Caterpillar Tractor Co.

Lawrance F Berg

Theodore B Hogg

Peter F Prillinger

PCT No. PCT/US80/00228 Sec. 371 Date Mar. 3, 1980 Sec. 102(e) Date Mar. 3, 1980 PCT Filed Mar. 3, 1980 A hydraulic servo steering system (10) for vehicles has a steering valve (24) for directing fluid to steering cylinders (16,17) in response to pilot fluid directed to one end of the steering valve (24) from a hand metering unit (31). A servo cylinder (19) directs a volume of fluid to the other end of the steering valve (24) sufficient for returning the steering valve (24) to its centered position in response to turning of the vehicle. A pair of pilot operated check valves (53,54) positioned in the lines (51,52) between the servo cylinder (19) and the steering valve (24) are opened in response to fluid pressure being established in the lines (51,52) by a means (71). Should one of the lines (51,52) rupture, the resultant drop in fluid pressure in the lines (51,52) causes the check valves (53,54) to close thereby isolating the steering valve (24) from the ruptured lines (51,52). Thereafter the steering valve (24) can be operated in a 'jerk steer' manner for emergency steering of the vehicle.

Hydraulic servo steering system

A crane comprises a lower frame having an upper frame rotatably mounted thereon. A pair of rear roadwheels are rotatably mounted on either end of an axle housing pivotally mounted on the lower frame and suspended thereunder by a pair of laterally spaced suspension cylinders. A boom, pivotally mounted on the upper frame, is adapted to be lowered and positioned forwardly of the crane when it is driven to a remote job site. During such forward positioning of the boom, either when loaded or unloaded, a cam secured to the upper frame trips an air valve for opening a pair of slave valves to communicate hydraulic fluid between the head ends of the suspension cylinders to permit the axle to oscillate. When the crane is placed in operation and the upper frame is rotated on the lower frame, the cam will release the air valve which closes the slave valves to block communication of hydraulic fluid between the suspension cylinders whereby the axle is placed in a lock-out condition of operation. The rod ends of the suspension cylinders are preferably disposed in unattached relationship adjacent to the axle housing, but could be secured thereto.

Lock out means for pivotal axle suspension cylinders

PCT No. PCT/US79/00920 Sec. 371 Date Oct. 29, 1979 Sec. 102(e) Date Oct. 29, 1979 PCT Filed Oct. 29, 1979 A steering system (36) for vehicles (10) in which a device (90) is provided for circulating fluid through the system when operating in a cold environment. The system includes a hand metering unit (58) which is connected to opposite ends of a pilot operated steering valve (42) through a pair of pilot lines (60,62). A pressure reducing valve (94) maintains a continuous flow of fluid to the pilot lines (60,62) at a first predetermined pressure level. A pressure responsive valve (94) positioned between the hand metering unit (58) and a reservoir (40) intermittently passes pilot control fluid, returned to the hand metering unit (58) from the pilot actuation of the steering valve (42), to the reservoir (40) in response to the pressure of such returned fluid reaching a second slightly higher predetermined pressure level such as occurs when the fluid in the system is cold. This passing of cold fluid to the reservoir and the subsequent replacement of such fluid establishes circulation of fluid through the pilot control system and overcomes the problems of increased operator input force and increased system response time caused by cold fluid in the pilot control system.

Steering system for cold environments

A fluid jack (10) has a cushioning device (21) positioned within a cylinder (11) between a piston means (12) and a closed end (13) with the cushioning device (21) being a self-contained unit independent of any major components of the fluid jack (10). A variable volume chamber (24) is formed between a pair of members (22,23) with the cushioning taking place by metering the fluid expelled from the variable volume chamber (24) in response to the piston means (12) engaging and moving one of the members (22,23) in a direction for decreasing the volume of the variable volume chamber (24).

Cushioning device for fluid jacks

The invention is concerned with an improved fluid operated hydraulic ram wherein the travel of the piston thereof is cushioned to reduce impact by progressively restricting fluid flow. The ram of the invention comprises a housing defining a generally cylindrical ram bore having a first wall at a first end thereof with a first hole generally centrally therethrough and a second wall at a second end thereof with a second hole generally centrally therethrough leading to a chamber. A piston fits reciprocally within the ram bore and includes a piston rod extending therefrom through the first hole and a snubber extending from the opposite side thereof towards the second hole. The snubber is sized to pass into the second hole in spaced flow restrictive relation thereto towards the chamber to create a relatively higher pressure in the ram bore adjacent the second end thereof than in the chamber. A valve forms a part of the ram, the valve being adapted to pass a first fluid flow from a first conduit which communicates with the chamber to a sump. A second conduit communicates a second fluid flow from the second end of the ram bore with the valve to adjust the valve to meter the amount of the first fluid flow. A third conduit communicates with the ram bore adjacent the first wall and a pump is provided which causes a third fluid flow from the sump selectively to either the first or third conduit.

Fluid operated ram

An outer bearing race is mounted in a bore defined in a support member and an inner bearing race is universally mounted in the outer race to form a ball and socket connection therebetween. An annular retainer is secured in the bore on each side of the outer race to retain an annular lip seal therebetween. A flexible lip of the seal extends radially inwardly into sealing contact with a convex spherical surface formed on the inner race.

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Lockport, IL, United States of America

Lawrance F Berg