Abstract: The present test apparatus provides for the simultaneous loading of a test sample with longitudinal forces and with torque. For this purpose a piston rod of a longitudinal loading cylinder and a piston of a torque cylinder are coupled for relative axial movement by a fork connected to the piston rod of the longitudinal loading cylinder and guided in a torque transmitting member connected to the piston of the torque cylinder. Frictional forces and play are minimized by providing the fork ends with bearing surfaces and providing the torque transmitting member with both stationary and tiltable bearings which may be adjustable. Another embodiment provides that the bearings of the torque transmitting member are hydrostatic bearings to further reduce friction.

Abstract: This hydraulic chucking head, especially for testing machines wherein the test sample must be held without play in the direction of load application, includes at least two test sample holding pistons movable along a common axis toward each other and toward a central axis through the chucking head. These pistons are hollow inside and movable in respective cylinders in the housing with a certain initial play. The piston walls or jackets are elastically yielding when the pressure inside the piston is increased, whereby the test sample is held and simultaneously said play is removed since the piston walls are pressed against the respective cylinder bores. Preferably a non-metallic coating is provided between the piston walls and the cylinder bores which coating acts as a sealing and reduces friction.