Basics of The Driveshaft or Propeller Shaft

What is Driveshaft or Propeller Shaft?

The driveshaft knows by many different names, such as propeller shaft, prop shaft, or driveline, and is a component of the drive train.

A drive shaft is a component for transmitting mechanical power and torque and rotation, usually used to connect other components of a drivetrain that cannot be connected directly because of distance or the need to allow for relative movement between them.  

As torque carriers, drive shafts are subject to torsion and shear stress, equivalent to the difference between the input torque and the load. They must therefore be strong enough to bear the stress while avoiding too much additional weight as that would in turn increase their inertia.

To allow for variations in the alignment and distance between the driving and driven components, drive shafts frequently incorporate one or more universal joints, jaw couplings, or rag joints, and sometimes a splined joint or prismatic joint.

Driveshafts are one method of transferring power from an engine and PTO to vehicle-mounted accessory equipment, such as an air compressor. Driveshafts are used when there isn’t enough space beside the engine for the additional accessory; the shaft bridges the gap between the engine PTO and the accessory, allowing the accessory to be mounted elsewhere on the vehicle

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Definition of driveshaft

The drive shaft (also called propeller shaft or prop shaft) is a component of the drive train in a vehicle, with the purpose of delivering torque from the transmission to the differential, which then transmits this torque to the wheels in order to move the vehicle.

How Does the Driveshaft Work?

The driveshaft is a spinning tube that transmits power from the engine to the back of the vehicle at the differential. It does this by transmitting the spinning power from front to back. The deliverance of torque from the transmission to differential then transmits torque to the wheels so the vehicle can move.

Without the torque transfer between the separate components, you cannot drive. The driveshaft absorbs movements and allows two separate parts to move without breaking drive train components in the process.

It’s important to note that front-wheel drive vehicles don’t have drive shafts. The transmission and axle are combined into a single unit called a transaxle. However, in four-wheel and rear-wheel drive vehicles, the transmission and axle are separate units. Hence the driveshaft transfers the turning motion of the transmission to the axle.

This component has a tubular design and is usually made from aluminum, steel, or carbon fiber to ensure its both strong and lightweight.

drive shaft

Advantages of Driveshaft

  • Drive system is less likely to become jammed.
  • The rider cannot become dirtied from chain grease or injured by “chain bite” when clothing or a body part catches between an unguarded chain and a sprocket.
  • Lower maintenance than a chain system when the drive shaft is enclosed in a tube.
  • More consistent performance. Dynamic Bicycles claims that a drive shaft bicycle can deliver 94% efficiency, whereas a chain-driven bike can deliver anywhere from 75 to 97% efficiency based on condition.

Disadvantages of Driveshaft

  • A drive shaft system weighs more than a chain system, usually 0.5–1 kg (1–2 lb) heavier.
  • Many of the advantages claimed by drive shaft’s proponents can be achieved on a chain-driven bicycle, such as covering the chain and sprockets.
  • Use of lightweight derailleur gears with a high number of ratios is impossible, although hub gears can be used.
  • Wheel removal can be complicated in some designs (as it is for some chain-driven bicycles with hub gears).

What are the different types of drivetrains?

The type of vehicle you drive dictates what kind of drivetrain system is in your vehicle. There are different systems for rear-wheel drive, four-wheel drive, and front-wheel drive vehicles.

1. Rear-wheel drive (RWD)

In a rear-wheel-drive vehicle, the rear wheels deliver the power. A long driveshaft is connected to the transmission on one end and the differential on the other end by universal joints.

2. Four-wheel (4WD) or all-wheel drive (AWD)

On a typical four-wheel drive or all-wheel drive vehicle, there are two driveshafts. There is the same driveshaft that is on a rear-wheel-drive car but there is also an additional front driveshaft that is connected to the front differential and the transfer case by u-joints.

3. Front-wheel drive (FWD)

On a front-wheel-drive vehicle, the front wheels provide power. Instead of having a long driveshaft like on a rear-wheel vehicle, all the drivetrain components are in the front of the vehicle. Rather than using universal joints, this setup uses constant velocity (CV) joints.

How Do I Know If My Drive Shaft Needs Repair?

If you are experiencing any of the following symptoms, there may be a problem with your driveshaft or your drive shaft’s U joint connection:

  • Clunking noises when the vehicle is in motion
  • Vibration that intensifies as the car accelerates
  • Strong vibration coming from the vehicle’s floorboards
  • Resistance when maneuvering the car around corners
  • Squeaking or rattling noises
  • Visible play in the U joints when you grab or otherwise manually move the drive shaft
  • Visible signs of U joint wear, such as rust around the yoke

Some Common Signs of a Failing Driveshaft

It’s important to note that the driveshaft by itself rarely fails. However, due to excessive stress and corrosion, it will eventually exhibit signs of failure.

1. Intense Vibrations and Shuddering

Vibrations and shuddering are the most common sign of a failing driveshaft. If the bushings or U-joint wear out you can experience excessive driveshaft vibration. This may also result from the driveshaft not being bolted down properly or the unit being out of balance. A driveshaft that’s vibrating excessively can also cause the wearing of other drivetrain components.

2. Unusual Noises

Unusual noises are another indicator of a worn drive shaft. If the bearings and bushings that support the driveshaft and U-joints fail or get worn they affect the driveshaft’s ability to rotate normally. When this happens, you will experience scraping, squeaking, clanking, and rattling sounds.

3. Shuddering During Acceleration

Are you experiencing a significant amount of shuddering as you accelerate from a low speed or a stop position? This is another key sign of failing driveshaft components. A worn center bearing or loose U-joint may cause this. You may also experience some strange sounds like your vehicle shudders.

4. Turning Problems

If you are experiencing problems when taking turns, there is a high likelihood that your driveshaft is worn. A damaged driveshaft prevents wheels from turning properly hence limiting your control of the vehicle.

To ensure that your driveshaft is always in good working condition you should keep it well lubricated. Lack of lubrication can cause damage to the driveshaft and its components. High-use driveshafts should be inspected regularly since they can wear prematurely due to excessive movement.

Drive Shaft Replacement Cost

If you’re just replacing a half-shaft for your front-wheel-drive car, then it will cost anywhere from $470 to $940. You can expect the cost of the parts to be anywhere from $320 to $750, while the labor costs are only around $150 to $190.

If you have a rear-wheel or four-wheel drive vehicle which has a long driveshaft to power the rear wheels, then expect to pay somewhere in the range of $600 to $2,000. Keep that in mind that the type of vehicle plays a major role in both the price of parts and labor.