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Pulleys : The different types and how they work

🔗 Mechanical transmission

Date of publication : 20/11/2023

Reading time : 3 Minutes


Discover our trapezoidal and synchronous pulleys : from simple to complex, explore the types and how they work.

What are the different types of pulleys ?

A pulley plays an essential mechanical role by ensuring the transmission of power and motion between two shafts via a belt. This is usually a wheel with a V-shaped groove, a flat or grooved surface on which the belt can sit and move.

Used in many industrial, mechanical and transportation applications, the pulley helps increase input force and move heavier loads with less effort. Additionally, it is often used to control the rotational speed of the output relative to the input.

For efficient and reliable transmission, it is important to choose the ideal pulley for your belt and application. There is a wide range of pulleys available to suit your needs.

Trapezoidal pulleys

trapezoidal pulleys are used in conjunction with a corresponding V-belt to transmit mechanical rotational force to a shaft. V-shaped grooves in the V-pulley prevent slipping and movement and provide maximum friction and torque in the drive system. They are found in many rotating mechanical devices such as fans, pumps, air compressors and conveyors.

Synchronous pulleys

synchronous pulleys are used when motors use gears. This type of pulley is often used in car engines, steering wheels and power tools. Synchronous belt drive systems typically require one or more flanged pulleys (synchronous pulleys) to prevent belt separation and resist lateral forces caused by lateral movement of the belt. We also offer a machining service that allows you to drill and machine tools to your specifications and requirements.

How to choose a trapezoidal pulley?

There are two types of trapezoidal pulleys: Firstly, there are trapezoidal pulleys with removable hubs, which allow quick assembly and disassembly, thus facilitating the installation and maintenance of the pulley.

Another type of pulley is the trapezoidal pulley, which allows them to be mounted on any type of shaft, allowing greater flexibility and easy customization in the selection of the shaft. Note that V-belt pulleys need to be cut to the required shaft diameter, this will cost more. The pulleys offered on our site are made of high quality cast iron. This type of trapezoidal pulley is used in agriculture and industry.

To choose a trapezoidal pulley, it is mandatory to know the section of your pulley as well as its number of grooves.

What are the different sections of trapezoidal pulleys?

The pulley can consist of one or more grooves, depending on the different models. The purpose of a grooved pulley is to allow the transmission of motion when attached to the belt. If a pulley has a groove, it can be used to move a load in a certain direction.

There are various shapes of trapezoidal pulleys, such as SPZ (10x8mm), SPA (13x11mm), SPB (17x11mm) and SPC (22x18mm). However, be sure to choose the one that suits your belt. It is imperative to know the size and number of grooves of the trapezoidal pulley to select it.

We remind you that the belt to be installed or already installed must have the same section as the pulley selected.

For example: if you have an “A52” belt, then you must choose the SPA, A, XPA pulley.

How to select a trapezoidal pulley from ITAFRAN?

Once you have selected the category and number of slots, it is essential to know the outer diameter (or initial diameter: this is the diameter of the pulley at the original width of the groove - the diameter at middle of the belt on the pulley).  

The outer diameter you choose determines the operating speed. Verify that the outside diameter meets your operating speed requirements.

Here is a diagram showing how to filter your searches on to find the pulley that meets your needs.

What is a toothed pulley?

A toothed pulley is a pulley whose contact surface with the belt consists of teeth. These teeth fit with the teeth of the belt to ensure more precise and efficient transmission of movement than with a conventional pulley.

Toothed pulleys are used in applications where precise, slip-free motion transmission is required, such as in machine tools, conveyors or lifting systems.

How to choose a synchronous pulley?

The choice of a synchronous pulley depends on several factors, including:

Tooth type: There are different tooth profiles, such as trapezoid-shaped teeth (T profile), rounded teeth (HTD profile), or half-moon-shaped teeth (GT profile). The choice depends on the specific application requirements, such as load, speed and torque.

Pulley size: The size of the pulley, measured in number of teeth, influences the rotation speed and torque. It is important to choose a size suitable for the mechanical configuration to avoid premature wear and ensure efficient power transmission.

Pulley material: Toothed pulleys are made of different materials such as aluminum, steel or plastic. The choice depends on environmental conditions, load and required durability.

Transmission accuracy: Some systems require very precise transmission of movement. In this case, it may be necessary to choose pulleys with finer teeth to ensure precise timing.

Type of associated belt: Toothed pulleys are often used with synchronous belts. It is important to choose a belt compatible with the selected pulley in terms of tooth pitch and profile.

ITAFRAN: Sale of pulleys in France

Good news, all the elements necessary for choosing a pulley are available. We invite you to visit “Pulleys and belts , order those who correspond best to your needs.

Do you have doubts ? Would you like to speak to a technician? It's possible! Our salespeople are ready to guide you in your choice.

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