Hydraulic clutch

摘要

A hydraulic clutch for transmitting torque from an input rotating member to an output rotating member when friction plates are brought into engagement with each other. Hydraulic fluid having pressure depending upon rotational speed of an input shaft is supplied from a hydraulic fluid source into a hydraulic pressure chamber, to cause an urging member to bring the friction plates into engagement with each other when the rotational speed of the input shaft reaches a predetermined value. A control mechanism controls opening and closing of a pressure regulating valve in response to the rotational speed of the input shaft. When the pressure regulating valve is opened, the hydraulic fluid is caused to flow from the hydraulic pressure chamber to a low pressure side, and when the pressure regulating valve is closed, the hydraulic fluid is prevented from flowing to the low pressure side. A pivot valve is operable to prevent the hydraulic fluid from flowing into the hydraulic pressure chamber when the pressure regulating valve is opened. The pilot valve regulates the hydraulic fluid to a predetermined value to permit the regulated hydraulic fluid to be supplied to the hydraulic pressure chamber when the pressure regulating valve is closed, thereby bringing the friction plates into smooth engagement with each other.