All About CRANKSHAFT

Crankshaft, as the name suggests is the combination of the word ‘Crank’ and the word ‘Shaft’, is the part of the engine.

The shaft is nothing but a rotating mechanical component that is in circular cross-section and is used to transmit the power from the machine producing the power to the other machine that uses that power.

The word Crank is defined as a right-angled movement that initiates a or receives a circular or reciprocating motion.

Talking about automobiles, the crankshafts are employed in all the automobiles and thus converts the reciprocating motion into the rotational motion.

The crankshaft takes up the reciprocating motion from the pistons inside the cylinders after the combustion process and then transfers it to the flywheel in the rotational motion that in turn powers the transmission system and finally to the wheels.

Parts of the Crankshaft

The main parts of a Crankshaft are:-

Journals

So the journals, in general, are the part of a shaft that rotates inside the bearings.

There are 2 types of journals ie Main Bearing Journals and Connecting Rod Journals.

The Main Baring journals are aligned in the axis of the bearings connecting 2 Counter Weights from the center, whereas the Connecting Rod Jurnal is eccentric from the central axis so present at the corners connecting the Counter Weights attached to the pistons.

Crank Pins

The Crank Pins are the mechanical components that are used to connect the crankshaft or the Connecting Rod Journal to the Connecting rod for each cylinder.

Crank Webs

It is defined as the portion of a crank between the crankpin and the shaft or between adjacent crankpins.

Counter Weights

As the Crankshaft, while rotating is highly exposed high amount of forces and pressures through the connecting rod and pistons that reciprocate, we need something to counter these forces for the smooth motion.

Hence counter Weights are needed.

Crankshaft Lubrication

Friction due to metal-metal contact produces heat and also wears the metal, so to prevent this a whole lot of lubrication passage is drilled, even at the angles to lubricate the crankshaft bot externally as well as internally.

Crankshaft Thrust Washer

These are simple small mechanical components that are employed at both the ends of the crankshaft in order to prevent the lengthwise motion of the crankshaft.

How is Crankshaft made??

Most of the crankshafts are made up of cast iron by pouring the molten metal ie iron into a mould

or others are made through the forging process that includes heating the metal into red hot temperature and then applying huge forces to change its shape.

After this process, the cast metal of the forged metal is machined smoothly and the drilling is done for the lubrication of the crankshafts (journals).

Conclusion

Crankshafts are thus one of the main mechanical components of the engine and thus functions to transmit the reciprocating motion of the piston into the rotational motion for the transmission system.

Originally published at https://www.carengineered.com on July 5, 2020.