When an engine produces power and clutch and transmission
convert it into required torque, some assembly is needed to carry this torque
to driving axle or usually to rear axle. This assembly is known as drive line.
A drive line consist one or more drive shaft (propeller shaft), universal
joints, and slip joints.
Various types of propeller shaft, universal joint, and slip
joints are used to carry engine power from the transmission box to the driving
wheels. Today I am going to tell you
about drive shaft component and there working in detail.
These are the main components of drive shaft-
Propeller shaft:
The propeller shaft is a driving shaft which connects the
transmission main shaft to the differential of the real axle. It transmits the
power from gear box to rear axle with the help of universal joints. The
propeller shaft is also known as drive shaft. It performs the following
function:
To receive the power from the gear box output shaft and
without any change in speed transmit it to the input pinion of the differential
for onward transmission to the rear axle and rear wheels.
To cope with the difference in line with the level of the
gear box output shaft and the differential input pinion shaft.
The propeller shaft has to operate at varied lengths and
varied angles. The engine of the automobile is somewhat rigidly attached to the
frame by springs. As the vehicle moves on the road there are jerks and bumps
due to which the springs expand and contract. This changes the angle of drive
between the propeller shaft and the transmission shaft. The distance between
the gear box and differential also changes due to the movement of the springs.
So the propeller shaft has to meet both the angular change coming between the
gear box and differential and change in length of the distance between the gear
box and differential. The propeller shaft is also not on the same line as the
gear box output shaft but it runs to the rear axle at an angle because the
level of the rear axle is lower than the gear box. So to adjust angular motion
universal joints are provided and to adjust for the change in length of the
propeller shaft , a slip joint is provided.
The propeller shaft has to withstand the torsional stresses of
the transmitting torque, and yet it must be light and well balanced so that
vibrations will not occur at high speed. So it is usually made of a strong
steel tube.
Universal joint:
A universal joint allows driving torque to be carried
through two shafts that are at an angle with each other. A simple universal
joint consist two Y- shaped yoke, one on the driving shaft and other on the
driven shaft. The four arms of spider are assembled in needle bearings in the
two yokes. The driving shaft and yoke force the spider to rotate. The other two
trunnions of the spider then cause the driven yoke to rotate. When the two
shafts are at an angle with each other, the needle bearings permit the yokes to
swing around on the trunnions with each revolution. A simple universal joint
does not transmit the motion uniformly when the shafts are operating an angle.
Because of this, two universal joints are used in a vehicle, one between the
gear box and the propeller shaft and other between the propeller shaft and the
differential pinion shaft.
Slip joint:
Slip joint is attached to the driven yoke in order the
increase or decrease the length of propeller shaft. It has outside splines on
the shaft and matching internal splines in a mating hollow shaft or yoke. When
assembled the splines cause the shafts to rotate together while they can move back
and forth. This changes the length of propeller shaft.
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