The diesel engine rocker arms shown in the...

🔍 Key Concepts

• Identify where the rocker arms are located in the cylinder head in the illustration and trace what each end of the rocker arm touches. • Recall the basic function of a rocker arm in a four-stroke diesel: it is moved by the cam/follower and pushes on something else. • Consider which engine components in the drawing control valve opening and which control fuel injection or starting air.

💭 Think About

• In the illustration, follow the motion path: cam → push rod (or cam follower) → rocker arm → ? What does the far end of the rocker arm act on? • Which of the labeled components in the cylinder head are intake valves, exhaust valves, starting valves, and fuel injectors? Do the rocker arms contact all of them or only some? • Ask yourself: does a rocker arm usually convert rotation directly to pressure, or does it mainly transfer motion between two reciprocating parts?

✅ Before You Answer

• Verify which valves (intake, exhaust, or starting) have rocker tips pressing on their stems in the picture. • Check whether the fuel injector or unit injector is operated by a separate rocker or linkage, or by the same rocker as the exhaust valve. • Confirm that the rocker arm’s job is to transfer cam motion rather than to be the primary device converting rotational to reciprocating motion.

The diesel engine rocker arms shown in the illustration serve to __________. Illustration MO-0122

operate the exhaust and starting valves

open the intake and exhaust valves

open the exhaust valves and operate the unit injectors

convert rotational energy to reciprocating pressures

🔍 Key Concepts

💭 Think About

✅ Before You Answer