Mechanical Drives- Belt, Chain, Gear | Advantages and Disadvantages

Written by Sachin Thorat in Machine Design

Mechanical Drives- Belt, Chain, Gear | Advantages, and Disadvantages 

INTRODUCTION :

Energy is required to drive the machines and equipments for a variety of applications. Available energy/power is required to be transmitted to get the desired motion and work. When the power is transmitted from input to output using mechanical elements is known as mechanical power transmission. Mechanical elements like friction disc, various types of belts, rope, chain, gears, couplings, etc. are used for power transmission. 

BELT DRIVE : 

To transmit power from one shaft to another, pulleys are mounted on the two shafts. The pulleys are then connected by an endless belt passing over the pulleys. The connecting belt is kept in tension so that motion of one pulley is transferred to the other without slip. The speed of the driven shaft can be varied by varying the diameter of the two pulleys.
The amount of power transmitted depends upon the following factors
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.
Belt drives are one of the common methods used whenever power or rotary motion is required to transmit between two parallel shafts.
Types of Belt drive
  1. Open belt drive
  2. Cross belt drive
  3. Quarter turn belt drive
  4. Belt drive with idler pulley
  5. Fast and loose pulley drive
  6. Cone pulley drive
  7. Compound belt drive
beltdrive
belt drive

Advantages and Disadvantages of belt drives :

  1. Made from flexible material, it can be used for
    the shafts whose axes are note parallel. 
  2. The initial cost is low.
  3. Lubricant is not required. 
  4. Noise is relatively less.
  5. It is a flexible member, it slips or breaks during
    overload and safeguards the machine. 

Disadvantages Of Belt Drive;

  1. Drive is not positive as the belt slip over the pulleys.  
  2. Oqupies relatively more space. 
  3. Speed ration can not be maintained because of the slipping of the belt.
  4. Adjust the tension in the belt is require time to time.
  5. Life is relatively low

ROPE DRIVE : 

When the center distance between the driver and driven shaft is very large and higher power is required to be transmitted, rope drives are used. Here instead of a belt, wire rope is used. Appropriate size and number of grooves are provided on the pulley rim. e.g elevator/lift, overhead crane, hoist, ropeway, etc.
Rope Drive Example
Rope Drive Example

Advantages Of Rope Drive:

  1. Large power can be transmitted by using no. of ropes.
  2. Easy and simple maintenance.
  3. More than one drive can be accommodated from the single pulley.
  4. Silent drive.
  5. Because of wedging action due to groove, the higher coefficient of friction compared to flat belt drive.
  6. 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 :

The chain drive consists of three elements – driving sprocket, driven sprocket, and endless chain wrapped around the sprocket as shown in fig. Pin joint contains, pin, bush, and roller to minimize the friction and such chains are known as
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.
Types of Chain
1. Hoisting and Hauling chains
2. Conveyor chains
3. Power transmission chains
Chain Drive Mechanical drives
Chain Drive Mechanical drives

Advantages of Chain drive;

  1. Positive drive as there is no slip, hence a constant velocity ratio. 
  2. Occupies less space compared to belt drive.
  3. Life is more compared to the belt drive.
  4. Used for large center distance.
  5. Transmission efficiency is larger than the belt drive.

Disadvantages Of Chain Drive:

  1. Noisy compared to belt drive.
  2. Initial cost is higher compared to belt drive
  3. Initial cost is higher compared to belt drive
  4. Adjustment in the center distance is necessary.
  5. 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
gear drives
gear drives

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:

  1. If the tooth geometry of the gear is not properly maintained, the drive may get locked.
  2. Not preferred when very high-speed transmission is required.
  3. If the lubrication arrangement is not provided, it may produce noise.  

See also: 19 Methods Of Manufacturing Of all types of GearsOpens in a new tab.

Difference between Belt Drives, Chain Drives, and Gear Drives 

Sr. No.ParticularsBelt driveChain driveGear drive
1.Main elementPulleys, beltSprockets, chainGears
2.SlipSlip may occursNo slip
(Positive drive)		No slip
(Positive drive)
3.SuitabilityFor large center distanceFor moderate center distanceFor short center distance
4.Space requiresLargeModerateLess
5. Design, manufacturing, complexity
SimplestSimplestComplicated
6.FailureFailure 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
7.LifeLessModerateLong
8.LubricationNot requiredRequiredRequires proper lubrication
9.Installation costLessModerateMore
10.UseFor low velocity ratioFor moderate velocity ratioFor high velocity ratio
More Resources /articles

Machine Design Notes , article , Interview Que. and Ans.

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Sachin Thorat
Sachin is a B-TECH graduate in Mechanical Engineering from a reputed Engineering college. Currently, he is working in the sheet metal industry as a designer. Additionally, he has interested in Product Design, Animation, and Project design. He also likes to write articles related to the mechanical engineering field and tries to motivate other mechanical engineering students by his innovative project ideas, design, models and videos.
 4 thoughts on “Mechanical Drives- Belt, Chain, Gear | Advantages and Disadvantages”
  2. Really the post is very helpful for those who are dealing belt drive and chain gear. Further if one want to find some more belt drive v belt specification may visit universaldelhi.org and download our free pdf
    Reply
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