Composite piston for IC engine - has sections joined by helical spring with external ball bearings to run on cylinder wall

摘要

The piston has an upper section which closes on a seat in the cylinder head to give a valve action. An asbestos sheet below this prevents transmission of heat to the remaining sections of the piston. The section immediately below the asbestos sheet has a groove containing a ring of ball bearings which run on the cylinder wall. Inside this groove there is a helical spring which presses the upper and lower sections apart and makes initial setting unnecessary. The lower sections contain further rows of ball bearings running on the cylinder wall. All the bearings are lubricated with heat resisting grease.