A differential is an integral part of car that’s powered by a petrol or diesel engine or in fact by any other engine. While the engine produces power that’s meant to be sent to the wheels, the power is sent to the wheels that are not solidly connected, rather they have a differential in between them to serve a special purpose. What’s that purpose? And how does it work etc.? In the following questions, we take a look.
What is the function of a differential?
Most cars are either front wheel drive or rear wheel drive. That means that power from the engine is sent to the front two wheels or rear wheels, whatever the case, the one set of wheels are trailing and roll independently.
In case if the car were to travel only in straight line the power from engine could have been sent to the two wheels directly without the use of differential. However, it’s not the case and when you turn the car around a corner, the inner wheel needs to rotate less than the outer wheels. So the function of the differential is to allow for this variation and let the outer wheel rotate more than the inner wheel without slipping. Without the differential, the car would not be able to negotiate the turn without slippage.
How does a differential work?
In its simplest configuration, a differential consists of a ring gear that’s driven by a pinion gear. The ring gear is connected to the spider gear. The spider gear can rotate along with the ring gear as well along its own axis. The spider gear is in mesh with two side gears that drive the half shafts of the wheels to which the power is to be sent. When the vehicle is moving in a straight line, the ring and spider rotate as one unit and transfer equal power to the half shafts, the spider does not rotate on its own axis in this case.
In case if the vehicle is turning right / left, the spider gear also starts rotating on its own axis to account for difference in resistance that the wheels face. The difference in velocity is added or subtracted from individual side gears depending on which wheel need to rotate more.
How many types of differentials are there?
The most common and first differential that automobiles started using was the Open Differential. Others like Locking Differential, Limited Slip Differential, Electronically Controlled Limited-slip Differential have come along the way as technical advancements have been made in the field.
The most advanced one that’s result of much late developments is the Torque-Vectoring Differential. It’s being used mostly in sport cars. Each differential has its own set of benefits and limitations.
Does only rear wheel drive cars have differential?
No, the differential and the propeller shaft are mostly visible in case of rear wheel drive cars when powered by front mounted engine. However, differential is present in case of cars that have front mounted engine and have a front wheel drive system too. So basically, all cars have at least one differential that split power between the wheels.
Can a car have two differentials?
In case of all wheel drive cars, there are two differentials, one at the back and one for the front wheels. A transfer case is used to split power between front and rear wheels.