Hitherto, lift assemblies and especially those that are adapted in use to facilitate access of mobility impaired and/or wheel chair bound persons are generally of the underfloor-type.

Underfloor-type lifts are known per se and generally include a stowage box which is fixedly mounted beneath the floor of the vehicle; a load-bearing platform which is mounted on a carriage which can be moved inwardly and outwardly of the stowage box, the platform being stowed away in the box when not in use and being presented for use when out of the box. Movement of the platform is provided by a lifting mechanism which is conveniently operated hydraulically.

Typically the platform is provided, at one or both ends, with a hinged bridging-plate. When the platform is deployed, the bridging-plate extends from the platform to the ground or to the interior of the vehicle (as the case may be).

Currently these lifts are impractical for use on emergency vehicles.

Reasons for this include lack of necessary ground clearance to fit the lift to the underside of the vehicle and the relatively slow deployment and stowage due to the entire operation being under precise hydraulic control or the like.

New legislation has directed that all emergency vehicles, especially ambulances, are to be fitted with a passenger lift. Currently no existing

lifts adapted to be fitted to vehicles and the like are suitable for such a purpose.

It is an aim of the present invention to provide a lift for such a purpose.

Accordingly the present invention provides, in a first aspect, a lift for use with a vehicle, the lift comprising a load-bearing platform and at least one hand rail, said load-bearing platform being in operative engagement with at least one arm member, the or each arm member being arranged for operative engagement with a supporting member located on the a vehicle.

The load-bearing platform is preferably of a ladder-type construction to allow for alteration of width and length of said platform.

The handrail is preferably powered from an inoperative condition to an operative condition by means of a hydraulically actuated piston. The handrail is preferably powered from an operative condition to an inoperative condition by means of a hydraulically actuated piston.

Alternatively, the handrail may be powered pneumatically or electronically.

The load-bearing platform is preferably adapted, in use, to be pivotally engaged with each arm member.

The arm members are disposed substantially parallel to each other.

Preferably the arm members may be in pivotal engagement with said fixed member. Suitably, the fixed member is located on an underfloor surface of the vehicle.

The arm members may suitably engage the fixed underfloor member at a spaced-apart distance of between 65mm and 75mm. Preferably they are at a spaced-apart distance of 70mm.

The arm members may suitably engage the load-bearing platform at a spaced-apart distance of between 70mm and 80mm. Preferably the arm members are at a spaced-apart distance of 75mm.

The spaced-apart orientation of the arm members is advantageous as known lifts relied on a substantially wedge shaped load-bearing platform which needed to be deployed to an intermediate condition and subsequently adjusted before being fully deployed to an operative condition; the spaced-apart arms allow for the omission of this intermediate step.

A roll-on ramp may be pivotally attached to the one end of the platform and a bridge-plate to the opposite end of the platform, both in a manner known per se.

The lift is preferably deployed as follows: The underside of the load-bearing platform is provided with one or more keyed portions which, when the lift assembly is in a stowed condition, are in positive meshing engagement with complementary keyed portions located on the vehicle.

The lift is then lowered so as to disengage the keyed portions.

The lift is then deployed manually, for example with the aid of one or more inertia belts located on the underside of the load-bearing platform.

The lift is then presented in an intermediate condition. The lift is secured

in this condition by locking means. The locking means preferably comprises a spring-bolt.

The lift is then powered to a fully deployed condition, for example by hydraulic means. Alternatively, pneumatic or electric means may be used.

When the lift is in a fully deployed condition, the roll-on ramp is concomitantly deployed to allow access for wheelchairs and stretchers and the like on to the platform. The handrail is also deployed into a fully operative condition.

The lift is then powered up to the floor level of the vehicle. When the lift reaches this level the bridge-plate is concomitantly deployed to span the gap between the load-bearing platform and the floor of the vehicle. This allows for access of the wheelchair or stretcher into the vehicle.

The lift can then be stowed by releasing the spring-bolt and manually stowing the load-bearing platform by means of a cable attachment.

It is an advantage of the lift of the present invention that it is separate from the door or doors of the vehicle on which it is mounted. This means that, when the doors are closed, the whole of the lift mechanism is on the outside of the vehicle, outside the doors. Therefore any dirt or debris left on the lift itself is not brought into the vehicle, where clean hygienic conditions are desirable.

The present invention also provides, in a second aspect, a lift in accordance with the first aspect and further comprising means for facilitating the manual deployment of the load-bearing platform to an intermediate position.

The means preferably comprises at least two gas-struts pivotally engaged at one end to an arm member and pivotally engaged at the opposite end to the underside of the load-bearing platform.

The means preferably also comprises at least one. torsion spring. The torsion spring is preferably in operative engagement with the load-bearing platform and a fixed portion of an arm member.

The combination of one or more gas-struts and one or more torsion springs is advantageous during manual deployment as they act to make manual deployment quick and easy.

Alternatively, the gas struts may be replaced by hydraulic or pneumatic means. This enables the load-bearing platform to be powered from a standard condition to a fully deployed condition.

Lift in accordance with the present invention also comprises means for removing the load-bearing platform in a partially or fully deployed condition along a lateral axis of a vehicle. This is advantageous as the load-bearing platform can be adjusted to avoid obstructions at an accident or obstructions in an emergency vehicle e. g. cabinets and medical equipment or the like.

The means preferably comprises a first member in pivotal engagement with the load-bearing platform and a second member in foxed or demountable engagement with a vehicle.

The first and second members have complementary keyed portions in sliding engagement. The first member is substantially U-shaped and is provided with at least one bearing distal of the keyed portion. The

second member is also substantially U-shaped and is provided with hydraulic, pneumatic or electronic means to dispose the first member along a longitudinal axis of the second member. This axis is perpendicular to the longitudinal axis of the emergency vehicle.

The present invention, according to a third aspect, provides a of the type defined, said lift comprising a load-bearing platform and at least one handrail, said load-bearing platform being in operative engagement with at least two arm members, each arm member being in pivotal engagement with displacement means located on a surface of a vehicle and acting, in use, to move the platform laterally with respect to the vehicle.

In one suitable embodiment of the present invention, the displacement means includes one or more block portions, whereby each arm member is in pivotal engagement with a block portion, each block portion is securely engaged by an elongate rod, and each elongate rod is in sliding engagement with said displacement means.

The displacement means preferably comprises a hydraulic assembly adapted, in use to displace said elongate rod such that the lift is displaced along a longitudinal axis of the elongate rod.

The hydraulic assembly is located in secure engagement with a support beam.

The support beam is suitably located on an underfloor member of a vehicle, for example, a chassis member.

The displacement means may alternatively comprise pneumatic, mechanical or electronic assemblies.

The present invention, provides according to a fourth aspect a lift as hereinbefore defined having a powered hand rail further characterised by having a proximal or upper portion and a distal or lower portion, the lower portion comprising a hollow cylinder adapted, in use, to receive a piston and a helical spring adapted, in the absence of an opposing force, to retain the piston within the cylinder, the rail being pivotally mounted so that the distal or lower end is received in a profiled socket, whereby, when a force opposed to the spring is applied to the cylinder, the piston is urged outwardly of the cylinder and into sliding contact with the profiled socket so that the rail is progressively raised and, when said force is released, the piston is retracted into the cylinder by the action of the helical spring so that the rail is progressively lowered.

The force opposed to the helical spring can be applied to the piston by means of a linear actuator. Alternatively, the force can be applied by means of pneumatic pressure or hydraulic pressure.

The present invention provides an access ramp or access platform including one or more powered rails according to the fourth aspect of the present invention.

The ramp or platform may be provided with a single powered rail.

Alternatively, the ramp or platform may be provided with two rails, one rail being disposed at each side of the ramp or platform.

The present invention also provides in a fifth aspect a vehicle including an access ramp, the ramp being provided with one or more powered rails.

The present invention, according to a sixth aspect, hereinbefore defined having a bridge plate and a control mechanism said mechanism being

adapted, in use, to dispose a bridging plate from a first inoperative, stowed, condition to a second operative, deployed, condition.

The control mechanism is preferably located within a support beam. The support beam may be located between the at least two arm members of the lift.

Alternatively the bridge plate mechanism may be located on the support beam.

The control mechanism may comprise a piston and a rocker member.

The piston may be hydraulically or pneumatically actuated.

The control mechanism is preferably activated to move the bridging plate between its stowed and deployed positions by detection means arranged to detect the position of a load bearing platform of the lift. For example, the control mechanism may be arranged to move the bridging plate into its deployed position when the load bearing platform reaches a position level with a floor of the vehicle, by an electronic switch in operative engagement with one of the arm members. The switch is preferably a micro-switch.

The piston preferably has a stoke distance of between 35mm to 55mm.

Preferably the piston has a stroke distance of 45mm.

The piston, in use, is preferably in sliding engagement with said rocker member.

The rocker member may be pivotally engaged with the platform at one end and the piston may engage the rocker member at an opposite end of the rocker member.

The rocker member may be substantially L-shaped.

The rocker member comprises a bevelled portion, adapted, in use, to be in sliding engagement with the piston, at an end of the rocker member distal from its pivoting point.

The rocker member may also comprise a further portion, which extends perpendicularly outwardly of the bevelled portion. The further portion may be located proximal to the bridge plate and may be adapted in use to be in sliding engagement with said bridge plate.

The rocker member may be provided with biasing means. The biasing means being adapted, in use, to urge against the rocker member such that the rocker member is biased away from the bridging plate.

One or more control mechanisms in accordance with the present invention may be used for each bridging plate.

According to a seventh aspect the present invention provides a bridge plate control mechanism comprising a piston in sliding engagement with an actuating means, and a substantially L-shaped rocker member in pivotal engagement with a pivot, said rocker member comprising a bevelled portion in sliding engagement with said piston and a further portion in sliding engagement with a bridge plate, said piston being adapted, in use, to engage said bevelled portion of said rocker member, located distal of the pivot, such that, in use, the piston urges against the bevelled portion to dispose said further portion of the rocker ember

upwardly to dispose the bridge plate from a deployed, operative, condition to a stowed, inoperative, condition.

The piston assembly may be an hydraulic or a pneumatically actuated piston.

Preferably the actuating means is hydraulic or pneumatic.

According to an eighth aspect, the present invention provides a bridge plate mechanism in accordance with the first and second aspects of the present invention in fixed engagement with a support beam located between at least two arm members of the lift as hereinbefore defined.

The present invention will now be described, merely by way of example, with reference to the accompanying drawings, in which Figure 1 shows a lift in accordance with a first embodiment of the invention in a stowed condition on an offside ambulance rear door; Figure 2 shows the lift of Figure 1 in a pre-deployed condition; Figure 3a is a side view of the lift of Figure 1 in the stowed condition; Figure 3b is a side view of the lift of Figure in the pre-deployed condition; Figures 4a, 4b, 4c and 4d show the operation of a cable operated ramp deployment mechanism attachment of the lift of Figure 1;

Figure 5 shows the lift of Figure 1 in an intermediate condition; Figure 6 shows the lift of Figure 1 with the handrails in an operative condition; Figure 7 shows the lift of Figure 1 in a fully deployed condition; Figure 8 shows the lift of Figure 1 at the floor height of the vehicle with the bridge plate deployed; Figure 9 shows a bridge plate deployment mechanism of the lift of Figure 1; Figure 10 shows a mechanism according to a modification of the lift of Figure 1 for disposing the load bearing platform laterally; Figure lla shows a lift in accordance with a second embodiment of the invention in a first operative condition; Figure llb shows the lift of Figure lla in a second operative condition; and Figure 12 is a side view of a support beam and clamp of the lift of Figure 11 a ; Figure 13A, 13B, 13C, and 13D are schematic part-perspective views showing the sequential operation of a powered rail according to a third embodiment of the present invention;

Figure 14 is a schematic part-perspective view of a lift platform including a pair of powered rails of the type shown in Figures 13A to 13D Figure 15 is a schematic part-perspective view of a vehicle ramp platform including a powered rail of the type shown in Figures 13A to 13D; Figure 16 is a side view of a bridge plate deployment mechanism according to a fourth embodiment of the invention in a first inoperative condition; Figure 17 shows the mechanism of Figure 16 in a second operative condition; Figure 18 shows a plan view of the mechanism of Figure 16; Figure 19 is a side view of the bridge plate mechanism of Figure 16 with the bridge plate in a stowed condition; and Figure 20 is a side view of the bridge plate mechanism of Figure 16 with the bridge plate in a deployed condition.

Referring to Figure 1, an ambulance 1 is shown having a lift 2 in accordance with the present invention in a stowed condition in which its load bearing platform 6 is arranged vertically against a rear offside door 3 of the ambulance. The lift 2 is pivotably mounted at its lower end by means of pivots 7a to a carriage portion 7, which in turn is pivotably mounted on the rear ends of two pairs of arm members 8. The load bearing platform 6 is maintained in this stowed position by meshing

engagement of complementary keyed portions 4,5 located on the load-bearing platform 6 of the lift 2 and the offside door 3.

Figure 2 shows the lift 2 in a pre-deployed condition having been lowered while still in an upstanding position relative to the ground. The lowering of the lift 2 is achieved by pivoting the arm members 8 downwards about pivot points 8a at their front ends and serves to disengage the complementary keyed portions 4,5. Raising and lowering of the platform, in is controlled by hydraulic piston and cylinder assemblies 8b acting between the upper and lower arm members 8. This enables both the lowering and raising of the platform in its vertical position, to release and engage the keyed portions 4,5, and the raising and lowering of the platform in its horizontal position when it use, for example to lift and lower patients in wheelchairs to and from the ambulance. The lift is maintained in an upstanding condition by means of two gas-struts (not shown) each having one end pivotally engaged with the one of the arm members 8 and the other end pivotally engaged with the under side of the platform. Locking means, such as a spring bolt, may also be provided to lock the lift in its deployed position.

Figure 3a is a side view of the lift in the stowed position of Figure 1.

The load-bearing platform 6 is in pivotal engagement with the carriage portion 7. The carriage portion 7 is in operative pivotal engagement with arm members 8. The keyed portions 4,5 are engaged with each other so that the platform cannot be lowered by rotation about the pivots 7a.

Figure 3b is a side view of the lift in the position of Figure 2. The arm members 8 have been lowered hydraulically so as to disengage the complementary keyed portions 4,5. The lift is now in a pre-deployed condition. From this position the platform 6 can be lowered manually to its horizontal deployed position, with the weight of the platform being

balanced by the force of the gas struts and torsion springs. In an alternative arrangement, actuation means such as hydraulic or pneumatic cylinders and pistons, or electric actuators may be provided to lower and raise the platform between its vertical and horizontal positions.

Referring to Figures 4a-d, as the platform is lowered into its deployed position, a roll-on ramp at the end of the platform remote from the vehicle is unfolded from a stowed position to a deployed position, by means of a cable 10 that controls the extension and retraction of the roll-on ramp 9. The cable 10 is connected between a point 10a on the roll-on ramp spaced from its point of pivotal connection to the platform, and a point 10b on the carriage portion 7 just forward of the pivots 7a. In Figure 4a the lift is shown in the stowed condition where the ramp 9 is held in its folded position against the platform by the cable 10. As can be seen from Figures 4b to d, as the platform 6 is lowered, the ramp 9 is allowed to pivot towards a deployed position in which it extends beyond the end of the platform 6 under the force of a spring (not shown). When the platform is raised again the further the platform is moved towards the stowed condition, the further the roll-on ramp 9 is retracted relative to the load-bearing platform 6. When the platform is in the horizontal fully deployed position, the ramp may be arranged to be substantially horizontal, or it may be arranged to be vertical thereby acting as a barrier to prevent a wheelchair on the lift from rolling off the lift.

Figure 5 shows the lift after being manually deployed to its horizontal position. The handrails 12,13 are in an inoperative condition within the overall outline of, and folded down against the load-bearing platform 6.

The roll-on ramp 9 is shown in an upstanding vertical position relative to the platform.

Figure 6 shows the lift of Figure 5 having the handrails 12,13 deployed into an operative condition by hydraulic means which will be described in more detail below. The offside handrail 13 is elongated with respect to the nearside handrail 12 so as to prevent a paramedic from accessing a patient the side nearest to the road. Instead the paramedic can only, easily, access the patient from the side farthest from the road.

Figure 7 shows the lift in a fully deployed and lowered condition with the roll-on ramp 9 deployed ready to accept a patient onto the load-bearing platform 6. The roll-on ramp 9 is lowered from the vertical position to its horizontal deployed position manually or automatically by the retraction of a metal rod (not shown).

Figure 8 shows the lift in a raised condition, level with the floor 20 of the vehicle. The roll-on ramp 9 is in an upstanding condition to prevent the stretcher/wheelchair from falling from the load-bearing platform 6. The bridge-plate 30 is automatically deployed when the load-bearing platform 6 is level with the floor 20 of the ambulance by means of a mechanism which will be described in more detail below. This bridge-plate 30 spans the gap between the load-bearing platform 6 and the floor 20 of the ambulance.

Figure 9 shows the mechanism for the lowering and raising of the bridge-plate 30. The bridge plate 30 is pivotally mounted on the rear end of the platform 6 about a pivot axis 31. The bridge-plate 30 is maintained in an upstanding condition by means of a plunger 40 which acts against an abutment surface 32 on the bridge plate 30. The plunger 40 is in sliding engagement with an actuation arm 41. A raised portion 42 is located on the uppermost surface 43 of the actuation arm 41. When the lift is raised the raised portion 42 contacts the underside 50 of the ambulance 51. This action causes the downward movement of the plunger 40 which allows the

bridge-plate 30 to rotate downwards about the pivot axis 31 in the direct of arrow A to be deployed into a substantially horizontal operative condition, in which it bridges the gap between the platform 6 and the floor of the ambulance 51.

In an alternative to this mechanical system, a switch can be located on the raised portion 42 which is closed by contact with the under side of the vehicle and triggers a hydraulic actuation system which lowers the plunger 40. In this case the raised portion 42 can be on one of the arms 8 rather than a separate actuation arm. Downward movement of the arms 8 is then detected by the switch which causes the hydraulic system to raise the plunger 40 to lift the bridging plate 30.

Referring to Figure 10, in a modification of the first embodiment, means 70 for lateral movement (relative to a vehicle) of the load-bearing platform are provided. The means 70 comprises first 71 and second 72 members having complementary keyed portions 73,74. The first member 71 supports the front ends of the arms 8, and the second member 72 is mounted on the vehicle.

The first member 71 is supported on a bearing 80 in engagement with the second member 72. The second member 72 is provided with a hydraulic cylinder 90 which acts between the first and second members and, in use, enables the first member 71 to be moved along a longitudinal axis of the second member 72, laterally of the vehicle. This allows the platform 6 to be moved laterally across the rear of the vehicle.

Referring to Figure 11a an ambulance 100 is shown having a lift 102 according to a second embodiment of the invention in a first operative condition. A load bearing platform 110 is supported on and in pivotal engagement with two pairs of arm members 103,104, similar to the arms

8 of the first embodiment. Each pair of arm members 103,104 is supported at its front end at upper and lower pivoting mounting points 103a, 103b on a respective mounting block 113, as shown in Figure 12.

The mounting blocks 113 are each clamped by means of screws 114 onto a horizontal rod 105 which extends across the rear of the vehicle. The elongate rod 105 is connected to a piston which is in sliding engagement with a hydraulic cylinder 106. The hydraulic cylinder 106 is mounted on a support beam 111 located on an underfloor member 7, for example, a chassis member of the ambulance 1. The rod 105 is slidingly supported in three mounting bearings 108,109, 112 which in turn are mounted on the support beam 111.

The flow of hydraulic fluid to the hydraulic cylinder 106 is controlled so as to control movement of the piston, and hence the rod 105 in the lateral direction, and hence lateral movement of the platform 110 across the rear of the vehicle.

Figure llb shows the lift 102 of Figure 11a in a second operative condition having been displaced along the longitudinal axis of the elongate rod 5 in the direction of arrow A.

Referring to Figures 13A to 13D and 14, in a third embodiment of the invention, an lift includes a platform 230 having two rails 210,210A, one on each side. Each rail includes a tubular support or upright 213, arranged to extend, and have its longitudinal axis, substantially vertical when the rail is in use, and the support 213 has an upper portion 211 and a lower portion 212. The lower portion 212 comprises a hollow circular cylinder 220, coaxial with the rest of the support, which, in use, receives a piston 221 and a helical spring 222, both of which are co-axial with the cylinder and therefore also with the support 213. The spring 222 is operatively associated with the piston 221 and cylinder 220 so that, in the

absence of an opposing force, the spring 222 acts to retain the piston 221 in a retracted position within the cylinder 220, whereby the rail assumes the position shown in Figure 13A where it is folded down against the platform 230.

Each rail 210 and 210A is disposed at one side of a platform 230 and each rail is pivotable about a horizontal pivot 231, which is offset from the longitudinal axis of the piston and cylinder, being vertically above it when the rail is folded down in its horizontal position. The lower end of the lower portion 212 of each rail which, in use, contains the cylinder 220 (with its associated piston 221 and spring 222), is received in a profiled socket 232.

Actuation means which in this case comprises hydraulic fluid supplied through a port 240, permits the application of a force to the cylinder 220, so that the piston 221 is urged outwardly from the cylinder and into sliding contact with the wall 233 of the profiled socket 232. When the handrail is in its stowed position, the axis of the piston and cylinder is horizontal. Extension of the piston tends to rotate the rail about the pivot 231 axis causing it to be rotated and be lifted upwards away from the platform 230 until it reaches its deployed position in which the support is vertical.

As the piston 221 is extended further it follows the profiled shape of the wall 233, and the rail is progressively raised, through the positions shown in Figures 13B and 13C, to reach the position shown in Figure 13D, where the support 213 is vertical and the rail is secured against movement by pressure of the piston 21 against the foot 34 of the socket 32.

To lower the rail, the hydraulic force is released, whereupon the piston 21 is retracted into the cylinder by the action of the spring 22. If

the piston is retracted slowly the piston again follows the shape of the wall 33 of socket 32 allowing the rail to be progressively lowered, for example under its own weight, through the positions shown in Figures 13C and 13B, to reach the position shown in Figure 13A.

Alternatively the piston may simply be retracted and the rail lowered manually.

Referring now to Figure 15, an ambulance or similar vehicle (shown schematically at 350) has an opening 351 in one side for the ingress and egress of patients or other passengers. When not in use, the opening 351 is closed by means of a ramp 352, which is pivotally attached, for example by means of a hinge, to the vehicle 350 and moveable in the direction of arrows AA'.

The ramp 352 is provided at one side with a powered rail 310 of the type shown in Figures 13A to 13D and 14.

On the underside of the ramp 352 which, when the ramp 352 is folded away in a stowed position, faces away from the vehicle 350, there is located an actuator for the powered rail 310. The actuator comprises a hollow circular cylinder 353 which, in use, receives a piston 354. The cylinder 353 is connected by means of a hydraulic hose 356 to the cylinder 220 in the rail 310. A helical spring 355 is operatively associated with the piston 354 so that, in the absence of an opposing force, the piston 354 remains outside the cylinder so that no hydraulic pressure is transmitted to the cylinder 220 in the rail 310 and the rail assumes a folded or stowed position equivalent to that shown in Figure 13A.

The stowed position of the rail is the position assumed when the ramp 352 is raised so as to cover the opening 351.

As the ramp 352 is lowered so as to expose the opening 351, the piston 354 is urged along the cylinder 353, so that pressure is transmitted, through hose 356, to the rail 310. The pressure causes the rail 310 to be raised to the"up"position (a position equivalent to that shown in Figure 13D) and locked in place.

When the ramp 352 is raised, the hydraulic pressure is released and the rail 310 is lowered through positions equivalent to those shown in Figures 13C and 13B, to the"down"position.

In an alternative to the above described method of powering the handrail mechanism of Figure 13, the hydraulic piston is a two-way piston which is coupled to a two-way hydraulic pump supplying pressurised fluid. The pump can operate in two directions to provide pressure to either side of the piston to urge it in either direction. The pump is controlled by an electronic control unit which is connected to a switch unit held by a user.

The switch and pump can therefore be used to control raising and lowering of the handrail. The two-way piston can be powered to the end of its stroke in either direction, which corresponds to the fully raised and fully lowered positions of the handrail, and when it reaches either of those positions it simply blows off, so that it can keep pumping without damaging the system.

Referring to Figure 16 a bridge plate control mechanism 401 which can be used in place of that shown in Figure 9 comprises a hydraulic cylinder 402 and piston 403. Figure 16 is a rear view of the mechanism 401. The mechanism is housed within a housing or support beam 409 which is located on the platform 412 between two arm members 410,411, corresponding to the arm members 8 in the first embodiment. The mechanism comprises a rocker member 405 pivotally mounted at a pivot 407 at one end to the support beam 409. The rocker member extends

horizontally across vehicle parallel to the beam 409, and has an upwardly extending abutment portion 406 at its other end. The rocker member 405 has a bevelled edge 404 towards its free end, facing downwards and away from the pivot 407 at approximately 45 degrees to the horizontal and vertical. A piston 403 extends horizontally beneath the free end of the rocker member 405, and is slidingly supported in a cylinder 402. The piston 403 is supported by a support block 408 and slides across its upper surface when it is extended or retracted. When the piston is extended from the cylinder it supports the rocker member in a raised position as shown in Figure 16 in which the abutment portion 6 of the rocker member 5 extends outside the cross beam 409. As the piston is retracted it moves along the bevelled edge 404 which allows the rocker member to drop down to a lowered position as shown in Figure 17 in which the abutment portion is retracted into the beam 409. Extending the piston again pushes against the bevelled edge 404 and forces the rocker member upwards again, raising the abutment portion 406.

In use as the piston 403 is moved outwardly of the cylinder 402 against the bevelled edge 404 of the rocker member 405, the bevelled edge 404 of the rocker member translates the lateral movement of the piston 403 into vertical movement of the abutment portion 406.

Referring to Figures 19 and 20 the bridge plate mechanism is used to raise and lower a bridge plate 413 corresponding to that of Figure 1, which is connected to a platform 412 of a lift. The bridge plate is rotatable about a horizontal pivot axis 414 between a vertical raised position and a horizontal lowered position. The cross beam 409 corresponds to the carriage portion 7 of Figure 1, and is pivotably connected to the platform and the two arm members 410,411 in a corresponding manner. The abutment portion 406 of the rocker member acts against the under side of the bridge plate 13. When the abutment

portion 406 is in its raised position, it pushes the bridge plate upwards as shown in Figure 19. When the abutment portion 406 is lowered, it allows the bridge plate 413 to be lowered towards its deployed position as shown in Figure 20. The rocker member is urged downwards towards its retracted position by a spring 414.

The bridge plate is moved from a stowed condition to a deployed condition when the load-bearing platform 412 is raised to a level of a floor of a vehicle as detected by a micro-switch 420. The micro-switch 420 is mounted on the side of the cross member 409 and is triggered by movement of the cross member 409 relative to the arm member 410 as the lift is raised and lowered. A control mechanism for the piston, which may be hydraulic or electric or pneumatic, responds by causing the piston 403 to be actuated and withdrawn into the cylinder 402. The rocker member 405 is then free to rotate downwards, about its pivot 407 as the piston 403 withdraws from sliding engagement with the bevelled portion 404 of the rocker member 405. The abutment portion 406 of the rocker member 405 moves to its retracted position under the influence of the spring 414, as well as its own weight. This allows the bridge plate 413 to move from its stowed condition to a deployed condition such that the bridge plate 413 spans a gap between the load bearing platform 412 of the lift and the floor of the vehicle, as shown in Figure 20. The piston 403 may be biased to towards its retracted position, for example by a spring. Since the rocker member is biased towards its lowered position, it will return to that position if there is any fault with the actuating mechanism for the piston 403, allowing the bridge plate to be raised and lowered manually.

Where appropriate, the lifting means used to raise and lower the lift platform in the embodiments described above can be in other forms known in the art, such as a vertical slide mechanism, powered hydraulically, pneumatically or electrically.