VARIABLE TORQUE RATE TEST JOINT

摘要

In a variable torque rate test joint, screw-threaded first and second elements are rotated relative to one another by a tool under test. At least one spring beam is cantilevered over a pivot point to exert an axial force between the first and second elements and the torque rate of the test joint can be varied by moving the pivot point to change the axial force. The first element may be a shaft that is fixed during testing and the second element is a nut rotatably mounted on the shaft, whereby the element rotated by the tool has a minimal moment of inertia. Whichever of the first and second elements is held stationary during the test may be mounted in a hub that is locked during the test but can be rotated at the end of the test to reset the test joint. Measurements may be made of the torque and the rotation angle to derive an actual torque rate of the joint, which allows correction of errors by moving the pivot point.