree of sliding movement in the direction of the plane of the lifting platform to provide a tolerance margin during the lifting movement.

[0060] In alternative embodiments of the present invention (not shown) the bolted connection between torsion bar 82 and shaft 84 may be replaced by a splined or keyed connection.

[0061] During operation, in the event that the pair of lifting actuators 40 expand or contract in length unevenly, torsion bar 82 advantageously resists uneven movement of carriages 43 and thereby tends to synchronise movement of the pair of carriages 43 along guide posts 38. Torsion bar 82 extends between lengthwise side edges 30 and is permitted to rotate with respect to the lifting platform 16 as the lifting platform 16 is lifted or as the lifting actuators 40 expand or contract in length. As illustrated in the sequence of Figures 2 to 6, it will be appreciated that carriages 43 undergo rotation about a generally horizontal axis during operation of the lifting mechanisms 26. In this regard, a lifting arm which imposes a load that tends to raise a carriage 43 2017100497 05 May 2017 20 higher than the corresponding carriage 43 on the opposing lengthwise side edge 30 will impose a torsional load on torsion bar 82 which will be resisted by the torsion bar 82 through its connection with the corresponding carriage 43. In this regard, the lifting arrangement 10 obviates the need for complicated hydraulic synchronisation systems advantageously reducing the cost and complexity of the present invention.

[0062] Furthermore, it will be appreciated with reference to Figures 1 to 6 that the use of the lifting arms facilitates lifting movement between the lower level to the upper level whilst the lifting mechanism is wholly contained between the lower and upper levels. Advantageously, and as illustrated in Figure 1, the articulation in the articulated lifting arms allows the lifting platform to be lowered below the top of the hydraulic actuators. This represents a significant improvement over alternative hydraulic lifting systems which connect an actuator directly to the lifting platform such that the whole of the actuator is always below the platform, which can therefore only be lowered as low as the top of the hydraulic actuator. In this regard the present invention provides a much greater range of lifting movement than is available from previous lifting systems.

[0063] The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the above description.

[0064] Throughout the description and claims of this specification the word “comprise” and variations of that word, such as “comprises” and “comprising”, are not intended to exclude other additives, components, integers or steps.

Claims (24)

1. The claims defining the invention are as follows:

   1. A platform lifting arrangement including: a lifting platform for lifting a load from a lower level to an upper level; and a plurality of lifting mechanisms, each lifting mechanism connected to a respective lifting point on the lifting platform and each lifting mechanism including: an articulated lifting arm connected to the respective lifting point and being extendable from a retracted position to an extended position to lift the platform from the lower level to the upper level; an upright guide member extending between the lower and upper levels and in guided connection with the lifting arm for guiding extension of the lifting arm between the retracted and extended positions; and an actuator pivotally connected to the lifting arm for actuating extension of the lifting arm.
2. 2. A platform lifting arrangement according to any one of the preceding claims, each articulated lifting arm including a primary arm pivotally connected to a secondary arm and the secondary arm being connected to the respective lifting point.
3. 3. A platform lifting arrangement according to claim 2, each secondary arm including a first end pivotally connected to the primary arm and a second end connected to the lifting point.
4. 4. A platform lifting arrangement according to claim 2 or 3, the actuators being pivotally connected to a point on the secondary arms intermediate of the first and second ends.
5. 5. A platform lifting arrangement according to any one of claims 2 to 4, the secondary arm being generally S-shaped.
6. 6. A platform lifting arrangement according to any one of claims 2 to 5, the primary arm being pivotally connected to an arm mounting point.
7. 7. A platform lifting arrangement according to claim 6, each actuator being pivotally mounted to an actuator mounting point.
8. 8. A platform lifting arrangement according to claim 7, the actuator mounting point and the arm mounting point being located at the lower level.
9. 9. A platform lifting arrangement according to claim 8, the actuator mounting point and the arm mounting point being located at the upper level.
10. 10. A platform lifting arrangement according to any one of the preceding claims, each lifting mechanism including a sliding member connecting the lifting arm to the guide member.
11. 11. A platform lifting arrangement according to claim 10, the sliding member comprising a carriage pivotally connected to the lifting arm and engaged with the guide member to facilitate movement of the carriage along the guide member between the lower and upper levels.
12. 12. A platform lifting arrangement according to any one of the preceding claims, the plurality of lifting mechanisms including a pair of lifting mechanisms and the lifting arrangement further including a synchronisation linkage connecting the pair of lifting mechanisms.
13. 13. A platform lifting arrangement according to claim 12, the pair of lifting mechanisms being on opposing sides of the lifting platform.
14. 14. A platform lifting arrangement according to claim 13, the synchronisation linkage extending between the opposing sides.
15. 15. A platform lifting arrangement according to any one of the preceding claims, the lifting platform being rectangular and including a pair of lengthwise side edges extending between a pair of end edges.
16. 16. A platform lifting arrangement according to claim 15, including four lifting mechanisms associated with four respective lifting points, the four lifting points comprising two lifting points on each of the lengthwise sides.
17. 17. A platform lifting arrangement according to claim 16, each of the four lifting points being adjacent an outer end of one of the lengthwise sides.
18. 18. A platform lifting arrangement according to any one of the preceding claims, the actuator being a hydraulic cylinder.
19. 19. A platform lifting arrangement according to any one of the preceding claims, each lifting mechanism including a locking mechanism for locking the lifting platform at a position along the guide members.
20. 20. A platform lifting arrangement according to claim 19, the locking mechanism including a ratcheting arrangement.
21. 21. A platform lifting arrangement according to claim 20, the ratcheting arrangement including a toothed rack mounted to each of the guide members.
22. 22. A platform lifting arrangement according to any one of the preceding claims, each guide member being a guide post.
23. 23. A platform lifting arrangement according to any one of the preceding claims the lifting platform being a vehicle-lifting platform.
24. 24. An actuating arrangement including: a drive member for pushing or pulling a load between a first position and a second position; and a plurality of actuating mechanisms, each actuating mechanism connected to a respective connection point on the drive member and each actuating mechanism including: an articulated arm connected to the respective connection point and being extendable from a retracted position to an extended position to actuate the drive member from the first position to the second position; a guide member extending between the first and second positions and in guided connection with the articulated arm for guiding extension of the arm between the retracted and extended positions; and an actuator pivotally connected to the arm for actuating extension of the arm.