Learn about conveyor pulleys
10-03-2022 753
A conveyor pulley is a mechanical device similar to a conveyor roller that is used to change the direction of a conveyor belt in a conveyor system or to drive a conveyor belt or to apply tension to a conveyor belt.
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What is Conveyor Pulley?
A conveyor pulley is a mechanical device similar to a conveyor roller that is used to change the direction of a conveyor belt in a conveyor system or to drive a conveyor belt or to apply tension to a conveyor belt.
Pulleys are heavier than rollers and are used at either end of conveyor belts or near drives and motors. Pulleys are used to transmit drive forces to the conveyor and thus bear dynamic conveyor belt stresses. There are several different types of pulleys available for use on conveyors as well as different design specifications for pulleys serving different functions on the same conveyor.

Components of the pulley include:
- Drum or Shell:
The drum is the part of the pulley that is in direct contact with the belt. The housing is fabricated from a rolled steel sheet or from a hollow steel tube. Cases with a specific 'face' width and diameter are determined by the width of the conveyor and the type and rating of the conveyor used on the conveyor.
- Diaphragm Plates:
The diaphragm plates or end plates of pulleys are round discs fabricated from thick steel plate and welded to the housing at each end to strengthen the drum. End plates are drilled in their centers to accommodate the pulley shaft and hubs for the pulley locking elements.
- Shaft:
Shaft is designed to withstand all forces applied by the belt or actuator, with minimal deflection. Shafts are positioned and locked to end disc axes by locking elements. The shaft is supported at both ends by bearings located in damping blocks, to support the shaft and pulley assembly on the conveyor structure.
Axes often include different diameters along their length due to bending moments and deflection limitations. The diameter of the shaft at the grounding of the bearing can be smaller to accommodate the required bearing diameter, which is more cost-effective (smaller). Likewise in the case of a drive shaft, the drive attachment, may differ from other diameters along the shaft and thus the pulley shaft is often stepped.
- Locking Elements:
These are high precision manufactured items that are mounted on shafts and into pulley hubs. The locking elements attach the pulley securely to the shaft through the end plates. Locking element operates on the principle of friction, whereby the element can be fastened to the shaft and shaft simultaneously and concentrically, by tightening a series of screws around the locking element.
- Hubs:
Hubs are fabricated and machined housings, welded to the end plates. Hubs are sized according to the size of the pulley, the diameter of the shaft and the size of the locking element required for the particular task.
- Delay:
Sometimes it is necessary or desirable to improve the friction between the conveyor and the pulley to improve the torque that can be transmitted through the drive pulley. Improved traction on the pulley also aids belt training.
In such cases, the pulley drum surfaces are 'delayed' or covered with rubbery material. This cover is typically 8mm to 12mm thick and can be plain or notched. The rubber delay is vulcanized to the pulley housing to ensure that it remains mounted under adverse operating conditions.
- Assembly bearings:
Bearings that support the rotating shaft and thus the pulley. The bearings are housed in the 'damping block' allowing the mass of the pulley assembly plus belt tension to be transmitted to the pulley support structure. The blocks are typically bolted to 'base plates' welded to the structure. bamboo. The base plates incorporate jack screws to allow the pulley to be aligned precisely and with relative ease.
Types of Conveyor Pulleys
Historically there have been several different types of pulleys, from cast iron pulleys to slab pulleys, rim pulleys and steel pulleys. Nowadays it is common to use steel pulleys on conveyors. Exceptions to this standard are mainly for the cases where the discharge point of conveyor belts is equipped with a magnetic separator on the head pulley. In this case, the pulley housings and end plates are usually manufactured from non-magnetic stainless steel.
Selecting the right conveyor pulley
- Drive pulley, head pulley: used for conveyor belt driving purposes. They are usually mounted in external type bearings and are driven by a motor and reducer. Conveyor head pulleys can be flattened or slotted and many pulleys have hysteresis to reduce conveyor slip. Conveyor belt pulleys, wing pulleys, and helical pulleys are the most common types of drive pulleys.
- Return pulley, tail pulley: used to redirect the conveyor belt towards the drive pulley. Conveyor tail pulleys can have an internal calf bearing or can be mounted in an external bearing and are usually located at the end of the conveyor bed. Conveyor tail pulleys typically serve the purpose of a take-off pulley to keep tension on the conveyor.
- Free pulley: Any freely rotating pulley used in the non-drive position used to support the belt.
- Tension Pulley: A conveyor pulley used to increase tension wraps a conveyor belt around a drive pulley, usually for the purpose of improving conveyor traction.
- Adjustable Pulley: A conveyor pulley can be adjusted in the rack to increase or decrease conveyor slack or conveyor tension.
- Bend Pulley: A conveyor pulley is used to redirect conveyor belts and provide conveyor tension where bends occur in the conveyor system.
A conveyor will always consist of at least two pulleys, the head pulley and the tail pulley, with additional pulleys used depending on the configuration. Standard pulleys are generally suitable for simple applications, but custom made pulleys work in mines and where heavy duty pulleys are required.