#AUTOMOBILE_ENGINEERING RAKESH_VALASA
Propeller shaft is connecting the drive from gear box to final drive. Hence it is also called Drive Shaft.
(or)
It is the group of parts connecting the transmission with the drive wheels. It consists of propeller shaft (also called Drive Shaft), Universal Joints/Constant Velocity Joints and Slip Joints.
Function of Propeller Shaft
Propeller shaft take power from the gear box output shaft without making any change in power, it transmits the same to the input pinion of the differential unit, from where power is transmitted to the drive wheels through rear axle.
To accommodate the change in line and level between gear-box output shaft and differential input pinion shaft.
Types of Propeller Shaft:
Single-Piece-Type Propeller Shaft:
In this type of drive shaft, the drive is transmitted to the differential of the rear axle by a long one piece propeller shaft.
This type of propeller shaft has universal joints at each end.
2.2-piece-type/3-piece-type Propeller Shaft:
In vehicles having long wheel base such as truck and buses, the propeller shaft is in two pieces and is supported at the center to avoid whipping action of a long shaft.
In center , a third universal joint between the two shafts and a center bearing to support the middle of the shaft assembly is provided.
The rubber rings are used on the center bearing to take care of the angular movement of shaft also to absorb vibrations.
Shaft: As this has to withstand torsional loads, it is usually made of tubular cross-section. It also has to be well balanced to avoid whirling at high speeds. Shafts are made of steel, aluminum or composite materials.
Universal Joint: One or two universal joints, depending upon the type of rear axle drive used. The universal joints account for the up and down movements of the rear axle when the vehicle is running.
Slip Joint: Depending upon the type of drive, one slip joint may be there in shaft. This serves to adjust the length of the propeller shaft when demanded by rear axle movements.
Constructional details of Propeller Shaft
The propeller shaft used to transmit the power from gear box output shaft to differential with tubular cross-section & one or two piece construction.
The two piece propeller shaft is supported at the center by rubber mounted bearing.
Propeller shaft should be rigid enough to absorb the twisting action due to driving torque and the torsional shock.
It should also be capable of resisting the vibration.
Tubular propeller shaft is generally used because...
It weight less
It can resist misalignment
It has good torsional strength
It provide less resistance to change of angular speed caused when hook type coupling is used.
Propeller shaft is running faster when overdrive is used, hence it should be produce as per required design specification and good limit of balances.
Requirements of 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.
6 сен 2020
