Differential: Definition, Types & How does it Work?

What is a Differential?

A differential is a gear train with three shafts that has the property that the rotational speed of one shaft is the average of the speeds of the others or a fixed multiple of that average.

As part of the front and/or rear axle assembly, the differential plays an important role in your car’s turns. The differential is designed so that it drives two wheels and can rotate at different speeds at the same time. This function provides proportional speeds between the left and right wheels.

If the inner tire rotates 15 rpm less than straight on a curve, the outer tire rotates 15 rpm more than straight ahead. For example, when your vehicle turns a corner, the outside wheel has to go faster than the inside wheel. The differential distributes the same torque to both wheels.

This allows the wheels to respond to resistance or provide traction to give the wheel more resistance to turn less. The wheel with less resistance will turn faster.

Some vehicles, such as go-karts are not equipped with a differential. In this case, both drive wheels are forced to rotate at the same speed, usually on a common axle driven by a simple chain-drive device. Front-wheel drive vehicles are designed differently in that the axle and differential assembly is located in the transmission axle assembly or the transmission.

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What is Differential Gear box?

Differential gear, in automotive mechanics, gear arrangement that permits power from the engine to be transmitted to a pair of driving wheels, dividing the force equally between them but permitting them to follow paths of different lengths, as when turning a corner or traversing an uneven road.

What is Car Differential?

The differential is a system of gears that allows different drive wheels (the wheels to which power is delivered from the engine) on the same axle to rotate at different speeds, such as when the car is turning. Note that a car with four-wheel drive can have two or more differentials.

A differential is also the component through which a rotating driveshaft can change direction; for example, in a rear-wheel-drive car whose driveshaft runs the length of the car, it joins and transfers its power to an axle that runs perpendicular to the car to drive the left and right wheels.

Car Differential

How does differential work in a car?

In simple terms, a differential is a system that transfers the torque from an engine to the wheels. The differential takes the power from the engine and divides it so that the wheels can spin at different speeds. Rotate it around a corner and you won’t have any problems as each wheel can turn independently from the other.

When you look at a complete modern differential, it looks incredibly complicated.

However, if you systematically break it down and understand the basics of what it is trying to achieve and how it is trying to achieve it, you will find that it is really a beautiful thing.

Check out this video of Chevrolet engines for a retro look at the differential.

Now that we understand the basics of a differential, or in this case an “open differential,” let’s discuss a little more about a limited-slip differential (LSD).

Imagine you are on the track trying to get out of a tight corner at 50km/h. All of this power will take the path of least resistance.

All weight has been shifted to one side. All of that power will only spin the inner wheel, resulting in a tremendous amount of power lost or spinning and a major crash.

The LSD is in place to minimize this drive loss. A clutch system creates friction on each side of the axle so that the car can redistribute torque to each wheel so you can get as much power as needed. If you know your way around the wheel, you can steer the car with nothing but power, even in a curve.

As you can imagine, the entire differential mechanism has to withstand an enormous force. This is just one reason why these components are made from the strongest possible materials. No straws and milk bottle caps.

Differentials have to be extremely durable. When cars were slower and less demanding, you could get away with cheaper metals. This is simply no longer the case.

Even today’s simplest vehicles can travel comfortably at over 150 km/h and are capable of safely cornering at relatively high speeds. High-quality components are no longer reserved for the racetrack.

Parts of Differential

Following are Differential Parts:

  • Bearing kits
  • Individual seals and bearings
  • Ring and pinion sets
  • Axle shafts
  • carrier/pinion shims, pinion nuts, crush sleeves and ring gear bolts
  • posi-traction and internal gear kits
  • housings carriers
  • These are just some of the component parts in stock. We even have used parts for most differential applications.
  • Pinion Drive Gear: this part transfers the power to the ring gear from the drive shaft.
  • Differential case assembly: this part holds the Ring gear along with other components which drive the rear drive axle.
  • Ring Gear: this section transfers the power to the previous part that is Differential case assembly.
  • Rear drive axles: these are the steel shafts which transfer the torque from differential case assembly to drive wheels.
  • Axle housing: these are the metal body that encloses the rear axles and also supports the rear axle assembly.
  • Rear axle bearings: these are the ball bearings which fit between the axle housing and the axles.
  • Side gears: these gears help both the wheels to turn independently while turning.

Types of Differentials in Cars and Trucks

There are main four different types of Differential:

  • Open Differential.
  • Limited-Slip Differential.
  • Locking Differential.
  • Torque-Vectoring Differential.

1. Open Differential

Open differentials are the most common differential found on passenger vehicles and allow the wheels to rotate at different speeds while the vehicle is turning a corner.

What is key to know about open differentials?

Advantages:
  • Open differentials are the original solution to a universal problem.
  • They allow the wheels to turn independently of each other, preventing wheel hop, vehicle instability, and excess tire wear.
Disadvantages:
  • Open differentials don’t work well on uneven or slippery surfaces because the engine torque is transmitted to the wheel with the least resistance (a.k.a. “traction”).
  • If the tire is off the ground or on ice, it spins freely and the vehicle is unable to move.
  • On asphalt, you get the infamous “one-wheel peel” under heavy acceleration.

2. Limited-Slip Differential

A limited-slip differential (LSD) is a type of differential that allows its two output shafts to rotate at different speeds but limits the maximum difference between the two shafts.

In an automobile, such limited-slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.

Mechanical limited-slip differentials are arguably the most common type of differential due to their wide range of applications. They work by shifting a portion of the torque to the wheel with the most traction while limiting the slip on the wheel with the least traction. Because of this, limited-slip differentials are often referred to as “torque sensing”.

Like an open differential, the wheels can rotate at different speeds. However, with a limited-slip differential, torque is not always balanced between the wheels. This allows the wheel with traction to receive more torque in order to continue to move the vehicle. In other words, the differential is said to “bias” more torque to the higher traction tire.

The amount of torque variation the differential can shift between wheels is referred to as the bias of the differential.

Disadvantages:

  • The key disadvantage, when compared to a locking differential, is that the amount of torque that can be transmitted to the wheel with traction is limited (thus the name, limited-slip). Since they cannot provide 100% lockup, during extreme situations (i.e., complete loss of traction at one wheel), there may not be enough torque to the wheel with traction to move the vehicle.

3. Locking Differential

A locking differential is designed to overcome the chief limitation of a standard open differential by essentially “locking” both wheels on an axle together as if on a common shaft. This forces both wheels to turn in unison, regardless of the traction (or lack thereof) available to either wheel individually.

A locked differential can provide a significant traction advantage over an open differential, but only when the traction under each wheel differs significantly.

Locking differentials (generically referred to as “lockers”) can lock the axles together to provide 100% of available torque to the wheel with traction. During turns, a locking differential operates as an open differential – the wheels can rotate at different speeds.

However, when traction is needed, the axles can be mechanically locked together forcing the wheels to rotate at the same speed. This is especially helpful in off-roading situations when one wheel is off the ground or on an otherwise very low traction surface.

When locked, the wheel in the air doesn’t receive any torque because there is no traction and the wheel on the ground receives all the torque, allowing the vehicle to move.

How do locking differentials work?

Locking differentials use various methods to lock the axles together and can be automatic or driver-selectable, depending on the model.

  • Automatic locking differentials: As the name says, automatic locking differentials require no driver action and automatically lock the axles together when torque is applied.
  • Driver-selectable locking differentials: Driver-selectable locking differentials require the driver to activate a switch, usually located on the dash, which activates the locking mechanism. Some lockers use a lever and cable to lock the axles together.

Disadvantages:

  • Some lockers are known for being noisy and harsh on the street, with sometimes unpredictable impacts on handling, especially in corners and wet/ice/snow conditions, but the ability to have fully locked axles is worth those trade-offs for some drivers. These types of lockers are primarily used in racing situations.
  • Drop-in or “lunchbox lockers” replace the stock spider gears or limited-slip clutches with a locker section and are an easy-to-install, lower-cost option. However, they are not as strong as a traditional locker because they rely on the OEM carrier and reliability could become an issue if power adders, larger wheels and tires, and other modifications are made to the vehicle.

4. Torque-Vectoring Differential

Torque vectoring is a technology employed in automobile differentials that has the ability to vary the torque to each half-shaft with an electronic system. This method of power transfer has recently become popular in all-wheel-drive vehicles.

Some newer front-wheel drive vehicles also have a basic torque vectoring differential. As technology in the automotive industry improves, more vehicles are equipped with torque vectoring differentials. This allows for the wheels to grip the road for better launch and handling.

Also known as active differentials, they work in the most efficient way which results in a truly dynamic, high-performance driving experience. Torque-vectoring differentials can be found in some high-performance rear-wheel drive and all-wheel drive vehicles.

FAQ

What is Differential?

A differential is a gear train with three shafts that has the property that the rotational speed of one shaft is the average of the speeds of the others or a fixed multiple of that average.

What is Differential Gear box?

Differential gear, in automotive mechanics, gear arrangement that permits power from the engine to be transmitted to a pair of driving wheels, dividing the force equally between them but permitting them to follow paths of different lengths, as when turning a corner or traversing an uneven road.

What is Car Differential?

The differential is a system of gears that allows different drive wheels (the wheels to which power is delivered from the engine) on the same axle to rotate at different speeds, such as when the car is turning. Note that a car with four-wheel drive can have two or more differentials.

What are the parts of Differential?

Following are Differential Parts:

1. Bearing kits
2. Individual seals and bearings
3. Ring and pinion sets
4. Axle shafts
5. carrier/pinion shims, pinion nuts, crush sleeves, and ring gear bolts
6. Positraction and internal gear kits
7. housings carriers
8. These are just some of the component parts in stock. We even have used parts for most differential applications.

What are the types of Differential?

There are main four different types of Differential:

1. Open Differential.
2. Limited-Slip Differential.
3. Locking Differential.
4. Torque-Vectoring Differential.