Patent ID: 8511181

Claim:
A variable torque rate test joint for the testing of rotary tools for threaded fasteners, comprising: a first element having an externally screw threaded shaft; a second element having an internally screw threaded bore; the screw threads of the first and second elements being engaged with one another so that relative rotation between the first and second elements can be effected by a tool under test; and means for exerting a variable force between the first and second elements in the axial direction of the shaft in order to vary the torque rate of the test joint, the force-exerting means comprising: a collar encircling the shaft and engaging one of the first and second elements; at least one spring beam mounted at a reaction point, cantilevered over a pivot point and engaging the collar so as to exert a force on the collar in the axial direction; and means for varying the distance between the pivot point and the central axis of the shaft in order to vary the axial force exerted by the spring beam on the collar; characterized in that: the first element is fixed against rotation during testing of a tool; the second element is a nut mounted for rotation on the shaft of the first element when acted on by a tool under test.