Caterpillar Tractor Co.

Sidney J Audiffred

Shairyl I Pearce

Albert L Woody

Lowell E Johnson

David S Ohaver

Raymond N Erkkila

David W Bump

Howard C Steury

A hydraulic control system for a multi-directional multi-speed transmission for the power train of a vehicle includes means responsive to the directional shift of the transmission at a predetermined minimum speed to automatically apply the brakes of the vehicle during a shifting period.

Control system to apply vehicle brakes during a transmission directional

A safety valve includes a movable piston which functions to prevent actuation of fluid operated drive conditioning clutches of a vehicle transmission unless the selector valve means are passed through a neutral position. Such safety valve spool also acts as a load piston for a pressure modulating relief valve of the system.

Modulating relief valve with hydraulic safety

A drive train for vehicles such as earthmoving machines having a prime mover coupled in driving relation with ground wheels for the machine through a power input member and a power output member. One or more implements are coupled to the power input member. In order to selectively match or mismatch power delivered by the prime mover with varying power requirements for the implements and wheels, a hydraulically operated slipping clutch is arranged between the power input and output members for adjusting power delivery from the prime mover to the output member and wheels with a manual control for regulating hydraulic operation of the slipping clutch. In other embodiments, the power input and output members are portions of a torque converter, a centrifugal valve also being provided to operate the slipping clutch in response to rotational speed of an element in the drive train and under regulation of the manual control. Another embodiment includes the slipping clutch disposed in a fluid housing subject to variable pressure with the centrifugal valve being responsive to the variable fluid pressure. In another embodiment, controls for a transmission in the drive train are also operative to provide regulation of the slipping clutch.

Torque converter with speed responsive slip clutch

A control system for a vehicular drive train including a slipping clutch for proportioning power from a prime mover to implements and a primary output shaft of the vehicle including a manual control conditioned by a manual selector to vary engagement of the slipping clutch through a regulating valve in a first mode of vehicle operation and to regulate acceleration of the prime mover in a second mode of vehicle operation. Additional elements of the control system include an adjustable wheel slip sensing mechanism preferably associated with the manual control, a bypass valve associated with the regulating valve and preferably with a hydraulically operable transmission in the drive train for maintaining at least limited engagement of the slipping clutch in order to prevent or limit reverse rotation of components within a torque converter coupled with the slipping clutch and an input valve also associated with the transmission to condition the slipping clutch for receiving a substantial portion of shock loading applied to the drive train.

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Washington, IL, United States of America

Sidney J Audiffred