The Basics of V Belts


  • To increase or reduce speed
  • To increase or reduce torque
  • To transfer power from one shaft to another


Understanding the prefix of any v belt part number is important. The prefix offers dimensional standards, and somewhat defines the purpose of the v belt. This knowledge allows you to understand which v belts can be substituted, and which cannot.

2L, 3L, 4L, and 5L prefix – The “L” stands for light duty, and is designed for use with fractional horsepower motors. Meaning less than 1 HP. “L” style v belts are often designated as light duty industrial, or lawn & garden.

A, B, C, D, E, And AX, BX, CX, and DX size v belts are more industrial. They’re sometimes referred to as “Conventional” v belts. The “X” is a standard specification for inside perforations also known as notched or cogged v belts. Although “Conventional” v belts can be substituted for “L” style v belts which appear to be the same, “L” style v belts should never be used as replacements for “Conventional” v belts.

My experience with “X” designation v belts is that they last longer than those without it. Meaning a “BX” belts last longer than a “B” Belt. Especially in cases where one or more of the pulleys are small in diameter. Smaller diameter pulleys offer less stress on “X” style v belts due to the notched under-bottom.

3V, 5V, 8V, AVX, BVX, CVX, DVX – IMPORTANT: Don’t Confuse “V” In The Part Number Prefix! I run this warning because common sense would lead you to believe a 3V belt is a comparable substitute for a 3L, or that an AVX v belt is a suitable substitute for an AX v belt. Common sense would be wrong. The “V” designation in the prefix is a difference in the profile of the v belt. Never substitute or mix these v belts. They do not fit properly into pulleys designed for 3L and AX v belts. They do not make full contact against the bottom and walls, and therefore will fail to perform.

This article comes from micrometl edit released

How Do Conveyor Belts Work?

A conveyor belt works by using two motorized pulleys that loop over a long stretch of thick, durable material. When motors in the pulleys operate at the same speed and spin in the same direction, the belt moves between the two.

If objects are particularly heavy or bulky — or if the conveyor belt is carrying them for a long distance or duration — rollers may be placed on the sides of the conveyor belt for support.

Parts of the Conveyor Belt System
While there are numerous types of conveyor systems, all serve the same purpose of transporting materials. Some products may require a system without a belt, using only rollers or wheels for flexible movement. However, many conveyor systems rely on a frame with a belt and possible support rollers to carry materials and products efficiently.

All conveyor systems have three main components — the aluminum profile, the driving unit and the extremity unit.

In a conveyor belt system, the aluminum profile consists of the frame, belt and any supports. Systems that use a belt are generally powered by a motor, though conveyor systems can also use gravity or manual force to function. Motorized conveyor belts are ideal for industrial use as they are more reliable and efficient — the driving unit for such systems would include the motor bracket, electrical drive and any counter bearings.

This article comes from semcor edit released

What is the example of transmission belt?

Just like conveyor belts, the origins and history of power transmission belts are lost in the mists of time. While we believe that the Babylonians and Assyrians used chains and cups for water-drawing machines, the earliest mention of a mechanical belt drive with a pulley machine is in a Chinese text from 15 BCE. This describes how it was set up to wind silk fibers onto bobbins for weavers’ shuttles. About a thousand years later, when the first reported mechanized spinning wheel was documented, again in China, it relied on a belt drive. I find this fascinating – because the textile industry is still home to numerous applications for power transmission belts today.

The belt drive has also been used in many other applications. We know that flat belts were frequently employed in the 19th and 20th centuries for power transmission in factories, as well as for logging, mining and farming applications, such as sawmills, conveyors and pumps.

Simple and efficient

Belts and pulleys offer the simplest and most efficient way to transmit power between shafts. Even today’s advanced computer-controlled machines rely on this attractive and proven solution.

Power transmission belts run smoothly and quietly, helping to protect machinery from overload and jamming, and shielding motors and bearings against load fluctuations. They need minimal maintenance, and are highly efficient (up to 98%).

Wide belts and large pulleys can deliver high power at high speeds – although these take up a considerable amount of space. This is why V-belts were later introduced, which are frequently used today for short-distance power transmission. On the other hand, V-belts are not as energy-efficient as flat power transmission belts and timing belts.

From leather to hemp to polyamide

As you’d expect, the materials used for power transmission belts have changed over the years. While in the past, flat belts were usually made of leather, in the mid-19th century they also used ropes made of cotton, hemp, flax, or even wire.

But power transmission with leather belts remained a popular solution for centuries. Even at the beginning of the 20th century, leather belts were the state-of-the art solution for efficient power transmission. You can see this in pictures that show, for example, a workshop with a main driving shaft on the ceiling, with milling machines, lathes, drilling machines and other equipment running off it, all driven by leather belts.

Multiple applications

Power transmission belts have found many new and important uses today. And while they continue to play a leading role in modern machine design, they are less visible than in the past, as in many cases they are protected by the machine frame and perform their task ‘under cover.’ The following examples illustrate the capabilities of this outstanding machine element in different industries:

Textile industry

In the textile industry, power transmission belts and spindle tapes (a specially designed power transmission belt to drive a group of four spindles) are employed in yarn manufacturing and processing, e.g. on spinning machines. The fashion industry and manufacturers of technical fabrics demand high- and consistent yarn quality at the best possible price. The performance of the power transmission belt is crucial to meeting these expectations, so that the final customer (in other words: you) can benefit from a durable shirt that keeps its shape over its entire lifetime. What’s more, using the right belt type contributes to savings on energy and operational costs.

This article comes from habasit edit released

Fan Belt? Alternator Belt? Serpentine Belt? Similarities

Look up “fan belt” in any modern automotive dictionary, and you’ll typically find a definition that reads, “An endless belt used to transmit power from a crankshaft-driven pulley to a pulley driving the fan, alternator, or other engine accessory. It is usually V-shaped in cross section with the point of the V fitting into a groove in the pulley”.

Even though cooling fans on most modern vehicles are driven by electric motors instead of actual belts, the term fan belt is still incorrectly used as a blanket expression to describe any single accessory belt that may be used to drive a water pump, alternator, power steering pump, or other items. Why?

In order to pull cooling air through a vehicle’s radiator, a cooling fan needs to be located at the front of the vehicle just behind the radiator. Traditional rear-wheel-drive vehicles with longitudinally-mounted engines had crankshaft pulleys right there at the front of the car, and they were convenient sources of power for cooling fans.

Since the fan belt tended to be the biggest and most noticeable one on the vehicle, the expression became universal for all other belts that looked similar – no matter what function they performed. Many original engine layouts also used that fan belt to spin water pump and alternator pulleys, and you may hear some people call this belt a “water pump belt” or “alternator belt” as well as a fan belt.

However, as vehicles with front-wheel-drive and sideways-mounted engines grew in popularity, the front of the engine was no longer at the front of the vehicle where the cooling fan was.

Engineers perfected electric fan motors, temperature sensors, and related computers to get the job done, and belt-driven fans were no longer necessary. Because cooling fans don’t always need to be running at steady cruising speeds, electric motors which can shut off proved more energy efficient than direct drive belts which are always connected. Since electric cooling fans are used even in modern vehicles with longitudinally-mounted engines, the term fan belt has become virtually obsolete. More fitting terms to use when searching for a replacement single belt of this kind would be accessory drive belt or V-belt.

Because drive belts are subject to constant rotation, load, and heat, they are constructed in a similar fashion as tires. An outer layer of rubber surrounds internal steel and cord reinforcements to minimize stretching and maximize strength when grip is needed under load.

This article comes from carid edit released

Timing Belt Safety Tips

We’re hoping you’re taking your car to a shop for timing belt service, but even if you’re just looking around under the hood, you need to be safe about it.

Don’t start grabbing random parts under the hood, especially if you’ve just finished driving it. Engines and engine components can get extremely hot.

Don’t wear loose-fitting clothing or dangling jewelry when working under a hood. Not only can you damage your trinkets, getting caught in a spinning belt or gear can cause some nasty injuries.

It’s a good idea to wear gloves and eye protection, especially when working on older cars. You never know when something will break and send shrapnel flying.

This article comes from thedrive edit released

When to use a cogged v belt?

However, cogged v belts may be a better choice when vibration damping is needed or shock loads cause abrupt torque changes that could shear a synchronous belt’s teeth. Synchronous belts also make a whirring noise that might be objectionable in some applications.

Are notched V-belts better?

Notched belts can use the same pulleys as cross-section standard V-belts. They run cooler, last longer, and are about 2% more efficient than standard V-belts. In contrast, V-belts have a sharp reduction in efficiency at high torque due to increased slippage.

Why should you use a narrow cogged v belt instead of a classical V-belt in a new installation?

Why should you use a narrow cogged v belt instead of a Classical V-belt in a new installation? They can handle more power, they use smaller diameter sheaves, and are more economical than a classical V-belt.

Where would a cogged v belt be used?

Cogged v belts are used widely in mechanical devices, including sewing machines, photocopiers and many others. A major use of cogged v belts is as the timing belt used to drive the camshafts within an automobile or motorcycle engine.

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How to Tension a V Belt (& How Not to)

A v belt’s purpose is to transmit energy between two components. What makes a v belt pulley stand out from other types of pulleys, such as a round belt or flat pulley, are the V-shaped grooves of the pulley; these grooves guide the belt and allow it to gain traction.

The number one cause of a power transmission belt failure is improper tensioning. In order to ensure a long and efficient belt operation, you must properly learn how to tension a v belt regularly.

If they are too loose, there is slippage, rapid belt or sheave wear and, ultimately, loss of both energy and productivity. Conversely, if there is too much tension, the excess strain on the belts, bearings and shafts causes premature wear of these components. The proper tension is the lowest tension at which the belt won’t slip or squeal under peak load. However, there is still a wide range of tension between these two extremes in which a drive will operate sufficiently. The primary goal of learning how to tension a v belt is to find this happy tension medium.

Important Note: Never apply belt dressing, as this will damage the belt and cause early failure. Always keep the drive free of foreign material which might cause slippage or damage to the belt and sheave surfaces.

This article comes from ibtinc edit released

V Belts Selection Guide: Types, Features, Applications


Three common designs of v belts include:

Fabric ply belts consist of several plies or layers that are made of cotton or synthetic fiber, with or without rubber impregnation. The number of plies determines the belt thickness that will help determine the minimum pulley diameter for the drive.

Fabric cord belts are constructed with multiple cords made from cotton or synthetic fibers such as rayon, nylon, plastic, or Kevlar. They are incased in rubber and covered with a fabric/runner covering. This type is generally classed as a heavy-duty v belt, used for high speeds, small pulley diameters, and shock loads. Steel cables can also be used as they have higher capacity and lower stretch than fabric cord v belts.

Synthetic v belts are made from nylon. Nylon offers flexibility, extremely high tensile strength, and operates effectively at high rim speeds. The belts are thin and they may consist of several plies of thin nylon bonded together to form a tough but flexible v belt.


Specifications that are important to consider include: belt type, belt width, and initial elongation. If any of these factors change, the belt must be recalculated.

Power transmission belt material types include polyester, aramide, and polyamide.

Polyester is the most common material due to it price-to-value ratio. It supplies a versatile belt that can be used in a wide range of operating temperatures with low energy consumption, high flexibility, and reliable performance.

Aramide is a strong choice for long belts due to the short take-up and high accuracy for number of revolutions (RPM) and belt speed. It is highly flexible, simple to join, has a high E-modulus, and low energy consumption.

Polyamide is reliable and has a long service life. It can work in a variety of conditions and functions well in extreme environments with intermittent overload and high temperatures. Polyamide is shock resistant and grooves enable high grip.

Belt width is simply the width of the belt. The tensile force for 1% elongation per unit of width after running-in (N/mm), k1% a.r.i., is the decisive value for calculating the required belt width and the resulting shaft load after belt relaxation


The power transmission v belt can be used in many forms of power transmission. It is known as a two pulley drive, consisting of a driving pulley, a driven pulley, and the belt. Below are examples of pulley design variations.

This article comes from globalspec edit released