Crankshaft

Introduction:

The crankshaft is located in the engine of a vehicle and converts the force created by the engine's pistons moving up and down into a force that moves the wheels in a circular motion so the car can go forward.  Located inside the car's engine, the crankshaft is connected to all the pistons in the engine and to the flywheel.

Properties of the crankshaft:

• Crankshafts are common machine elements which transfer rotational movement into linear.

• Crankshaft design in modern internal combustion engines is driven by the desire for more power at higher efficiency rates and reduced weight.

• The demands on crankshaft material, therefore, are increasing, while the crankshafts themselves become smaller.

• The many different designs of crankshaft vary considerably, and even during mass production there can be subtle differences from one to another.

 

Fig: Crankshaft parts

 

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.