š Key Concepts
ā¢ Rocker arm function in a 4-stroke diesel: a lever that transfers motion from the pushrod to the valve stem
ā¢ How to visually trace the path from the camshaft ā tappet/lifter ā pushrod ā rocker arm ā valve in the sectional drawing
ā¢ Distinguishing a rocker arm from a valve spring/retainer or pushrod in a cutaway illustration
š Think About
ā¢ Starting at the camshaft in the crankcase, can you follow the long slender pushrod up to the cylinder head and see which labeled part it actually pushes on?
ā¢ Look at the top of each cylinder head: which labeled part is a short, curved lever pivoting around a shaft, with one end over the valve stem and the other end over the pushrod?
ā¢ Compare the shapes of the items marked by C, Y, Z, and ZZ: which two are clearly the pivoting levers, and which are covers, guides, or fasteners?
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Before You Answer
ā¢ Verify that the labels you choose sit between the pushrod and the valve stem, not directly on the camshaft or valve spring.
ā¢ Confirm that each chosen part has a pivot point (rocker shaft or pin) somewhere near its middle, indicating a lever action.
ā¢ Make sure you are not picking parts that are simply valve springs, retainers, or the rocker cover; the true rocker arm should be a distinct lever.