Implements or apparatus for applying pushing or pulling force – Fluid pressure – Vehicle attached
Patent
1991-08-27
1992-03-31
Hartman, J. J.
Implements or apparatus for applying pushing or pulling force
Fluid pressure
Vehicle attached
254423, B66F 324
Patent
active
051001055
ABSTRACT:
A lifting and lowering system for a trailer includes one or more extendible and retractable legs, with the legs being provided with springs or the like urging the legs toward their retracted position. The system is a pressurized air/hydraulic system, and includes an air-operated booster valve for extending the legs when loaded. A master valve assembly is provided for controlling supply of air to the system and for allowing retraction of the legs. The master valve and air valve include a common actuator shaft so that the system is selectively connected to pressurized air or vented, as appropriate, when leg extension or retraction occurs. The master valve includes a cam actuator/cam follower piston operated system for selectively providing fluid pressure to a lock valve associated with each leg. The lock valve is biased toward a normally closed position, and is selectively movable to an open position for allowing extension or retraction of the legs.
REFERENCES:
patent: 4377190 (1983-03-01), Pierrat
patent: 4523743 (1985-06-01), Wang
Raffensperger, Jr. John W.
Schneider Robert H.
Hartman J. J.
Versa Technologies, Inc.
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