High-flow, automatically reversible oil pump provides positive-displacement oil lubrication.

Crankcase venting system equalizes pressure during startup and assures oil return to sump.

Oversize sump holds extra oil in crankcase to prevent levels dropping below safe lubrication range during flooded starts.

Contoured pistons lower cylinder clearances to increase compressor capacity and efficiency.

High-efficiency valves provide increased refrigerant flow and lower pressure drops.

Electronic oil-pressure switch.