Exp 2,Slider and Crank(Change radius) PDF

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Summary

lab report...

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Experiment no: 2 Slider and Crank Mechanism Objective: To study the effect of changing the crank radius and connecting rod length.

Apparatus: 

Slider



Connecting rod



Crank Radius

Slider and Crank apparatus

Theory: It is showed that the piston positions are associated with each angle of the crank. The displacement of the piston does not move in equal amount. However, it follows a smooth path which is non-linear. For different crank radius, the ratio between the connecting rod and crank is different. Consequently, the point of maximum displacement will also different. The higher the ratio, the lower the maximum point of its displacement. The same theory goes to the length of connecting rod. As when we use the same crank radius but different length of connecting rod, the ratio also varies. So, the point of maximum displacement will also different. In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion. Connecting rods may also convert rotating motion into linear

motion. As a connecting rod is rigid, it may transmit either a push or a pull and so the rod may rotate the crank through both halves of a revolution, i.e. piston pushing and piston pulling.

Procedure: 1. On the circular scale, set the crank to zero. 2. Both knurled nuts are slacken and adjust the position of the piston pivot so that the connecting rod is 7 inch long. Make sure that the spacer washer is between the piston and the connecting rod. In normal use, the knurled nuts will be just slack. However, the motion of the slider crank chain can be locked at any position by tightening both knurled nuts. 3.

Record the piston displacement and the cross-scale readings in table for every 30° of crank rotation. Note that with the crank angle set to zero, note the initial reading of the cross-scale. This will need subtracting from all subsequent readings in order to obtain the true reading.

4. Steps 1 to 3 are repeated for connecting rod lengths of 7,6 and 8 inches along with radius.

Observation and Calculation:

Slider length =6inch R=1

30 60 90 120 150

R=2

R=3

Slider length =7inch R=1

R=2

R=3

Slider length =8inch R=1

R=2

R=3

180

Conclusion: In conclusion, by doing this experiment, the relationship between the crank angle and the stroke have been learnt. By studying this experiment, the effect of changing the crank radius and connecting rod length can be obtained easily. The higher the ratio of crank and connecting rod, the lower the maximum point of its displacement. The relationship between the angular and linear speed of the mechanism has been learnt....