What is a Drive Shaft? | How does a Drive Shaft work?

What is a Drive Shaft?

drive shaft is a most important part of a vehicle that transfers torque from the transmission to the differential, and then the differential delivers this torque to the front wheels to run the vehicle. The drive shaft is also known as a Cardan shaft, propeller shaft, or prop shaft.

In simple words, the main function of the propeller or drive shaft is to deliver the engine torque from the differential to the vehicle wheel. 

Drive shaft
Diagram of Drive Shaft

The position of the driveshaft changes according to the car model and configurations of the car front-wheel drive, four-wheel drive, and front-engine rear-drive. Many other vehicles such as boats, locomotives, motorcycles, trucks, and vans also have prop shafts.

These shafts have a different number of prismatic joints, leaf joints, universal joints, or jaw couplings to enable change in distance and alignment between drive and driving parts.  

Working of Drive Shaft

The main purpose of the drive or prop shaft is to transmit the torque of the engine from the differential or gearbox to the vehicle wheels. In addition, any changes in angle or length caused by manipulation or deflection must be compensated for in order to ensure excellent synchronization between the shaft joints.

driveshaft working

The drive shaft with a front-wheel drive has a connecting shaft, an inner constant velocity joint, and an outer fixed joint. It also has some other parts like torsional dampers and anti-lock system rings.

The vehicle has flexible bearings or mountings, which uses to connect the transmission unit and engine. However, the suspension spring uses to connect the wheels, differential, and rear axle.

Look at the above arrangement; the transmission input shaft and the output shaft of the rear axle casing are in several planes. This arrangement helps the drive shaft to connect the input and output shafts in an inclined angle.

When the rear wheels hit uneven surfaces, the rear axles move downward and upward, expand and compress in suspension spring. This changes the angle between the propeller shaft and the transmission output shaft.

Due to this process, the length of the prop shaft varies. This change appears because the drive shaft and rear axle rotate in an arc along with a point of their rotational axis.

Parts of the Drive Shaft

The driveshaft has the following major parts:

  1. Flanges
  2. Slip yoke and Tube yoke
  3. End yoke
  4. Midship shaft
  5. Universal joint
  6. Centre bearing
  7. Tube

1) Tube

The rear-drive vehicles and front engine vehicles also have tubes. It uses to maintain the position or placement of the rear end during the braking and acceleration process.

Read Also: Different types of Engines

2) Flanges

The flange uses to link the propeller shaft with the differential, transfer case, and transmission. These also use to link the propeller shafts with the hydraulic pumps, power take-offs, and many other components of the vehicle.

3) Center Bearing

The center bearing uses to link the two parts of the propeller shaft. In this way, the center bearing ensures the exact position of the drive shaft parts and decreases the harmonic vibration during the motion of the car. 

4) Universal Joint (U-joint)

The universal joint is a most important part of the propeller shaft. The universal joint is also known as a U-joint. It connects the revolving shafts of the vehicle.

At present, driveshafts with universal joints can be most commonly seen in four-wheel drive and rear-wheel drive vehicles.

5) End Yoke

The end yoke uses to ensure the durability and accuracy of the prop shaft.

The main purpose of the end yoke is to decrease the vibration and noise during the vehicle acceleration. In this way, it ensures comfortable driving.

6) Midship Shaft

It is a major component of the drive shaft and coupling shaft linked with the housing on the center bearings.

7) Tube Yoke and Slip Yoke

The slip yoke directly connects with the drive shaft via a universal joint. This yoke slides inward and outward of the transfer case to deliver the power. A tube yoke also requires to successfully rotating the driveshaft and U-joint.

Read Also: Working of Planetary Gearbox

8) Tubular Shaft

This shaft uses to correct the distance factor between the rear axle and the gearbox. The driveshaft may have more than one tubular shaft according to the drive shaft types and vehicle types.

The length of this shaft varies according to the shaft distance from the gearbox. A short tubular shaft uses for front-wheel drive, and a long tubular shaft uses for rear-wheel drive and.

The tubular cross-section delivers excellent flexibility and strength than the filled cross-section. These shafts have lightweight.

Types of Drive Shafts

The drive shaft has the following major types:

  1. Single Piece shaft
  2. Two or Three Piece shaft
  3. Front Wheel Drive

1) Single Piece Shaft

These types of drive shafts are used in four-wheel-drive vehicles and many other vehicles that have a small distance between the axle and the engine. There is applied friction welding to improve the durability, quality, and strength of the single-piece drive shaft.  

Single Piece propeller shaft

This type of propeller shaft is made of lightweight material like aluminum which needs a larger diameter to attain the similar excellent strength as a steel shaft. Following are some problems with this approach:

  1. It can be damaged more easily.
  2. Large clearance requires for the shaft accommodation and its harmonics.
  3. The single piece shaft has a high manufacturing cost.

2) Two or Three-Piece Propeller Shaft

These shafts are used to stop the driveshaft damage due to bending at high speed. Two or three-piece shaft uses for four-wheel-drive vehicles and vehicles with a large distance between the axle and engine. You can reduce the speed by dividing the driveshaft into two or three parts.

two piece drive shaft

When the shaft doesn’t bend, the floor or the transmission tunnel above the shaft lowers to create more space for passengers or luggage.

3) Front-wheel Drive (FWD) 

First of all, you need to know that the front-wheel vehicle doesn’t use a driveshaft. In front-wheel drive vehicles, the front wheel provides the power to drive the vehicle.

Front wheel drive

In contrast to the long drive shafts as rear-wheel vehicles, all parts of the drive train of the front-wheel-drive vehicle are located in the vehicle’s front area. The wheel drive shaft uses constant velocity (CV) joints instead of universal joints.

In the front-wheel vehicle, the axle and the transmission are joint in one unit, known as a transaxle.

Symptoms of Bad Drive Shaft

The proper working of the drive shaft is too much important for the proper operation of the car or any other vehicle. In case of driveshaft failure, you must replace it immediately.

Following are some most common signs of a bad or failing drive shaft. If you observe the below-given symptoms, you need to replace your propeller or drive shaft immediately.

  1. Vibration
  2. Knocking noise
  3. Squeaking noise
  4. U-joint motion
  5. Turning issues
1) Vibration

The wear of the drive shaft bushing can cause vibration. The bushing usually prevents the shaft from vibrating at an early stage.

As you identify this issue in your vehicle, you need to fix it quickly; otherwise, the vibrations will be worst.

In case of extensive vibration, you and your passengers will be felt uncomfortable. In the worst case, other components of the transmission system may also be affected and damaged. Follow the manufacturer instructions in the user manual to fix this issue.

2) Knocking Noise

If you hear a knocking or unusual noise while driving the car, there may be a problem with the driveshaft, and you should check it well in advance. In maximum cases, this noise occurs due to a bad slip yoke.

Read and follow the manufacturer’s manual to fix the clunking noise. If you are unable to identify or fix the problem, immediately contact a professional technician to fix it. 

3) Squeaking Noise

If you continue to hear squeaking noises under the vehicle during driving, it is a sign of a bad or damaged drive shaft. If you don’t fix this issue as soon as possible, then it can cause unbalancing or wear out to others. It can also cause complete failure of the other parts of the engine.

5) Universal Joint Movement

If the drive shaft’s universal joint revolves very fast or cannot revolve, then there is an issue with your shaft. This is because, with the passage of time, the bearing seal cap can rust. In such a case, the vehicle can no longer be propelled, and the drive shaft must be replaced as soon as possible.

6) Turning Problems

If the front wheels of your vehicle don’t turn quickly or turn very slow when attempting to steer the vehicle, this is one of the most common symptoms of a bad propeller or drive shaft. In such conditions, you will need to put a lot of force on the power steering to turn the wheels.  

You need to fix this issue immediately; otherwise, it may become worse for you.  

If the steering wheel generates problems to steer the wheels, the power steering pump may need to be checked.

Read More: Sympthoms of a bad Power Steering System

Advantages and Disadvantages of Driveshaft

The drive or propellr shaft has the following advantages and disadvantages: 

Advantages of Drive Shaft

  • There are no or very low power losses.
  • These shafts have high durability.
  • The drive shaft doesn’t have complex construction.
  • It generates very low noise at high torque.
  • They need less maintenance compared to the chain system.
  • The Drive system doesn’t jam easily.

Disadvantages of Drive Shaft

  • This shaft has high weight than a chain system.
  • The chain system has more efficiency than a propeller shaft.
  • The prop shaft has many damages when the speed is very high.
  • These have oil leaking issues at the spline.
  • Hollow driveshaft has a high cost.
  • These are not the best shafts for counter bending forces.

Applications of Propeller shaft

  • The drive shafts use in different heavy-duty machines.
  • They are utilized for various constructional motor vehicles.
  • They also use in commercial cars.
  • The drive shaft was also used in earlier airplanes.
  • They also use in ships.

How do I know if my drive shaft needs repair?

If you observe any of the below-given symptoms in your vehicle, you need to repair your drive shaft:

  1. Extreme vibration while driving the vehicle.
  2. Knocking noise
  3. Extreme vibration coming from the floorboards of the vehicle.
  4. Rust around the yoke.
  5. Steering Problems

Drive Shaft Repair Cost

The repairing and replacement cost of the drive shaft varies according to the area where you live and the part which you want to be repaired. The average replacement cost of a drive shaft varies from $490 to $1100.

If you don’t replace it yourself and hire labor, the labor can also charge up to $250. Even for a simple repair, you would need to pay from $1400 to $1800 for the repairing process.

If you want to repair only half a section of your shaft, you would need to pay from $340 to $860 for this process, with the labor cost from $140 to $260.

In the case of 4-wheel drives, the repairing price will rise. For this type of repairing, you will need to pay from $650 to $1850 according to your residential area.

FAQ Section

What is the function of the drive shaft?

The main function of the drive shaft is to transfer torque from the transmission to the differential.

What happens if my drive shaft breaks while driving?

If the drive shaft breaks while driving, the traction it offers will eventually be lost. Your vehicle stability will also lose because it will not have the ability to depend on the wheelbase. In this situation, you may also completely lose control of your car which may cause the accident.

What conditions are required for a good propeller shaft?

The propeller shaft requires the following conditions for excellent functionality;

  • Low thrust load
  • Dynamically balanced
  • High torsional Strength
  • High hardness
  • High Toughness

What are the materials used to make a propeller shaft?

The following are the most commonly used materials for the construction of the propeller shaft:

  • Thermoplastic polyamide
  • Glass fibers
  • Kevlar
  • Carbon fibers
  • Epoxy composite

What happens when the drivetrain goes out?

A common symptom of a bad driveshaft is severe shaking under the vehicle. The vehicle may also start vibration due to worn-out bushings or universal joint. If you don’t repair your worn-out bushings or universal joint, it may cause complete failure or damage other parts of the drivetrain. 

How long does it take to replace a drive shaft?

The replacement time of a drive shaft depends on which part do you want to replace. This time scale varies according to the replacement time of the drive shaft parts. In maximum cases, this type of job is completed in just 1 day or lower than 8 service hours.

What causes the drive shaft to break?

The drive shaft breaks due to the following reasons:

  • Worn universal joints
  • Worn out bushings
  • Deficiency of grease
  • Damaged tubing
  • Miss balancing

What are the components of drive Shaft?

The drive shaft has the following major components:

  1. Tube
  2. Flanges
  3. Centre bearing
  4. Slip yoke and Tube yoke
  5. Universal joint
  6. End yoke
  7. Midship shaft

What are the types of Propeller Shaft?

The propeller shaft has the following types:

  • Single piece propeller shaft
  • Two or three piece propeller shaft

What are the signs of bad propeller shaft?

As your car propeller shaft or drive shaft goes bad, your car shows some signs through that you can identify the failed or bad propeller shaft. Following are the common signs of a bad propeller shaft:

  1. Your vehicle generates extreme vibration
  2. You may hear knocking noise
  3. Squeaking noise
  4. If the drive shaft’s U-joint rotates very fast or cannot rotate, then there is an issue with your shaft.
  5. The front wheels of your vehicle don’t turn quickly or turn very slow when you attempt to steer the vehicle.
Read More
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  2. Working of Steering System
  3. Different types of Pumps
  4. What is the function of Power Steering Fluid?

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