A Keilriemen is a power transmission belt with a trapezoidal cross-section that transfers mechanical power from a motor or drive to a driven machine through pulleys. Typically made from rubber compounds reinforced with fibre and Polyester or aramid cords, V-belts are designed to fit into pulley grooves, combining flexibility, strength and reliable power transmission.

A Keilriemen transmits mechanical power between pulleys through friction. Its trapezoidal cross-section fits into the matching groove of a pulley, creating a wedging action between the belt sidewalls and the pulley groove that provides frictional engagement and enables power transmission.

As the driving pulley rotates, friction between the belt and pulley transfers the driving force to the belt and then to the driven pulley. This design allows V-belts to transmit power reliably while accommodating shock loads and vibration.

Proper belt tension is essential for performance and service life. Insufficient tension can cause slippage and reduced power transmission, while excessive tension can increase loads on bearings, shafts and other drive components, potentially leading to premature wear.

Want to learn more? Explore “Everything You Need to Know About V-belts”.

V belts are widely used across a broad range of industries and equipment. Common applications of V-belts include:

• Manufacturing and industrial machinery: pumps, fans, compressors, lathes and mills, industrial grinding and washing machines.
• Agricultural equipment: tractors, combines, balers, sprayers and grain augers.
• Commercial and household appliances: washing machines and dryers, orange squeezer, coffee machines.
• Automotive systems: alternators, power steering systems, A/C compressors and water pumps.
• Mining and heavy equipment: crushers, drilling rigs and loaders.
• Lawn, garden and outdoor power equipment: mowers, snow blowers, tillers and compact utility equipment.

V-belts are available in different sections, constructions and materials, allowing them to be selected for different load requirements, speeds, operating temperatures and environmental conditions.

See V-belts in action! Explore real-world applications in our “MEGAV” videos.

The main difference between a Keilriemen und eine timing belt, also known as synchronous belt, is how power is transmitted between the belt and pulley.

• Keilriemen transmit power through frictionbetween the belt and pulley.
• Zahnriemen transmit power through positive engagement between belt teeth and matching pulley grooves.

V-belts vs timing belts: which one should you choose? The choice depends on your application’s requirements.

• Choose a V-belt for general power transmission applications.
• Choose a timing belt when precise timing, accurate positioning, synchronised shaft movement and higher energy efficiency is required.

Other factors, including power requirements, operating speed, load conditions, noise, maintenance and installation constraints, should also be considered when selecting a belt drive.

For a more detailed comparison, see “Synchronous belts Vs V-belts”

The main difference between wrapped and raw-edge V-belts is their construction and operating characteristics.

• Ummantelte Keilriemen have a protective fabric cover that helps resist wear, contamination and oil exposure. They are commonly used in general industrial applications requiring reliable, smooth operation.
• Raw-edge V-belts have exposed rubber sidewalls and often feature a cogged profile that can improve flexibility. This design makes raw-edge V-belts well suited to smaller pulleys and many higher-speed applications.

Expert tip: Wrapped V-belts are typically selected for durability and environmental resistance, while raw-edge V-belts are often chosen where flexibility is important. The most suitable option depends on the application’s power requirements, pulley sizes and operating conditions.

The letters Z, A, B, C, D and E identify a V-belt’s cross-sectional size, including its width and height. These standardised section codes help ensure the belt matches the correct pulley groove and transmits the required power.

Common classical V-belt sections:

In addition to classical sections, V-belts are also available in narrow wedge profiles (SPZ, SPA, SPB, SPC, 3V, 5V, 8V), raw-edge cogged profiles (AX, BX, CX, XPZ, XPA, XPB, XPC, 3VX, 5VX) and other specialised constructions for specific applications.

What does the number after the letter mean? A V-belt designation typically combines a section letter and a length measurement, such as A40 or B92.

• Das letter identifies the belt section (cross-sectional size).
• Das number identifies the belt length. The exact length reference may vary depending on the belt standard and profile.

Expert tip: When replacing a V-belt, always match both the section und die length. Using the wrong belt profile can reduce performance, accelerate wear and lead to premature belt failure.

Learn more on “How to Identify a V-belt”.

Choosing the right V-belt depends on your drive’s power requirements, available space and operating conditions. The correct belt type should match the application’s load, speed, pulley sizes and environmental conditions.

Before selecting a V-belt, identify:

• Power requirement (HP or kW) – How much power must the belt transfer?
• Operating speed (RPM) – Is your system running at low, moderate, or high speeds?
• Pulley Size – Smaller pulley requires more flexible belts
• Centre distance between pulleys
• Operating environment (temperature, dust, moisture and contaminants)
• Belt dimensions and length – Check existing belt label, most belts have type and length printed.

These factors help determine whether a raw-edge, wrapped oder banded V-belt is the most suitable option for your drive.

Expert tip: Always follow the equipment manufacturer’s recommendations and ensure the belt profile matches the pulley groove. Correct belt selection helps maximise performance, reliability and service life.

To identify the correct replacement V-belt, measure the belt’s top width, height, inner circumference and outer circumference. Then use a V-belt measurement chart to determine the correct belt length and section. Check any markings on the old belt, as this information is often printed directly on the belt.

After determining the correct size, confirm it against a standard V-belt size chart. Ensure the replacement belt also matches the pulley groove profile and minimum pulley diameter requirements to help prevent slippage and premature wear.

Expert tip: Avoid stretching the belt during measurement. A worn belt can elongate by 1% to 2%, so cross-reference the measurement with the pulley centre distance whenever possible.

Check our video to see how to properly install a V-belt.

Yes, in almost all standard cases. V-belt sections are defined by international standards. You can replace a V-belt with an equivalent from another manufacturer, such as Megadyne, as long as the cross-section profile, length, and construction type match.

EPDM (Ethylene Propylene Diene Monomer) raw-edge cogged V-belts are commonly used in high-temperature applications thanks to their excellent heat resistance, flexibility and durability. Depending on the belt design, EPDM V-belts can operate at temperatures of up to 130°C (266°F). Always verify the temperature rating of the specific belt before selection.

Expert tip: Explore Megadyne EPDM raw-edge cogged V-belt range to compare available profiles, specifications and operating capabilities for your application.

With the right tension, alignment and operating conditions, a quality V-belt should run thousands of hours. A V-belt that fails prematurely is often a sign of an underlying drive system issue rather than a defect in the belt itself. Common causes include:

• Incorrect belt tension or installation
• Pulley misalignment
• Worn or damaged pulleys
• Incorrect belt size or profile
• Oil or chemical contamination
• Excessive heat caused by belt slippage
• Storage damage.
• Belt retention

Expert tip: Before replacing a failed V-belt, inspect the pulleys, alignment and belt tension. Correcting the root cause can help improve belt life and prevent repeat failures

A V-belt slips when it cannot maintain sufficient grip on the pulley to transmit the required torque. Slippage may be accompanied by squealing noise, but not always. Common signs include excessive heat, glazed belt surfaces, reduced equipment speed and belt dust accumulation on the pulleys.

Common causes of V-belt slippage include:

• Incorrect belt tension
• Worn or damaged pulleys
• Excessive load on the drive
• Insufficient pulley contact area
• Oil or chemical contamination

Expert tip: If a V-belt is slipping, inspect the entire drive system rather than simply replacing the belt. Correcting the root cause can help improve performance, reliability and belt life.

Uneven wear on one side of a V-belt is typically caused by a condition that prevents the belt from running correctly in the sheave groove.

Common causes include:

• Pulleys misalignment: The most common cause. If the pulleys are not parallel and properly aligned, the belt enters the groove at an angle, causing one sidewall to wear faster than the other.
• Bent shafts or worn bearings: Excessive shaft movement can cause the sheave to wobble, creating dynamic misalignment during operation.
• Incorrect belt section: A belt that is too narrow for the sheave groove may sit unevenly, leading to accelerated wear on one side.
• Lack of regular inspection: small issues can become major failures if not detected early.

Expert tip: Proper belt tension and sheave alignment are essential for maximising belt life. Insufficient tension can cause slippage, overheating and excessive wear, while excessive tension can overload bearings, shafts and sheaves. V-belts should ride on the sidewalls of the sheave, not on the bottom of the groove.

How do I tension a V-belt properly? Check our video Schnitt.

V-belt squealing is usually a sign that the belt is slipping against the sheave groove walls, causing a high-pitched noise. While the noise itself is easy to identify, it is typically a symptom of an underlying drive system issue rather than the root cause.

Common causes include:

• Insufficient belt tension
• Worn pulley grooves
• Oil or grease contamination
• Excessive load on the drive

Expert tip: If a V-belt begins to squeal, inspect the entire drive system rather than simply replacing the belt. Correct belt tension, properly maintained sheaves and a clean operating environment can help reduce slippage and extend belt life

A V-belt typically comes off the pulley due to pulley misalignment, incorrect belt tension, worn pulley grooves, contamination, damaged bearings or loose mounting components.

Expert tip: When replacing a V-belt, inspect the pulleys as well. A new belt installed on a worn pulley can wear prematurely, while a worn belt can accelerate wear on a new pulley.

To help maximise drive performance and service life, explore our metal drive components portfolio, including pulleys and other drive system components designed to work together with Megadyne belts.

V-belt overheating is usually caused by excessive friction or operating conditions that prevent heat from dissipating effectively. If left unresolved, overheating can reduce belt life and affect overall drive performance.

Common causes include:

• Insufficient airflow: Poor ventilation around the drive can increase operating temperatures.
• Improper pulley alignment: Misaligned pulleys create additional friction and heat.
• Belt wear or slippage: A worn or slipping belt generates excess heat and reduces transmission efficiency.
• Incorrect belt tension: Both insufficient and excessive tension can increase operating temperatures and accelerate wear.
• Contamination: Oil, grease or debris can affect belt performance and contribute to overheating.

Expert tip: Regular inspection of belt tension, pulley alignment, ventilation and pulley condition can help prevent overheating and extend the service life of both the belt and the drive system.

The service life of a V-belt depends on the application and operating conditions. In practice, a V-belt may last from several months to several years, depending on factors such as:

• Operating hours
• Belt material and construction
• Working temperature
• Verunreinigungen
• Load conditions
• Installation accuracy
• Maintenance practices

A V-belt operating under excessive load, incorrect tension or poor alignment will typically have a shorter service life than a belt running under stable operating conditions with proper installation and maintenance.

Expert tip: There is no universal replacement interval for V-belts. Regular inspection and preventive maintenance are the best ways to maximise belt life and drive reliability. If you need support selecting or maintaining the right belt for your application, watch Megadyne’s video on V-belt oder Kontaktieren Sie unsere Experten.

Yes, V-belts have a shelf life. When stored under appropriate conditions, they can typically remain serviceable for 4 to 5 years. Over time, the rubber compounds and reinforcing materials may degrade, which can reduce belt performance and service life.

Proper storage can help preserve their condition and performance over time. Store V-belts in a cool, dry environment away from direct sunlight, chemicals and ozone-generating equipment. Improper storage can accelerate rubber deterioration and reduce belt life.

Expert tip: Avoid bending belts sharply or hanging them on small hooks, which can damage their structure.

You know a V-belt needs replacing when you see visible cracks, frayed edges, or hear a loud squealing noise from the drive system.