GB1413490A - Apparatus and method for determining coefficient of friction - Google Patents

Abstract

1413490 Friction testing; measuring coefficient of friction electrically CATERPILLAR TRACTOR CO 15 Dec 1972 58086/72 Headings G1N and G1S To measure the coefficient of friction between a substantially planar test surface 11, e.g. of a friction clutch or brake disc, and a reference surface defined by the annular end surface 30 of a member 24 adapted to be rotated by an electric motor 26 through spindle 28 about an axis Y, the test surface 11 is mounted to be pivotable about the axis X of a shaft 18 (the axes X and Y preferably being coincident) such that when the member 24 engages a portion of the surface 11 at a point on its periphery the surface 11 is induced to pivot about axis X, means being provided, such as a flexible cantilevered link 40 which abuts a fixed stop 42 tending to resist such pivoting and bearing a strain gauge 44, for measuring the torque applied to the test surface 11 by the member 24. The test surface 11, which is preferably annular, and its mounting 12-17 can be forced against the member 24 by loading the shaft 18 with a variable axial load supplied by a pneumatic cylinder arrangement 20. The speed of rotation of the member 24 can be increased from zero in a test in order to measure both static and dynamic friction, the speed being measured by a magnetic pick-up head 50 responsive to the movement of splines 49 on the spindle 28. A housing 10 for the apparatus may be filled with oil to a level 38 to simulate working conditions. The coefficients of static and dynamic friction can be directly calculated from the measured torque.