The Differential’s Job: Let Drive Wheels Turn at Different Speeds While Delivering Torque

The main function of a vehicle’s differential is to allow the left and right drive wheels to rotate at different speeds while still transmitting engine or motor torque to both. This is essential when turning, because the outside wheel travels a longer path than the inside wheel; without a differential, the tires would scrub, handling would suffer, and parts would wear quickly. In modern vehicles, differentials also work with traction systems to optimize grip and stability.

Why Different Wheel Speeds Matter

When a vehicle turns, the outside wheel traces a larger radius and must spin faster than the inside wheel. If both wheels were forced to rotate at the same speed, the drivetrain would bind, tires would skip across the pavement, and the car would resist turning. The differential relieves this conflict by permitting a speed difference between the two drive wheels while ensuring power still reaches the ground.

How a Differential Achieves This

Inside a typical differential, a set of gears—often bevel “spider” gears meshing with side gears—splits torque between the two axle shafts. While driving straight, both wheels turn at roughly the same speed; during a turn, the gears allow one axle to rotate faster than the other, maintaining smooth power delivery and control. In longitudinal rear-drive layouts, the differential is housed in the axle and commonly turns power 90 degrees from the driveshaft to the wheels.

Core Functions, Explained

The following points summarize what a differential does in everyday driving beyond its central role:

• Enables left and right drive wheels to rotate at different speeds during turns.
• Continuously transmits torque to both drive wheels, even when their speeds differ.
• Provides final-drive reduction (via the ring-and-pinion gearset) to multiply torque.
• In longitudinal layouts, redirects power 90 degrees from the driveshaft to the axle.
• Works with traction aids (mechanical or electronic) to manage wheel slip.

Taken together, these functions preserve tire life, improve steering precision, and maintain stability while ensuring usable torque reaches the road.

Types of Differentials and Where They’re Used

Automakers choose different designs to balance cost, comfort, and traction. Here are the most common types and how they behave:

• Open differential: Default in many cars; freely allows speed difference but will send most torque to the wheel with least grip if one slips.
• Limited-slip differential (LSD): Uses clutches, cones, viscous fluid, or helical gears (e.g., Torsen) to bias torque to the wheel with more traction while still permitting some speed difference.
• Locking differential: Mechanically locks both axle shafts together on demand (manual or automatic engagement) for off-road or low-traction use; not ideal for tight turns on high-traction surfaces.
• Torque-vectoring/e-diff: Uses gear actuators or targeted braking to actively apportion torque side-to-side, improving cornering and traction.
• Center differential (AWD): Splits torque front-to-rear and accommodates speed differences between axles; may be mechanical, clutch-based, or electronically controlled.

While open differentials prioritize smoothness and cost, LSDs and torque-vectoring units deliver better traction and performance, especially in adverse conditions or spirited driving.

What Happens Without a Differential?

Without a differential—or with a locked axle on high-traction pavement—turns become jerky as tires must slip to reconcile the speed mismatch. This leads to increased tire wear, drivetrain stress, and compromised handling. That’s why even performance and off-road vehicles only lock differentials selectively and revert to differential action for normal turns.

EVs and the Future

Electric vehicles that drive each wheel with its own motor can emulate differential action in software, eliminating a traditional mechanical differential for that axle. Many EVs still use differentials when a single motor powers both wheels on an axle, and some employ advanced torque-vectoring for sharper handling.

Summary

The differential’s primary function is to let the left and right drive wheels spin at different speeds while delivering torque to both—crucial for smooth, stable turns and tire longevity. Modern variants enhance traction and performance, from basic open units to limited-slip, locking, and torque-vectoring systems, with EVs increasingly achieving similar effects through motor control.

What is the main use of differential?

Its primary function is to enable the wheels to rotate at varying speeds, especially when a vehicle is taking corners or navigating uneven terrain. By permitting this speed differentiation, the differential ensures that each wheel can receive the appropriate amount of power while maintaining traction and stability.

What is the main function of differential media?

Differential media are used to distinguish and differentiate between different types of microorganisms that can grow on the same culture plate, often in a mixed culture, by highlighting specific biochemical or metabolic differences. They achieve this by containing indicators that cause visible changes in the medium or microorganisms, such as color changes due tosugar fermentation, which allows for the visual identification and differentiation of microorganisms with related characteristics.
 
How they work:

• Contain specific components: Differential media have specific ingredients, like dyes, sugars, or blood, that allow different bacteria to produce characteristic changes. 
• Visual differentiation: These changes can be observed as distinct growth patterns or visible alterations in the medium or on the colonies themselves. 
• Examples of changes:
  • Color changes: Many differential media contain indicators that change color based on the fermentation of specific sugars or the production of acids, as seen in Mannitol Salt Agar (MSA). 
  • Hemolytic properties: Blood agar is used to study the hemolytic (red blood cell-lysing) properties of bacteria, another form of differential characteristic. 

Why they are used:

• Identify microorganisms: They help identify specific genera or species, even in complex or mixed bacterial samples, by making them visibly distinct from each other. 
• Isolate organisms: While selective media primarily inhibit the growth of unwanted organisms, differential media work alongside them to provide a dual function, enabling both selection and differentiation in a single step. 
• Speed up identification: The visual clues provided by differential media allow for rapid identification of bacteria of interest, which is crucial in clinical microbiology and research settings. 

What is the main function of a differential?

A differential allows a vehicle’s driven wheels on the same axle to rotate at different speeds while still receiving power from the engine, which is essential for making turns. During a turn, the outside wheel must travel a greater distance than the inside wheel, so the differential adjusts the speeds accordingly. It accomplishes this through a system of gears that can adjust the rotational speed of the wheels, enabling them to turn at different rates and providing optimal traction and handling.
 
Why a differential is necessary:

• Turning corners: When a car turns, the outside wheel travels a longer path than the inside wheel. If both wheels were forced to rotate at the same speed, one would have to slip, causing tire wear, inefficient handling, and potential loss of control. 
• Distributing torque: The differential ensures that torque (rotational force) is transmitted to both wheels, even when they are turning at different speeds. 

How it works: 

1. Power input: Engine power is transmitted to the differential’s ring gear.
2. Spider gears: The ring gear drives a set of spider gears, which mesh with side gears connected to each wheel’s axle.
3. Straight driving: When driving straight, the spider gears rotate along with the ring gear but don’t turn on their own axis.
4. Turning: When turning, the spider gears begin to spin on their own axes, allowing one side gear (connected to the outside wheel) to speed up while the other (connected to the inside wheel) slows down.

Types of differentials:

• Open Differential: Opens in new tabThe most common type, it allows wheels to spin at different speeds but sends equal torque to both, which can cause a problem if one wheel loses traction. 
• Limited-Slip Differential (LSD): Opens in new tabA more advanced type that limits the amount of slip by using clutches and plates to transfer more torque to the wheel with better traction. 
• Torque-Vectoring Differential: Opens in new tabA highly complex and expensive system that uses extra gears to precisely control the torque sent to each wheel, significantly improving performance. 

What does the differential do?

A differential allows a vehicle’s drive wheels on the same axle to rotate at different speeds while still receiving power from the engine. This is crucial when turning, as the outer wheel travels a greater distance and must spin faster than the inner wheel to maintain control and traction. The differential accomplishes this through a system of gears, which also provides a gear reduction that affects the vehicle’s speed and acceleration.
 
This video explains the function of a differential: 59sSabin Civil EngineeringYouTube · Jun 12, 2014
Why is a differential necessary?

• Turning: When a car makes a turn, the inner wheel travels a shorter distance than the outer wheel. A differential allows the outer wheel to spin faster, preventing tire slippage and maintaining smooth handling. 
• Traction: By sending power to both wheels and allowing for different rotational speeds, the differential ensures that power is not lost through the wheel with the least traction, which can happen in an open differential. 

This video explains how a differential works in detail: 59sThe Engineers PostYouTube · Feb 6, 2022
How does it work?

1. Power input: The drive shaft transmits power from the engine to the differential. 
2. Gear rotation: Inside the differential, a bevel pinion gear turns a larger ring gear. 
3. Spider and side gears: The ring gear is connected to a set of spider gears (or planet gears), which mesh with two side gears. 
4. Wheel speed differentiation:
   • When driving straight, the spider gears rotate as a unit with the ring gear, moving the side gears (and the attached axle shafts) at the same speed. 
   • During a turn, the spider gears rotate on their own axes, allowing the side gears to rotate at different speeds, which drives the wheels independently. 

Types of Differentials

• Open Differential: Opens in new tabThe most common type, it balances power between the wheels but sends most of the power to the wheel with the least traction. 
• Limited-Slip Differential (LSD): Opens in new tabThis type limits the speed difference between the wheels, improving traction in slippery conditions. 
• Locking Differential: Opens in new tabOften found in off-road vehicles, it locks the wheels together to ensure they rotate at the same speed for maximum traction. 

This video explains the different types of differentials: 49sDonutYouTube · Jul 18, 2018