Transmission Shafts: Working, Types, Material & Applications

Automobiles use transmission shafts to transfer power or motion. It won’t be wrong that vehicles’ operations can’t be complete without this component. Understanding transmission shafts and their work is key to knowing how different vehicles move. 

 

This component is used not only in vehicles but also in many other machines. Despite its utmost value, people have a lesser understanding of it. In this article, I’ll dig into transmission shafts and their types. In the end, you’ll be able to learn everything related to this crucial part. So, let’s get started!

 

Overview of Transmission Shaft

 

Let’s first look at what the transmission shaft is!

 

The transmission shaft is a component used to transmit rotational motion between two points. Vehicle engines produce power. The shafts carry that power (rotational motion) and shift to the vehicle’s wheels. The wheel moves upon getting power. Various types of shafts work differently. 

 

The operation of the shaft and gearbox is directly related to each other. Motors or vehicles’ engines produce power. However, engines do not transfer this power to different vehicle parts. Remember, vehicles’ wheels and other parts require power for their movement.

 

This power is transferred through the transmission shaft. Simply put, the shaft acts as a bridge between the point where power is produced and the point where it is absorbed. As I said, the gearbox of automobiles and shafts work together. The engine delivers more power when you shift the vehicle into higher gear. 

 

The shaft transmits more power to the wheels and other parts. This is an integral component that ensures the smooth movement of vehicles. It is made with durable material that does not break or show wear and tear. Remember, if this component malfunctions, the car may not be able to perform at its best.

 

How Does a Transmission Shaft Work?

 

Let’s discuss the working or mechanism of these shafts from an elementary level. In automobiles, different shafts work together to ensure power distribution. Once the engine starts, it generates power or energy. However, the power is in the form of linear motion at the start. Therefore, automobile engines come with an attached crankshaft. 

 

It converts the linear energy into rotational power. Now, the role of the clutch comes into use. An automobile clutch (manual transmission) controls the flow of this rotational power. If you press the clutch, the rotational power won’t flow in the drivetrain. The power can flow to the rest of the system after releasing the clutch. 

 

Similarly, a vehicle’s gearbox controls the speed of rotation power transmitted to different parts. But how does rotational power go into wheels and other parts? That’s where the transmission shafts play their role. They take the rotational power the crankshank generates and carry it to the wheels. The transmission shaft distributes this information by spinning freely. 

 

Remember, shaft spinning is not straightforward. Instead, Universal Joints (U-joints) and bearings ensure smooth spinning. The U-joints are essential as they make the transmission shaft more flexible. So, if any connected part is not perfectly positioned, it won’t affect the transmission shaft’s workings. It would bend so that its movement is not affected. 

 

The transmission shaft correctly shifts the power from one point to another (differential). The differential then splits the rotational power into different parts. Depending on the needs, it can send the required power to each wheel. In summary, the transmission shaft takes the engine’s power to the differential.

 

Types of Transmission Shafts

 

There are numerous types of transmission shafts, and they vary in terms of how they operate. However, their basic functionality and mechanism remain the same. In the section below, I’ll explain those transmission shaft types. You should carefully understand each shaft and know which shaft is best for what.

 

1- Main Shaft

 

The main shaft is critical in defining the vehicle’s speed. Why? Because it directly connects to the gearbox. A higher gear transmits more torque, and vice versa. This shaft is located at the rear of the transmission. The front or head of this shaft consists of a bearing. 

 

This tiny bear ensures that the shaft can move smoothly without facing any sort of resistance or friction. In automobiles, the engagement and disengagement of gears adjust the speed and torque. It defines the pace at which the rotational power will transmit from one point to another (wheels).

 

2- Counter Shaft

 

The countershaft is parallel to the main shaft, and both are associated with gears. The countershaft directly connects to the input shaft and receives power through a pinion gear. When the input shaft spins, the power is transferred to the countershaft, which also causes it to spin.

 

The countershaft has gears attached to it. As it spins, the gears on the countershaft also spin. These gears mesh with the gears on the main shaft. This interaction between the gears controls the speed and torque, allowing the car to change gears and adjust its movement. It would be correct to say that the countershaft is the helper of the main shaft.

 

3- Idler Shaft

 

The idler shaft does not directly relate to the transfer of motion. Instead, it only reverses the direction of rotation. Generally, this shaft contains an idler gear that connects two working or functional gears. The other two gears can be associated with the speed of power transmission. However, the idler gear attached to the idler shaft has nothing to do with it. It just provides a connection between two gears.

 

4- Drive or Propeller Shaft

 

The usability of the drive shaft is prominent in rear-wheel-drive or four-wheel-drive vehicles. Its job is to transfer power or rotation from the gearbox to the differential. The differential then spits out the power and helps the wheels move. As this shaft provides power for vehicle movement, people also call it a propeller shaft.

 

Remember, the driveshaft also comes with some joints, such as U-joints and slip joints. These joints ensure that the shaft moves smoothly and transmits torque effectively. These shafts are generally lightweight but very strong and durable. Manufacturers use steel or aluminum in their manufacturing.

 

5- Axle Shaft

 

Have you ever wondered how power from the drivetrain gets to the wheels? That’s where the axle shaft comes into play. It connects the drivetrain to the wheels of the vehicles. As said earlier, the differential splits the power for each wheel. 

 

Once the system splits the power, it transmits it to the wheels through the axle shaft. This shaft works closely with the differential, ensuring power transmission to the wheels. It is robust and can bear the weight of the vehicles on turns.

 

6- Hollow Shaft

 

These shafts are very popular due to their lightweight nature. They are hollow inside instead of being solid. So, they use less material, which makes them cost-effective as well. But you might think the use of less material might make them weak. That’s not the case, as manufacturers make these shafts with aluminum or steel. Such lightweight but strong materials give these shafts an excellent weight-to-strength ratio.  They can easily handle and absorb the twisting force. 

 

How Transmission Shafts are Manufactured?

 

The manufacturing of transmission shafts is a complex process. It involved various steps and procedures to get the final products. Let’s dig into the details of how these shafts come into existence:

 

1. Material Selection: Different materials are available that can be used in making transmission shafts. Among those, carbon steel and alloy steel are very popular. It depends on the needs and requirements of the manufacturers. For exceptional durability, manufacturers prefer alloy steels. 
2. Forging: Once the material is selected, it undergoes the heating process. The higher temperature makes the material softer and malleable. This step allows the manufacturers to shape the material by pressing it. But this shaping is not accurate and needs many corrections.
3. Rough Machining: As said earlier, the malleable material requires some correction. So manufacturers use lathe machines to shape as per their needs. Remember, these lathe machines are very accurate and cut the material as per instructions. So, the material’s shape becomes similar to what the manufacturer wants.
4. Heat Treatment: You get a very weak shaft in rough machining. Moreover, its shape has some issues. The manufacturers put that shaft under the heat treatment. This ensures that the material becomes strong and durable. Remember, manufacturers perform this step at a controlled temperature.
5. CNC machining: The shaft can have some abnormalities in its shape or size. This is where CNC machining comes into play. CNC milling, grinding, and turning give the shaft the exact dimensions. For example, CNC turning helps make cylindrical shapes. CNC milling and grinding are excellent for creating grooves and smooth surfaces.
6. Surface Treatment: The above step completes the manufacturing process of the transmission shaft. You get a shaft that can be used. However, manufacturers add some additional coats of paint to it. These additional surface treatments help in increasing rust protection and overall durability.

 

Material of Transmission Shaft

 

In this article, I’ve emphasized the correct working of the automobile transmission shaft. If the transmission shaft malfunctions, the vehicle’s performance will suffer. Imagine a car moving at high speed, and its transmission shafts break. That’s nothing short of a disastrous nightmare. 

 

Remember, these shafts hold the weight and transmit power across the drivetrain of cars. Therefore, they must be strong, durable, and resistant to wear. Manufacturers use the following materials in the manufacturing of transmission shafts:

 

• Carbon steel
• Alloy steels
• Stainless steel
• Cast iron
• Aluminium alloys
• Composite materials

 

Generally, average-priced shafts are made with mild steel. However, shafts that face extreme stress typically consist of alloy steel. The popular alloy steel used in making transmission shafts is nickel. The popular alloys of steel used are nickel, nickel-chromium, or chromium-vanadium steel.

 

Applications of Transmission Shafts

 

I’m pretty sure that you know the purpose of transmission shafts. Right? But in which industries these shafts are used? Remember, these shafts are handy for transmitting power and motion in various sectors. Here is a table showing the use of transmission shafts in multiple fields:

 

Industry	Use of Transmission Shaft
Automotive	Transmits power to wheels (propeller, drive, axle shafts).
Aerospace	Transfers torque in engines and landing gear.
Marine	Transmits power to propellers in ships and boats.
Industrial Machinery	Transfers power in turbines, conveyors, and gear systems.
Wind Energy	Connects rotor blades to generators in wind turbines.
Construction	Transfers torque in cranes and heavy machinery.

Conclusion

 

Transmission shafts are a must-have for vehicles, and their use in many other machines is also noticeable. The primary role of these shafts is to help transmit power from one specific point to another—I said point, not wheels. People consider these shafts only used for transferring power to the vehicle’s wheels. That is wrong, as different machines use shafts for various purposes. 

 

In automobiles, they shift power to wheels. On the other hand, they can transmit torque to landing gears in airplanes. Similarly, they help shift power to the propeller of boats. Their usage is very diverse, which indicates they are of utmost value. In this article, you’ll learn all things related to transmission shafts.