Mazda CX-5 Service & Repair Manual: Crankshaft, Main Bearing

Purpose, Function

• The crankshaft converts the reciprocating movement of the piston to a rotational movement via the connecting rod.

• The main bearing forms an oil film on the outer surface of the crankshaft journal to prevent wear due to sliding.

Construction

Crankshaft

• The crankshaft is installed to the inside (crankcase) of the cylinder block.

  

  
  

• The crankshaft has a key groove to match timing to the crankshaft pulley.

• The crankshaft has the following parts shown in the figure.

  

  
  

• The optimized shaft diameter ratio of the crankshaft journal and crank pin has reduced sliding resistance while maintaining rigidity.

• The steel crankshaft has five bearings and eight counterweights for improved accuracy in the rotational balance.

• The crankshaft journal and crank pin have been induction hardened* to bear high loads.

• The crankshaft has an oil passage for supplying engine oil to the crankshaft journal and crank pin.

  

  
  

Main bearing

• The main bearing is installed to the outer surface of the crankshaft journal.

• The upper main bearing and lower main bearing are made of aluminum alloy.

• The upper main bearing has an oil groove and oil hole.

• Thrust force is suppressed by the thrust bearings on both sides of the No.3 journal.