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Untitled Document
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The
Crankshaft And How It Works
| Crankshaft:
The crankshaft is designed to convert the up and down motion of
the pistons into horizontal rotation. The shaft is one solid piece
made from cast iron or forged steel. Steel is usually used in high
loading situations, such as diesel or turbocharged engines. Oil
passages are either cast or drilled into the crankshaft to distribute
lubricant to the main and rod journals.
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Main
Journals:
The crankshaft's main journals (1) are the highly polished surfaces
located at the center of the shaft. The rotation axis of the crankshaft
runs through the center point of the main journals. The main journals
rotate in the main bearing bore created by the engine block and main
caps.
Rod Journals:
The rod journals (2) are highly polished surfaces to which the connecting
rods attach. They circle around the crankshaft's axis of rotation.
The amount of torque they deliver is determined by the distance
between the journal's center axis and the axis of rotation. The
journals are designed so there is always at least one piston on
a power stroke.
Counterweights:
Counterweights (3) balance the crankshaft. The weight of the piston
and connecting rod, in combination with the offset of the rod journal,
will produce a violent vibration if the crankshaft were not balanced.
Snout:
The crankshaft snout (4) extends through the front end of the engine
block. The camshaft timing assembly is directly connected to the
snout, as are engine-driven accessories.
Flange:
The crankshaft flange (5) is the mounting structure for the engine's
flywheel. The center of the flange has a pilot hole for the transmission's
input shaft or torque converter.
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Harmonic
Balancer:
The harmonic balancer (also called vibration damper) is designed
to dampen crankshaft vibration. The down force on each rod journal
can be as high as one ton. This flexes the crankshaft causing
vibration. Without damping, engine damage (crankshaft failure)
would result. The damper is a heavy disk mounted in rubber. The
unit is attached to the crankshaft's snout. Shown are the Inertia
Ring (1), Rubber Ring (2), and Crankshaft Pulley (3).
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The
information on this page is provided from the "Road Machines"
learning CD. Buy it Today and continue
your learning !
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