LABORATORY REPORT
MECHANICS OF MACHINE LABORATORY
Subject Name ENGINEERING LABORATORY IV
Title of Experiment BELT FRICTION
Course Code BNJ 37301 Section
Semester and session
Lecturer/Instructor 1. Encik Wan Mohd Wardi Bin Wan Abdul
Name Rahman
2.
Group Members Matric
Assessment
No.
Prakash A/L Ramakrishanan CN200153 Theory (C2) 10 %
1.
Shasmita Lakshmi A/P CN200211 Observation (P3) 20 %
2. Murualikaran
Muhammah Sholehin Bin DN210105 Results (P2) 15 %
3. Nordin
Calculation (P4) 10 %
Discussions 25 %
(C4&C5)
Date of Experiment Conclusion (C3) 15 %
14.12.2022 References (C1) 5%
Date of Submission TOTAL 100%
21.12.2022 TOTAL
55%
COGNITIVE
Approved stamp
TOTAL 45%
PHYSCOMOTOR
1.0 INTRODUCTION
1.1 Theory
Power transmission at various speeds is frequently accomplished via belt drives. The
ability to transmit power from a source to a load operating quite a distance away is the key
benefit. Belt drives are more flexible to orient the output shaft at various angles with regard
to the input shaft than gear drives are. Additionally, compared to other types of drives, belt
drives require less maintenance and are simpler to operate. A wider range of applications
employ belt drives. A vehicle engine can use a variety of belt drives. Automobile cooling fan
and air conditioning compressor motors are often connected to the crankshaft by belt drives.
Belt drives are used by some machine machines to attain various speeds.
r1 = Drive pulley radius, r2 = Load pulley radius, ω1 = Rotational speed of the drive pulley,
ω2 = Rotational speed of the load pulley. The belt speed is given by;
v = r1ω1 = r2ω2
Therefore, the speed ratio is given by
The aforementioned equation is correct provided that the belt does not slip,
stretches, or assumes 100% efficiency. It is now evident from the toque equation that T1
exceeds T2. This indicates that one side of the belt drive is tighter than the other (slack
side). The friction between the pulley and the belt is said to be the cause of the disparity. The
goal of a belt drive design is to transmit the most power while maximising the differential
between T1 and T2. Due to the friction between the belt and pulley, this lab will investigate
the relationship between the two tensions.
1.2 Objectives
1) To understand the frictional behavior applicable for belt drives.
2) To understand the effect of angle of lap around the pulley on torque
transmission.
3) To understand the effect of friction in different types of belts, such as flat, vee
and round belts.
4) To experimentally evaluate the coefficient of friction between the belt and the
pulley.
2.0 EQUIPMENTS (attach with pics)
1) Pulley
2) Hand crank
3) Pulley support
4) Column
5) Swivel-type belt holder
6) Locking pin
7) Spring balances
8) Same
9) A threaded stem
10) Base plate
3.0 SAFETY PRECAUTIONS
1. The belting materials which are worn out and older may become more rough or
smoother, changing the sliding friction.
2. The readings of spring balances F1 and F2 are observed and noted down while the
pulley is turned evenly with a constant speed.
3. The pulley is turned as evenly as possible in the anticlockwise direction to produce a
steady indication
4. In order to be able to assess the measurement, both ends of the belt must be
tensioned.
5. The friction between the belt and pulley may decrease substantially if the belt
happens to be muddy or wet, as it may act as a lubricant between the surfaces.
6. The setup involves the initial conditions of the construction, such as the angle at
which the belt is wrapped around and geometry of the belt and pulley system.
4.0 PROCEDURES
1. The apparatuses are set up as shown.
2. Before the experiment is started, we need to remove the belt.
3. The clamping lever and support are loosen, and the pulley is lowered and the belt is
slacken off.
4. Disengage spring balance at swivel-type belt holder, handwheel at threaded stem is
removed. Detach belt connectors from spring balances by removing the retaining ring
and pull out pin.
5. Then, we can start to fit the belt with the first belt which is the hemp or we call it rope.
6. The rope is attached to the spring balances and the pin is secured with a retaining
ring. The spring balance is fit at a swivel-type belt holder in pin in line with belt groove
selected.
7. The other way spring balance is inserted with a threaded stem through the
corresponding hole in the lower spring holder and screw the handwheel back on
again.
8. The clamping lever at support is loosen and the pulley is raised until there is tension
at both ends.
9. The next step is setting the arc of contact, which the first angle of degree is at 30˚
position.
10. Steps 3 and 4 are repeated to set the arc of contact of 30˚ position.
11. The locking pin is re-engaged. The clamping lever at support is loosen and pulley is
raised and belt is re-tension.
12. A tension is set and needs to be fixed until the end of the experiment. The handwheel
is turned to the lower end of the threaded stem.
13. The clamping lever at support is loosen and raised pulley until belt is slightly
pretensioned. The initial tension with the handwheel at the threaded stem is set as
10N.
14. The pulley is turned as evenly as possible in the anticlockwise direction to produce a
steady indication.
15. The readings of spring balances F1 and F2 are observed and noted down.
16. Steps 10 to 15 are repeated with angles 30˚, 60˚, 90˚, 120˚, 150˚ and 180˚ positions.
17. The clamping lever at support is loosen and raised pulley until belt is slightly
pretensioned. The initial tension with the handwheel at the threaded stem is set as
10N.
18. For each experiment, the readings obtained are recorded and tabulated.
𝐹1 𝐹1 μα
19. The ratio 𝐹2
is calculated using the formula given, which is 𝐹2
=𝑒 .
20. A graph on the development of the Force Relationship as a function of arc of contact
𝐹1
(μ = 0.43) 𝐹2
vs. Arc of contact α [degrees] is plotted.
21. The whole experiment is repeated by using nylon and leather with an arc of contact
(α) = 180° = π.
22. The nylon and leather - grey cast iron combination ensures that the spring balance is
fit at a swivel-type belt holder in pin in line with belt groove selected.
23. The forces (F1 and F2) are measured and the coefficient of friction (μ) is calculated
and tabulated as a function of material combination.
5.0 OBSERVATION
Based on table 1, we have observed that the ratio for the rope force as a function of
arc of contact at the angle of 30 has a smallest ratio which is 1.4. The ratio of the rope force
as a function of arc of contact at the angle of 180 has a biggest ratio which is 3.
On table 2, the measured ratio of the rope force for angle of 30 is the smallest which
is 1.40 and the calculated ratio of the rope force for the same angle is also the smallest
amount which is 1.25. Furthermore, the measured ratio of the rope force for angle of 180 is
the biggest amount which is 3.00 but the calculated ratio for the same angle stil the biggest
which is 3.86.
6.0 RESULTS & CALCULATION
Figure : Data of Table 1 and Table 2
Figure : Calculation of Table 1 and Table 2
Graph 1.0 : F₁/F₂ vs. Arc of contact α (degrees)
Figure : Data of Table 3
7.0 DISCUSSION
Based on the data Table 1 and Table 2, the graph of Table 1 vs Table 2 was plotted
according to the arc of contact α (degrees). In this experiment, there are relations between
the change of force with the arc of contact. From the graph, it is found that when the force
increases, the angle also increases which causes the slope of the line plotted to increase.
This means the higher the angle of lap, the lesser value of F1 required to stabilize the pulley
from rotating. This graph also shows a curvilinear relationship between the ratio of belt
tension and the lap angle. However, there are still some errors while conducting this
experiment, which is, the pulley has a high friction and is very hard to rotate. Also, there may
be some parallax error from a student who has to stabilize the pulley placed on F1.
It was observed that the entire system was always at the state of equilibrium
irrespective of the angle before the rope slides slowly. It was discovered that the ratio of the
belt tensions gradually reduced over a constant lap angle of θ in position on the plate. Also,
the ratio of the belt tensions increased with variation in the lap and groove angles while the
load, F2, was kept constant on the slack side hanger.
Based on the data from experiment 2, at a constant angle of 180⁰, we found that
leather has the higher coefficient of friction followed by hemp and nylon. This experiment
was quite a success because based on the result, the coefficient of friction (measured) for
leather was slightly different from the coefficient of friction (literature), while other belts were
the same.
8.0 CONCLUSION
In conclusion, three tables were to be filled in order to complete the belt friction
experiment. Table 1 required to find the F1 and F2 of each of the angles given from 0º to
180º. Positions of F1 are varied based on the direction of rotation of the pulley. When the
pulley is rotated in an anticlockwise direction the F1 will be at the left and vice versa. Ratios
𝐹1 μα
were then obtained. The calculated ratio was obtained by using the formula of 𝐹2
= 𝑒 ,
µ=0.43 in table 2 to compare with the experimental ratio. Ropes were used in the
experiment. Whereas in Table 3 (the coefficient of friction, µ) has been determined between
the pulley and the use belt (Leather, Hemp and Nylon). The µ value changes as the angle
changes. The values if µ are 0.86, 0.35 and 0.33 for Leather, Hemp and Nylon respectively.
Therefore, the experiment is considered successful and the objective of the experiment is
achieved. Although there are some errors that occur when conducting the experiment, it
does not affect the results of the experiment. In applications requiring power transfer and
transmission, particularly over long distances, the idea of belt friction is fundamental.
REFERENCES (pls do in APA citation)
https://www.citethisforme.com/citation-generator/apa
❖ Belt friction sample report - 1 objective to determine the coefficient of friction
between belt and (no date) Studocu. Available at:
https://www.studocu.com/row/document/rajshahi-university-of-engineering-an
d-technology/mechanical-engineering/belt-friction-sample-report/16649822
(Accessed: December 20, 2022).
❖ Thayer, K. (no date) 10 safety precautions you must be aware of when
performing conveyor system maintenance, Engineering360. Engineering360.
Available at:
https://insights.globalspec.com/article/7518/10-safety-precautions-you-must-be
-aware-of-when-performing-conveyor-system-maintenance (Accessed:
December 20, 2022).
❖ R. C hibbeler, Engineering Mechanics: Statics, 12th Edition in S. I. Unit (2010),
Person
❖ Education South Asia Pte. Ltd.2.
❖ 2. Ferdinand P. Beer, E. Russell Johnston, Jr. Vector Mechanics for Engineers,
Static
❖ and Dynamics, International Edition 1996, McGraw-Hill Co., New York.
(436-438)3.
❖ 3. Wan Abu Bakar Wan Abas Ph.D. (1989). Mekanik Kejuruteraan Statik. Kuala
❖ Lumpur:Dewan Bahasa Pustak
APPENDIX (attach pics)
