An In-Depth Look at Differentials and Their Function in a Vehicle

Do you ever wonder how a car knows when to turn one wheel faster than the other? Or, why does it seem like one of your wheels gets better traction during certain turns than the others? The answer lies in differentials. 

Differentials are vital transmission components in vehicles located between the driving wheels. They transfer power from the engine to the axle, allowing each vehicle wheel to rotate at different speeds. This is especially important when the vehicle turns, as the absence of differentials causes the wheels to skid quickly or fail to turn correctly due to a loss of grip.


Types of Rear Differentials

There are three main types of rear differentials: open, limited slip, and locking. Each differential operates differently, depending on the vehicle and its purpose.

Open Differential

An open differential is a standard rear differential found in pickup trucks, SUVs, and minivans. It is an affordable and versatile solution for most vehicles, allowing the two output shafts to rotate at different speeds.

For example, when turning around a corner, an open differential allows the outer wheel to spin faster than the inner wheel with no resistance from the system. This helps maintain traction over slippery roads or obstacles. However, this system cannot handle larger differences in wheel speeds, making it less useful in off-road situations that require superior traction and torque control.

Locking Differential

A locking differential improves traction and grip on numerous surfaces, including slippery and unsteady terrains. Unlike an open differential, which sends power to both wheels at equal torque, a locking differential allows only one wheel to rotate when encountering low resistance.

This ensures that all the power generated by the engine is distributed directly to either wheel to maximize traction, guaranteeing stability even when driving off-road. As a result, it provides a higher level of protection against wear and tear. Full-size trucks and four-wheel drive off-roaders benefit most from a locking differential.

Limited Slip Differential

A limited-slip differential sends power to both wheels at an equal rate. But when more traction is needed, such as during turns, the system can apply additional torque to the wheels with less resistance. Due to the extra traction, they offer in rocky terrain or when the driver makes sharp maneuvers quickly, limited slip differentials are among the most common choices.

These differentials limit slipping between the drive wheels by reducing the power on one wheel to ensure both wheels have sufficient grip and torque at any given time. Although this slightly reduces the overall power transfer, it dramatically improves driver control and responsiveness, making the vehicle safer to drive even on rough terrain or at high speeds.

How an Open Differential Works

An open differential is a component of a vehicle’s powertrain that uses carefully selected gears and pinions inside a lubricated casing to enhance handling during turns. This mechanism analyzes the amount of rotation between each wheel. It reduces the speed of the inside wheel to match the outside wheel. This feature helps to minimize premature tire wear caused by uneven pressure distributions when driving.

In addition, when a car turns, the outside wheel travels farther than the inside wheel and needs to move faster to complete its rotations in equal time. An open differential allows the outside wheel to increase speed to provide extra traction for better steering control, enabling smoother driving even on slippery or uneven surfaces.

Moreover, an open differential controls the torque delivered to each wheel, providing equal amounts of torque to both wheels to maintain traction on slippery surfaces or rough terrain by enabling the wheels to turn at different speeds, which keeps them from slipping and losing grip.

Advantages of a Locking Differential

A locking differential is a beneficial feature that provides consistent torque and power to each wheel by inducing the same angular velocity. Here are some of its main advantages:

  • Both wheels spin at the same rate, regardless of whether one wheel has more traction than the other. This ensures maximum power transmission, especially when towing heavier loads or driving on slick roads.
  • Unequal torque levels help improve traction, allowing for more even traction on uneven surfaces and reducing slipping. This enhances driver control and stability when navigating challenging terrains or high speeds.
  • Suitable for low-traction environments and off-road situations. This differential allows the driver to adjust the power delivered to each wheel accordingly, helping to maintain a steady and secure grip on slippery roads. It also increases vehicle stability at higher speeds, making it ideal for performance driving.

Features of a Limited Slip Differential

The limited slip differential is a type of vehicle differential that combines the advantages of both open and locking differentials. It provides equal power to both wheels but can be engaged to apply additional torque when needed. Here are some of its features:

  • Allows for some slip to prolong tire longevity. A unique feature of this type of differential is that it provides a small slip between the drive wheels – a trait not found in other classes that can help prolong tire life.
  • Limits slip for improved traction, resulting in increased traction and improved handling. This benefits vehicle that experiences frequent wheel spin when navigating bumpy roads or slippery surfaces.
  • Reduces power loss by directing more torque to the wheel with a better grip. This helps to improve fuel economy and the overall performance of a vehicle.
  • Provides balanced torque delivery, applying the same amount of torque to both wheels regardless of their traction. This helps maintain stability and control over different surfaces.

Bottom Line

Differentials are an essential component of a vehicle’s powertrain that come in several types. Open differentials increase the speed of the outside wheel while distributing equal amounts of torque to both wheels when a vehicle turns. Locking differentials provide consistent torque and power to each wheel regardless of traction levels. Limited slip differentials limit slip between drive wheels with additional torque if needed. Understanding differentials will help you know how your wheel rotates at varying speeds, avoiding sliding or losing control of your vehicle when making sharp turns.


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About the author, Laurence Perkins

Laurence Perkins is the passionate car enthusiast behind the blog My Auto Machine. With over a decade of experience in the automotive industry, Perkins has knowledge and experience with a wide range of car makes and models. His particular interests lie in performance and modification, and his blog covers these topics in-depth. In addition to his own blog, Perkins is a respected voice in the automotive community and writes for various automotive publications. His insights and opinions on cars are highly sought-after.