Mechanics of Machines 2 Lab report

Mechanical Engineering Department.

Mechanics of Machines 2

Student no:
Date of Laboratory experiments:
Place:
Date completed:
Due Date:

Experiment 1: The Plate Clutch

Objective:
The Aim of this experiment is to find the relation between the axial load W and the frictional torque T, using a single plate clutch.
To find the coefficient of friction between the clutch surfaces using the uniform wear theory.
To experimentally conclude whether the average radius of the friction plate is proportional to the frictional torque.

Apparatus used:

Weights,
String
Plate clutch
Hangers
Pulleys
5 x 2kg weights for axial load
Theory:
It is stated theoretically that T = µWR
This means that as the axial load (W) increases, so does the torque and vice versa. Also that if the mean radius (R) increases, so will the torque.

Method:
Make sure all the surfaces are clear of oil and dirt before putting the plates on
Measure the mass and diameter of the top steel plate
Make note of the inside and outside radius of each plate clutch
Put the clutch plate on in position underneath the top plate
Make sure the strings are correctly positioned on the pulleys and that the system is moving freely
Place a 2 kg mass on the plate. Determine the frictional force necessary to rotate the top plate at a constant speed. Put another 2kg mass on the top plate. Determine the frictional force necessary to rotate the top plate at the same steady constant speed as before.
Add additional mass pieces of 2kg to a maximum of 10 kg and determine, in each case the frictional force necessary to rotate the top plate at the same steady constant speed.
Follow the same steps as before for the other two plates

Calculations and results:

Mass of top plate = 1.78kg

Mean radius of first plate is:

Rtt = 0.125m (Radius of turntable)

Torque is:

Axial load is:

Coefficient of friction is:

Table of results:
Plate 1
R1 = 0.06m and R2 = 0.04m
Mass on Top (M) in (kg)
Mass on String (m) in (kg) µ 2
0.5
0.33
4
0.75
0.324
6
1
0.321
8
1.25
0.319
10
1.5
0.318

Plate 2
R1 = 0.085m and R2 = 0.065m
Mass on Top (M) in (kg)
Mass on String (m) in (kg) µ 2
0.7
0.308
4
0.95
0.274
6
1.3
0.278
8
1.6
0.272
10
1.8
0.254

Plate 3
R1 = 0.11m and R2 = 0.09m
Mass on Top (M) in (kg)
Mass on String (m) in (kg) µ 2
0.9
0.297
4
1.3
0.281
6
1.7
0.273
8
2.1
0.268
10
2.4
0.254
Average value of coefficient of friction =
Plate 1 average: µ = 0.322
Plate 2 average: µ = 0.277
Plate 3 average: µ = 0.274