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

Thank you…