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Q.12.Explain with Sketch Pantograph


Link AB - End A is fixed

link BC

link DE

link DF

Pairs -

Turning Pair - AB & BC

Turning Pair – AB & DE

Turning Pair – BC & DF

Turning Pair – ED & DF

Construction –

This mechanism is an inversion of four bar chain . It has four turning pairs. One link is fixed to the table. The stylus is attached to the junction of link DE and DF and the pen is attached to the end C of the link BC. The lengths of all links are adjustable through the holes provided on the links.

Working –

As the operator traces the "Drawing" with the stylus, the same drawing is reproduced by the pen either in enlarged or reduced scale depending upon the links lengths. The links have holes for the adjustment of magnitude of enlargement or reduction.

Application – The mechanism is used for

1. Reducing large drawing.

2.Used in copy machining such as copying lathe using hydraulic system.3.Used in electric train supply system on top of train, which supplies current to electric train from cables on top.