2401071 - Introduction - ENGINE CRANKCASE

The engine block is cast iron, with high mechanical strength.The crankshaft is supported by means of five main bearings.The cylinders are formed directly in the engine block, and are graded into three sizes plus one oversize.There are special channels in the engine block walls which allow the flow of coolant and lubricating oil.

SPECIFICATIONS

The lower crankcase is made out of pressure cast aluminium alloy, with co-cast iron main bearing caps.The mounts and main bearing caps are machined together with the upper crankcase.The lower crankcase is fitted to the upper crankcase by means of bolts and locating dowels to ensure greater precision.A strip of sealant is applied between both crankcases to prevent oil leaks.

COMPOSITION

The upper and lower cylinder block/crankcase are illustrated in the diagram below.

OPERATION

The lower crankcase performs the following functions:

• It acts as a load bearing structure together with the upper crankcase.
• It supports reactions and crankshaft loads.
• It acts as a rigid element together with the gearbox by means of a reaction bracket.
• It allows oil to return to the sump.
• It supports the sump and lubricant oil.