Apparatus and method for testing thrust bearings

An apparatus for testing the take off speed of a thrust bearing in a device having a housing, a rotary shaft, and a journal bearing for radially supporting the shaft within the housing, wherein the thrust bearing axially supports the shaft within the housing, the apparatus comprising:

• a stationary torsion transducer for mounting the shaft of device thereto and measuring the torque thereof;
• a load motor located adjacent to the torsion transducer for rotating the housing of the device relative to the shaft and applying radial loads to the housing;
• a linear stage mounted to the load motor for selectively generating radial load forces on the housing;
• a load cell mounted adjacent to the linear stage for monitoring the radial load exerted by the linear stage on the housing;
• an axial load applicator that selectively applies an axial load on the housing and an equal reactive force on the thrust bearing such that the friction torque generated by the device is dominated by the thrust bearing in order to measure the take off speed of the thrust bearing;
• wherein
• the axial load applicator is adapted to provide the axial load without any physical contact with the device;
• and wherein
• the axial load applicator comprises a magnet.

A method for testing the take off speed of a thrust bearing, the method comprising:

• (a) providing a device having a housing, a rotary shaft, a thrust bearing for axially supporting the shaft within the housing, and a journal bearing for radially supporting the shaft within the housing;
• (b) mounting one of the housing and the shaft to a torsion transducer for measuring the friction torque generated by the device;
• (c) rotating the other of the housing and the shaft and applying a radial load thereto;
• (d) applying a selected axial load to the device such that an equal reactive force is exerted on the thrust bearing and the friction torque generated by the device is dominated by the thrust bearing;
• (e) measuring the friction torque with the torsion transducer such that the take-off speed of the thrust bearing may be ascertained while the loads are being applied;
• and wherein
• step (d) comprises attracting an axial end of the device with a magnetic force.