WELCOME

PRESENTATION ON WHITWORTH QUICK RETURN MECHANISM :

PRESENTED BY,

GOWTHAM.S -15BME110

KINEMATICS OF MACHINERY

In slotter, the rotary motion of the electric motor will be converted into reciprocating motion of the ram.

More over, the return stroke will be faster than the cutting stroke.

QUICK RETURN MECHANISM :

The whitworth quick return mechanism generally used in slotter.

An electric motor drives a pinion at constant speed.

The pinion drives a bull gear at uniform speed.

The bull gear has a crank pin (C) fitted with a sliding block.

A crank plate is pivoted eccentrically on the bull gear at the point ‘o’ by a pin.

WHITWORTH QUICK RETURN MECHANISM :

The crank plate has a slot along its length. The crank pin with sliding block slides along

the slot of the crank plate. The other end of the crank plate is

connected to a connecting rod through a pin ‘p’.

The ram is fitted to this connecting rod. It is unlike the crank and slider mechanism,

the forward reciprocating motion is slower rate than the return stroke.

WHITWORTH QUICK RETURN MECHANISM :

When the bull gear rotates, the crank pin rotates about its centre.

At the same time, the sliding block slides along the slot of the crank plate.

This makes the crank plate to rotate about the point ‘o’.

Thus the rotary motion of the crank plate is converted into the reciprocating motion of ram through the connecting rod.

WORKING :

In the fig, C1 & C2 represent the two extreme positions of crank pin with sliding block.

During the cutting stroke, the crank pin rotates from C1 to C2in anti-clockwise direction through an angle θ1

During the return stroke, the crank pin rotates from c2 to c1 in anti-clockwise direction through an angle θ2.

The speed of the bull gear & the length of stroke during both the strokes are same.

Referring the fig, angle (return stroke) is less than angle (cutting stroke).

So the time taken for return stroke is less. Hence the ram moves faster during return stroke.

WHITWORTH QUICK RETURN MOTION :

Quick return mechanisms are found throughout the engineering industry in different machines : Shaper Screw press Power-driven saw Mechanical actuator revolver mechanisms Water pumping system

APPLICATION OF WHITWORTH QUICK RETURN MECHANISM :

Shaping machine

Water pumping system

Power driven saw machine

ROTARY ENGINE :

THANK YOU