Caterpillar Inc.
Clutch hydraulic control circuit with a pilot operated failure mode response valve

Abstract:

A transmission for a machine is disclosed. The transmission may comprise a first torque path for transmission of torque from an input shaft to an output shaft, and a single clutch element along the first torque path. The transmission may further comprise a clutch actuator configured to actuate engagement of the clutch element, and a clutch pressure control (CPC) valve configured to permit a flow of hydraulic fluid to the clutch actuator when in an open position to cause the clutch actuator to actuate engagement of the clutch element. The transmission may further comprise a FMR valve having a failure position obstructing flow of the hydraulic fluid from the CPC valve to the clutch actuator when the CPC valve is in the open position. The FMR valve actuated by pilot pressure from a CPC valve that controls actuation of other clutch elements that are not on the first torque path.