Posted tagged ‘drive pulley’


August 23, 2011


01-standard pulley-spun end curve crown pulley-steel pulley-straight faced pulley-pulley mechanism-pulley ratio-pulley size-pulley selection

The diameters of standard pulleys are: 200, 250, 315, 400, 500, 630, 800, 1000, 1250, 1400 and 1600 mm. pulley may be straight faced or crowned. The crown serves to keep the belt centered. The height of the crown is usually 0.5% of the pulley width, but not less than 4 mm. The pulley diameter Dp depends on the number of plies of belt and may be also be determined from the formula:

Dp > K.i (mm)


K = a factor depending on the number of plies (125 to 150)

i = no of plies

The compound value should be rounded off to the nearest standard size. While selecting the pulley diameter it should be ascertained that the diameter selected is larger than the minimum diameter of pulley for the particular belt selected.

The drive pulley may be lagged by rubber coating whenever necessary, to increase the coefficient of friction. The lagging thickness shall vary between 6 to 12 mm. The hardness of rubber lagging of the pulley shall be less than that of the cover rubber of the running belt.

Pulley types:

Pulleys are manufactured in a wide range of sizes, consisting of a continuous rim and two end discs fitted with hubs. In most of the conveyor pulleys intermediate stiffening discs are welded inside the rim. Other pulleys are self cleaning wing types which are used as the tail, take-up, or snub pulley where material tends to build up on the pulley face. Magnetic types of pulleys are used to remove tramp iron from the material being conveyed.

Typical welded steel pulley-Drum conveyor pulley

01-typical welded steel pulley-pulley types-pulley design-pulley system-pulley problems-pulley size

Spun end curve crown pulley

01-conveyor pulleys-spun end crown pulley-self cleaning wing pulley-snub pulley-pulley face-magenetic pulley

Spiral drum conveyor pulley

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Welded steel pulley with diamond grooved lagging

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Welded steel pulley with grooved Lagging

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Spiral Wing Conveyor pulley

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Power calculation for the drive unit:

The horse power required at the drive of a belt conveyor is derived from the following formula:

H.P = Te . V


Te is the effective tension in the belt in N

V = velocity of the belt in m/s

The required effective tension Te on the driving pulley of a belt conveyor is obtained by adding up all the resistances.


August 23, 2011

Conveyor Take-up Arrangement:

01-belt conveyor-take up arrangement-screw take up-take up pulley-automatic take up device-fixed take up device-manual take up-self adjusting take up devices

All belt conveyors require the use of some form of take-up device for the following reasons:

  • To ensure adequate tension of the belt leaving the drive pulley so as to avoid any slippage of the belt
  • To ensure proper belt tension at the loading and other points along the conveyor
  • To compensate for changes in belt length due to elongation
  • To provide extra length of belt when necessary for splicing purpose.

Usually there are two types of take up arrangements.

  • Fixed take up device that may be adjusted periodically by manual operation
  • Automatic take up devices for constant load type

In a screw take up system the take up pulley rotates in two bearing blocks which may slide on stationery guide ways with the help of two screws. The tension is created by the two screws which are tightened and periodically adjusted with a spanner. It is preferable to use screws with trapezoidal thread t decrease the effort required to tighten the belt.

01-hydraulic take up device-pneumatic take up device-electrical take up device-self adjusting take up device-automatic take up device

The main problem with the use of manual take-up is that it requires a vigilant and careful operator to observe when take up adjustment is required. Perfect tension adjustment with this system is also not possible. For this reason these devices are used only in case of short conveyors of up 60 m length and light duty.

In automatic take up arrangement the take up pulley is mounted on slides or on a trolley which is pulled backwards by means of a steel rope and deflecting pulleys. The carriage travels on guide ways mounted parallel to the longitudinal axis of the conveyor, i.e., horizontally in horizontal conveyors and at an incline in inclined conveyors. Hydraulic, pneumatic and electrical take up devices are also used.

Automatic take-up has the following features:

  • It is self adjusting and automatic
  • Greater take-up movement is possible.