ConCar Variable Speed Belts 22x8 - 1250 Li

ConCar Variable Speed Belts 22x8 – 1,250 mm inner length – DIN 7719 / ISO 1604

The ConCar Variable Speed Belts with a 22x8 profile and a 1250 mm inner length, is an open-flanked, toothed variator belt conforming to DIN 7719 and ISO 1604. It transmits drive power exclusively via its two flanks, moving radially on the conical, axially displaceable pulley halves during operation. This movement is the principle behind a mechanical speed converter: when one pulley closes, it pushes the belt outwards to a larger effective diameter, while on the opposite side it slides inwards. This allows the transmission ratio to change continuously without the need for shifting, clutching, or electronic control.

This length in the drive

With an inner length of 1,250 mm, this belt is one of the longer versions of the 22x8 profile. For two equally sized pulleys with an effective diameter of 315 mm, this corresponds to a center distance of approximately 150 mm. Long belts are less prone to bending stress; at 20 m/s, they rotate only about 15.5 times per second. However, they require more attention to tension: the slack side tends to flutter with large center distances, and the belt's own mass generates additional centrifugal force during operation, which reduces the contact pressure on the pulley.

For design and comparison with an existing belt, the three length specifications are important because manufacturers use different reference dimensions. The inner length (Li) is 1,250 mm; it is measured at the inner circumference of the belt and is the standard ordering dimension in Germany. The effective length (Ld) of 1,290 mm refers to the neutral axis and is the dimension used in many catalogs and drive calculations. The outer length (La) of 1,300 mm is measured at the back of the belt. With a profile height of 8 mm, the difference between the inner and outer lengths is 50 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): 1,250 mm

• Effective length (Ld): 1,290 mm

• External length (La): 1,300 mm

• Profile: 22x8 according to DIN 7719 / ISO 1604

• Top width: 22 mm

• Height: 8 mm

• Flank angle: 25°

• 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: 0.2 kg

• Article number: G422081250

• EAN: 4059213020752

• Manufacturer: ConCar

Structure and materials

The belt consists of a chloroprene blend (CR) with an embedded polyester tensile cord. Chloroprene was deliberately chosen here: it is resistant to oil mist, ozone, UV radiation, and weathering, and retains its elasticity in a temperature range of approximately -30 to +80 degrees Celsius. The polyester cord absorbs the tensile forces and keeps elongation low over the belt's lifespan, which is particularly important in a variator because an elongated belt length directly translates into a shift in the control range.

The 25° 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 upper width of 22 mm 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 typically found in compact drives: bench drills and small lathes with continuously variable spindle speed, feed drives on band and circular saws, laboratory centrifuges and shakers, dosing and small conveyors in packaging lines, as well as garden equipment and small drives where the installation space does not allow for large pulleys.

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 22x8 profile and a 1250 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 22x8 / VARIO POWER 22x8

• GATES: Multi-Speed ​​22x8 / Predator V Variable Speed

• CONTITECH: VARIO Speed ​​22x8 / CONTI-V VARISPEED

• MEGADYNE: VARISECT 22x8

• MITSUBOSHI: VARI-SPEED 22x8

• BANDO: Variable Speed ​​22x8

• PIX: Variable Speed ​​22x8

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.