1. Chapter 2
BELTING SYSTEM

2. NAS, msy-rev1
01/07/2019
Conveying system
1-Rope 2-Chain 3-Belt

3. NAS, msy-rev1
01/07/2019
Belting

4. NAS, msy-rev1
01/07/2019
If not belt????

5. Timing belt vs Timing chain
NAS, msy-rev1
01/07/2019
Timing belt vs Timing chain

6. NAS, msy-rev1
01/07/2019
Type of belts

7. Selection of Belt Drive
NAS, msy-rev1
01/07/2019
Selection of Belt Drive
Speed of the driving and driven shafts,
Positive drive requirements,
Speed reduction ratio,
Shaft layout,
Power to be transmitted,
Centre distance between the shafts,
Space available,
Service conditions.

8. factors that affect the amount Of power transmitted:
NAS, msy-rev1
01/07/2019
factors that affect the amount Of power transmitted:
The velocity of the belt.
The tension under which the belt is placed on the pulleys.
The arc of contact between the belt and the smaller pulley.
The conditions under which the belt is used.

9. NAS, msy-rev1
01/07/2019
Types of Belt Drives
Open belt drive

10. Crossed or twisted belt drive
NAS, msy-rev1
01/07/2019
Crossed or twisted belt drive

11. D – large pulley diameter d – small pulley diameter
NAS, msy-rev1
01/07/2019
D – large pulley diameter
d – small pulley diameter
 - angle of contact
C – center distance

12. NAS, msy-rev1
01/07/2019
Belt length
Angle of contact,
ANGLE IN RADIAN

13. D – large pulley diameter d – small pulley diameter
NAS, msy-rev1
01/07/2019
D – large pulley diameter
d – small pulley diameter
 - angle of contact
C – center distance

14. NAS, msy-rev1
01/07/2019
Belt length
Angle of contact,
ANGLE IN RADIAN

15. Velocity Ratio, Ratio of tensions and power transmission
NAS, msy-rev1
01/07/2019
Velocity Ratio, Ratio of tensions and power transmission
D1 = diameter of the driver
D2 = diameter of the driven/follower
N1 = speed of the driver in rpm and
N2 = speed of the driven/follower in rpm and

16. Velocity of the belt on the driving pulley,
NAS, msy-rev1
01/07/2019
Velocity of the belt on the driving pulley,
Velocity of the belt on the driven or follower pulley
when there is no slip, then V1 = V2,

17. Ratio of Tensions T1 = Tension in the belt on the tight side
NAS, msy-rev1
01/07/2019
Ratio of Tensions
T1 = Tension in the belt on the tight side
T2 = Tension in the belt on the slack side
 = coefficient of friction
θ = wrap/contact angle (usually at smaller diameter pulley, θd)

18. NAS, msy-rev1
01/07/2019
Open belt
Crossed

19. Power Transmitted P = (T1 –T2).v Note that, T1 >T2 NAS, msy-rev1
01/07/2019
Power Transmitted
P = (T1 –T2).v
Note that, T1 >T2

20. NAS, msy-rev1
01/07/2019
Example 1
A flat belt drive system consists of a two parallel pulleys of diameter 200 mm and 300 mm, which have a distance between centres of 500 mm. Given that the maximum belt tension is not to exceed 1.2 kN, the coefficient of friction between the belt and the pulley is 0.4 and the larger pulley rotates at 300 r.p.m. Find :
angle of contact between the belt and each pulley,
the length of the belt required,
the power transmitted by the belt system.

21. Centrifugal Effect on belts
NAS, msy-rev1
01/07/2019
Centrifugal Effect on belts
Centrifugal Tension, Tc is given by
Total tension at the tight side,
Total tension at the slack side,

22. NAS, msy-rev1
01/07/2019
Strength of belt
Maximum tension in the belt is equal to the total tension in the tight side(Tt= Tmax) of the belt
Velocity of belt for maximum power,

23. NAS, msy-rev1
01/07/2019
Torque on THE shafts
Shaft

24. NAS, msy-rev1
01/07/2019
For big pulley,
For small pulley, T2 T2 T1 T1

25. efficiency Efficiency is given by Power input, Power Output,
NAS, msy-rev1
01/07/2019
efficiency
Efficiency is given by
Power input,
Power Output,

26. NAS, msy-rev1
01/07/2019
EXAMPLE 2
An open belt drive connects two pulleys 1.2 m and 0.6 m diameter on parallel shafts 3.6 m apart. The belt has a mass of 1 kg/m length and the maximum tension in it is not to exceed 2 kN. The 1.2 m pulley, which is the driver, runs at 250 r.p.m. Due to the slip on one of the pulleys, the velocity of the driven shaft is only 450 r.p.m. If the coefficient of friction between the belt and the pulley is 0.3, find
Torque on each of the two shafts
Power transmitted
Power lost in friction, and
Efficiency of the drive