Abstract: A piston assembly for engaging two selectively engageable parts comprising: a housing defining a piston cylinder; a piston; and an adjuster assembly comprising: a piston stroke limiter configured to limit the length of a return stroke of the piston from an extended stroke position and a retracted stroke position, the piston stroke limiter comprising a spring and a spring guide; and an inner crushable tube, acting between the piston and the piston stroke limiter, the inner crushable tube being arranged to reduce in axial length when a length of an extension stroke exceeds a length of a retraction stroke to maintain the length of the return stroke; wherein the inner crushable tube comprises an inner crushable thin-walled tube surrounding at least a portion of the piston.

Abstract: A piston assembly for engaging two selectively engageable parts comprising: a housing defining a piston cylinder; a piston; and an adjuster assembly comprising: a piston stroke limiter configured to limit the length of a return stroke of the piston from an extended stroke position and a retracted stroke position, the piston stroke limiter comprising a spring and a spring guide; and a crushable body, acting between the piston and the piston stroke limiter, the crushable body being arranged to reduce in axial length when a length of an extension stroke exceeds a length of a retraction stroke to maintain the length of the return stroke; wherein the crushable body comprises an inner crushable thin-walled tube surrounding at least a portion of the piston and an outer crushable thin-walled tube mounted around and radially outwards of the inner crushable tube.

Abstract: The present application relates to crushable body in the form of a corrugated thin walled tube e.g. for use in a piston assembly for engaging two selectively engageable parts. The piston assembly has a housing defining a piston cylinder and a piston. The assembly also has a piston stroke limiter. The piston stroke limiter is configured to limit the length of a return stroke of the piston from an extended stroke position and a retracted stroke position. A crushable body in the form of a corrugated thin walled tube acts between the piston and the piston stroke limiter and is arranged to reduce in axial length when a length of an extended stroke exceeds a length of a retraction stroke to maintain the length of the return stroke.