Torque limiting device

Torque limiting device of simple 3-piece construction which reliably automatically disengages the driving and driven members when the latter is subjected to a predetermined overload. Device comprises a pair of cooperating coupling members which respectively engage the driving and driven members, and a helical compression spring interengaging the two coupling members. The direction of lay of the spring is selected in accordance with the direction of rotation of the output shaft of the driven member. Overloading the driven member increases the diameter of the spring which causes it to disengage itself from the driving coupling member to thus prevent torque from being transmitted to the driven member while overloaded.