Drive shaft
A drive shaft is a mechanical
car parts for
transferring power from the engine or motor to the point where useful
work is applied. Most engines or motors deliver power as torque through
rotary motion: this is extracted from the linear motion of pistons in a
reciprocating engine; water driving a water wheel; or forced gas or
water in a turbine. From the point of delivery, the components of power
transmission form the drive train.
Drive shaft is carrier of torque: it is subject to
torsion and shear stress, which represents the difference between the
input force and the load. They thus need to be strong enough to bear the
stress, without imposing too great an additional inertia by virtue of
the weight of the shaft.
Automotive drive shafts
Vehicles
Every automobile today use rigid drive shafts to
deliver power from a transmission to the wheels. A pair of short drive
shafts is commonly used to send power from a central differential,
transmission, or transaxle to the wheels.
In front-engined, rear-drive vehicles, a longer
drive shaft is also required to send power the length of the vehicle.
Two forms dominate: The torque tube with a single universal joint and
the Hotchkiss drive with two or more joints.
Early automobiles often used chain drive or belt
drive mechanisms rather than a drive shaft. Some used electrical
generators and motors to transmit power to the wheels.
A car parts shaft connecting the gearbox to a rear
differential is called a propeller shaft, or prop-shaft. A prop-shaft
assembly consists of a propeller shaft, a slip joint and one or more
universal joints.
Where the engine and axles are separated from each
other, as on four-wheel drive and rear-wheel drive vehicles, it is the
propeller shaft that serves to transmit the drive force generated by the
engine to the axles.
A drive shaft connecting a rear differential to a
rear wheel may be called a half shaft. The name derives from the fact
that two such shafts are required to form one rear axle.
There are different types of drive shafts in
Automotive Industry:
- 1 piece drive shaft
- 2 piece drive shaft
- 3 Slip in Tube drive shaft
Advantages
-4 Drive system is less likely to become jammed
or broken, a common problem with chain-driven bicycles
- 5 The use of a gear system creates a smoother
and more consistent pedaling motion
- 6 The rider cannot become dirtied from chain
grease or injured by the chain from "Chain bite", which occurs when
clothing or even a body part catches between the chain and a sprocket.
- 7 Lower maintenance than a chain system when
the drive shaft is enclosed in a tube, the common convention
-8 More consistent performance. Dynamic Bicycles
claims that a drive shaft bicycle consistently delivers 94% efficiency,
whereas a chain-driven bike can deliver anywhere from 75-97% efficiency
based on condition.
-9 Greater clearance: with the absence of a
derailleur or other low-hanging machinery, the bicycle has nearly twice
the ground clearance
-10 For bicycle rental companies, a drive-shaft
bicycle is less prone to be stolen, since the shaft is non-standard, and
both noticeable and non-maintainable. This type of bicycle is in use in
several major cities of Europe, where there have been large municipal
funded, public (and automatic) bicycle rental projects.
Disadvantages
- A drive shaft system weighs more than a chain
system, usually 1-2 pounds heavier
- Many of the advantages claimed by drive
shaft's proponents can be achieved on a chain-driven bicycle, such as
covering the chain and gears with a metal or plastic cover
- Wheel removal can be complicated in some designs
- Use of lightweight derailleur gears with a
high number of ratios is impossible, although hub gears can be used
