Title; Slider Crank

Objective; To obtain the velocity and acceleration of the slider crank.

Theory;

The slider crank mechanism is probably the most common of all mechanism because of its simplicity and versatility. We are familiar with it in the reciprocating pump and compressor in which the input rotation is changed to reciprocating motion of the piston. In the piston engine the situation is reversed and the piston is the driver.

If there are several cylinders, the various pistons alternate as driver and if the engine is a single-cylinder, the energy stored in the flywheel and other components actually drives the piston between power strokes. An ingle slider crank mechanism and the associated cam and valve train typical of a multi-cylinder internal combustion are shown the piston and connecting rod of a small one cylinder gasoline-powered engine.

Procedure;

  1. Firstly, all of equipment for experiment of slider crank is make sure all complete.

  1. The angle of the circle is set to 00 and the piston at 00.

  1. The angle of the circle is twist at 300 and the movement of the piston result is taken.

  1. After that, we twist the angle of the circle at 600 and take a result. We will doing this steps with the increasing the angle of the circle to 300.

  1. At the 1800, piston is moving to the front, then at the 2100 pistons moving to the back.

  1. Finally at 3600 piston will moving to the back side and we also set a result equal to 00.

  1. All the result we got will fill in the table to make the graph.

Apparatus;

Slider crank

Slider crank linkage

Readings;

When O = 00, AO = r + l

Therefore for any position O => [ x = ( r + l ) – q ]

O0

q ( cm )

0

0

30

1.51

60

5.27

90

9.69

120

13.25

150

15.34

180

16.00

210

15.36

240

13.33

270

9.80

300

5.36

330

1.56

360

0

Sample calculation;

a. Theoretical Calculation:

** O0 = 300, q = 1.51 Where constant

O0 => rad

300 x 3.142 = 0.54 rad

3600

x = ( r + l ) – q

= ( 7.85 + 19.5 ) – 1.51 = 25.84 cm

x = rx sin O

( r cos O – x )

= ( 7.85 ) ( 25.84 ) sin 30 x 1

( 7.85 cos 30 – 25.84 )

= - 5.33 cm / s

x = x2 + 2rx sin O w + rx cos O w2

( r cos O – x )

= ( - 5.33 )2 + [ 2 ( 7.85 ) ( - 5.33 ) sin 30 ( 1 ) ] + [ ( 7.85 ) ( 25.84 ) cos 30 ( 1 )2

7.85 cos 30 – 25.84

= - 8.54 cm / s2

b. Experimental calculation:

. ..

For experiment, we get the value of c and c from the slope at the graph that has been plotting

.

To find the value of c we are referred graph displacement (c cm) versus angle (q°).

When q =30°

The coordinate is (0, 27.4) and (30, 25.92)

.

c = (27.35 – 25.84)

(0 – 30)

To find the value of c we are referred graph velocity (c cm/s) versus angle (q°)

When q = 30°

The coordinate is (0, 0) and (30, -0.0473)

..

c = (-0.0473- 0)

(0 – 30)

= -0.0016cm /s²

Results;

a. Theoretical Calculation:

O0

q ( cm )

radian

x ( cm )

x ( cm / s )

x ( cm / s2 )

0

0

0

27.35

0

- 11.01

30

1.51

0.53

25.84

- 5.46

- 8.54

60

5.27

1.05

22.08

- 8.27

- 2.35

90

9.69

1.57

17.66

- 7.85

3.49

120

13.25

2.09

14.10

- 5.32

5.51

150

15.34

2.62

12.01

- 2.51

5.05

180

16.00

3.16

11.35

0

4.64

210

15.36

3.69

11.99

2.50

5.05

240

13.33

4.21

14.02

5.31

5.52

270

9.80

4.73

17.55

7.85

3.51

300

5.36

5.26

21.99

8.28

- 2.34

330

1.56

5.76

25.79

5.33

- 8.52

360

0

6.28

27.35

0

- 11.01

Experiment graph:

Graph: Displacement versus Angle

Graph: Velocity versus Angle

Graph: Acceleration versus Angle

b. Experimental calculation:

When,

l = 27.35 cm, r = 7 .85 cm

x

x

x

0

0

27.4

0

0

30

1.48

25.92

-0.0493

-0.0016

60

5.24

22.16

-0.1267

-0.0026

90

9.73

17.67

-0.1497

-0.0008

120

13.28

14.12

-0.1183

0.0001

150

15.35

12.05

-0.0690

0.0016

180

16.0000

11.4

-0.0217

0.0016

210

15.35

12.05

0.0217

0.0014

240

13.30

14.1

0.0683

0.0016

270

9.80

17.6

0.1167

0.0016

300

5.37

22.03

0.1477

0.0010

330

1.60

25.8

0.1257

-0.0007

360

0

27.4

0.0533

-0.0024

Graph: Velocity versus Angle

Graph: Acceleration versus Angle

Discussion;

The slider crank mechanism is probably the most common of all mechanism because of its simplicity and versatility. We are link with it in the reciprocating pump and compressor, in with the input rotation is changed to reciprocating motion of the piston.

From the graph of x against O, as we known at length x was increased and at 1800 the length x was decreased. Then at 3600, the length increased again, we can conclude that for the perfect cycle, the piston must cycle by 3600.

Constant velocity is happen until θ = 60º, after that, the velocity look become bigger when approaching the end of the reading taken ( θ = 300 º), but after that, the constant value is come again same as the initial condition. In case of acceleration, the highest acceleration would be when θ = 120º and becomes lowest at θ = 120º.

A single slider crank mechanism and the associated cam and valve train typical of s multi cylinder internal combustion engine shows the piton and connecting rod of a small one cylinder gasoline-powered engine.

Conclusion;

In conclusion, position and displacement is the most important thing that considered in this experiment, it have a big relation to the velocity and acceleration. That is why the movement of the velocity and acceleration can not moved smoothly. When we do this experiment,. we have tried to achieve the minimum value of error so that the best value can be found.

From this experiment also, we can conclude that the piston work in the cylinder is simplicity and versatility. Piston is a driver an the cylinder is a place that stored energy to transfer engineering application for example in the car and water pump.

The slider crank normally used in the part of engine like cylinder, the motion of piston and air-conditioning and heat pump compressor. This application also can use in hydraulic cylinder equipment example like backhoe that can arrange to give it a wide range of operating position.