CLUTCH MODULATING SYSTEM

摘要

CLUTCH MODULATING SYSTEM In an agricultural vehicle in which a power takeoff modulating valve is shifted in response to a control lever so as to pass pressurized hydraulic fluid through a groove in the outer surface thereof between recesses in an adjacent bore wall for application to a power takeoff clutch to cause engagement of the clutch, application of the hydraulic fluid pressure to the clutch is modulated by an arrangement which selectively diverts the pressurized hydraulic fluid away from the clutch and to a sump in accordance with the rate of pressure increase of the hydraulic fluid to prevent excessively rapid engagement of the clutch. The hydraulic fluid is sumped by a trimmer valve having a first end which immediately responds to high fluid pressures by sliding into a position which sumps the conduit supplying hydraulic fluid to the clutch by an amount directly related to the pressure. An opposite second end of the trimmer valve also responds to the pressure of the hydraulic fluid but much more slowly because of a restriction in the conduit coupling the second end to the hydraulic fluid supply conduit. As sufficient hydraulic fluid passes through the restriction so as to equalize the fluid pressure at the opposite ends of the trimmer valve, the trimmer valve is returned to a position in which the sump is cut off and the hydraulic fluid pressure is applied to the power takeoff clutch.