CAMSHAFTS
7-28. The camshafts in 4-stroke cycle diesel engines carry the cams for actuating the inlet and exhaust valves.
The camshaft may also carry cams for fuel injection pumps, fuel-spray valves, or air-starting valves.
Depending on the engine design, some engines have two camshafts, others have only one. The camshaft may
be constructed in several ways. It can be forged in one piece, including the cams themselves, as integral cams.
It may consist of a steel shaft with separate forged-steel or cast-iron cams keyed onto the shaft. Very few of the
cast-iron cams keyed onto the shaft are still in service. Another construction used on large engines is to make
up the camshaft in sections. Each section handles one cylinder and enough sections are bolted together to
handle the whole engine.