Abstract: A trash compactor has a wheeled housing with a laterally accessible compaction chamber wherein a vertically movable pressure plate is carried on a plurality of inflatable bladders which are suspended from the ceiling of the chamber. A gas bottle carried underneath the chamber bottom is connectable via a control valve to these bladders so as to expand them, pushing the pressure plate downwardly to compress loose trash in the compaction chamber. A plurality of cables connected to the corners of the pressure plate pass upwardly into a control compartment where they are led about rollers carried on piston rods of pneumatic cylinders also connectable by the valve to the gas bottle so as to allow these pistons to pull the pressure plate into an upper position at the top of the compaction chamber.