A gas spring (10; 110; 210) for forming equipment, comprising: a casing (12; 112; 212) including an axially extending side wall (20; 120; 220), an open end (24; 124; 224), a transversely extending closed end wall (22; 122; 222) axially spaced from the open end (24; 124; 224), a pressure chamber (17; 117; 217) established in part by the side (20; 120; 220) and end walls (22; 122; 222) to receive a gas under pressure, and a vent passage (63; 163; 263) through the side wall (20; 120; 220); a piston rod (16; 116; 216) received at least in part in the casing (12; 112; 212) for reciprocation between extended and retracted positions; a piston rod housing (44; 144; 244) received at least in part in the casing (12; 112; 212) between the piston rod (16; 116; 216) and the casing (12; 112; 212) and axially movable into the casing (12; 112; 212) in the event of an overtravel condition; and an overtravel pressure relief feature (18; 118; 218), characterized in that the overtravel relief feature (118; 118; 218) is carried in the vent passage (63; 163; 263) of the casing (12; 112; 212) and having a through passage (64; 164; 264) and an annular seal (62; 162; 262) that seals against the piston rod housing (44; 144; 244) to prevent escape of the gas through the vent passage (63; 163; 263); a recessed feature (67; 167; 267) in the piston rod housing (44; 144; 244) axially adjacent to and normally downstream of the annular seal (62; 162; 262); and in the event of an overtravel condition, the piston rod housing (44; 144; 244) being axially displaced into the casing (12; 112; 212) sufficiently to move the recessed feature (67; 167; 267) into fluid communication with the through passage (64; 164; 264) to allow pressurized gas in the chamber (17; 117; 217) to escape through the vent passage (63; 163; 263). a casing (12; 112; 212) including an axially extending side wall (20; 120; 220), an open end (24; 124; 224), a transversely extending closed end wall (22; 122; 222) axially spaced from the open end (24; 124; 224), a pressure chamber (17; 117; 217) established in part by the side (20; 120; 220) and end walls (22; 122; 222) to receive a gas under pressure, and a vent passage (63; 163; 263) through the side wall (20; 120; 220); a piston rod (16; 116; 216) received at least in part in the casing (12; 112; 212) for reciprocation between extended and retracted positions; a piston rod housing (44; 144; 244) received at least in part in the casing (12; 112; 212) between the piston rod (16; 116; 216) and the casing (12; 112; 212) and axially movable into the casing (12; 112; 212) in the event of an overtravel condition; and an overtravel pressure relief feature (18; 118; 218), characterized in that the overtravel relief feature (118; 118; 218) is carried in the vent passage (63; 163; 263) of the casing (12; 112; 212) and having a through passage (64; 164; 264) and an annular seal (62; 162; 262) that seals against the piston rod housing (44; 144; 244) to prevent escape of the gas through the vent passage (63; 163; 263); a recessed feature (67; 167; 267) in the piston rod housing (44; 144; 244) axially adjacent to and normally downstream of the annular seal (62; 162; 262); and in the event of an overtravel condition, the piston rod housing (44; 144; 244) being axially displaced into the casing (12; 112; 212) sufficiently to move the recessed feature (67; 167; 267) into fluid communication with the through passage (64; 164; 264) to allow pressurized gas in the chamber (17; 117; 217) to escape through the vent passage (63; 163; 263).