Question
Download Solution PDFWhich is a positive drive?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFExplanation:
Positive drive: A drive-in which slip does not occur is known as a positive drive.
In any Flat, Round, or Crossed belt drive, the belt can slip on the surface of the pulley, since there is no projection or tooth-like structure to lock it in place.
Timing Belt has projections all around the inner surface of the belt, so as to restrict the slipping between the belt and the pulley therefore it is a positive drive.
The timing belt is used in IC Engine to open and close the engine's valves at the proper times in synchronization with the rotation of the crankshaft and the camshaft(s).
Additional Information
Following is the relation between Belt, Chain and Gear drive.
| Particulars | Belt drive | Chain drive | Gear drive |
|
Main element |
Pulleys, belt |
sprockets, chain |
Gear |
|
Slip |
Slip may occur |
No-slip (Positive drive) |
No-slip (Positive drive) |
|
Suitability |
For large centre distance |
For moderate centre distance |
For short centre distance |
|
Space requires |
Large |
Moderate |
Less |
|
Design |
Simplest |
Simple |
Complicated |
|
Life |
Less |
Moderate |
Long |
|
Lubrication |
Not required |
Require |
Require proper |
|
Installation cost |
Less |
Moderate |
More |
|
Use |
For low-velocity ratio |
For moderate velocity ratio |
For high-velocity ratio |
|
Example |
Use as the first drive in transmission |
Bicycle, Automobile |
Gearboxes, automobile |
Last updated on May 30, 2025
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