A gas spring (10; 10') for forming equipment, comprising: a casing including an axially extending side wall with an interior surface , an open end , a transversely extending closed end wall axially spaced from the open end , and a pressure chamber established in part by the side and closed end walls to receive a gas under pressure therein; a piston rod housing (44; 44') including an inner end and an outer end axially spaced from the inner end and the piston rod housing (44; 44') is received in the casing adjacent the open end of the casing ; a piston rod extending through the piston rod housing (44; 44') and having an inner end received in the pressure chamber and an outer end normally outside of the casing ; and characterized by a piston rod seal encircling and bearing on the piston rod , including an inner lip in sealing engagement with the piston rod and an outer lip in sealing engagement with one of the piston rod housing (44; 44') or the casing and providing a seal between the piston rod and the one of such casing or piston rod housing (44; 44'); an overtravel pressure relief collar slidably received around the piston rod and having a collar outer end that projects axially beyond the open end of the casing and a collar inner end configured to contact at least a portion of the piston rod seal so that generally during an overtravel condition of the piston rod , axial movement of the collar toward the closed end of the casing displaces at least part of the piston rod seal from the piston rod to provide a path for escape of a gas under pressure from the pressure chamber to the exterior of the gas spring (10; 10'). a casing including an axially extending side wall with an interior surface , an open end , a transversely extending closed end wall axially spaced from the open end , and a pressure chamber established in part by the side and closed end walls to receive a gas under pressure therein; a piston rod housing (44; 44') including an inner end and an outer end axially spaced from the inner end and the piston rod housing (44; 44') is received in the casing adjacent the open end of the casing ; a piston rod extending through the piston rod housing (44; 44') and having an inner end received in the pressure chamber and an outer end normally outside of the casing ; and characterized by a piston rod seal encircling and bearing on the piston rod , including an inner lip in sealing engagement with the piston rod and an outer lip in sealing engagement with one of the piston rod housing (44; 44') or the casing and providing a seal between the piston rod and the one of such casing or piston rod housing (44; 44'); an overtravel pressure relief collar slidably received around the piston rod and having a collar outer end that projects axially beyond the open end of the casing and a collar inner end configured to contact at least a portion of the piston rod seal so that generally during an overtravel condition of the piston rod , axial movement of the collar toward the closed end of the casing displaces at least part of the piston rod seal from the piston rod to provide a path for escape of a gas under pressure from the pressure chamber to the exterior of the gas spring (10; 10'). <EOS>