The invention relates to a single-use injector comprising a housing (200) accommodating a mechanical spring energy reservoir (50), a cylinder/piston unit (100), a piston-actuating ram (60) and a trigger unit (80), the spring-loaded piston-actuating ram being supported on the housing via support rods (240) or draw hooks (250) and each contact zone between an individual support rod or draw hook and the piston-actuating ram representing a wedge gear pairing that forces the respective support rod or draw hook radially outwards. The housing of the injector consists of a thin-walled sheet metal part. Said sheet metal part has at least two limbs (220, 250) arranged in parallel to each other. The sheet metal part has a least two pressure bars or at least two draw hooks the free ends of which are bent in an angular fashion to define a supporting section for the piston-actuating ram.