3 – SHORT BLOCK
25
Piston Engine Fundamentals
TC010-05-01S
CRANKSHAFT
The crankshaft is the component that changes the up-and-down motion of
the pistons into rotational motion that drives the wheels of the vehicle. The
crankshaft attaches to the cylinder block supports with main bearing caps,
as shown in Figure 14. When the bearing caps are bolted on, they hold
the crankshaft in place. When the block is machined, main bearing
surfaces are aligned and bored on the crankshaft’s center line (line-bored),
so bearing caps must never be interchanged.
FIGURE 14. Main
bearing caps are
used to attach
the crankshaft to
the cylinder
block.
Cylinder
block
Crankshaft
Main bearing
Thrust
bearing
Main bearing
cap
Main bearing
cap mounting
bolt