Mechanical Drives- Belt, Chain, Gear | Advantages, and Disadvantages
BELT DRIVE :
1. The velocity of belt.
2. The tension under which belt is placed on pulleys.
3. The arc of contact between the belt and the smaller pulley.
- Open belt drive
- Cross belt drive
- Quarter turn belt drive
- Belt drive with idler pulley
- Fast and loose pulley drive
- Cone pulley drive
- Compound belt drive
Advantages and Disadvantages of belt drives :
- Made from flexible material, it can be used for
the shafts whose axes are note parallel.
- The initial cost is low.
- Lubricant is not required.
- Noise is relatively less.
- It is a flexible member, it slips or breaks during
overload and safeguards the machine.
Disadvantages Of Belt Drive;
- Drive is not positive as the belt slip over the pulleys.
- Oqupies relatively more space.
- Speed ration can not be maintained because of the slipping of the belt.
- Adjust the tension in the belt is require time to time.
- Life is relatively low
ROPE DRIVE :
Advantages Of Rope Drive:
- Large power can be transmitted by using no. of ropes.
- Easy and simple maintenance.
- More than one drive can be accommodated from the single pulley.
- Silent drive.
- Because of wedging action due to groove, the higher coefficient of friction compared to flat belt drive.
- Due to flexibility in the rope little misalignment in the drive is permissible.
Disadvantages of Rope Drive:
- Power loss due to slip.
- Oqupies larger space.
- Constant speed ratio can not be maintained.
- Adjustment in the center distance is always necessary.
- Wear rates for the wire rope pulleys is higher
- The initial cost is relatively higher.
CHAIN DRIVE :
roller bush chains. The chain drive is a positive drive where there is no slip & constant velocity ratio can be maintained. Chain drive used in bicycle, motorbike, printing machine, textile machine, etc.
2. Conveyor chains
3. Power transmission chains
Advantages of Chain drive;
- Positive drive as there is no slip, hence a constant velocity ratio.
- Occupies less space compared to belt drive.
- Life is more compared to the belt drive.
- Used for large center distance.
- Transmission efficiency is larger than the belt drive.
Disadvantages Of Chain Drive:
- Noisy compared to belt drive.
- Initial cost is higher compared to belt drive
- Initial cost is higher compared to belt drive
- Adjustment in the center distance is necessary.
- Maintenance cost is higher & complex compared to belt drive.
Advantages of chain drive over a belt drive
a) No-slip takes place in chain drive as in belt drive there is slip.
b) Occupy less space as compared to belt drive.
c) High transmission efficiency.
d) More power transmission than belts drive.
e) Operated at adverse temperature and atmospheric conditions.
f) Higher velocity ratio.
g) Used for both long as well as short distances.
GEAR DRIVE :
- A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque and power.
- In order to transmit a definite power from one shaft to another shaft to the projection on one disc and recesses
on another disc can be made which can mesh with each other.
- In the early days, friction discs as shown in the figure were used for transmitting the power from one shaft to another shaft. In such a case, the power transmission capacity depends on the friction between surfaces of two discs.
- Therefore, this method is not suitable for transmitting higher power as a slip occurs between the discs
Types Of Gear Drives :
- Spur gear
- Helical gear
- Rack and Pinion gear
- Bevel gear
- Worm and worm wheel
- Spiral gear
Advantages and disadvantages of gear drive :
Advantages Of Gear Drive:
- Positive drive and has more efficiency than belt and rope drive.
- The operation of the drive is simple and effective.
- Life is more compared to other drives.
- With one input speed, no. of output speeds can be obtained by using a suitable gear drive.
- Safe and compact.
- Constant velocity ration is obtained.
- Using different types of gears, power can be transmitted between shafts whose axes are parallel, inclined, or intersecting to each other.
Disadvantages of Gear Drive:
- If the tooth geometry of the gear is not properly maintained, the drive may get locked.
- Not preferred when very high-speed transmission is required.
- If the lubrication arrangement is not provided, it may produce noise.
Difference between Belt Drives, Chain Drives, and Gear Drives
|Sr. No.||Particulars||Belt drive||Chain drive||Gear drive|
|1.||Main element||Pulleys, belt||Sprockets, chain||Gears|
|2.||Slip||Slip may occurs||No slip|
|3.||Suitability||For large center distance||For moderate center distance||For short center distance|
|5.|| Design, manufacturing, complexity||Simplest||Simplest||Complicated|
|6.||Failure||Failure of belt does not cause the further damage of machine.||Failure of chain may not seriously damage the machine.||Failure of gear may cause serious break down in the machine|
|8.||Lubrication||Not required||Required||Requires proper lubrication|
|10.||Use||For low velocity ratio||For moderate velocity ratio||For high velocity ratio|
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