What is The Drive Shaft？

The drive shaft is a component of the vehicle system that delivers torque, mechanical power, and rotation from automobile gears to the wheel. Based on its function, the shaft is known by names like Cardan, tailshaft, driving, or propeller shaft. 

Even though the operation of the drive shaft seems pretty straightforward, like the transmission of torque to the wheel from the gearbox, many complex mechanisms are involved in its working. These systems provide a reliable vibration-free package in that numerous systems are used.

In light vehicles, the torque is transmitted to the final drive from the transmission due to the trans axle straight to the wheels. To achieve this goal, the driveshaft must be able to work through changing angles and alter its overall length to accommodate movement in the suspension. 

The drive shaft's position varies depending on the vehicle's configuration and model: front-engine, rear-wheel, four-wheel and front-wheel drive. 

The drive shaft varies from vehicle to vehicle, model, and configuration of cars. It can be present. Other than cars, vehicles like locomotives, vans, trucks, motorbikes, tippers, and boats also contain tailshaft that differ in size, design, couplings, and joints.

Drive Shaft Construction

The drive shaft combines different parts that combine and work together to perform their task. All the parts play a significant and equal role in proper functioning and need to replace quickly in case of malfunctioning or damage.

Here are those parts;

1. Flanges

The flange is a transmission component that joins the propeller with the transfer case, gear system, and gearbox. These flanges are castoff to interlink the hydraulic pumps, power takeoff, drive shafts, and other parts.  

2. Tube Yoke & Slip Yoke 

A tube or weld yoke is an integral part of the shaft. This yoke with a directing pivot permits the flexion of the shaft when the vehicle is on an uneven and rough surface. However, the slip yoke is used for power transmission with its in and out movement. Using the universal joint, the slip yoke is connected with the tailshaft. This tube ensures the proper rotation of universal joints of shafts on rough terrain.  

3. End Yoke

The end yoke provides a noise, and vibration-free comfortable drive experience as the coupling minimizes the vibration even when the vehicle is speeding up. Other than comfort, the yoke guarantees the precision and sturdiness of the driveshaft. 

4. Midship Shaft

The midship shaft is an element of the tailshaft and a significant part of the coupling shaft that links the shaft's end yoke with the center bearing frame. 

5. Universal Joint 

In rotatory shafts, the universal or u-joint works as intersecting mechanical connections that transfer rotating force/torque. 

6. Centre Bearing

Center bearing sustains the angel change in shafts using universal joints. The primary function of this bearing is to maintain the position of the shaft at any angle without producing much vibration and noise. As mentioned above, it is linked with a midship shaft from one end that is attached with a u-joint through the end yoke. 

7. Tube

The tube is usually used in the rear-drive and front-wheel vehicle’s drive shaft that sustains the rear ends position while braking and vehicle acceleration.

How Does Drive Shaft Works?

The Driveshaft is a hollow propeller that transfers the engine rotatory energy to the vehicle's wheels which is essential to run the car. During this process, a slight change in driveshaft length or angle while driveshaft joints must reimburse operation to ensure high coordination in all wheels and engines. 

The elements in the drive shaft are the input shaft, yoke, universal joint with cross structure, slip joint spline, output shaft, and center/pinion bearing. The slip and universal joints help adjust the length when the shaft is inclined at a specific angle.  

The propeller shaft and universal joint work together at a constant speed when there is no operating angle on the production yoke and universal joint. However, when the car changes its driving surface from smooth to bumping, an operating angle is created on the front end of the tail shaft. In this situation, the universal and slip joint starts traveling in an ellipse rather than being in a perfect circle to adjust the length of the shaft. 

The torsional and inertial vibration is produced by keeping the pace of output yoke vibration with the help of increasing and decreasing the speed of the tail shaft even though the output yoke itself is maintaining a constant speed. 

The center lines of driven members and driving correspond when the variable velocity is conveyed to the input yoke due to a change in operating angle at every end of the tail shaft. 

It will automatically make the universal joint operating angles equal at each end of the shaft with equal operating angles. The non-uniform velocities of both the rear ad front yoke cancel the effects of each other, those results in the driven member's constant speed. Any problem in car phasing will cause the production of inertial and torsional vibrations in the vehicle. 

This is why you should marl the components of a drive shaft before taking it apart; that will help you reinstall the components to maintain the correct phasing and reduce the chances of driveline vibration.

Types of Drive Shaft

1. Hotchkiss Drive 

In Hotchkiss shaft drives drive, the spring’s exterior end is fixed on the frame with brackets, and the rear end is sustained in shackles with pins. These drive spring takes a load of torque reaction, driving thrust, braking thrust, and side thrust. 

Because of the torque reaction, first-half spring section may deflect near the bracket, and due to deflection, the bevel gear shaft will tend to tilt. If there is just a single u-joint near the gearbox, then under torque reaction propeller shaft will bend. 

Therefore to dodge this bending of th shaft, an additional u-joint. In Hotchkiss drive, when the axle moves to-and-fro relative to the frame. It must travel circle whose center lies at the front end of spring and whose center lies at the front end of spring.

Therefore propeller shaft should move circular, keeping it’s circularly at the front universal joint. As the two centers do not coincide, then the shaft length always varies in order to adjust this variation.

A sliding joint is provided where in torque  bar. Since both the bevel shaft and drive shaft will move about the same center while moving up and down, then no universal joint will be necessary.

The Hotchkiss shaft usually comes up in two separate pieces for easy installation and to minimize vibration problems while driving. The two-piece drive shaft requires dustproof ball bearing housing to support the shaft in the center. However, the rubber is used while the pieces are fitting to minimize vibration and noise. 

In this type, the torque tube transmits force by directly coupling the axle differential to transmission. The drive shaft is commonly used on passenger cars like Volkswagen, tata motors, and heavy commercial vehicles like Ashok Leyland trucks.

2. Torque Tube Drive

In torque tube drive, both ends of springs are bonded to the frame instead of the rear end. In these shafts, the axle casing is bolted at the center of the spring, so the spring takes only the side thrust and weight of the vehicle.

In this tube drive, the torque tube takes the torque reaction, braking torque, and driving thrust. Here the propeller shaft is enclosed in a torque tube, the rear end of torque. The tube is fixed with an axle casing, and the front end is joined to the back of the gearbox. 

In torque tube drive, the bevel pinion, propeller, and torque tube coincide. However, if the shaft is connected to the gearbox shaft by a universal joint, then no other universal joint will be needed. The torque reaction and driving thrust are transmitted from axle to frame in this type. 

The ball and socket type of joint is used at one end of the torque tube to allow relative motion between axle and transmission. The torque tube drive is usually used in American ford cars.

Based on the number of pieces and way of installation, the drive shafts are divided into three main types:

•  Slip-in-tube Drive Shaft

As the name indicates, the slip-in-tube shafts are actually collapsible like a telescope structure. It is the latest type of drive shaft that increases the safety level of the driver while a car crashes as its compressible body absorbs the accident energy.

• Single Piece Drive Shaft

The single-piece tailshaft is used in vehicles that have a short distance between engine and axle, like the FWD (four-wheel drive) vehicles. The single piece maximizes the strength, robustness, and quality by applying friction welding. 

These propellers are usually made from aluminum, achieving steel-level durability and a large diameter. However, their increased diameter makes them highly sensitive to damage.

• Two or Three-Piece Driveshaft

These shafts are used in high-speed vehicles. The Hotchkiss shaft is an excellent example of two-piece driveshafts. The speed of a vehicle can easily reduce by using the two or three-piece shafts like in FWD, front drive, and front engine vehicles. 

Conclusion

If you are into high-end vehicles or you are about to buy your first car, it's important to know the importance of drive shafts as they are responsible for safe and comfortable driving. The drive shafts are available in different types, and all of the types are usually model or vehicle specific. So, when replacing the old shaft or while repairing it, make sure to find which specific type of shaft is installed in your car.