Abstract: An apparatus for detecting cracks in a flexible rotating coupling is disclosed in which the flexible coupling includes a flexible element having a plurality of flexible discs. An electrically conductive, normally continuous, line is affixed to at least one of the flexible discs and connected to a circuit. The conductive line becomes discontinuous if the disc cracks. The circuit is mounted on the coupling and transmits a signal indicative of the continuous or discontinuous condition of the conductive line and thereby the intact or cracked condition of the flexible disc. The transmitted signal is received by a stationary circuit which provides an output indication of the disc's intact or cracked condition.

Abstract: Apparatus for limiting the amount of torque to a driven shaft having a tool for applying power to a workpiece is continuously adjustable throughout a predetermined range. A housing defines a cylindrical chamber open at one end having an adjustable plate disposed therein. First and second shafts enter the housing through opposite ends and have first and second disks attached thereto within the housing. Disks are frictionally coupled by a force generated by a spring disposed about the first shaft between the adjustable plate and the first disk. When the preselected limit of torque is exceeded the disks slip with respect to one another thus, limiting the amount of torque delivered by the apparatus. Adjustment of the plate selectively increases or decreases the compression of the spring and thus, alters the maximal amount of torque that can be delivered. An alternative embodiment is disclosed for incorporating the apparatus within the housing of a power tool such as a drill motor.