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Explain the working of Scotch Yoke mechanism with neat sketch.

Scotch yoke mechanism. This mechanism is used for converting rotary motion into a reciprocating motion. The inversion is obtained by fixing either the link 1 or link 3. In Fig. link 1 is
fixed. In this mechanism, when the link 2 (which corresponds to crank) rotates about B as centre,
the link 4 (which corresponds to a frame) reciprocates. The fixed link 1 guides the frame

 

 

Explain with neat sketch method of drawing displacement diagram for SHM of follower.

The displacement diagram is drawn as follows for SHM of follower :
1. Draw a semi-circle on the follower stroke as diameter.
2. Divide the semi-circle into any number of even equal parts (say eight).
3. Divide the angular displacements of the cam during out stroke and return stroke into the
same number of equal parts.
4. The displacement diagram is obtained by projecting the points as shown in Figure

Compare Belt Drive and Chain Drive (four points)

PARTICULERS
BELT DRIVE

CHAIN DRIVE

Slip
Slip may occur
No slip (Positive drive)

Use
For low Velocity Ratio
For moderate Velocity Ratio

Suitability
For large centre distance
For moderate centre distance

Space requires
Large
Moderate

Lubrication
Not required
Require

Installation
cost Less
Moderate

Example
 
Floor Mill, Compressor,Conveyors
Bicycle, Automobile

 

State the necessity of Acceleration diagram of a mechanism.

1) Acceleration diagram is important in mechanism , because acceleration is directly related to
force. F = m * a
2) By calculating acceleration, we calculate inertia force acting on different links.
3) Design of machine parts rotating at higher speed becomes safe.

Define completely constrained motion and successfully constrained motion.

1)Completely constrained motion :- When the motion between a pair is limited to a definite
direction irrespective of the direction of force applied, then the motion is said to be a completely
constrained motion.
2)Successfully constrained motion:- When the motion between the elements, forming a pair, is
such that the constrained motion is not completed by itself, but by some other means, then the
motion is said to be successfully constrained motion.

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