ConCar Variable Speed Belts 70x18 - 2500 Li

ConCar Variable Speed Belts 70x18 – 2,500 mm inner length – DIN 7719 / ISO 1604

This ConCar Variable Speed Belts with a 70x18 profile and an inner length of 2,500 mm, is a toothed variator belt conforming to DIN 7719 and ISO 1604. Variable Speed Belts are the mechanical alternative to frequency converters: they regulate the output speed purely through geometry, without electronics, harmonics, or an additional heat source in the control cabinet. In many woodworking, textile, and agricultural machines, this remains the more robust solution because it operates reliably even in dusty, humid, and vibration-prone environments.

This length in the drive

The inner length of 2,500 mm is a long version for the 70x18 profile and is intended for drives with a large center distance, approximately 505 mm with two identical pulleys of 500 mm effective diameter. At 3.425 kg, this belt weighs correspondingly more than the shorter lengths of the same profile. With this length, plan for a guide or support for the slack side if the drive operates with highly variable loads, and check the tension again after the initial break-in period.

For design purposes and comparison with an existing belt, the three length specifications are important because manufacturers use different reference dimensions. The inner length (Li) is 2,500 mm; it is measured at the inner circumference of the belt and is the standard ordering dimension in Germany. The effective length (Ld) of 2,585 mm refers to the neutral axis and is the dimension used in many catalogs and drive calculations. The outer length (La) of 2,613 mm is measured at the back of the belt. With a profile height of 18 mm, the difference between the inner and outer lengths is 113 mm, which corresponds to twice the difference in circumference across the belt height. When replacing an old belt, always compare using the same reference dimension; otherwise, you can easily be off by several centimeters.

Dimensions and specifications

• Internal length (Li): 2,500 mm

• Effective length (Ld): 2,585 mm

• External length (La): 2,613 mm

• Profile: 70x18 according to DIN 7719 / ISO 1604

• Top width: 70 mm

• Height: 18 mm

• Flank angle: 28°

• Construction: open-sided, toothed

• Mixture: Chloroprene (CR)

• Tensioning material: Polyester cord

• Antistatic: yes, according to ISO 9563

• Temperature range: -30 °C to +80 °C

• Belt speed: up to 30 m/s

• Weight: 3.425 kg

• Article number: G470182500

• EAN: 4059213024811

• Manufacturer: ConCar

Structure and materials

In terms of materials, ConCar combines a chloroprene body with a polyester tensile member. This pairing is the industry standard for variator belts because it simultaneously fulfills two opposing requirements: The belt must be flexible enough to bend over a small diameter, yet stiff enough longitudinally to resist flexing under load. Antistatic treatment according to ISO 9563 is standard on ConCar belts and is not an additional cost option.

The 28° flank angle is the crucial difference compared to a conventional V-belt, which operates at 34 to 40 degrees. The shallower angle generates less wedging effect per millimeter of radial travel, ensuring smooth belt operation across the entire pulley adjustment range and preventing binding at the end positions. Simultaneously, the large 70 mm upper width provides the necessary contact area to transmit torque solely through friction. The toothed underside reduces bending stiffness to such an extent that the belt can operate even on small effective diameters without the flanks overheating due to internal flexing.

Typical areas of application

Belts of this size are used in heavy-duty drives: threshing and drum drives on combine harvesters, intake and chopping units on forage harvesters, sawing and chipboard plants, large conveying and crushing plants, as well as compressor and blower drives where the speed must follow the demand without shifting a gearbox.

What these applications have in common is that the rotational speed must be adjusted during operation to suit the material, batch, or demand. A Variable Speed Belts solves this problem purely mechanically, without any electronics in the drive train. This is advantageous wherever dust, moisture, vibration, or temperature would damage a frequency converter, and it remains the only economical solution for existing machines because the variator is an integral part of the machine's design.

Assembly and tension

For installation: Open the pulleys, place the belt on without tension, then adjust it to the required tension using the adjustment mechanism or the motor rocker. The belt must never be pulled over the pulley edge or pried open with a tool. After approximately 24 hours of operation, the belt will have settled; at this point, the tension should be checked a second time and adjusted if necessary. Insufficient tension leads to slippage and burns the belt edges, while excessive tension puts unnecessary stress on the bearings and tension members.

Transverse cracks on the underside indicate an insufficient bearing diameter or cold brittleness, while longitudinal cracks and frayed edges point to misalignment between the pulleys. It's worthwhile checking the alignment with a ruler or laser when changing the belt, as even a few millimeters of misalignment over a one-meter center-to-center distance can halve the belt's lifespan.

Similar names for other brands

Variable Speed Belts are standardized according to DIN 7719 and ISO 1604. A belt with a 70x18 profile and a 2,500 mm inner length is therefore dimensionally identical regardless of the manufacturer; no modification of the pulleys is required for replacement. This ConCar belt replaces, among others:

• OPTIBELT: VB 70x18 / VARIO POWER 70x18

• GATES: Multi-Speed ​​70x18 / Predator V Variable Speed

• CONTITECH: VARIO Speed ​​70x18 / CONTI-V VARISPEED

• MEGADYNE: VARISECT 70x18

• MITSUBOSHI: VARI-SPEED 70x18

• BANDO: Variable Speed ​​70x18

• PIX: Variable Speed ​​70x18

Delivery

The belt is supplied as a single, endless belt. Standard lengths and common profiles are available from stock; custom lengths and widths are available upon request. If you are unsure which length your drive requires, please send us the part number of your old belt or the dimensions of your pulleys, and we will check the compatibility.