Force limiter

A force limiter to be interposed between an actuator and a device to be moved by the actuator to limit the force applied by the actuator, the force limiter comprising:

• a body having a main chamber and open at at least one end;
• a first piston slidable within the body;
• a piston rod extending from the piston and extending through and slidable within the open end of the body;
• resilient means in the main chamber between the first piston and an end of the main chamber, remote from the first piston, the resilient means being calibrated to provide the necessary force limit and able to apply that force limit in both directions of movement of the actuator, the resilient means being so calibrated that the force limiter acts as a solid rod up to the calibrated force limit, provides the necessary force limit and is able to apply that force limit in both directions of movement of the actuator;
• a subchamber adjacent the main chamber;
• the first piston being in the subchamber;
• a transition retainer threadedly attached to the distal end of the piston rod and including means to eliminate backlash in the threaded attachment, the transition retainer being a slidable fit in the body;
• the resilient means being interposed between the piston and the transition retainer;
• an extension rod extending from the transition retainer to the device to be moved;
• means to attach the force limiter to the actuator;
• and
• means to attach the force limiter to the device.