Abstract: Test apparatus comprises a wheel means including a hub and wheel web rotatably mounted on wheel bearings set in the wheel hub and mounted on a non-rotatable axle mechanism. The wheel means is rotatable by motor means. A load application mechanism including hydraulic load cylinders and load sensors effects selective imposition of radial, axial and moment loading upon the wheel web, wheel hub and wheel bearings so that the bearings experience operting conditions during rotation and at rest. Acoustic sensing means enable determination of the onset of bearing failure. Operation of test apparatus is preferably controlled by a computer.