Engine Components PowerLeash™, 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. 5 CYLINDER HEAD 4 Figure 4 — Cylinder Head with Valves and Camshaft Supports Main features of the cylinder head are: One-piece cast iron Integral thermostat housing Figure 5 — Valve Train Separate chambers for exhaust and inlet at each cylinder make this a “crossflow” design. The fuel channel, drilled from front to rear, connects with grooves machined around each injector opening. A plug at the rear of the cylinder head seals this channel. 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. CAMSHAFT AND VALVE TRAIN 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. Rollers in the ends of the rocker arms contact the cam shaft. The contacts with the yokes have ball sockets for flexibility.
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 PowerLeash™) with the addition of a “brake” cam at each cylinder. The camshaft is induction-hardened. Timing marks for valve and injector adjustment are located on the flange forward of the No. 1 camshaft journal. These marks are for adjusting valve clearance. They do not apply to camshaft timing. 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 Camshaft thrust washers are integral on the No. 7 journal bearing. Smooth rotation is ensured by means of a vibration damper on the camshaft gear. Teeth on the damper interact with the camshaft position sensor for input to the EECU. Page 17 DESCRIPTION AND OPERATION 1. Inlet Valve Yoke (Bridge) 2. Inlet Valve Rocker Arm 3. Injector Rocker Arm 4. Exhaust Valve Rocker Arm 5. PowerLeash™ Rocker Arm 6. Exhaust Valve Yoke (Bridge) 7. Shim Retaining Screw