Control of cooling oil flow for a hydraulic clutch

摘要

A hydraulic circuit (30) for lubricating a tractor transmission (20) and associated master clutch (25) is disclosed wherein a high cooling flow of lubrication oil is delivered to the master clutch (25) whenever the clutch is being modulated, but a normal lower oil flow is delivered to the clutch (25) whenever the clutch is either disengaged or fully engaged. The hydraulic circuit (30) includes a clutch lubrication control spool (38) operatively associated with a pilot line (41) sensing pressure from the hydraulic system controlling the application of the master clutch (25) and a transmission brake (29) that is engaged to stop the transmission (20) when the master clutch (25) is disengaged. The pilot line (41) controls the positioning of the clutch lubrication control spool (38) to shift the spool to a high flow position whenever less than full pressure is sensed in either the clutch applied or brake applied hydraulic lines (33, 34). <IMAGE>