Abstract: An oil-less gas compressor comprises at least one cylinder block mounted on a crankcase, the outer end of the cylinder block being closed by a cylinder head. A piston in the cylinder block bore is reciprocated by a motor-driven crankshaft in the crankcase. The cylinder blocks and cylinder heads are generally square in cross section. On all four sides of the cylinder block and cylinder head there are spaced cooling fins which extend in an axial direction. Axially extending cooling air passages between the fins communicated at their lower ends with the interior of the crankcase. Air drawn into the crankcase by a fan on the crank shaft flows into and through these cooling air passages to cool the cylinder block and head. In one corner portion of the cylinder block and head there is an integral axially extending suction bore containing a filter. In an adjacent corner portion of the cylinder block there is an axially extending compressed air bore.

Abstract: In a torque transmitting coupling between a cylindrical shaft and a female member having a bore to receive the shaft, the shaft has a secant face and the female member has a connecting bolt bore which intersects the shaft bore and faces the secant face of the shaft. A connecting bolt in the bolt bore of the female member has a secant face which tightly engages the secant face of the shaft. In one embodiment, the shaft axis, secant faces of the shaft and bolt and the bolt bore are all parallel. In another embodiment the axis of the bolt bore is inclined at a small angle to the secant face, the bolt being of wedge form. A screw extending through a hole in the female member and screwed into a tapped hole in the bolt is rotatable to move the bolt axially and thereby wedge the secant face of the bolt against the secant face of the shaft. The secant faces of the shaft and bolt may have intermeshing longitudinally extending serrations.