US3801151A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Double-acting lift cylinder with integral velocity fuses
Assignee: Enerpac Tool Group Corp
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Filing: 1972-08-30
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Granted: 1974-04-02
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Expires: 1992-08-30
Abstract
Abstract A truck has a cab tiltable between full-down and full-tilt positions by means of double-acting hydraulic lift cylinders. The double-acting cylinder and the control system therefor, which includes a manually, electrically or air driven pump and a manually operable selector valve, enables the cab to be positively moved from full-down to overcenter position whereupon the cab then slowly descends under the force of gravity to fulltilt position. Furthermore, it enables the cab to be positively moved from full-tilt position to overcenter position whereupon the cab then slowly descends under the force of gravity to fulldown position. Each cylinder is provided with two integrally mounted velocity fuses as a safety feature. In the event of a hydraulic system failure, one fuse prevents free-fall movement of the cab when the cab is in any position between full-down and overcenter position. In one embodiment of the invention, both fuses are located in the lower end of the cylinder. In another embodiment, the fuses are located at opposite ends of the cylinder.
Inventors
- 👤 Roy Reynolds
- 👤 William T Neill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:48
CPC Classifications
B; B62; B62D; B62D33/00; B62D33/06; B62D33/063; B62D33/067; B62D33/07; F; F15; F15B; F15B15/00; F15B15/08; F15B15/14; F15B15/1423; F15B15/1433; F15B15/149
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
334 words
In combination: a truck comprising a chassis and a cab mounted thereon for movement between a full-down position and a full-tilt position past an overcenter point; a double-acting hydraulic jack connected between said chassis and cab for moving said cab and comprising a cylinder housing having a cylinder and a piston therein dividing said cylinder into an extend chamber and a retract chamber, said jack being operable in one direction to move said cab from full-down position past said overcenter point whereupon said cab tends to descend under the force of gravity toward full-tilt position and moves said piston further in said one direction, said jack being operable in a direction opposite to said one direction to move said cab from full-tilt position past said overcenter point whereupon said cab tends to descend under the force of gravity toward full-down position and moves said piston further in said opposite direction; a fluid reservoir; a selectively operable pump for receiving fluid from said reservoir and for supplying pressurized hydraulic fluid to operate said jack; a selectively operable control valve connected between said pump and said jack for directing fluid from said pump to either chamber of said jack to effect operation of said jack in either direction; check valve means connected to said pump to prevent back-flow of fluid from said jack through said pump when said pump is being operated to operate said jack in either direction; and first and second velocity fuses integrally mounted in said cylinder housing of said jack, each fuse being connected in a fluid passage between said control valve and one chamber of said jack, and comprising a movable valve member in said fluid passage, each valve member having an open position enabling fluid flow to and from its respective chamber when said cab is moving, and each valve member being responsive to a decrease of fluid pressure to prevent fluid flow from its respective chamber and thereby stop further descent of said cab under the force of gravity.
Claim 2
Dependent Claim
334 words
In combination: a truck comprising a chassis and a cab mounted thereon for movement between a full-down position and a full-tilt position past an overcenter point; a double-acting hydraulic jack connected between said chassis and cab for moving said cab and comprising a cylinder housing having a cylinder and a piston therein dividing said cylinder into an extend chamber and a retract chamber, said jack being operable in one direction to move said cab from full-down position past said overcenter point whereupon said cab tends to descend under the force of gravity toward full-tilt position and moves said piston further in said one direction, said jack being operable in a direction opposite to said one direction to move said cab from full-tilt position past said overcenter point whereupon said cab tends to descend under the force of gravity toward full-down position and moves said piston further in said opposite direction; a fluid reservoir; a selectively operable pump for receiving fluid from said reservoir and for supplying pressurized hydraulic fluid to operate said jack; a selectively operable control valve connected between said pump and said jack for directing fluid from said pump to either chamber of said jack to effect operation of said jack in either direction; check valve means connected to said pump to prevent back-flow of fluid from said jack through said pump when said pump is being operated to operate said jack in either direction; and first and second velocity fuses integrally mounted in said cylinder housing of said jack, each fuse being connected in a fluid passage between said control valve and one chamber of said jack, and comprising a movable valve member in said fluid passage, each valve member having an open position enabling fluid flow to and from its respective chamber when said cab is moving, and each valve member being responsive to a decrease of fluid pressure to prevent fluid flow from its respective chamber and thereby stop further descent of said cab under the force of gravity.
Claim 3
Dependent Claim
24 words
A combination according to claim 1 wherein both of said velocity fuses are located in passages at the same end of said cylinder housing.
Claim 4
Dependent Claim
45 words
A combination according to claim 2 wherein the passages for both velocity fuses are formed in said cylinder housing, and wherein one passage for one velocity fuses is connected by means of a rigid tube located exteriorly of said housing to one of said chambers.
Claim 5
Dependent Claim
24 words
A combination according to claim 1 wherein the passages for said velocity fuses are located in and near opposite ends of said cylinder housing.
Claim 6
Dependent Claim
133 words
A combination according to claim 1 wherein each velocity fuse comprises a bore having a reduced portion defining a valve seat on one side thereof, a ball valve in said bore for cooperation with said valve seat to prevent fluid flow through said bore in one direction, a fluid port connected to said bore on the other side of said reduced portion, adjustable spring means in said bore and engageable with said ball valve to maintain said ball valve unseated under normal conditions of fluid flow, guide spring means in said bore and engageable with said ball valve to maintain said ball valve in position to properly seat against said valve seat, and a passage connected between said bore on said one side of said reduced portion and one of said cylinder chamber.
Claim 7
Dependent Claim
59 words
A cylinder according to claim 5 wherein the pair of velocity fuses are located at the same end of said cylinder housing, wherein the passage for each fuse is formed in said cylinder housing, and wherein the passage for one fuse is connected by means of a tube located exteriorly of said cylinder housing to one of said chambers.
Claim 8
Dependent Claim
22 words
A cylinder according to claim 6 wherein the bores of said velocity fuses are transverse to the axis of said cylinder housing.
Claim 9
Dependent Claim
41 words
A cylinder according to claim 7 wherein the pair of velocity fuses are located at opposite ends of said cylinder housing and wherein the passages for connecting the bores thereof to said cylinder chamber are both formed in said cylinder housing.
Claim 10
Dependent Claim
39 words
A cylinder according to claim 8 wherein the bore of one velocity fuse is transverse to the axis of said cylinder housing and the bore of the other velocity fuse is parallel to the axis of said cylinder housing.
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) | 1977-04-01 | 1977-10-01 | 1978-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-01 | 1981-10-01 | 1982-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-01 | 1985-10-01 | 1986-04-02 | $7700.00 | Window Closed / Lapsed |