the rear face of working piston acting as pumping member and co-operating with a pumping chamber isolated from crankcase, the connecting-rod passing through the chamber and co-operating with movable isolating member

Full Title

Engines characterised by provision of pumps for charging or scavenging > Engines with reciprocating-piston pumps; Engines with crankcase pumps > with reciprocating-piston pumps other than simple crankcase pumps > with the pumping cylinder situated between working cylinder and crankcase, or with the pumping cylinder surrounding working cylinder > the rear face of working piston acting as pumping member and co-operating with a pumping chamber isolated from crankcase, the connecting-rod passing through the chamber and co-operating with movable isolating member