Abstract: Detent mechanisms are useful for retaining a stem of a control valve at predetermined operating positions. The ball type detents commonly used in control valves tend to slide thereby causing the operator to extend additional energy to overcome the sliding friction. The subject detent mechanism includes a roller rotatably disposed on a pin carried by a roller carrier. The roller has an annular arcuate surface in rolling contact with the peripheral surface of the stem. The arcuate surface increases the contact surface between the roller and the stem to thereby insure that the roller rolls on the stem and minimizes the lever effort necessary to move the stem.

Abstract: Spring-applied, pressure-released brakes are useful, for example, in construction vehicles or other vehicles that require an automatic braking in the event of an engine failure. In order to tow the vehicle for service, the brakes must be released. Most brake release systems require an alternate pump and associated valves on each vehicle with the fluid from the alternate pump being controlled by the brake valve on the vehicle. The alternate pump on each vehicle add cost to the vehicle and the spool of the brake valve is a known path for fluid leakage thus requiring an alternate pump of a larger capacity than is actually needed. The present brake release mechanism provides an isolating mechanism that is effective to isolate a work port of a brake valve from a valving element in a housing. The isolating mechanism is adapted to connect with an alternate source of pressurized fluid and adapted to direct the pressurized fluid to a brake for release thereof.

Abstract: A hydraulic transmission control circuit includes a hydraulically responsive modulating valve for modulating a first fluid pressure and a differential valve for establishing a second fluid pressure communicated to a master clutch, the control circuit also including a manually controlled modulating valve for precisely adjusting the second pressure and for selectively adjusting the first fluid pressure during regulation of the second fluid pressure, the manual modulating valve also being adapted for selectively communicating the hydraulically responsive modulating valve with a drain in order to assure a proper rate of modulation for both the first and second fluid pressures.