ENGINE COMPONENT AND LOCATION 77 Camshaft and Valve Train W2033300 1. Inlet Valve Yoke (Bridge) 5. Volvo Engine Brake Rocker Arm 2. Inlet Valve Rocker Arm 6. Exhaust Valve Yoke (Bridge) 3. Injector Rocker Arm 7. Shim Retaining Screw 4. Exhaust Valve Rocker Arm The engine has an overhead camshaft and rocker arm shaft in support of four valves per cylinder. The camshaft rides on seven journals with a bearing cap and support block (saddle) at each point. The bearing inserts (shells), bearing caps and support blocks are replaceable. In standard configuration (with VGT exhaust brake only), there are three cams for each cylinder, including inlet, injection and exhaust.
There are four cams per cylinder in the optional configuration (VGT exhaust brake plus Volvo Engine Brake) with the addition of a "brake" cam at each cylinder. The rocker arms are positioned on the shaft (front to back) in the order of inlet, injector, exhaust and brake, if so equipped. Both the inlet and exhaust rocker arms each drive the valve pairs via a pinless yoke (bridge). On engines equipped with Volvo Engine Brake, the "brake" rocker arm works in combination with the exhaust rocker arm to precisely control the opening and closing of the exhaust valves for engine braking. Exhaust valve yokes include a shim for adjustment.
Replaceable valve guides and seats are made of alloyed cast iron and steel respectively. All valve guides have oil seals. Exhaust valves have double valve springs.