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Types Of Vehicle Axles: a Complete Overview

Those of you who know anything about automobile machinery must have heard of vehicle axles. This is a part of the propulsion system in an automobile. This part is sometimes referred to as a differential as well.

A car needs a lot of intricate parts to operate. This axle is one of the more significant ones. Are you familiar with the definition, types and function of a vehicle axle? Give this blog a read if you’re interested in learning more.

What is an axle?

Axles are the steel rods that join two wheels together. They move the wheels by applying rotational force, or torque, to the car’s transmission. The axle functions as a link between two tyres and propels the wheels ahead, causing the vehicle to move with the help of power coming from the transmission.

A car usually has one axle for every two wheels. One wheel on one side and another wheel on the other are connected by the axle. Cars have two axles because they have four wheels. As one might anticipate, larger cars occasionally have more axles. For example, a huge pickup truck can have an extra axle.

Types of axles

There are different axles with various applications, each of which is designed for specific objectives. Here are three types of axles:

1. Front Axle
2.Rear Axle
3.Stub Axle

Most cars have two types of axles – front axle and rear axle. The rear axle works to propel the vehicle in the forward direction and the front axle works to give direction to the wheels. 

 

There may be more than two axles in certain situations, particularly in trucks and bigger automobiles.

The type of axle to be used depends on the car’s design, purpose and performance needs. Different axle types give different benefits regarding stability, load capacity and traction. 

1. Front Axle: The axle doing the heavy lifting

The purpose of the front axle is to support the weight of the front portion of the car, aid in steering, and cushion impacts from uneven surfaces. The front axle of a vehicle transfers the weight of the front portion of the vehicle to the road surface through the front wheels. Therefore, the construction of the front axle needs to be right and robust.

Typically, the front axle is a drop forging made of 0.4% carbon steel or 1%–3% nickel steel. Its centre section is an I-section, and its ends are either elliptical or circular.

With this construction, the front axle takes the bending loads from the vehicle’s weight. Also, there is a downward sweep given to the torque centre part. The key components of the front axle include the beam, stub axle, swivel pin, and track rod.

Types of Front Axles

Steel drop forgings are usually used to make front axles; 0.4% carbon steel or 1-3% nickel steel are frequently utilized. The extremities of the axle are elliptical or circular, while the centrepiece of the axle is built as an I-section. Because of its design, the axle can bear the bending loads caused by the weight of the car. To improve strength and stability, the torque centre part is additionally given a downward sweep.

Dead Front Axle:

These axles are known as the dead front axles because they are immovable and do not spin with the wheels. These axles are very stiff and strong, enough to support a car. The front axle is made to accommodate the stud axles at its ends. The front axles are usually dead axles since they are non-rotating.

Live Front Axle:

Live front axles have an additional role beyond supporting the vehicle’s weight and facilitating steering. Unlike dead axles, which do not rotate, live front axles are equipped to transmit driving power taken from a transfer gearbox to the front wheels, employing a different swivelling mechanism.

2. Rear Axle: Keeping the wheels afloat

The rear axle is positioned between the driving wheels and the differential to transfer power from the differential to the wheels. This technology is utilized in rear-wheel drive cars.

On the rear axle, bearings are included. Via the springs, the vertical load applied to the axle casing is transferred to the shaft and, ultimately, the wheels and the ground through these bearings. The load’s reaction acts upward on the wheel between it and the ground.

Types of Rear Axles

Based on how they support and mount wheels, rear axles in automotive systems can be divided into three categories:

Semi Floating Axle:

A semi-floating axle, which is seen in light-duty cars, has an axle shaft on both sides and a spline where it joins the differential at the inner end. It is made up of a wheel flange on which the studs are mounted on the other end. 

It is attached to the end of the axle housing utilizing a bolted flange configuration. Because of this, it not only transfers power to the wheels but also uses torsional, shear, and bending forces on the axle shaft to support the weight of the car.

Full Floating Axle:

These axles are designed only to transfer power to the back wheels via the differential; they do not bear the weight of the car. Rather, the spindle linked to the axle housing supports the weight. This spindle is also where the wheel hub is fastened. Heavy-duty trucks frequently employ these kinds of axles. This is a result of the axle’s higher load capacity. A damaged axle shaft can be removed while the wheel can still spin unpowered due to the way the wheels are mounted.

Three Quarter Floating Axle:

The purpose of a three-quarter floating axle is to transfer the vehicle weight only to the axle casing by placing a bearing between the axle casing and the hub. The axle absorbs the driving torque and side thrust. The axle and hub are fastened firmly. It assists in keeping the wheel aligned and supplying the driving connection. This axle’s inner end is constructed similarly to a semi-floating axle. Although it is not as easily constructed, it is more dependable.

3. Stub Axle

A stud axle is an axle that fastens to just one wheel. These can be utilized to support wheels that aren’t receiving power in cars with front- or rear-wheel drive. Stub axles, for instance, may support the back wheels of a car with front-wheel drive. These axles also feature a wheel bearing supporting the wheel hub. A kingpin is also used to secure these kinds of axles to an axle.

In case you weren’t aware, a kingpin is a big bolt that serves as a pivot. Furthermore, the cotter is a wedge or pin that attaches the kingpin to the axle by passing through a hole in the pin. It ensures that the kingpin stays in the joint that connects the stub axle to the other axle.

Types of Stub Axle

  • Elliot: An Elliot stub axle fits inside the main axle’s yoke to connect to the axle. Next, a cotter and a kingpin are used to join the stub axle through the yoke.
  • Reverse Elliot: The stub axle for the Reverse Elliot stub axle goes around the main axle and features a yoke. After that, a kingpin and a cotter pin join the two axles via the Reverse Elliot stub axle.
  • Lamoine: This axle is equipped with an L-shaped spindle that fastens to the axle with a cotter and kingpin. The axle is also locked in place by the cotter. On tractors and other heavy vehicles, this is a typical stub axle.
  • Reverse Lamoine: The Reverse Lamoine takes the form of an inverted L as the Lamoine stub axle forms an L-shaped spindle. It connects via a cotter and kingpin much like the Lamoine stub axle

Factors That Decide the Type of Axle in a Car

The type of axle in a car is determined by various factors, reflecting design considerations, vehicle usage, and engineering priorities. Here are the key factors:

Drive Configuration

Front-wheel-drive (FWD) cars utilize a front axle for both steering and driving. Rear-wheel-drive (RWD) cars employ a rear axle for driving. All-wheel-drive (AWD) or four-wheel-drive (4WD) cars may engage both front and rear axles in driving.

Vehicle Type

The choice of axles might vary depending on the kind of vehicle, including trucks, SUVs, passenger cars, and performance vehicles. Compared to regular passenger cars, trucks and SUVs intended for off-roading or heavy towing may require different axle specifications.

Performance Requirements

High-performance vehicles often demand specialized axle features to cope with increased power and torque.

Weight Distribution

The axle design is influenced by the weight distribution in the vehicle’s front and back. Different axle designs may be needed for cars that are front- or rear-heavy to achieve the best possible weight distribution and balance.

Cost Considerations

The choice may be influenced by the cost of producing and installing various axle types. Manufacturers try to strike a balance between cost-effectiveness, performance, and safety of the end product.

Fuel Efficiency

Fuel efficiency may vary depending on the axle selection. For instance, because front-wheel drive systems have less weight and mechanical losses than rear-wheel drive systems, they are typically more fuel-efficient.

Off-Road Capability

Off-road vehicles like SUVs and trucks require specific axle features such as increased ground clearance and reinforced components.

Regulatory Compliance

Axle selection is influenced by the need to comply with safety and emission regulations.

Manufacturer’s Design Philosophy

Each automaker may have distinct design philosophies, favouring specific axle types for particular vehicle models or classes.

Signs of a bad axle

After learning what an axle is and how it operates, it’s time to find out more about how to identify a malfunctioning axle. This is, after all, a component that is vital to the functioning of your car. A bad axle could cause problems for your car later on.

The good news is that you can identify if you have a problematic axle by looking for certain indicators, which include the following:

  • You feel vibrations while driving
  • Your car does not move
  • There is a grease leakage all of a sudden
  • You have started to hear a clunking or clicking sound. 

However, no matter the axle type—be it front or rear—they function differently in front-wheel, rear-wheel, and all-wheel-drive vehicles. For accurate solutions, it’s best to always consult with experts who can provide precise assistance.