Flat Drive Belts

What are flat drive belts?

Flat drive belts are thin, flat belts that transmit power between flat or slightly crowned pulleys. Instead of wedging into a groove like a V-belt, a flat belt grips the pulley face by friction across its full width. Modern flat drive belts are made from high-performance rubber with strong reinforcing cores, which makes them light, flexible, and able to run smoothly and quietly at high speeds.

A standard flat drive belt has these main features:

• A thin, flat profile, often around 1mm thick
• A high-performance rubber, such as polychloroprene, which gives a high-friction grip on the pulleys
• Nylon-reinforced cores, which give the belt high strength and stop it stretching
• An endless construction, made as a continuous loop with no joint.

Flat belts are thin, light, and flexible.

• Their low profile lets them bend easily around small pulleys and run at high speeds with very little vibration or noise.
• The reinforced core keeps the belt the same length in use, so it holds its tension and drives accurately.

Flat drive belts are sized by their length, width, and thickness.

Why are flat drive belts essential?

Flat drive belts are the ideal choice where a drive needs to be smooth, quiet, and efficient, especially at high speed or with small pulleys. Because the belt is thin and light, it wastes very little energy bending around the pulleys and puts less load on the bearings. Its full-width grip spreads the load evenly, and the endless construction avoids the bumps and weak points of a joined belt.

They also need very little maintenance once fitted, as the reinforced core resists stretching, and the constant thickness and high-friction rubber give a reliable grip over a long service life.

Typical applications include:

• Textile and spinning machinery
• Machine tools and spindle drives
• Conveying and transfer equipment
• Light industrial machinery
• Domestic appliances, such as vacuum cleaners and sewing machines
• Office equipment, printers, and paper handling machines
• Record players, tape drives, and audio equipment
• Small fans, pumps, and hobby machinery

The main types of flat drive belts

• Endless reinforced rubber flat belts - Continuous loops of high-performance rubber with nylon reinforced cores. They are strong, flexible, and quiet, and suit a wide range of light and general drives.
• Narrow flat belts - Flat belts in narrow widths, such as 10mm or 15mm, for small pulleys, appliances, and light-duty drives.
• Wide flat belts - Wider flat belts, such as 30mm or 40mm, for greater power or larger pulleys, such as on machine tools and conveyors.
• Long and short length belts - Flat belts are made in a wide range of lengths, from short belts of a few hundred millimetres for compact drives up to long belts of more than two metres.

How to choose the right flat drive belt?

• Width - Choose a belt width that suits the pulley face and the power needed. Wider belts carry more power.
• Length - Match the length of the original belt, or work it out from the pulley sizes and distance between centres. Endless belts cannot be cut to length, so the correct size is important.
• Thickness - Choose the same thickness as the original belt, as this affects how well it bends around small pulleys and how it tensions.
• Speed and pulley size - For high speeds and small pulleys, choose a thin, flexible belt that bends easily without wasting energy.
• Conditions - Check the belt suits the operating conditions, such as oil, heat, or dust, as these can affect the rubber.

Essential references and specialised ranges

How the numbering works:

Flat drive belts are usually referenced by their dimensions, in mm:

Length x width x thickness

For example, a 1140 x 40 x 1 flat belt is 1140mm long, 40mm wide, and 1mm thick.

A 510 x 15 x 1 flat belt is 510mm long, 15mm wide, and 1mm thick.

Some references put the width or length first, so always check which figure is which before ordering.

Suffixes:

FB = flat belt

Suffix codes vary between manufacturers, so check the supplier’s catalogue for the exact meaning.

FAQ - All you need to know about flat drive belts

What is the difference between a flat belt and a V-belt?

A flat belt grips the face of a flat pulley by friction across its width. A V-belt wedges into a V-shaped groove. Flat belts are thinner and more flexible, so they run more quietly and efficiently at high speeds and around small pulleys, while V-belts suit higher loads on compact drives.

What does endless mean?

An endless belt is made as a continuous loop, with no joint. This gives a smooth, even running surface with no weak point, which makes it quieter and more reliable than a belt that has been cut and joined.

How do I measure a flat drive belt?

Measure the width and thickness with callipers. For the length, lay the belt flat and measure around it, or measure the outside circumference with a tape. If the belt has stretched or broken, work out the length from the pulley sizes and centre distance.

How tight should a flat belt be?

The belt should be just tight enough to drive without slipping. Because reinforced flat belts do not stretch much, they need less tension than older belts, and over-tightening can put extra load on the bearings.

How do I fit a flat drive belt?

Loosen the motor or tensioner so the belt can be fitted without stretching or levering it. Fit the belt centrally on the pulleys, check they are aligned, then tension the belt and turn the drive by hand to make sure it runs straight.

How do I identify the belt I need?

Check the size on the old belt or in the machine’s manual. If it cannot be read, measure the width and thickness of the old belt, and measure or work out the length.

How can I tell if a flat drive belt needs replacing?

Warning signs include:

• The belt slipping or squealing under load
• Cracks, splits, or frayed edges
• A glazed, shiny surface that has lost its grip
• The belt running off the side of the pulleys
• Stretching that stops the belt from tensioning correctly
• Exposed or damaged reinforcing cords