Driveshaft
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A drive shaft, driving shaft, propeller shaft, or Cardan shaft is a mechanical device 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 shafts are carriers of torque: they are 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.
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[change] Automotive drive shafts
[change] Vehicles
Most automobiles 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 to the wheels.
In British English, the term "drive shaft" is restricted to a transverse shaft which transmits power to the wheels, especially the front wheels. A drive shaft connecting the gearbox to a rear differential is called a propeller shaft, or prop-shaft. A drive shaft connecting a rear differential to a rear wheel may be called a half shaft. The name comes 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
- Slip in Tube drive shaft
The Slip in Tube Drive shaft is the new type which also helps in Crash Energy Management. It can be compressed in case of crash. It is also known as a collapsible drive shaft.
[change] Motorcycle drive shafts
Drive shafts have been used on motorcycles almost as long as there have been motorcycles. As an alternative to chain and belt drives, drive shafts offer relatively maintenance-free operation and long life. A disadvantage of shaft drive on a motorcycle is that gearing is needed to turn the power 90° from the shaft to the rear wheel, losing some power in the process. On the other hand, it is easier to protect the shaft linkages and drive gears from dust, sand and mud.
[change] Drive shafts in Bicycles
The drive shaft has served as an alternative to a chain-drive in bicycles for the past century, although never becoming very popular. A shaft-driven bicycle is described as "acatane". When used on a bicycle, a drive shaft has several advantages and disadvantages:
[change] Advantages
- Drive system is less likely to become jammed or broken, a common problem with chain-driven bicycles
- The use of a gear system creates a smoother and more consistent pedaling motion
- 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
- Lower maintenance than a chain system when the drive shaft is enclosed in a tube, the common convention
- 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.
- Greater clearance: with the absence of a low-hanging machinery, the bicycle has nearly twice the ground clearance
- 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.
[change] Disadvantages
- A drive shaft system weighs more than a chain system, usually 1-2 pounds heavier
- At optimum upkeep, a chain delivers greater efficiency
- 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
- Use of lightweight gears with a high number of ratios is impossible, although hub gears can be used
- Wheel removal can be complicated in some designs (as it is for some chain-driven bicycles with hub gears).
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