Abstract: A compressor which provides for minimum clearance in the compression chamber while substantially reducing the heat normally experienced by the piston during the compression stroke of a compressor of this type. The suction valve(s) of the compressor is concentrically mounted in the piston while the discharge valve(s) is concentrically mounted in a stationary position within the cylinder. Since the high heat of compression occurs at the discharge valve, the piston will be much cooler than in prior art compressors of this type which improves the efficiency of the compressor and which substantially extends the operational life of the piston rings.