V-belt

What is a smooth V-belt ?

A smooth V-belt is a power transmission element used in many mechanical systems. It is made from a synthetic rubber, polybutadiene, and has a V-shaped trapezoidal cross-section. This shape enables the belt to fit into the corresponding groove on the pulley.

The advantage of using a smooth V-belt is that it offers durable, low-maintenance and quiet power transmission. It is also efficient for applications requiring high efficiency. What's more, smooth V-belts are relatively easy to install. It is known for its excellent resistance to oil and heat, and requires no lubrication.

Where and when are they used?

Smooth V-belts are used in many fields and applications where power transmission is required. Here are just a few examples of where smooth V-belts are commonly used:

• Industrial machines: they transmit power between different components such as electric motors, pumps, compressors, fans, conveyors, etc.
• Household appliances: smooth V-belts are also used in household appliances such as washing machines, tumble dryers and lawnmowers to drive drums, blades, etc.
• Agricultural equipment: smooth V-belts are used in agricultural equipment such as combines, tractors, balers and sprayers to transmit power to the various components.
• Machine tools: in the manufacturing industry, smooth V-belts are used in machine tools to drive spindles, work tables, cutting tools and so on.

What are the different types of smooth V-belts?

V-belts are designed for flexibility, easy installation and maintenance. They enable efficient transmission and are suitable for many applications thanks to their wide range of sizes. Below is a non-exhaustive list of smooth V-belt sections:

Z: Z smooth V-belts have a cross-section of 10 mm wide by 6 mm high.
A: A smooth V-belts have a cross-section 13 mm wide by 8 mm high.
B: Smooth V-belts B have a cross-section 17 mm wide by 11 mm high.
C: C smooth V-belts have a cross-section 22 mm wide by 14 mm high.
SPZ: SPZ smooth V-belts have a cross-section of 9.7 mm wide by 8 mm high.
SPA: SPA smooth V-belts have a cross-section 12.7 mm wide by 10 mm high.
SPB: SPB smooth V-belts have a cross-section 16.3 mm wide by 13 mm high.
SPC: SPC smooth V-belts have a cross-section 22 mm wide by 18 mm high.
3V: 9 mm wide by 8 mm high.
5V: 15 mm wide by 13 mm high.
8V: 25 mm wide by 23 mm high.
3L: 3L smooth V-belts have a cross-section of 9.5 mm wide by 6 mm high.
4L: 4L smooth V-belts have a cross-section of 12.7 mm wide by 9 mm high.
5L: 5L smooth V-belts have a cross-section of 15.8 mm wide by 9.5 mm high.

How to choose a smooth V-belt?

When looking for a smooth V-belt, we always recommend using the same belt as the original. To do this, you'll need to know its reference number and/or dimensions. The part number is usually written on the belt, if it's not too damaged. If not, you'll need to determine the type of belt you need. Is it a trapezoidal belt? Is it smooth or toothed? Once you have the answers to these questions, you'll need to determine the desired cross-section (height x width), as well as its inside or outside length.

Understanding Belt Lengths

Lo (or Bo): Outside Length This is the circumference measured on the outside surface of the belt (its "back"). It's a simple physical measurement, often used when outside clearance is a critical factor.

Li: Inside Length This is the circumference measured on the inside surface of the belt. It's the easiest measurement to take on a disassembled belt and is very commonly used for identification.

Le: Effective Length This is the length measured along the neutral axis of the belt. The neutral axis is the part of the belt that doesn't undergo compression or stretching as it wraps around a pulley. This measurement is crucial for ensuring a perfect fit and efficiency under load.

Ld: Datum Length This is a standardized measurement used primarily for V-belts. It's very close to the effective length and serves as a reliable reference to compare different belts and ensure their compatibility with pulleys. Note: For V-belts, Datum Length (Ld) and Pitch Length (Lp) are often interchangeable terms.

Lp: Pitch Length This measurement is fundamental for toothed (synchronous) belts. It corresponds to the length of an imaginary line that passes through the center of the belt's reinforcements (the "pitch line"). It's this length that ensures the belt's teeth mesh perfectly with the pulley's teeth.

Lw: Working Length This is the length of the belt when it's under its operating tension. This measurement accounts for the stretching or deformation that occurs when the belt is in service. It ensures that the tension and alignment remain correct during use.

In Summary

• Easy Measurement: Li (Inside) and Lo (Outside). Perfect for quick on-site identification.

• Manufacturer's Reference: Ld / Lp (Datum / Pitch). This is the most reliable measurement for ordering the correct part and ensuring compatibility.

• Theoretical Measurement for Performance: Le (Effective) and Lw (Working). Important for system design.

Matched Belts

Some machines use several belts in parallel, which is called a "matched belts" setup. For these applications, it's crucial that all belts have a strictly identical length. For this type of setup, "generic" brand belts are not suitable, as you risk receiving products from different manufacturers, which could lead to small variations in length. In this case, only the shortest belt will work, wear out very quickly, and break, making the installation ineffective.

If you're in an urgent situation, stick to one single brand to ensure manufacturing consistency, such as with Optibelt belts, for example. If waiting for a delivery time doesn't bother you, contact us. We can place a special order with the supplier to get belts from the same manufacturing batch, ensuring they are perfectly identical.

Find your smooth V-belt on 123Bearing

At 123Bearing, we have a wide range of belts in different cross-sections and lengths to suit your different applications. Our smooth V-belts are shipped worldwide. Thanks to our extensive stocks, we can offer you rapid delivery. You'll find a multitude of belts and other quality products available in different brands. Don't wait any longer and buy now the reference you need at the best price.