Method Of Calibration Of A Hydraulically Operated Clutch Of A Continuously Variable Transmission Using Pressure Between A Hydrostatic Pump And Motor

A method of calibrating a hydraulically operated clutch in a continuously variable transmission of a vehicle, characterized by steps of:

• preventing movement of the vehicle;
• controlling the clutch in a like manner as for a shift, using a predetermined control signal value and determining a change in a pressure difference condition in a hydrostatic power unit of the transmission resulting from the control signal value;
• and:
• if the determined change is indicative of initial engagement of the clutch, then recording a value representative of the control signal value;
• if the determined change is indicative of engagement of the clutch sufficiently to cause movement of the vehicle or the determined change is greater than a predetermined value, then emptying the clutch and refilling the clutch using another control signal value, to a test pressure less than the previous test pressure;
• and
• if the determined change is indicative of lack of engagement of the clutch, then emptying the clutch and refilling the clutch using another control signal value, to a test pressure greater than the previous test pressure.

A method of calibrating a hydraulically operated clutch in a continuously variable transmission of a vehicle, characterized by steps of:

• preventing movement of the vehicle;
• filling the clutch in a like manner as for a shift, to a test pressure and determining a resulting change in pressure conditions in fluid lines between a fluid pump and a motor of a hydrostatic system of the transmission;
• and:
• if the determined change is indicative of initial engagement of the clutch, then recording a value representative of the test pressure;
• if the determined change is indicative of engagement of the clutch sufficiently to cause movement of the vehicle or is greater than a predetermined value, then emptying the clutch and refilling the clutch to a test pressure less than the previous test pressure;
• and
• if the determined change is indicative of lack of engagement of the clutch, then emptying the clutch and refilling the clutch to a test pressure greater than the previous test pressure.