What is differential
Wheels receive power from the engine via drive shaft.
Main function of the differential is to allow these wheels to turns at different R.P.M. while recieving power from engine.
Consider these wheels which are negotiating a turn.
It clear that the left wheel has to travel more distance compare to right wheel this means the left wheel has to rotate at a high speed.
If these wheels were connected using a solid shaft as shown.
The wheel would have to slip to accomplish the turn.
Then ingenious mechanics is a differential allows left and right wheels to turn at different R.P.M. while transferring the power to both wheels.
We will learn how differential achives these in a step by step manner using its simple configuration.
Power of engine is transferred to the ring gear through a pinion gear. The ring gear is connected to a spider gear.
Spider gear is free to make 2 kind of rotation.
One along with ring gear and second in its own axis. Spider gear is meshed with 2 side gear, so power from the engine to left and right wheels as shown.
Now consider different different cases
1 the vehicle moves straight
N left = N right
In this case spider gear rotate along with ring gear but not rotate on its own axis spider gear will push and make the side gear turn and both wheels turns at the same speed.
2 when vehicle is taking right turns
N left = N right
The spider gear plays a vital role have along with the rotation of the ring gear, it rotate on its own axis, so the slider gear is having a combined rotation.
The effect of combined rotation, on the side gear is interesting when properly meshed gear had to have same peripheral velocity as that of the spider gear, when the spider gear is spinning as well as rotating, peripheral velocity at the left side of spider gear is sum of spinning and rotational velocity but at right side gear will have higher speed compared to right side gear.
This is the way differential manages to turn just left and right wheels at different speed.
While taking a left turn the spider gear will spin in opposite directions.
in order to carry load one more slider gear is usually used, 4 slider gear arrangement is also used for heavy load vehicles.
Apart from allowing wheels to rotates at different R.P.M. differential has got two more function-
1)- Speed reduction at pinion gear.
2)- Turn the power flows direction by 90°.
It is capable to turning wheels at different R.P.M. but it has got one major draw back.
Consider a situation where one wheel of vehicle is in a surface with good traction and other is on slippery track in this case a standard differential will send the majority of power to the slippery wheels so vehicle wouldn’t able to overcome to this problem.
For this problem LSD & MLD differential are introduced.
And About these differential we will discuss in another article.
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