What is Axle in a Car? Definition, Type, Checking, Measurement, Signs of Broken, Repair

Friends, do you have any idea about What is Axle in a Car? Your car’s wheels are connected by axles, which are responsible for supporting the vehicle’s whole weight. In addition to bearing the vehicle’s weight, your car’s axles also help to drive it, as well as act as a steering mechanism.

The transmission and axle are sometimes combined into a transaxle. In rear-wheel-drive cars, the drive axle resides at the back and is connected to a driveshaft that turns it.

The CV joint, we will learn at the end of this article, is used to allow the transmission of power from one shaft to another, protected by a flexible boot. The CV joint boots should be checked every time your car is on the lift as any cracked or leaking boots can lead to serious damage to the joint. As a result, it is essential to maintain the CV joint so that the axles perform their functions properly.

What is Axle in Car? Definition

Car and Driver explain the axle, or rod or shaft, is what rotates the wheels and helps support the weight of the car. Since axles are what turn the wheels, every vehicle needs them to function properly.

what axle car definition type checking signs broken repair basics
What axle car definition type checking signs broken repair basics

Split axles are used in modern axles, which means that each wheel is connected to its own shaft. This allows your left and right wheels to be suspended independently, resulting in a smoother ride. It also allows each wheel to turn at a different speed as the vehicle moves.

How many Axles Does a Vehicle have?

There are usually two axles in a car, but larger vehicles with more wheels and more passengers may have more axles. You can easily find out how many axles your car or any other vehicle has by looking from the side and counting how many sets of tires it has. It is common for cars to have four tires in total – one set in front, one in back. There are two axles for every set of tires. Now, based on the type of cars or vehicles, nos. of axles are different, it may be

  • Two (2) Axles
  • Three (3) Axles
  • Four (4) Axles
  • Five (5) Axles,
  • Multiple Axles

Two (2) Axles Vehicle

  • It has two axles normally it can be seen in normal cars which we see all the times.
  • For example:  Maruti 800, Hundai i10, Toyota Rav4, etc. Small & medium car trucks like Toyota Tundra, Ford F-350, etc. also have 2 nos. axles.  

Three (3) Axles Vehicle

  • It has three axles normally it can be seen in extra-weight cars, trucks, and buses.  
  • For example:  Mercedes Old Car, Tata Tipper Truck, Grayhound Bus, Mercedes Bus.
three 3 axle type vehicle car example
Three 3 axle type vehicle car example Image: Google

Four (4) Axles Vehicle

  • It has four axles normally it can be seen in heavy vehicles like dumper trucks.
  • For example: Tata Signa 3525.TK Bogie Truck.  

Multiple Axles Vehicle

  • It has multiple axles and used in very large vehicles or cars.
  • For example: Limousine car is very large in size and its length is more with respect to normal cars. Many trucks which carry big equipment, small cars, etc, are very large.
multiple axle type vehicle car example
Multiple axle type vehicle car example Image: Google

Also read: Types of bikes

Types of Axle

Front Axle

Power from the transfer case is transmitted to the driveshaft of a front axle, so that the wheels of a vehicle can be steered. There are some vehicles that have front axles and use differential housings set off-center in their axle housings to allow the driveshaft to pass beside the engine oil pan and maintain sufficient road clearance.

A front axle is responsible for steering the vehicle and absorbing shocks from uneven ground. This axle has four main components, namely the beam, the swivel pin, the track rod, and the stub axle. Carbon steel or nickel steel is typically used for front axles, which must be as strong as possible. Front Axle is classified into the following types:

Live Front Axle

The live front axle delivers driving power from the gearbox to the front wheels.  It is an axle with a differential mechanism by which the power of the engine is transmitted to the front of the wheels from the gearbox. It receives power from the gearbox and transmits it to the road wheels.

The constant velocities joints help bend the stub axles around the kingpin to drive the front wheel. These joints are used to drive the front wheel.

Dead Front Axle

Dead axles and differentials stay stationary and aren’t rotated by the wheels. They are usually enclosed with housings, so they don’t come into contact with water or dirt. There is no connection between this axle and the engine, just like a dummy axle does not rotate with the driver. The dead front axle has sufficient rigidity & strength to carry the load of the vehicle from the springs to the front wheels.

In order to assemble the stub axle, the axle beam ends are shaped appropriately. It is typically configured as a yoke or an unfrozen surface with a drilled hole to accommodate a swivel pin connecting the sub-axle portion of the assembly.

Also Read: What is Governer

Rear Axle

Depending on the vehicle and the drive axle it uses, the rear axle may or may not support the weight of the vehicle. Rear axles connect differential side gears to drive wheels.

It is common for car axle components to be constructed with harder materials than other axle components because it provides increased strength.  In most cases, rear axles are live, meaning that the wheels rotate with them. They come in two halves, called half shafts that are connected by a differential. Rear Axle is classified into the following types:

Full Floating Axle

Full-floating axles, as their name implies, float in place and are designed only to transmit driving torque. They are preferred by larger vehicles, such as heavy-duty trucks. There are also some mid-size trucks that benefit from full-floating axles, such as those with higher towing capacities or those that drive extensively on four wheels.

Semi Floating Axle

One bearing supports the axle shaft, while the other is inside the axle casing. The wheel is connected to the flange on the outside of the axle shaft, so it is held securely. Despite having two bearings, this axle type can only produce the same torque as a semi-floating axle. A semi-floating axle is typically used for cars, SUVs, and mid-sized trucks, such as half-ton and light-duty pickup trucks.

3 Quarter Floating Axle

In addition to maintaining wheel alignment and handling side thrusts and driving torque, it is also more complicated and more reliable than a semi-floating axle. When the vehicle skids or turns, the side thrust that occurs on the axle shaft is still taken by the wheel, which is securely keyed to the taper on the end of the axle shaft.

Also Read: What is Engine

Stub Axle

The front wheels are attached to the vehicle’s Stub axles by kingpins. The Stub axles are connected to the front axle by kingpins.

In the forked ends of the axle, phosphor bronze bushes provide a bearing surface for the kingpin. The pink pin is a light drive that fits into the axle beam eye and locks with a cotter pin. On the top fork of the stub axle or between the lower fork and the axle beam, a steel washer or thrust bearing takes the vertical loads. Stub Axle is classified into the following types:


The axle kingpin and cotter are typically used to connect it to the axle end of the yoke. The swivel pin is mounted in the stub axle forging so as to enable the axle beam to be forced shut. In addition to the stub axle, an axle beam forms a yoke on which a thrust washer is positioned.

Reverse Elliot

A reverse Elliot-type stub axle is used to form the fork end to receive the front axle beam. The front axle end forms the eye and the thrust washer is located next to the front axle beam where it contacts the stub axle. As the stub axle and front axle form a yoke, a thrust washer is placed at the bottom to increase the life of the front axle and stub axle together.


The vision formed by the front axle beam end takes the support of the stub axle. The stub axle and kingpin integrate to form reverse. The front axle is received with an L shape assembly. The thrust washer sits between the stub axle and front axle beam. In this case, a cotter pin in the joint locks the front axle in place. The kingpin can freely move in the bushes in the eye of the axle, while a thrust washer bears the vertical load.

Reverse Lamoine

The integrated stub axle and kingpin combine to form an inverted L shape assembly to hold the front axle. The end beams of the front axle form an eye to hold the stub axles. Located in the center of the shaft, the thrust washer takes the vertical load and enhances the life of both the stub axle and the thrust washer. The cotter pin in the joint is used to lock the front axle in place. The kingpin can move in the bushes in the eye of the shaft.

Also Read: Fuel Pump

Life Span of Axle

There are still some instances where car axles can end up wearing out faster than normal because of the fact that different cars are driven on different terrains. Therefore, you must know the symptoms of a bad car axle. A leaky boot on your CV axle will deteriorate the axle faster when exposed to the rain and snow. More dirt and outer elements will get inside the CV axle and corrode it.

Why should you check your Car Axles?

An inspection of the axle is an essential part of car maintenance because you can detect problems early on which will help you avoid costly repairs later on. If you need to replace an axle, the cost can greatly increase. You shouldn’t wait six months to fix or replace your CV axle if you live in a rainy area. A bad axle can get worse quickly. It is unsafe if you are having a bad axle. You must take your vehicle to the local mechanic to have the bad axle replaced.

When is the time for Checking?

Mechanics will usually inspect your axles when you have your car serviced, but you can do the same yourself. You won’t need any tools for it, but you will need to get underneath the car so that you can inspect it. If your car is low, you may need to lift it. You can do this by using a carjack or a vehicle ramp.

Also Read: Gear Box

How to Measure Length of Car Axle?

When you are searching for replacement parts for your vehicle, it’s critical to accurately measure the axle length. Most vehicles need axle shafts of a specific size, durability, and weight handling ability, and they are difficult to find.

A database of axle shaft lengths for your vehicles can be compiled based on the axle shaft lengths of your vehicles, which is particularly useful for fleet managers. As a result, it becomes easier to locate suppliers for rare axles, axles with custom-width housings, or even axles that need replacement on a routine basis because of frequent business or industrial use.

  • By removing the wheels and tires, you can access the hubs of the trailer axle.
  • Your tape measure should be placed on the outside edge of the first trailer hub.
  • Tape measure the other side of the other trailer hub until the other end lies on its outer edge. You can measure from the outside edge to the outside edge, not from inside to outside.
  • Identify the hub face measurement by recording the length and labeling it so.

Types of Car Axle Checking

Driving Checking

If you notice any of the following signs, your axle could be in disrepair. You can also take a test drive to find out if anything is wrong.

  • The car runs, but it won’t move forward or backward.
  • Your car vibrates when you operate it.
  • If you turn your car, you hear popping or clicking noises.
  • There is a loud clunk sound when you put your car into gear.

Visual Checking

It’s easy to inspect the boot of the vehicle, which keeps joints lubricated and prevents dirt and water from getting in. They explain that the boot has ribs to allow it to bend and move with the car. Look for any holes, fractures, or grease leaks on the shaft as well as any signs that anything may be rubbing against it.

How to determine the right measurement of Axle for your Car?

  • The type of axle that a vehicle needs is determined by a variety of factors, such as technical requirements and the amount of force generated. The spline length can be optimized for a spool or differential when axle lengths are calculated correctly and axles are individually manufactured.
  • The following steps will ensure that a car’s rear end assembly is narrow enough to accommodate a large tire if you’re building a new car or updating an existing one.
  • Preferably, you’ll need a set of tires and wheels the size you’ll be using. Keep in mind that backspaces is very important. A 3″ to 4″ space between wheels and tyres is often recommended to allow for easier removal at the track.
  • Axles are pre-designed in standard formats in some vehicles, but are customized to fit the specifics of the car in others. Customized axles are usually the best option for cars since they allow more personalized control over the wheels. Speed and torque of the wheels can be adjusted more precisely with these axles.

Also Read: Diesel Engine

Axle Housing

Cases for axle housings can be manufactured as a one-piece unit or as a split unit, with the split unit being referred to as a banjo housing by many because it resembles the instrument. The axle housing has front and rear openings, with a differential carrier closing the front opening, and a spherical cover plate covering the rear opening.

Axle housing supports the weight of commercial vehicles, but it is heavier on heavy-duty trucks and truck-trailers because they are constructed to transport heavyweights. The axle housing in light-duty trucks may be made from cast steel tubes, cast iron tubes, or a combination of both. The differential and final drive case is typically a cast and machined assembly, while the axle itself is welded or extruded from steel tubing.

Why Does Axle Broken? Main Causes

We have already learned about the basic details of axle, but it may be broken also even though it’s very strong & durable. Let’s see the root cause of axle failure:

Road Accidents

In any road accident, a car or vehicle is being hit by another vehicle and created a large impact load on the vehicle. The load depends on the type of accident, speed of the vehicle, loads of both, etc. If impact load is high, the vehicle may torn and axle get a huge load which also be broken or damaged. 

Material Strength

The material of axle should be properly selected to take the loads of the vehicle. If the load is very high, then its strength should be very high so that the vehicle can take that loads.

Size & Thickness

The size and diameter of the axle shall be properly selected based on the type of vehicles.

No Rust

Formation of rust on the axle will reduce the strength of materials. Hence, it is very vital to select the material so that there will not be any rust formation.

Type of Application

Axle shall be selected based on the type of applications. If the vehicle is used for mud or slurry roads normally, then its axle will be made suitable to it.

Speed Humps

Speed humps are provided on the road to slow down the speed of the car or any vehicle. Many drivers forget the hump & jump on that which results a very high impact load on the axle. Many times, axle got directly hit by the hump & get damaged. 

CV Joint

Constant velocity joints help to transfer the torque from drive shaft for the transmission of the car. As it is a joint, it may be weaker point which can be impacted & result the failure of axle on high loads.

Signs of Broken Car Axle

Stains of Vehicle

Car axles are tough, but when they’re strained, you’ll notice it in the gas pedal. An axle that has been bent or damaged may cause your vehicle to strain when you put it in gear. When you notice it, you’ll know how much power isn’t being transferred to the wheels. Even if your vehicle is straining, it does not necessarily mean that you have a damaged axle. A damaged axle should go along with other signs of damage.

Wheel Vibration

Your vehicle may also vibrate if your tires are underinflated, your wheels are misaligned, or your lug nuts are loose. But if you notice any other sign of axle damage, do not ignore it. If you notice vibrations in your car caused by a damaged axle or other suspension problems, it becomes extremely dangerous to drive.

Vehicle not moving

There are no electrical issues, no dashboard warning lights, and no strange clicking sounds when your car tires won’t rotate. The car will turn on fine and its engine will sound fine when you rev it.

This typically occurs when an axle joint is bent and ultimately snaps. In order to inspect and repair the axle damage, you’ll need a tow truck.


Vehicles’ brake seal may shift and begin to leak oil to the brake drum as the driveshaft shifts. This will be noticeable when looking at the brake drum. As well as leaking grease, axle CV joints can also collect dirt, dry out, and degrade rapidly once this happens.

Bad Noises

As well as straining to move forward, the vehicle may also make sputtering, bumping, or clunking noises. This occurs when the axle cannot transmit enough power to the wheels. You will hear these bad axle sounds when the car starts moving and when turning the wheels. If your vehicle makes a loud clunking or clang as you put it into gear, or if it seems to have difficulty getting power as it starts moving, there may be damage to the axle joints. 

Transmission Problem

Due to slack in the joints, this kind of noise indicates that the transmission is unable to transmit power properly to the wheels. 

If you hear a loud clanking or clunking noise, check with a professional to determine if you need a transmission repair. You may also hear a clicking sound when turning the vehicle when constant velocity axles fail due to lose joints. Clicks can occur on either side of the faulty axle shaft, and they usually become more pronounced during sharp turns.

Misalignment of Break Pad

As soon as your bent axle begins to fail, you will notice some braking issues, since the brake pads will begin to shift and become out of alignment with the rotors and wheels, causing the vehicle to skid or slip. The brakes will eventually stop working over time.

Also read: car radiator

How to Repair Car Axle?

  • You should remove the center cap from the wheel you want to replace. For vehicles without wheels, you will need to remove the hubcap.
  • After you ensure your vehicle is well parked, you must apply the parking brake so that it balances before you can remove the wheel. After you do this, you must lift the car so that the jack can properly be installed. You will be able to see the lug nuts at this point. Remove the lug nuts, and the wheel will come out.
  • The old axle must first be removed by removing the cotter pin. Once the axle nut has been removed, you can proceed to removing the old axle.
  • If it does not come loose immediately, you might need to forcefully break the seal. This joint switches between the axle and the lower ball joint’s transmission, so look through that part where the axle is removed.

How long axle needs to be repaired?

If all tools are available, and there are no other issues such as difficulty removing axle end caps or difficulty replacing axle nuts other than the front axle replacement being done. The average car can be repaired in two hours. Some vehicles may need more complex work to be done instead of just replacing the axle, which will extend the time.

What is CV Joint?

Continuous velocity joints (CV joints) allow the transmission of power from one shaft to another at constant angles and constant speeds. They are generally made from medium carbon steel, which poses chipping issues when fully automated operations are used. Hard machining operations are also necessary.

Function of CV Joint

They attach the main drive axle to the shaft that connects to the front wheels. Front-wheel-drive cars need CV joints to function properly. They are usually found on the front axle of the vehicle, but can also be found on the rear.

The planetary gears are used to transfer power from one side of the shaft to the other, allowing the shaft to be rotated at any angle. They are located near the front wheels, protected by black rubber boots filled with MoS2 grease. The boots can be found under the front wheel wells.

Lifespan of CV Joint

Ideally, you should check the CV joint boot every 30,000 miles, to ensure that they aren’t cracked, torn, or dry. However, if you’re already underneath the car doing something else it makes sense to check them as well.

Performing periodic inspections of the boots can prevent the need to replace the axles if you catch and fix a torn boot as soon as possible. However, because of the way it is designed, the axles would have to be removed if the boots needed to be replaced. Using split CV joint boots is an easy remedy for replacing a damaged joint, but the solution is only temporary until a proper fix is done.

Define Axle Pad

Scales used for weighing vehicles with high capacities are called axle pads. Axle pads are used to estimate the weight of any type of vehicle, its axle weight, and its gross weight, usually in pairs. One axle pad is used for the left wheel, while the other one is used for the right. It is often used to find out if a vehicle is legal to use the road depending on its weight.

Advantages of Axle Pads

Prevent Road Surface Damage

The most important reason for avoiding unbalanced axle weight on all vehicles is to prevent damage to the road. This is particularly true for commercial vehicles, which are typically loaded with heavier loads than their consumer counterparts.

As an example, vehicle axle weights are manufactured with specific maximum axle weights that cannot be exceeded in order to ensure they are not exceeded when creating road structures that will withstand pressure. In order to avoid spending tax payer money on unnecessary road maintenance, owners should make sure their vehicle meets the manufacturer’s specifications.

Cost Effective

Weight increases result in a vehicle being much less economical since the engine requires more fuel to travel at the same speed. Fuel consumption can become a financial burden for your company if it is not managed quickly, hurting your profit margins.

You may also void your insurance policy if you exceed your vehicle’s maximum weight limits. Likewise, insurance rates are significantly higher on commercial vehicles than they are on consumer vehicles, so it’s essential to comply with the eligibility requirements. Regular axle inspections will contribute to maximizing your vehicle’s fuel efficiency as well as complying with the insurance policy’s terms.

Driver Protection

If you place an overabundance of weight on one side of the vehicle, you will naturally create an imbalanced load and your rear wheels may not make contact with the earth in extreme cases.

Due to hindered braking capabilities and reduced stability, a vehicle can easily become more susceptible to crashes regardless of the distribution. Due to a longer stopping distance in overweight vehicles compared to the vehicle that meets the manufacturer’s standards; this can prove fatal under certain circumstances.

Prevent Your Vehicle’s Damage

Loading one or more axles can also damage the vehicle, in addition to damaging the road. The components within large industrial vehicles are extremely durable and have high strain tolerances; however, those components are still subject to maximum thresholds.

Weight distribution must be checked regularly in order to avoid damaging axles, drive shafts, tires, and other parts from overloading. In addition to more frequent maintenance, some components may have to be replaced completely. Furthermore, excessive payload can affect the driving experience significantly. The steering and braking systems of a truck can malfunction when it exceeds its weight limits, making it difficult to control.

Saving Penalty

You may face substantial financial penalties if you exceed your vehicle’s maximum axle weight. Unless the difference exceeds one ton, there will not be a penalty if the difference is less than 5%.

Besides preventing unbalanced vehicles from putting undue stress on road surfaces, these restrictions are also put in place to regulate the weight of commercial vehicles. As a result, it is imperative that company vehicles meet their predefined maximum weights in order to avoid incurring penalties, and axle pads can help to accomplish this.

What is Half Shaft?

Most modern drive axles have short rods with a flexible rubber boot that covers two CV joints at each end. They are also known as half-shafts. It is important for the boot to hold grease inside and to keep dirt out so that the CV joint can function properly. Modern cars have better traction, ride, and handling because they are more complex, but there is also an increased chance of something going wrong.

Does Car Axle Repair include in Insurance?

Typically, car repairs and maintenance are your responsibility if you’re dealing with a damaged or faulty axle. However, if you have collision or comprehensive coverage, a damaged axle caused by an accident may be covered. Because accidents can occur at any time, you need to make sure your car is properly insured.


In many ways, your car axle keeps it going so it’s important to know how to recognize the signs of a bad axle and to get whatever repairs are needed in order to keep it safe and in good working condition. You should also consider car insurance as part of your overall auto maintenance.

In addition to making sure your car has gas and oil, rotating the tires, changing the oil, and checking all of the fluids, you should keep it locked when you’re not in it, and wear a seatbelt when you’re in it. You might never need to replace your front axle, but there are other big issues. When you get new tires or a tire rotation, have the technician check out the front axle. Your vehicle will be on a lift and they will be able to view things like the car axle, axle caps, and other components.


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