A disposable injector with a housing (10) in which are arranged at least one mechanical spring energy reservoir (50), at least cylinder/piston unit (100) filled with an injection solution, at least one piston-actuating ram, and at least one trigger unit. The spring-loaded piston-actuating ram is supported on the housing via at least one support rod (21), wherein the contact zone located between an individual support rod and the piston-actuating ram represents a wedge gear pairing that forces the respective support rod radially outwards. The support rod or support rods bear on at least one activation element (82) that is mounted on the housing and positioned in a locking position. The activation element can be brought by displacement into a triggering position that releases the piston-actuating ram.
