LO 9-1 Identify the purpose and list the names of components associated with the cylinder head and valve train

LO 9-01: Identify the purpose and list the names of components associated with the cylinder head and valve train.

Integral to the cylinder head is the valve train, which is the engine system responsible for synchronizing piston and crankshaft position with the opening and closing of intake and exhaust valves. The valve train controls the flow of intake air and exhaust gases passing through the engine cylinders and compression release-type engine brakes used by many heavy-duty (HD) diesels Figure 3. To regulate valve operation and engine breathing, a rotating camshaft with a lobe for each of the intake and exhaust valves controls valve lift, valve closing, and the duration of valve opening. Camshafts are located either in the block or the cylinder head. Valve train components not only include camshafts but also gear or belt drive systems to synchronize the rotation of the camshaft to the crankshaft. Other essential components of the valve train in any engine include intake and exhaust valves, valve guides and seats for valves, valve springs, rocker levers, valve bridges, pushrods, camshaft followers, and valve lifters.

Information in this chapter adds more detail to this outline of the cylinder head and valve train components. As a major component of the diesel engine that regularly encounters various types of failure and is routinely serviced, technicians should be familiar with construction operation and service of the cylinder head and valve train components. Information on this topic will help technicians acquire skills related to correctly servicing, maintaining, and diagnosing problems with cylinder head and valve train components.

FIGURE 09-3: The smaller fifth valve in this MBE 4000 engine is for the compression release brake.

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