Download - Types of pulley
Topic : TYPES OF PULLEYCreated by Rajesh Goswami
Pulley Pulleys are used to transmit power from one shaft to
another with the help of belt or rope running over them. Pulleys are made from cast iron,cast steel, wrought iron
or aluminium.
The main part of pulley RimHub or bossArms or rib
Rim It is the periphery of the pulley on which the
belt runs. The outer face of the rim is made slightly
convex which is called crowning. This keep belts at centre when pulley is
misaligned.
Hub or boss It is the central hollow cylindrical portion of
pulley as shown in figure. The size of bore on hub is corresponds to the
diameter of the shaft. It is mounted on shaft. A keyway is provided to fasten the pulley to
the shaft with the help of a key.
Arms or rib It is joining member of the hub and the rib of
pulley. It may be straight or curved. It’s cross section may be circular or elliptical. Pulleys with smaller diameter are provided
with a rib which is like a circular disc joining hub and rim.
Types of pulley Solid pulley Split pulley Stepped or cone pulley Fast and loose pulley Jockey pulley Guide pulley Grooved pulley
Solid pulley It is made from single piece of cast iron . Solid pulley relatively smaller in size. This pulley can be mounted on shaft by
inserting from one end.
Solid pulley
Split pulley It is split in two halves ,and it can be joined at
the rim and the hub by means of bolts or links.
This pulley can be mounted on the shaft at any place without changing the assembly of bearing and shaft.
Split pulley
Stepped or cone pulley Stepped pulley is used when the speed of
the driven shaft is to be changed very frequently as in case of machine tools such as lathe , drilling machine etc. a stepped pulley is an integral casting having three or more number of pulleys of different diameter as show in figure.
Each stepped pulley is mounted on driving and driven shaft can be varied by shifting the diameters of driving and driven pulleys are such that same belt will operate when shifted on different pairs of pulley.
Stepped or cone pulley
Fast and loose pulley When a number of machines run from a main driving shaft , it may
require to start or stop some of the machines intermittently without start or stop the main driving shaft every time.
This is possible by mounting pair of pulleys is securely keyed to the machine shaft so that it can rotate along with shaft while the loose pulley fitted with brass bush so that it can freely rotate on the shaft as shown in figure .
The wider driving pulley keyed to the main driving shaft , hence it rotates along with it.
When the belt on the fast pulley , the power is transmitted from driving shaft to the machine shaft.
When belt shifted from fast pulley to loose pulley , the loose pulley rotates through belt, but machine shaft not rotates along with it because loose pulley can freely rotates on shaft .
The movement of belt from fast to loose pulley or loose to fast pulley take place by axial movement of belt shifter.
Fast and loose pulley
Jockey pulley Jokey pulley is idler pulley and is used to
increase the angle of contact in open belt drive.
It is mounted near the smaller pulley of the two pulleys and is placed on the slack side of the belt as shown in figure.
It increases angle of contact lead to increased power transmission capacity of drive.
Jockey pulley
Guide pulley The guide pulleys are used to guide the belts
when connecting non-parallel, intersecting or non-intersecting shafts.
The guide pulleys guide the belt to keep the belt in a proper plane as shown in figure.
Guide pulley
Grooved pulley Grooved pulley have V-grooves or circular
grooves on the rim to carry V-Belt or ropes. It is generally made from cast iron. The grooves on the rim is help to increase the
frictional grip of the belt or rope on the pulley. Therefore the chance of slip is reduced. Figure shows grooved pulley for V-belt and
figure shows grooved pulley for rope drive.
Grooved pulley
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