Abstract: A pre-tensioned shape memory actuator for providing remote actuation at relatively high loads. The actuator utilizes a two-way shape memory alloy which is pre-tensioned to a pre-tensioned position, then partially compressed to a position intermediate its original position and the pre-tensioned position so as to allow the actuator unit to then fore-shorten back to the original position when heated, and to expand back to the intermediate position when again allowed to cool. The alloy is a part of a clamping device which applies compressive force to a work object at the intermediate position under normal temperatures and releases the compressive force when heated. Upon cooling, the cycle is completed as the memory alloy reverts to the intermediate position and once again applies the compressive force to the work object.