US3968890A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vehicle load lifting and lowering units
Assignee: John Ratcliff Tail Lifts Ltd
•
Filing: 1975-04-08
•
Granted: 1976-07-13
•
Expires: 1995-04-08
Abstract
Abstract There are disclosed two forms of load lifting and lowering unit for attachment to a vehicle. The units are of the kind in which a load platform is carried between two parallel spaced-apart articulated parallelogram linkages, movable in unison up and down guide members spaced across an access opening of the vehicle to raise and lower a load to and from the access opening. An inextensible tie member, pivotally connected between the platform and a swinging arm of the parallelogram linkage, causes the platform automatically to close off the access opening when the linkages are folded towards the vehicle. In one embodiment, the swinging arm cooperates with a fixed stop during upward movement of the linkages to effect such closure: in the other embodiment, a fluid operated ram swings the platform upwardly about its pivot to fold the linkages towards the vehicle and cause the platform to close off the access opening.
Inventors
- 👤 Robert Robson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:15
CPC Classifications
B; B60; B60P; B60P1/00; B60P1/44; B60P1/4414; B60P1/4421; B60P1/4442; Y; Y10; Y10S; Y10S414/00; Y10S414/13
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
248 words
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.
Claim 2
Dependent Claim
248 words
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.
Claim 3
Dependent Claim
81 words
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.
Claim 4
Dependent Claim
59 words
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.
Claim 5
Dependent Claim
21 words
The unit of claim 3, in which the ram is connected between the platform and the platform-supporting arm of the linkage.
Claim 6
Dependent Claim
43 words
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.
Claim 7
Dependent Claim
25 words
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.
Claim 8
Dependent Claim
34 words
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.
Claim 9
Dependent Claim
74 words
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.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-07-13 | 1980-01-12 | 1980-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-07-13 | 1984-01-12 | 1984-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-07-13 | 1988-01-12 | 1988-07-13 | $7700.00 | Window Closed / Lapsed |