Chain and belt drive

It is power point presentation on belt and chain drive. you can find working and mechanism of chain and belt drive and their advantage and disadvantages.....enjoy.

1. Belt and chain driveBelt and chain drive

2. INTRODUCTIONINTRODUCTION
1.1.A belt is a looped strip of flexible material, used to mechanically link A belt is a looped strip of flexible material, used to mechanically link
two or more rotating shafts. two or more rotating shafts.
2.2.They may be used as a source of motion, to efficiently transmit They may be used as a source of motion, to efficiently transmit
power, or to track relative movement. Belts are looped over pulleys. power, or to track relative movement. Belts are looped over pulleys.
3.3.In a two pulley system, the belt can either drive the pulleys in the In a two pulley system, the belt can either drive the pulleys in the
same direction, or the belt may be crossed, so that the direction of same direction, or the belt may be crossed, so that the direction of
the shafts is opposite. the shafts is opposite.

3. Advantages of belt driveAdvantages of belt drive
•They are simple. They are economical.
•Overload and jam protection are provided.
•Noise and vibration are damped out. Machinery life is
prolonged because load fluctuations are cushioned
(shock-absorbed).
•They are lubrication-free. They require only low
maintenance.
•They are highly efficient (90–98%, usually 95%). Some
misalignment is tolerable.
•They are very economical when shafts are separated by
large distances.

4. FLAT BELT
TYPES OF BELTS

5. V- BELT

6. TIMING BELT

7. ROUND BELT

8. Open belt drive

9. Cross belt drive

10. OPEN BELT DRIVE WITH IDLER PULLEY

11. MULTIPLE BELT DRIVE:

12. QUARTER TURN BELT DRIVE

13. COMPOUND BELT DRIVE:

14. Desirable properties of materials used for belt
•High coefficient of friction
•High flexibility
•Durability
•High strength

15. Materials
•Leather
•Fabric
•Rubber
•Polyester or polyamide

16. Velocity ratio of belt
• it is the ratio between the velocities of the
driver and the follower or driven.
d1 = Diameter of the driver,
d2 = Diameter of the follower
N1 = Speed of the driver in r.p.m., and
N2 = Speed of the follower in r.p.m.

17. Length of the belt that passes over the driver
and the follower in one minute will be l
1
= πd
1
N
1

and l
2
= π d
2
n
2
, respectively.
Since, the lengths are equal
πd
1 N
1 = π d
2 N
2
Where, N
2
/N
1
is the velocity ratio. If we take the
thickness of belt into account then above
expression can be written as
N
2
/ N
1
= (d
1
+ t) / (d
2
+ t)

18. Velocity of belt drive considering slip
•The motion of belts and shafts assuming a firm frictional
grip between the belts and the shafts. But sometimes, the
frictional grip becomes insufficient. This may cause some
forward motion of the driver without carrying the belt with
it. This may also cause some forward motion of the belt
without carrying the driven pulley with it. This is called slip
of the belt and is generally expressed as a percentage.
•The result of the belt slipping is to reduce the velocity ratio
of the system. As the slipping of the belt is a common
phenomenon, thus the belt should never be used where a
definite velocity ratio is of importance (as in the case of
hour, minute and second arms in a watch).
Let s1 % = Slip between the driver and the belt, and
s2 % = Slip between the belt and the follower.
If thickness of belt is considered
N2/N1= (d1+t)/[d2+t(1-s/100)]

19. In a flat belt pulley, the rim surface is given a convex shape by
increasing the thickness of a rim at the center. This increased
thickness is called crown and the process is known as crowning of
pulley.
OBJECTIVES OF CROWNING OF PULLEY
i)In flat belt drive, if the two shaft are not exactly parallel, there is
tendency of belt to come off from the pulley in running condition.
The crowning prevents the coming off of the belt from the pulley.
ii)The crowning helps to keep the belt near the mid plane of the
pulley in running conditions.
CROWNING OF PULLEY

20. The angle of contact
The wedge angle of the belt (and groove).
Because you will be selecting a standard belt you are not able to change this angle which
is usually 34° or 38° depending upon the size of the belt and the size of the pulleys.

The coefficient of friction.
You have little control over this because it is determined by the belt material and the
pulley material (and finish).
The pulley diameters.
The larger the diameters, the greater the torque and power. This is simply because for a
given belt tension force, the larger the pulley, the larger the torque (torque = force x
radius) and hence the greater the power for a given speed.

SELECTION OF FLAT BELTS FROM MANUFACTURING
CATALOUGE

21. The size of the belt.
The larger the belt section, the greater the tension that can be carried by the belt
and the greater the torque and power.
The number of belts.
Belt drives with a single belt are the most common but belt drives are often used
with 2 to 6 belts in parallel on multi-grooved pulleys.
Initial belt tensions.
The higher the initial tension in the belts, the greater the torque and power that
can be transmitted. At rest, when no power is being transmitted, the belt
tensions are equal on both sides of the pulleys.

22. Selection of v-belt from manufacturer
catalogue
1.The data is available :-
a.power to be transmitted
b.Input and output speed
2. Select the service factor or load correction factor for the
given application
3.Select type of v-belt cross section
4. calculate the power
5. select the standard pulley
6. calculate pitch length of the belt
7.Select nearest standard pitch length of the belt from manufacturer
catalogue and calculate the exact center distance

23. Selection of v-belt from manufacturer
catalogue
8. Find the power rating of the selected v- belt from
manufacturer catalogue
9.Calculate arc of contact for the smaller pulley and find arc of
contact correction factor
10.Find belt length correction factor
11.Calculate the modified power rating of the v-belt
12.Find the number of belt required

24. Creep In Belt
•When the belt moves over the pulleys to transmit the power, the
tension in the right side is more than the tension in the slack side.
•As the belt material is elastic, it elongates more on the tight side
than on the slack side, resulting in unequal stretching on two sides
of the drive.
•Therefore the length of the belt received by the driving pulley is
more than the length of the belt that moves off the driving pulley.
•On the other hand length of the belt received by the driven pulley is
less than the length of the belt that moves off the driven pulley.
Hence, the belt must creep forward slightly relative to the driven
pulley rim.

25. Creep In Belt

26. Creep In Belt
•This motion of the belt relative to drive and driven pulley due
to unequal stretching of two sides of the drive is known as
creep.
•The effect of creep back on the driving pulley is to slow down
the speed of the belt with respect to driving pulley and the
effect of creep forward on the driven pulley is to slow down
the speed of the driven pulley with respect to the belt.
•It is important to note that, the creep which is due to the
elastic property of the belt is totally different than the
conventional slip, which is due to insufficient frictional grip
between the belt and pulley.

27. Method of belt tensioning
•In order to transmit the power, the belt must be provided
with the sufficient initial tension. The power transmitting
capacity of the belt drive also depends upon the initial
tension.
•Some of the method use to adjust the belt tensions are as
follows:-
1.Manual adjustment
2.Weighted idler pulley

28. •The angular-velocity ratio is not necessarily constant or The angular-velocity ratio is not necessarily constant or
equal to the ratio of pulley diameters, because of belt equal to the ratio of pulley diameters, because of belt
slip and stretch. slip and stretch.
•Heat buildup occurs. Speed is limited to usually 7000 Heat buildup occurs. Speed is limited to usually 7000
feet per minute (35 meters per second). Power feet per minute (35 meters per second). Power
transmission is limited to 370 kilowatts (500 transmission is limited to 370 kilowatts (500
horsepower). horsepower).
•Operating temperatures are usually restricted to –31 Operating temperatures are usually restricted to –31
to 185°F (–35 to 85°C). to 185°F (–35 to 85°C).
•Some adjustment of center distance or use of an idler Some adjustment of center distance or use of an idler
pulley is necessary for wear and stretch compensation. pulley is necessary for wear and stretch compensation.
•A means of disassembly must be provided to install A means of disassembly must be provided to install
endless belts.endless belts.
Disadvantages of belt drive

29. Introduction to chain drive
•Chain drive is a way of transmitting mechanical
power from one place to another. It is often used
to convey power to the wheels of a vehicle,
particularly bicycles and motorcycles. It is also
used in a wide variety of machines besides
vehicles.
•Most often, the power is conveyed by a roller
chain known as the drive chain or transmission
chain, passing over a sprocket gear, with the
teeth of the gear meshing with the holes in the
links of the chain.

30. Advantages of chain drive
•As no slip takes place during chain drive, hence perfect velocity ratio is
obtained.
•Since the chains are made of metal, therefore they occupy less space in
width than a belt or
rope drive.
•It may be used for both long as well as short distances.
•It gives a high transmission efficiency (unto 98 percent).
•It gives less load on the shafts.
•It has the ability to transmit motion to several shafts by one chain only.
•It transmits more power than belts.
•It permits high speed ratio of 8 to 10 in one step.
•It can be operated under adverse temperature and atmospheric
conditions.

31. Limitations of chain drive
•The production cost of chains is relatively
high.
•The chain drive needs accurate mounting and
careful maintenance, particularly lubrication
and slack adjustment.
•The chain drive has velocity fluctuations
especially when unduly stretched.

32. Types of power transmission chain
•Roller chain
–Large reduction ratio (usually up to 1:7)
–Chains can be used with long shaft center distances (normally up to
4m). By changing the number of links it is possible to freely adjust the
shaft center distance.
–The chain can be used on both sides and drive multiple shafts at the
same time.
–Easy installation and replacement (easy to cut and connect chains).
–If the distance between shafts is short, it can be used vertically.
–The sprocket diameter of a chain drive could be smaller than a belt
pulley while transmitting the same torque.
–Transmitting power by meshing many teeth results in less wear of
sprocket teeth than gears.
–Chain drives have greater shock absorption than gear drives.

33. Roller chain drive

34. •Inverted tooth drive chains
–Inverted tooth drive chain are the optimal
solution for requirements exceeding those met by
other chains (e. g. roller chains). They allow for
low-backlash drives with exact positioning. They
are also highly effective, inured to vibration and
have minimal noise emission.

35. Inverted tooth chain drive

36. Lubrication of chain
•It is very important for the effective and
durable functioning of chains.
•The chains are lubricated by light or medium
mineral oils like SAE30.SAE40,SAE50
•Methods of lubrication
1.Manual
2.Oil bath
3.Oil stream

37. THANK
YOU..
Made by:
Akash lal-14meu010
Akash rajain-14meu011
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Akshat Kapil-14meu013