Overtravel pressure relief for a gas spring

A gas spring for forming equipment, comprising:

• a casing including an axially extending side wall, an open end, a transversely extending closed end wall axially spaced from the open end, a pressure chamber established in part by the wall and closed end wall to receive a gas under pressure;
• a piston rod received at least in part in the casing for reciprocation between extended and retracted positions;
• a piston rod housing received at least in part in the open end of the casing between the piston rod and the casing and slidably receiving the piston rod for reciprocation between its extending and retracting position, and including:
• an interior end communication with the pressure chamber,
• an exterior end axially spaced from the interior end and adjacent the open end of the casing, and
• an overtravel pressure relief passage extending generally axially into the piston rod housing and intersecting the exterior end;
• and
• an overtravel pressure relief member carried in the overtravel pressure relief passage and having an exterior end that projects axially beyond the piston rod housing.