Abstract: An improved safety clamp device for use with movable platforms and the like includes a body member having a safety cable receiving cradle, a lever arm having a safety cable engaging portion, an elongate member carrying a pulley at either end, and a control arm. The control arm is in the form of a modified bellcrank having one arm portion pivotally connected to the body member, its apex connected to the elongate member and a pulley connected to a second arm portion. The lower end of the elongate member is rigidly connected to the movable platform. A drive or support cable passes on one side of the two pulleys on the elongate member and on the other side of the control arm pulley. The elongate member is maintained in a first position relative to the body member such that the safety cable engaging portion confronts but does not engage the safety cable when the drive or support cable is subjected to a predetermined tension.