So, crankshafts are a key component, of internal combustion engines.

Basically, they drive everything that moves, inside and outside of your engine.

Consequently, through some sort of connection, they move everything from: camshafts, pumps, belts and your vehicle.

But, most of that stuff, is not taken into consideration, when thinking of what the crankshafts basic job is.

Crankshafts convert the reciprocating (up/down) movement of the pistons/connecting rods; into a rotational movement that drives the wheels and allows a vehicle to move forward.

So, they are also, of a one piece design, and actually have no moving parts. But, there are names and functions of, different areas of the crankshaft. Also, know as the bottom end of the engine.

The most common ones include:

  • Main Journals
  • Connecting Rod Journals
  • Crankshaft Front End
  • Crankshaft Back End

Main Journals

So, if we talk about where the crankshaft is in the engine, we also have to talk about main bearings. They are what actually, hold the crankshaft in the engine. The crankshaft rotates, within the engine block, with the use of main bearings.

Connecting Rod Journals

So, the connecting rod journals, are offset from the axis of rotation. And, are attached to the big ends, of the connecting rods. Confusingly, they are commonly called, crank pins or rod bearing journals.

Front End

Most often, a torsional or vibrational damper is at the front end of the crank. Consequently, that damper may have a pulley attached, to drive other accessories.

Back End

In most cases, the crankshaft attaches to the flywheel through the flanges. The diameter of the flywheel end is larger than the other end. This gives a flange face to mount the flywheel on.

Crankshaft do wear out over time

So, all journals wear over time. They may develop a rough surface, or become out-of-round or tapered. Consequently, grinding, can bring them back to a useable size. Engine bearing replacement is the next step.

Wear usually occurs, when there is, not enough oil pressure available. As a result, if it makes contact with the journal bearing surfaces; it gradually increases clearance and worsens the oil pressure.


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