GB2287927A

GB2287927A - Vehicle platform lift

Info

Publication number: GB2287927A
Application number: GB9505178A
Authority: GB
Inventors: David Phillips
Original assignee: Passenger Lift Services Ltd
Current assignee: Passenger Lift Services Ltd
Priority date: 1994-03-15
Filing date: 1995-03-15
Publication date: 1995-10-04
Also published as: GB9404965D0; GB9505178D0

Abstract

A hydraulically-operated wheelchair lift, for a vehicle, comprises a platform (10, Fig 1) which can be raised hydraulically between ground level and a floor of the vehicle. A pivotally mounted flap 24 extends along an outboard edge of the platform and is movable between a raised stop-forming attitude and a lowered ramp-forming attitude by means of a hydraulic cylinder 34. The cylinder comprises a reciprocable operating rod 36 arranged to bear against a camming block 40 to cause rotation of the flap to its raised attitude upon advance of the operating rod from a retracted position to a first advanced position. The operating rod is arranged to be advanced beyond its first advanced position to assume a locking position as shown in which retraction by any lowering force which may be applied to the flap is precluded. <IMAGE>

Description

VEHICLE PLATFORM LIFTS This invention relates to vehicle platform lifts, and in particular to hydraulically-operated wheelchair lifts for vehicles.

A wheelchair lift of the kind to which this invention relates comprises a lifting platform which can be raised and lowered hydraulically, in a horizontal attitude, between the ground and a floor of the vehicle. To enable a wheelchair to be rolled on to or from the platform when on the ground, a pivotal flap is ordinarily provided along an outboard edge of the platform to form a short ramp leading up from the ground on to the platform. Once the wheelchair is loaded the flap can be pivoted to an upright attitude, so as to act as a stop which would prevent the wheelchair from rolling backwards off the platform.

In one known mechanism, the pivotally-mounted flap is spring-urged into an upright attitude in which it serves as a stop. A rocker secured to the flap is arranged to be brought into engagement with the ground surface, upon the platform being lowered to the ground, to cause rotation of the flap downwards (against the action of the spring) until it has arrived at a ramp-forming attitude. Upon raising the platform, after loading or unloading a wheelchair, the action of the spring automatically returns the flap to its upright, stop-forming, attitude.

It is also known to have hydraulic operation of the flap. In a known system an operating cylinder is secured alongside a side edge of the platform and acts upon a linkage which enables it to rotate the flap between ramp-forming and stop-forming attitudes. The operating cylinder is a single-acting cylinder with a return spring, acting when pressurised to raise the flap to its upright, stop-forming, attitude. - For safety, a separate latch is provided to secure the flap in its upright attitude, so as to ensure that the flap cannot become inadvertently lowered. Such a hydraulic system, in which platform-operating cylinders and the flap-operating cylinder are pressurised in common, provides the safety advantage that the platform cannot become raised until the flap has been raised, there always being a higher pressure requirement for the former than the latter.

It is an object of the present invention to provide a lift having hydraulic flap actuation of an improved design.

In one of its aspects the invention provides a hydraulically-operated wheelchair lift for a vehicle, the lift comprising a platform, first hydraulic actuating means operable to raise the platform between a lower level and a floor of the vehicle, a pivotally mounted flap extending along an outboard edge of the platform and movable between a raised stop-forming attitude and a lowered ramp-forming attitude, and second hydraulic actuating means operable to move the flap from its lowered to its raised attitude, the second actuating means comprising a reciprocable operating member arranged to cause rotation of the flap to its raised attitude upon advance of the operating member from a retracted position to a first advanced position, the flap and the operating member being so arranged as to permit the operating member to be advanced beyond its first advanced position to assume a locking position, the interengagement between the flap and the operating member in the locking position being such as to preclude retraction of the operating member by any lowering force which may be applied to the flap.

In a convenient arrangement, the operating member is in the form of a rod having a cylindrical outer surface over which a camming member of the flap slides as the operating member is advanced beyond its first advanced position; a similar result could, of course, be achieved with any form of rod if the camming member slid against a longitudinally-directed portion of the external surface of the rod. In this manner it can be ensured that no significant axial force can be applied, which would tend to retract the rod, through any rotational force applied to the flap. In a preferred construction a planar surface of the camming member slides against a parallel longitudinally-directed surface of the operating member as the operating member is advanced to its locking position, the camming member so lying flat against the operating member.

There now follows a description, to be read with reference to the accompanying drawings, of a roll-off stop mechanism in a hydraulic wheelchair lift which illustrates the invention by way of example.

In the accompanying drawings: Figure 1 is a plan view of an outboard portion of a platform of the lift; Figure 2 is a view on section II-II of Figure 1, though showing a flap in an alternative, ramp-forming, attitude; Figure 3 is a view similar to Figure 2, but showing the flap raised to an upright, stop-forming, attitude as in Figure 1; Figure 4 is a view on section IV-IV of Figure 1 illustrating the use of a fixed locking peg; and Figure 5 is a view in the direction of arrow "A" in Figure 1 showing a pivotal mounting for the flap.

A hydraulically-operated wheelchair lift, for installation in a vehicle, comprises a structure forming a generally rectangular platform 10. The platform is extensible in a telescopic manner, a movable outboard portion 12 of the platform being shown deployed in Figure 1. The outboard portion comprises side frame members 14 and 16, which are mounted to slide longitudinally on supporting main members 18 and 20 of the structure, and a cross-member 22 which interconnects free end portions of the side frame members.

An elongate, generally rectangular, sheet metal panel of a flap 24 extends parallel to the cross-member 22, with an inboard edge 26 of the flap close to the cross member. The flap is pivotally mounted to rotate about an axis 28, which is positioned adjacent to the inboard edge 26 of the flap and parallel to the edge and the cross-member, by means of pivot pins 30 (Figure 5) mounted in end plates 32 fixed to end faces of the cross-member 22. The flap is so mounted to rotate freely between an upright, stop-forming, attitude (Figures 1,3,4, and 5) and a lowered, ramp-forming, attitude (Figure 2).

The platform 10 is arranged to be raised and lowered hydraulically, between a lower level (ground level) and the level of a floor of a vehicle in which the lift is installed, in a conventional manner. As an extension of the hydraulic actuation system for moving the platform, a flap-actuating cylinder 34 is secured centrally and perpendicularly to the cross-member 22.

The cylinder is secured within the outboard portion 12 of the platform, a cylindrical operating rod 36 being able to project outwardly through an opening 38 through the cross-member (Figures 2 and 3) for actuation of the flap as hereinafter described.

As shown in Figures 2 and 3, a camming block 40 of the flap 24 is secured adjacent to its inboard edge 26 to enable the rod 36 to displace the flap about the pivot axis 28. When the flap is in its lowered, ramp-forming, attitude (Figure 2) the block 40, positioned below the axis 28, faces the opening 38 in the cross-member 22 and opposes the operating rod 36.

Upon the operating rod being extended from the cylinder 34, the advancing rod displaces the block rotationally until the flap as a whole has been rotated to its upright, stop-forming, attitude. At that stage, a flat locking face 42 of the block becomes parallel to, and commences to slide against, the cylindrical surface 44 of the rod as the rod advances still further; until that stage is reached it is a rounded end surface 46 (Figure 3) of the rod which bears against the block. It will be apparent that from this condition of the flap and the rod the geometry of the arrangement is such that the rod 36 cannot be caused to retract simply by force applied to the flap. Until the rod is otherwise withdrawn, therefore, the flap is locked in its upright, stop-forming, attitude.

The flap-actuating cylinder 34 is a single-acting cylinder having a return spring, the rod being advanced under hydraulic pressure and retracted under spring pressure. In use of the lift, and starting from the condition of Figure 3 in which the flap is in its stop-forming attitude, the platform is lowered to the ground with the flap maintained in that attitude. Upon the platform reaching the ground the hydraulic pressure in the system can be released, resulting in the operating rod 36 of the flap-actuating cylinder becoming retracted and the flap 24 (being suitably weighted) pivoting down under its own weight until it engages the ground in its ramp-forming attitude (Figure 2).Upon re-pressurisation of the hydraulic system to raise the platform, the flap-actuating cylinder first advances the rod 36 to raise the flap (and lock it) before any raising of the platform can occur, even should raising of the flap be obstructed (e.g. by a person standing on it).

The lift also comprises a secondary locking member for locking the flap in its stop-forming attitude when the platform is unextended (i.e. the outboard portion 12 of the platform is not stowed). A peg 48 (Figure 4) similar to the operating rod 36, projects from a fixed cross-member 50 of the platform in alignment with a further opening in the cross-member 22 of the outboard portion 12. When the outboard portion 12 of the platform is in the stowing position the peg 48 projects beyond the cross-member 22 by a similar distance to the rod 36 when fully advanced. A second camming block 52, similar to the first block 40, is secured to the flap so that, in a similar arrangement to the rod 36 and the first block 40, the flap can be moved to its upright stop-forming attitude (and locked in that position) by the relative advance of the peg 48 when the outboard portion is stowed. In this manner it is ensured that the flap remains locked upright, in the stowed condition of the platform, even if the hydraulic system becomes depressurised and the operating rod 36 withdrawn.

Claims

1. A hydraulically-operated wheelchair lift for a vehicle, the lift comprising a platform, first hydraulic actuating means operable to raise the platform between a lower level and a floor of the vehicle, a pivotally mounted flap extending along an outboard edge of the platform and movable between a raised stop-forming attitude and a lowered ramp-forming attitude, and second hydraulic actuating means operable to move the flap from its lowered to its raised attitude, the second actuating means comprising a reciprocable operating member arranged to cause rotation of the flap to its raised attitude upon advance of the operating member from a retracted position to a first advanced position, the flap and the operating member being so arranged as to permit the operating member to be advanced beyond its first advanced position to assume a locking position, the interengagement between the flap and the operating member in the locking position being such as to preclude retraction of the operating member by any lowering force which may be applied to the flap.

2. A lift according to claim 1 in which the operating member is arranged to bear against a camming member of the flap, advancement of the operating member to its first advanced position causing rotational displacement of the camming member to rotate the flap.

3. A lift according to claim 2 in which the camming member presents a planar surface against which the operating member lies parallel when in its locking position.

4. A lift according to any one of claims 1 to 3 in which the platform is extensible and the lift comprises a secondary locking member which in an unextended condition of the platform engages the flap so as to preclude lowering of the flap from its raised attitude even should the operating member become retracted.

5. A hydraulically-operated wheelchair lift for a vehicle comprising flap-actuating means substantially as hereinbefore described with reference to the accompanying drawings.