Propeller Shaft | Function , types , Components and Requirement
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. The drive shaft is primarily used to transfer torque between components that are separated by a distance, since different components must be in different locations in the vehicle. A front-engine rear-wheel drive car must have a long drive shaft connecting the rear axle to the transmission since these parts are on opposite sides of the car.
Drive shafts are used differently in different vehicles, varying greatly in cars with distinct configurations for front-wheel drive, four-wheel drive, and the previously mentioned front-engine rear-wheel drive. Other vehicles also use drive shafts, like motorcycles, locomotives, and marine vessels.
Below is the drive shaft configuration for a common front-engine rear-wheel drive vehicle (some cars have the transmission at the back).
- Propeller Shaft is the shaft that transmits power from the gearbox to the differential gear in a motor vehicle from the engine to the propeller in a boat or flying machine.
- Propeller shaft, sometimes called a cardan shaft, transmits power from the gearbox to the rear axle. Regularly the shaft has a tubular section and is made in maybe a couple piece construction.
- The two-piece arrangement is supported at the mid point by an elastic mounted bearing. Short drive shafts are incorporated for the transmission of power from the last drive assembly to the road wheels in both front and rear wheel drive layouts.
FUNCTIONS OF THE PROPELLER SHAFT
In most of the automotive vehicles, the engine is located at the front and the rear wheels of the vehicle are being driven. This arrangement stipulates a longer propeller shaft to be used. In some arrangements two or three propeller shafts are used to make up the length.
In some vehicles, the engine is kept at the front and the front wheels of the vehicle are being driven. In some other vehicles, the engine is at the rear and the rear wheels are being driven. For such arrangements a short propeller shaft is used to drive each wheel.
The engine and the transmission unit are attached to the vehicle frame with some flexible mounting. The rear axle housing with differential and wheels are attached to the vehicle frame by suspension springs.
Due to the above arrangement, the transmission output shaft and the input shaft to the rear axle housing are in different planes. This compels the propeller shaft that connects these two shafts to be kept inclined.
Further, whenever the rear wheels encounter irregularities in the road, the rear axle housing moves up and down, compressing and expanding the suspension springs. As this happens, the angle between the transmission output shaft and the propeller shaft changes. Further, the length to be occupied by the propeller shaft also changes.
The variation in the length of the propeller shaft happens because the propeller shaft and the rear axle housing rotate on arcs with different points as their centres of rotation.
The rear axle housing moves in the shorter arc than that of the propeller shaft. This is because the centre of the rear axle housing arc is the point of attachment of the rear spring or control arm to the vehicle frame. This aspect causes a reduction in the length occupied by the propeller shaft as the angle between the transmission and the propeller shaft increases.
TYPES OF PROPELLER SHAFT:
1. Single-Piece-Type Propeller Shaft:
- Used in vehicles with a short distance between the engine and axles, and MR based four-wheel-drive vehicles.
- The friction welding adopted at the junction contributes to an improvement in the strength, quality, and durability of the junction.
2-piece-type/3-piece-type Propeller Shaft:
- Utilized as a part of vehicles with a long distance between the engine and axles, and Front engine front drive base four-wheel-drive vehicles.
- The division of the propeller shaft into two- or three-parts allows the critical number of revolution to lowered preventing vibration issue from occurring, when the overall length of the shaft increased.
COMPONENTS OF PROPELLER SHAFT:
- The propeller shaft transfers engine torque to the rear axle through one or more universal joints.
- The splines on the ends at the propeller shaft fit perfectly into the splines in the sleeve. This permits a length variation between the driving and the driven unit to vary slightly without damaging the output and input bearings.
- The main bearing support and guide the propeller shaft.
- The flanges associate the propeller shaft to the gearbox.
REQUIREMENTS OF PROPELLER SHAFT:
For achieving efficient functions, the following are expected in a propeller shaft
- High torsional strength: Therefore, they are made of solid or hollow circular cross section
- Toughened and hardened: Therefore, they are made of superior quality steel and are induction hardened
- Efficiently jointed: Therefore they are generally welded by submerged are carbon dioxide welding process.
- Dynamically balanced: Since the phenomenon of whirling may be critical at higher speeds, therefore, propeller shafts are tested on electronic balancing machine.
- Reduced thrust loads: Since resonance is dangerous for the life of shaft. It also transmits excessive dynamic force to the shaft’s end supports, and so its occurrence should be avoided.
NOTE: Since the propeller shaft sleeve end is pulled out from the transmission extension housing with the transmission still mounted, overflow of the transmission oil, damage of oil seal lip or entrance of dust may result if the vehicle is raised higher toward its front end. Use extreme care in removing the propeller shaft.
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