Abstract: A pneumatic metal forming press which employs at least one pneumatic drive unit which has an expansion chamber defined by a flexible diaphragm acting on a support mechanism and a shock absorber underlying the support mechanism to absorb the impact thereof following the release of a working tool such as a punch after penetration of a work piece during a working stroke. The drive unit may incorporate a plurality of diaphragm chambers arranged one above the other and connected in parallel to a source of high pressure air. The drive unit may also incorporate a pressure multiplier having a fluid chamber pressurized in response to movement of the diaphragm of a drive mechanism and an output drive shaft driven in response to pressure thereto by the fluid in the multiplier chamber.