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Title: Vehicle load lifting and lowering units
Claims: I claim: 1. For attachment to a vehicle, a load lifting and lowering unit comprising: a pair of parallel spaced-apart guides, mountable in a vehicle so as to stand substantially upright across an access opening of the vehicle, b. a pair of articulated parallelogram linkages, slidably supported one on each of said guides, c. a load lifting and lowering platform pivotally carried between said linkages, d. a prime mover connected to said articulated linkages to move the linkages up and down the guides, e. means to actuate the articulated linkages, during movement thereof in one direction along a predetermined length of said guides, to alter the configuration of the linkages and thereby move the platform towards the interior of the vehicle for storage purposes, and to actuate the articulated linkages in the opposite sense, during reverse movement of the linkages along said predetermined length, thereby to move the platform away from said interior towards an operative position, and f. an inextensible tie member, pivotally connected between said platform and a swinging link of said parallelogram linkage at points which lie on the same side of the platform pivot, so that, when the linkage is actuated to move the platform towards the interior of the vehicle, the platform is swung about its pivot to fold with the linkage towards the vehicle interior, and when the linkage is actuated in the opposite sense the platform is swung in the opposite direction about its pivot to unfold with the linkage into its operative position. 2. The unit of claim 1, in which said means to actuate the linkage comprises an extension of said swinging link of the parallelogram linkage and a cooperating stop, fixed relative to the linkage on the opposite side of the guide to the platform-supporting arm of the linkage so that, on movement of the linkage in said one direction along the guide, said stop engages said arm to articulate the linkage and swing the platform about its pivot towards the vehicle interior. 3. The unit of claim 1, in which said means to actuate the linkage comprises a fluid operated ram, connected between the platform and one of the arms of the linkage so that operation of the ram causes the platform to be swung about its pivot towards the vehicle interior when the linkage is actuated in the said one direction. 4. The unit of claim 3, in which the ram is connected between the platform and the platform-supporting arm of the linkage. 5. The unit of claim 4, further comprising control means which first prevent further operation of said prime mover after said predetermined length of movement of the linkages along the guides has occurred and then initiate operation of said ram to close the platform. 6. The unit of claim 5, further comprising a torsion bar in one of the linkage pivots which biasses the linkage towards its closed inoperative position. 7. The unit of claim 6, in which said torsion bar is provided in the platform pivot and is fixed at one end to the platform and at the other end to the platform-supporting arm. 8. The unit of claim 7, in which a hook is formed on the guide and a cooperating projection is formed on an external part of the linkage to move therewith, the projection initially coming to rest above the hook when the platform is swung into its inoperative position, and means then operating said prime mover to lower the projection into engagement with the hook to retain the platform and linkage in the inoperative position. Other info: Inventors: Robson, Robert (Welwyn Garden City, EN) Application Number: 566113 Filing Date: 1975-04-08 Publication_date: 1976-07-13 Assignee: John Ratcliff (Tail Lifts) Limited (EN) Primary Class(es): 414/540 414/545, 414/917 Other Classes: US Patent Ref:
Other Refs:
Primary Examiner: Werner, Frank E. Assistant Examiner: Oresky, Lawrence J. Attorney: Young & Thompson |
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