Independent Power Take Off (IPTO) with Mechanically Operated Multiplate Wet Clutch for Agricultural Tractors 2010-01-1982

Tractors along with implements are used to prepare the soil. There are two broad classification in implements attached, one is passive or trailed implements and other one is active tilling implements which will take drive from engine through Power Take Off (PTO). The drivelines for transmission and PTO should have clutches to engage / disengage them from the engine while changing gears and switching PTO On/Off respectively. In present scenario, there are independent clutches for both drivelines to operate PTO driven implements without disrupting vehicle speed.

In general, IPTO is being achieved by dry clutch which is integral with engine mounted clutch operated by separate linkages or by hydraulically operated wet clutch located in PTO driveline after auxiliary pump. An attempt is made with mechanically operated wet clutch in the PTO driveline to have an IPTO.

Design proposals for mechanically operated multiplate wet clutch and linkage mechanism for engagement/disengagement were generated by considering the design targets to be met and having equivalent performance as that of hydraulically operated wet clutch. A mathematical model for drag torque based on Newton's law of viscosity is developed. The drag torque increases linearly with increasing speed at low speed region. However; in actual case, drag torque decreases with increasing rotational speed at high speed range due to the lower coefficient of viscosity of interface oil. This is attributed to the air trapped between friction disc and separator disc. Hence, the law of viscosity cannot be used to explain this (high speed range i.e. greater than 1500) phenomenon. The torque response is calculated by determining the hydrodynamic torque and asperity torque as a function of oil film thickness and time by another mathematical model. Actual torque transmitted is increased to a maximum value of 390 Nm within 0.8 to 1.2 second where as the simulated torque response value is approximately 1.3 seconds. Parameters like force required to disengage the clutch, oil temperature rise were also compared with test results.