GB1602453A - Load lifting apparatus - Google Patents

Description

(54) LOAD LIFTING APPARATUS (71) We, PARKWOOD ENGINEERING COMPANY LTD., a British Company, of Brooklands Close, Windmill Road, Sunbury on Thames, Middlesex, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to load lifting apparatus for vehicles.

Such apparatus is usually attached to the rear opening of a van and comprises a frame and a platform having slides movable vertically in the frame using a ram operated cable system.

When a vehicle provided with a load lifting apparatus is travelling along the road the platform is stowed in its vertical position.

In the prior art the platform is prevented from movement into its horizontal position by two captive wedge devices, one located on each side of the platform. The wedge devices are manually engaged by the lift operator and are attached to the slides allowing the closed platform to be raised until the slides abut stops mounted on vertical guides.

Thus, the cables to which the slides are secured are put under tension and the hydraulic fluid in the ram cylinder is under pressure.

A valve is additionally provided to lock the fluid in the ram and maintain the platform in the raised position. The valve is closed manually by the lift operator. If the operator fails to close the valve and the fluid seeps away, the slides and platform will drop while the vehicle is in motion.

According to the invention, there is provided a vehicle provided with lifting apparatus comprising two upright guide members and pivotably mounting between their lower extremities a load lifting platform, means for securing the platform in its closed raised position comprising displaceable latch means fixedly mounted relative to the upright guide members and biased into a position for preventing the platform descending relative to the guide members, synchronising means for synchronising the displacement of said latch means, and means for preventing the platform from pivoting relative to the slides and means for releasing the platform from its closed raised position arranged to act on said synchronising means.

Thus, in the closed upright position of the platform the platform is not supported by the cables and the hydraulic fluid trapped in the ram, as in the prior art apparatus.

Other features of the load lifting apparatus form the subject of co-pending applications Nos. 7997/77, 7518/78 and 7520/78 1602451, 1602452, and 1602454. Features and advantages of the invention will be apparent from the following description, given by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic perspective exploded view of a lifting apparatus according to the invention attached to the rear of a lorry or van, the body of the van being omitted for clarity, and Figures 2 to 4 are diagrammatic views of the mechanical, platform-latching arrangement of Figure 1 showing different stages in the platform lifting and latching procedure.

In the particular embodiment of the invention shown in the drawings, the mechanical supporting means comprises two lugs 38 which project from the platform rear edge and two lugs 39 which project from the platform work face. Two pivotable latches 40 are provided one on each end of a load beam or toe guard 41, the latches being mounted on the load beam by a common axle 42 so that they are pivotable in unison.

Also acting on the axle 42 is a handle 66 by which the latches can be pivoted through a small angle. There is also provided a stop (not shown) which acts to limit the clockwise angular movement of the latches 40, the latches being biased in that clockwise direction by springs 43, Two pockets 44 are attached one to each guide 61.

When the platform 63 is in its open or down position illustrated in Figure 2 the latches 40 are released and normal operation of the platform is permitted. To close the platform it is lifted to the position illustrated in Figure 3 so that the lugs 38 and 39 are aligned below pockets 44 and latches 40 respectively.

To latch the platform a ram 32 is operated to raise the platform 63 from the position illustrated in Figure 2 to that illustrated in Figure 3 by means of cables 5 connected to slides 62. The lugs 39 displace the latches 40 which pivot anti-clockwise against the bias of springs 43 until the platform reaches such a height that the lugs 39 clear the latches 40, the latches then springing back to their normal positions but now below the lugs.

Simultaneously with the action of the latches 40, the lugs 38 engage in the pockets 44 and thus the platform is restrained from pivotal and vertical movement until the latches 40 are released by the handle 66.

Thus, the platform is locked automatically and does not require the operator to actuate valves, as in the prior art apparatus. Furthermore, the retention of the platform in the upright position illustrated in Figure 4 is not dependent upon pressurisation of the ram or the support of the cable. It avoids the disadvantage of the prior art apparatus in which creep of the platform downwardly is possible which results in the platform bouncing in transit and causing flexure and stressing of the cables, thus shortening the cable life. Severe creep results in the platform dropping to such an extent that it covers the vehicle rear lights and eventually contacts the ground.

WHAT WE CLAIM IS: 1. A vehicle provided with lifting apparatus comprising two upright guide members, and slides movable along said guide members and pivotally mounting between their lower extremities a load lifting platform, means for securing the platform in its closed raised position comprising displaceable latch means fixedly mounted relative to the upright guide members and biased into a position for preventing the platform descending relative to the guide members, synchronising means for synchronising the displacement of said latch means, and means for preventing the platform from pivoting relative to the slides and means for releasing the platform from its closed raised position arranged to act on said synchronising means.

2. A vehicle as claimed in claim 1, wherein said latch means are mounted on the upright guide members.

3. A vehicle as claimed in claim 1 or 2, wherein the platform has lugs extending from the workface thereof adapted to engage said latch means.

4. A vehicle as claimed in any preceding claim wherein said means for preventing pivoting of the platform comprises members fixed on the platform and members fixed on the guide members adapted to engage said members on the platform.

5. A vehicle as claimed in claim 4, wherein said members on the platform comprise lugs extending from the rear edge of the platform and said members on the guide members comprise pockets adapted to receive said lugs.

6. A vehicle as claimed in any preceding claim, wherein the latch means comprises a pivotable latch mounted on each upright guide member, said synchronising means comprising a common axle on which the latches are mounted so that the latches pivot in unison.

7. A vehicle as claimed in claim 6, wherein said releasing means comprises a handle acting directly on said common axle.

8. A vehicle as claimed in claim 5 or 6, wherein said common axle extends through a housing connecting said upright guide members.

9. A vehicle as claimed in claim 7, wherein said housing is arranged to be substantially at the floor level of the vehicle when the apparatus is installed on a vehicle.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. aligned below pockets 44 and latches 40 respectively. To latch the platform a ram 32 is operated to raise the platform 63 from the position illustrated in Figure 2 to that illustrated in Figure 3 by means of cables 5 connected to slides 62. The lugs 39 displace the latches 40 which pivot anti-clockwise against the bias of springs 43 until the platform reaches such a height that the lugs 39 clear the latches 40, the latches then springing back to their normal positions but now below the lugs. Simultaneously with the action of the latches 40, the lugs 38 engage in the pockets 44 and thus the platform is restrained from pivotal and vertical movement until the latches 40 are released by the handle 66. Thus, the platform is locked automatically and does not require the operator to actuate valves, as in the prior art apparatus. Furthermore, the retention of the platform in the upright position illustrated in Figure 4 is not dependent upon pressurisation of the ram or the support of the cable. It avoids the disadvantage of the prior art apparatus in which creep of the platform downwardly is possible which results in the platform bouncing in transit and causing flexure and stressing of the cables, thus shortening the cable life. Severe creep results in the platform dropping to such an extent that it covers the vehicle rear lights and eventually contacts the ground. WHAT WE CLAIM IS:

1. A vehicle provided with lifting apparatus comprising two upright guide members, and slides movable along said guide members and pivotally mounting between their lower extremities a load lifting platform, means for securing the platform in its closed raised position comprising displaceable latch means fixedly mounted relative to the upright guide members and biased into a position for preventing the platform descending relative to the guide members, synchronising means for synchronising the displacement of said latch means, and means for preventing the platform from pivoting relative to the slides and means for releasing the platform from its closed raised position arranged to act on said synchronising means.

2. A vehicle as claimed in claim 1, wherein said latch means are mounted on the upright guide members.

3. A vehicle as claimed in claim 1 or 2, wherein the platform has lugs extending from the workface thereof adapted to engage said latch means.

4. A vehicle as claimed in any preceding claim wherein said means for preventing pivoting of the platform comprises members fixed on the platform and members fixed on the guide members adapted to engage said members on the platform.

5. A vehicle as claimed in claim 4, wherein said members on the platform comprise lugs extending from the rear edge of the platform and said members on the guide members comprise pockets adapted to receive said lugs.

6. A vehicle as claimed in any preceding claim, wherein the latch means comprises a pivotable latch mounted on each upright guide member, said synchronising means comprising a common axle on which the latches are mounted so that the latches pivot in unison.

7. A vehicle as claimed in claim 6, wherein said releasing means comprises a handle acting directly on said common axle.

8. A vehicle as claimed in claim 5 or 6, wherein said common axle extends through a housing connecting said upright guide members.

9. A vehicle as claimed in claim 7, wherein said housing is arranged to be substantially at the floor level of the vehicle when the apparatus is installed on a vehicle.