Abstract: An isolating device (10) isolates fluctuations in torque of a drive shaft about a nominal torque value. The device comprises a first annular member (11) for connection to a rotary driving shaft and a second annular member (12) designed for connection to a driven piece of equipment such as a fan or alternator in an internal combustion engine. The first (11) and second (12) annular members are interconnected by a plurality of elastomeric elements (23) which are pre-compressed in a circumferential direction between retaining plates fixed to the first and second annular members (11, 12). The pre-compression permits a minimum torque of the drive shaft for a nominal torque level to be transmitted to the driven member load substantially without deflection of the elastomeric element (33). Hence there is little or no relative rotational displacement of the first and second members (11, 12) of the isolating device (10) during start up until the working range of the device is reached.