To study the characteristics of a two-stagereciprocating air compressor, air and water cooled. Two stages are separatedand can be operated at different speeds. Both stages are connected by V-beltsto the same motor dynamometer with spring balance. Speed indicator and control.Second stage with alternative pulleys to vary pressure ratio. Intercoolerbetween first and second stages. Air inlet box with orifice plate andmanometer. Air receiver with drain valve and safety valve. Piping systemfacilitates bypass of intercooler or second stage. The unit is mounted on amobile bench. 220V, 1ph, 50Hz or as required.