Pulley Mechanism

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Transmission of PowerPulley Mechanism

ByManoj Tiwari
DFT/NIFT-G’Nagar

Learning ObjectivesTo understand the Pulley
Mechanism
To develop the
understanding of Mechanical
Advantage using pulleys.
To explore the applications of
Pulleys for mechanical power
transmission
Class room Teachings by Manoj Tiwari

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Pulley…
The pulley a variation of the axle and wheel;
the wheel is grooved to guide a rope, chain
or cable along the circumference of the
wheel, which moves freely around the axle.

Class room Teachings by Manoj Tiwari

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Pulley…
At its most simple use, the pulley works to
change the direction of force applied in a
system. More complex uses of pulleys are
frequently used to gain mechanical
advantage in a system.

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Pulley Systems…
Fixed (Class 1) Pulley
Moveable (Class II) Pulley
Combination (Class III) Pulley

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Fixed Pulley…
Often used to alter the direction
of force in a system
Weight of force is equal to the
weight of the object being
moved.
Advantage is gained by moving
the operator away from the load

Class room Teachings by Manoj Tiwari

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Fixed Pulley…
•A fixed pulley does not
increase your force and
therefore gives you no
advantage.
•It helps a person lift
things by changing the
direction of force. It allows
a person to pull down in
order to lift a load up.
Class room Teachings by Manoj Tiwari

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Fixed Pulley…

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Movable pulley (Floating Pulley)…
Used to gain mechanical
advantage to lift weight (W) by
multiplying the forces
Weight of force (F) required to
move the object is equal to the
number of ropes (N) supporting
the load (W). F = W/N

Class room Teachings by Manoj Tiwari

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Movable Pulley…
It is called a movable
pulley because it moves
with the load.
The pulley is suspended
by a rope with one
portion of the rope
(called a rope segment)
on each side. Each rope
segment supports half
the load.
Class room Teachings by Manoj Tiwari

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Movable Pulley…
The pulley is suspended and as
a consequence the mechanical
advantage is increased.
The rope on the left and right of
the pulley are both lifting the
LOAD, they each lift half its
weight hence the load is split
into 2 parts.

Class room Teachings by Manoj Tiwari

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Combination Pulley…
•The problem with movable pulleys is that
a person has to pull up to lift a load.
•In order to make the job of lifting a load
easier, a fixed pulley can be added to
allow lifting a load by pulling down.
•By combining a fixed pulley to a movable
pulley, a person gets the advantages of
both. The movable pulley doubles the
person’s force, and at the same time the
fixed pulley let the person pull down to lift
the load up.
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Combination Pulley…

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Combination Pulley…

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Combination Pulley…

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Questions…

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