Compressor

At the rear of one of the Blondin winding enginehouses at Pen-yr-Orsedd slate quarry stands this Ingersoll-Sergeant piston-valve compressor dating from the 1890s.

The Ingersoll-Sergeant piston.valve compressor was introduced in about 1891 and was distinguished by the method of admitting air to the cylinder, it being drawn in down a hollow piston tail-rod. The piston itself was hollow and provided with internal inlet valves. The idea was to accelerate the operation of the inlet valves by utilising the reversal of the piston at the end of each stroke, thus improving the volumetric efficiency of the compressor, and to reduce the clearance volume in the cylinder to permit the development of high pressures in a single stage. This example was made in the United States to a design of which production ceased in 1900.

Originally powered by a steam engine, the electric motor that provided drive after 1906 can be seen in the background.