🔍 Key Concepts

• Rocker arm function in a 4-stroke diesel: a lever that transfers motion from the pushrod to the valve stem • How to visually trace the path from the camshaft → tappet/lifter → pushrod → rocker arm → valve in the sectional drawing • Distinguishing a rocker arm from a valve spring/retainer or pushrod in a cutaway illustration

💭 Think About

• 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? • 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? • 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?

✅ Before You Answer

• Verify that the labels you choose sit between the pushrod and the valve stem, not directly on the camshaft or valve spring. • Confirm that each chosen part has a pivot point (rocker shaft or pin) somewhere near its middle, indicating a lever action. • 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.