Dynamic Balancers And Auxiliary Camshaft

Dynamic engine balancing is performed by two weighted dynamic balancers, located at the front and rear of the cylinder block. The dynamic balancers oppose and cancel out vibrations created by the engine's rotating components.

The front and rear dynamic balancers comprise a sprocket with an offset weight.

Both dynamic balancers are fitted with two needle roller bearings. A threaded shaft passes through the needle roller bearings and bolts through the rear main bearing cap for the rear dynamic balancer and idler. A threaded shaft passes through the needle roller bearings and screws into a threaded hole in the front main bearing cap for the front dynamic balancer. A shoulder on the shaft maintains the correct lateral position of the dynamic balance. Thrust bearings on either side of the dynamic balancer control lateral movement.

The rear dynamic balancer is driven by a dedicated drive chain which is driven by a sprocket which is integral with the crankshaft. An non-weighted idler sprocket, supported on needle roller bearings, is fitted in the same way on the opposite side of the crankshaft main bearing cap. The drive chain connects the two sprockets and the drive gear on the crankshaft.

The front dynamic balancer is driven by the auxiliary drive chain, which also drives the auxiliary camshaft used to operate the two high pressure fuel pumps. The auxiliary drive chain is driven off the crankshaft sprocket, and also provides drive the auxiliary camshaft sprocket and the oil pump sprocket.

The dynamic balancers rotate at crankshaft speed in opposite directions. The equally sized weights are phased so that the inertia reaction to their counter-rotation cancels out vibration caused by the engine in both horizontal and vertical planes.

Both dynamic balancers must be timed to the crankshaft position by their position on the drive chain.

For additional information, refer to: FUEL PUMP CAMSHAFT TIMING ADJUSTMENT 

The auxiliary camshaft is located on three machined bosses on the windage tray and secured with a camshaft carrier which is secured to windage tray with eight bolts. The auxiliary camshaft has two cam lobes, with each lobe operating a high pressure fuel pump, via a tappet. The camshaft is fitted with a drive sprocket which is a press fit on the camshaft. The sprocket is timed to the cam lobes to match the pump delivery strokes with crankshaft position and therefore must not be removed.

The auxiliary camshaft is driven at crankshaft speed by the auxiliary drive chain, which also drives the oil pump and the front dynamic balancer from the crankshaft sprocket. The two lobes on the camshaft act, through tappets located in the camshaft carrier, against a plunger on each single cylinder high pressure pump.

For additional information, refer to: FUEL CHARGING AND CONTROLS