What is an Axle? | How does a Car Axle work?

What Is a Car Axle?

An axle or axletree works as a central axis that turns the car gear or wheel. The axle is a mechanical device that makes a connection between the vehicle’s tires and wheels. The main function of the axle is to receive power from the engine through a power transmission system and deliver this power to the vehicle wheels to move or turn the vehicle.

At one end of the axle, there is a long bolt attached to the wheel with a lug nut, and the other end is connected to the car’s power transmission system, which turns the wheels after receiving power from the engine.

car axle

In the case of a vehicle with wheels, the axle is connected to the wheel and rotates the wheels. In another case, the axle can be attached to the vehicle, and the wheels rotate around it. In the first case, the bushing or the bearing install at the attachment point where the axle provides support. In the second case, the bushing or bearing installs in the wheel center hole, which allows the gears or wheels to reciprocate about the axles.

Design of Axle

The car axle design is derived from the chariots employed in ancient Greece. When a horse forced a chariot, this axle turned the wheel. The axles also tolerated the traveler’s cabin weight. With the passage of time, this model was used in horses and carriages and eventually in vehicles.

A front-wheel-drive vehicle contains an axle that links the front wheel to the engine and drivetrain. This design is exceptional for front-wheel-drive cars. The front-wheel-drive links the transmission and engine directly to the differential gears on the front wheel axle.

The rear-wheel drive contains a standard axle that links the rear gear to the driveshaft and transmission. When the drive shaft rotates, the rear gear rotates the wheels of the car. It uses gear drive technology to turn the wheel around the axle with a precise gear ratio.

A Four-by-four car contains gears on the rear and front axles. This causes the front and rear wheels to rotate according to the engine speed. This complicated construction increases the installation and repair costs of the four-by-four axle.

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Types of Axles

The axle has the following three major types:

  1. Rear axles
  2. Front axles
  3. Stub axles

1) Rear Axle

These types of axles have a responsibility to deliver power to the drive wheel. It has two halves called the half shafts that link to the differential. In maximum conditions, the rear axle rotates with the wheels of the vehicles.

2) Front Axles

As the name of this axle represents that it installs at the front of the car. It helps to turn the vehicle and communicate with the car shocks while driving on bumpy roads.

The front axle has the following four major components:  

  1. Stub axle
  2. Tie rod
  3. Swivel pin
  4. Beam

This axle should be as strong as possible. Therefore, nickel steel or carbon steel is used for its construction.

3) Stub Axle

It is to the front wheels of the car, and the kingpin connects it with the front axle.

Types Of Front Axle

The front axles have the following two types:

  1. Dead Front Axle: These are static axles and don’t spin with the rotation of the wheels.
  2. Live Front Axle:These axles also supply steering system power to the front wheel.

Types Of Stub Axle

The stub axles have the following major three types:

  1. Elliot: It has a cotter, a yoke, and a kingpin that connect with the front axle.
  2. Lamoine: It has an L-shaped spindle instead of a yoke-type hinge.
  3. Reverse Elliot: It has a totally reverse arrangement to the standard Elliot stub axle.

How to Choose the Right Axle Ratio for Your Pickup Truck?

  1. Stickers on the car windows represent the fuel consumption data for the standard axle ratios. If you want your vehicle to consume a low amount of fuel, choose a vehicle that contains a custom axle ratio.
  2. Maximum suppliers mention high axle ratios as short gear and low axle ratios as high gear. The former can pull heavier loads than usual, while the latter has better fuel economy.
  3. A comparison of the available axle ratios from different vehicle manufacturers is not possible. Different tire sizes influence the running of the vehicle and the final design.

Symptoms of a Bad car axle

1) Vibration While Driving

This is a most common and tricky symptom than other symptoms because your car may also vibrate because of many other reasons such as bad carburetor, bad steering system, and many others.

However, if you notice extreme vibration which increases with speed, or an unusual “bouncy” feeling in your driving, this may be due to a faulty constant velocity (CV) axis. In such a condition, you must stop your vehicle, inspect it, and fix the source of vibration. If you cannot find the problem, contact a technician and ask him to fix it.  

2) Brake Pad Misalignment

If the bent axle starts to deteriorate, your car braking system will start to generate problems. In such a case, your car brake pads start moving, and they will be misaligned with the rotor and wheels. In this case, the car may skid or stop.

If you do not fix or replace your axles on time, your car brakes will ultimately fail to work.

3) Grease on edge or inside the tires

The constant speed axle’s joints contain a protective greased cover to prevent lubrication leakage during the rotation of the axle. If the protective cover leaks, there will not be enough lubricated to decrease the axle’s wear and tear while rotating.

This insufficient lubrication can cause CV joint failure. Therefore, as you observe grease on the inner side or edges of the wheels, immediately fix it; otherwise, it can lead to a costly repair.

4) Knocking Sound

As you notice muffled or knocking sounds, immediately find the reason for this sound. There are many reasons due to that your vehicle can suddenly produce this sound. A damaged CV axle is also a common reason for knocking sound.

In some conditions, the knocking sound increases as you reverse your car, and you can hear it more clearly. In such a situation, you must immediately call a specialist to fix it. So that you can save yourself from more severe results.

5) Car Won’t Budge

The most common symptom of a damaged axle is the inability of the vehicle’s tires to spin. The car starts normally. When switched on, the motor sounds happy as normal. No electrical issues, no dash warning lights, or weird clicking sound.

Why is this happening? This usually occurs due to a bent CV joint that eventually breaks like a Slim Jim. In such a situation, drive your vehicle to a nearby repair facility to inspect and repair CV joint damage.

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