Abstract: A hydraulic circuit (32), for example, remotely controls a work element (14) and contains first apparatus (34), such as a master cylinder (42), which passes a fluid pressure signal through a fluid pathway (38, 40) in response to an input signal. Second apparatus (36), such as a slave cylinder (44), correspondingly delivers an output signal for controlling the work element (14). Temperature variation can cause fluid volume changes which disrupt synchronized operation of the master and slave cylinders (42, 44). Third apparatus (74) positions the fluid pathways (38, 40) in fluid communication with a tank (28) in the absence of the fluid signal. If the signal passes through one pathway (38, 40), that pathway (38, 40) is automatically blocked from communication with the tank (28). Thus, when the fluid signal is absent from the fluid pathways (38, 40), volume compensation occurs because of dilution of the fluid in the circuit (32) with the tank fluid.

Abstract: A brake cylinder includes a housing within which a piston is reciprocable, such piston acting on a cup seal. An annular resilient member of, for example, polyurethane material, is interposed the outer periphery of the cup seal and the adjacent outer periphery of the piston, and cooperates with such piston to engage the inner surface of the bore to prevent any portion of the seal being pinched between a portion of the piston and the inner surface of the bore.

Abstract: An air brake control system of high reliability is provided for a vehicle of the type having front wheel brakes, rear wheel brakes, a first brake control element such as a pedal which actuates the front and rear brakes, and a second brake control element such as a pedal which also actuates the front and rear brakes. First and second pneumatic circuit means for controlling the brakes are duplicated back to the outlet of the air compressor in an arrangement where one side of the circuit is automatically isolated from the other to maintain braking capacity if a loss of air pressure occurs on the one side. Means is associated with air streams of only a selected one of the first and second means for providing a function absent in said first and second means.

Abstract: An air brake control system of high reliability is provided for a vehicle of the type having front wheel brakes, rear wheel brakes, a first brake control element such as a pedal which actuates the front and rear brakes, and a second brake control element such as a pedal which also actuates the front and rear brakes. First and second pneumatic circuit means for controlling the brakes are duplicated back to the outlet of the air compressor in an arrangement where one side of the circuit is automatically isolated from the other to maintain braking capacity if a loss of air pressure occurs on the one side. Means is associated with air streams of only a selected one of the first and second means for providing a function absent in said first and second means. A transmission neutralizer is also operated by one of the pedals.