Apparatus for continuous wear measurements during wet clutch durability tests

Wet clutches are used in many applications today such as automatic transmissions and limited slip differentials in cars as well as in heavy duty equipment such as wheel loaders. The present study is concerned with the wear and engagement behavior of wet clutches in the latter type of application. A test rig is developed in which the wet clutch engagement is monitored during an arbitrary number of test cycles.This rig has many similarities with the SAE #2 test rig in that they are both inertia type test rigs. However, the test rig presented here has several original parts from heavy duty equipment in production incorporated into it. The data collection includes a continuous measurement of the position of the piston used to apply force on the clutch pack in addition to the separator disc temperatures, hydraulic actuating pressure and torque transfer characteristics. The measurements of the piston position can then be related to the clutch wear during a long test series.

► A new wet clutch test rig designed using standard size clutch parts from heavy duty equipment.
► Direct monitoring of clutch wear through the use of a displacement sensor.
► A phenomenon of a transition in wear characteristics was discovered during the test.
► Using a liquid gallium alloy as temperature interface material for thermocouples.