Needleless disposable injector with a housing in which or on which are arranged, in each case at least in some areas, at least one mechanical spring energy reservoir, at least one cylinder/piston unit that can be filled at least temporarily with active substance, at least one piston-actuating ram and at least one trigger unit, - wherein the piston-actuating ram is positioned between the spring energy reservoir and the piston of the cylinder/ piston unit, - wherein the spring energy reservoir comprises at least one pretensioned spring element, and - wherein the spring-loaded piston-actuating ram is supported on the housing via support rods or tension hooks, and wherein the contact zone situated between an individual support rod or tension hook and the piston-actuating ram represents a wedge gear pairing that forces the respective support rod or tension hook outwards, characterized in that - the housing is made from a thin-walled sheet-metal part (201, 202), - the sheet-metal part (201, 202) has a central end plate and at least two branches (220, 250) projecting therefrom virtually perpendicularly, - the branches each have, at the free ends thereof, an angled retaining element as a means of receiving the cylinder of the cylinder/piston unit, which angled retaining elements engage in a holding notch of the outer contour of the cylinder, - the sheet-metal part (201, 202) has at least two pressure rods or at least two tension hooks, the free ends of which are each bent at an angle to form a supporting portion (241, 251) for the piston-actuating ram, - the trigger unit comprises at least one trigger element arranged slidably on the housing, - wherein the trigger element is a square tube surrounding the sheet-metal part (201, 202), - wherein the trigger element holds the support rods or tension hooks, which hold the piston-actuating ram in its pretensioned position, in a blocking position and, in order to trigger the disposable injector, is brought movably in the longitudinal direction to a position in which the radially outward forcing of the support rods or of the tension hooks caused by the wedge gear pairing is released, and the trigger element is configured with windows, which receive the supporting portions of the support rods after the triggering of the disposable injector, or is configured with longitudinal grooves which receive the supporting portions of the tension hooks after the triggering of the disposable injector. - wherein the piston-actuating ram is positioned between the spring energy reservoir and the piston of the cylinder/ piston unit, - wherein the spring energy reservoir comprises at least one pretensioned spring element, and - wherein the spring-loaded piston-actuating ram is supported on the housing via support rods or tension hooks, and wherein the contact zone situated between an individual support rod or tension hook and the piston-actuating ram represents a wedge gear pairing that forces the respective support rod or tension hook outwards, - the housing is made from a thin-walled sheet-metal part (201, 202), - the sheet-metal part (201, 202) has a central end plate and at least two branches (220, 250) projecting therefrom virtually perpendicularly, - the branches each have, at the free ends thereof, an angled retaining element as a means of receiving the cylinder of the cylinder/piston unit, which angled retaining elements engage in a holding notch of the outer contour of the cylinder, - the sheet-metal part (201, 202) has at least two pressure rods or at least two tension hooks, the free ends of which are each bent at an angle to form a supporting portion (241, 251) for the piston-actuating ram, - the trigger unit comprises at least one trigger element arranged slidably on the housing, - wherein the trigger element is a square tube surrounding the sheet-metal part (201, 202), - wherein the trigger element holds the support rods or tension hooks, which hold the piston-actuating ram in its pretensioned position, in a blocking position and, in order to trigger the disposable injector, is brought movably in the longitudinal direction to a position in which the radially outward forcing of the support rods or of the tension hooks caused by the wedge gear pairing is released, and the trigger element is configured with windows, which receive the supporting portions of the support rods after the triggering of the disposable injector, or is configured with longitudinal grooves which receive the supporting portions of the tension hooks after the triggering of the disposable injector.