Caterpillar Tractor Co.

Lucien B Shuler

William J Spivey

James E Schimpf

Roland E Hasselbacher

Hydrostatic transmissions are commonly employed in the drive train of earthmoving and industrial vehicles. It is difficult to stop some such vehicles at a precise location on a slope due to the presence of a delay valve included in the controls for delaying application of a friction brake until the vehicle has been stopped by the hydrostatic transmission. In the present control system, a manual control valve (74) is moved to a first operative position and a hand control lever (25) is manipulated in combination therewith to reduce the displacement of a variable displacement pump (12) to establish a minimum drive condition sufficient to hold the vehicle motionless. Thereafter the manual control valve (74) can be moved to a second operative position to apply a friction brake (18) while the transmission maintains the vehicle motionless. In order to start the vehicle from the stopped position on a slope without unwanted roll, the transmission is either maintained at the minimum drive condition while the vehicle is stopped or the control lever (25) is manipulated to reestablish the minimum drive condition such that when the friction brake (18 ) is released by returning the control valve (74) to the first operative position, no undesired vehicle motion will occur. Normal vehicle motion may then resume by further manipulation of the control lever (25) and/or the manual control valve (74).

Control system for hydrostatic transmission

A control arrangement comprises a pivotal control member having a pair of arms and a pivotal lever disposed between the arms. The stop member is secured on the lever to engage a snubber upon relative pivoting between the control member and lever. The control arrangement is adapted for connection to a control valve to alert the operator when the control lever has over-travelled a 'run' condition of operation when the stop member engages the snubber.

Control arrangement with snubber means

Sequential preconditioning circuit for hydrostatic transmission

A brake system for a vehicle having spring applied, pressure releasable brakes (10) including a manual pump (28), a terminal board (14) having ports (16,18,20) terminating the system fluid pressure line (22), the brake pressure line (12) and the pump pressure line (76), and a U-tube (120) connecting two of the ports on the terminal board. In the alternative embodiment, an emergency brake release system for a vehicle having spring applied, pressure releasable brake (130) including a pump (166), and a control valve (140) for selectively connecting the pump (166) to the brakes (130) while connecting the fluid pressure supply line (133) to a reservoir return line (136). The valve (140) includes modes for connecting the brakes (130) to the supply line (134) through an orifice (192), and a brake outlet line (138) to the reservoir return line (136) for bleeding the brakes (130), and for isolating the supply line (134) while venting the brake line (133), for checking system pressure. A limit switch (200) prevents engine starting while the brakes (130) are manually released.

Parking brake system

PCT No. PCT/US79/00415 Sec. 371 Date June 13, 1979, Sec. 102(e) Date June 13, 1979 PCT Filed June 13, 1979 PCT Pub. No. WO80/02824 PCT Pub. Date Dec. 24, 1980 The drives (34,34') of a vehicle are each driven by a pump (18) and motor (22) of a hydrostatic transmission (23). A servo-system (20) associated with each pump (18) is adapted to be controlled by a steering arrangement (35,36) for selectively rotating the drives (34,34') relative to each other. An interlock valve (43,44) is associated with each steering arrangement to stop the drives (34,34') of the vehicle when steering pedals (37,38) thereof are both depressed into certain positions (N,R) of operation. Thus, the operator of the vehicle is prevented from placing the vehicle in an unwanted mode of operation, such as in reverse, when the operator desires another mode of operation, such as braking of the vehicle.

Steering system with interlock valves

An actuating mechanism for selectively actuating the control valve of a transmission or the like comprises a rotary input shaft connected to a pair of links at a lost-motion connection. Opposite ends of the links are pivotally connected to a crank assembly pivotally mounted on a rotary input shaft connected to the control valve. A torsion spring is interconnected between the rotary output shaft, the crank assembly and one of the links to selectively rotate the rotary output shaft in opposite directions in response to rotation of the rotary input shaft in opposite directions.

Actuating mechanism for hydrostatic transmission

A speed control system for an internal combustion engine having a variable speed throttle includes an operator input control member connected through suitable linkage to vary the setting of the variable speed governor and includes a balance mechanism having spring means operating in opposition to the reactive forces of the governor for providing a relatively uniform control feel over the range of the operator control member.

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Bettendorf, IA, United States of America

Lucien B Shuler