ConCar Variable Speed Belts 28x8 - 2240 Li

ConCar Variable Speed Belts 28x8 – 2,240 mm inner length – DIN 7719 / ISO 1604

This ConCar Variable Speed Belts with a 28x8 profile and an inner length of 2,240 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 2,240 mm is a long version for the 28x8 profile and is intended for drives with a large center distance, approximately 355 mm with two identical pulleys of 500 mm effective diameter. At 0.448 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 2,240 mm; it is measured at the inner circumference of the belt and is the standard ordering dimension in Germany. The effective length (Ld) of 2,280 mm refers to the neutral axis and is the dimension used in many catalogs and drive calculations. The outer length (La) of 2,290 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): 2,240 mm

• Effective length (Ld): 2,280 mm

• External length (La): 2,290 mm

• Profile: 28x8 according to DIN 7719 / ISO 1604

• Top width: 28 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: 0.448 kg

• Article number: G428082240

• EAN: 4059213021636

• Manufacturer: ConCar

Structure and materials

The belt consists of a chloroprene rubber core with a longitudinally inserted polyester cord as a tensile member. The flanks are open, meaning they are not covered with fabric. This noticeably increases the coefficient of friction on the pulley and thus improves the transmissible torque, but in return requires clean, unworn pulley flanks. The compound is antistatically conductive according to ISO 9563, which allows the belt to be used in dusty areas and in ATEX-relevant environments.

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, allowing the belt to run smoothly across the entire adjustment range of the pulleys and preventing binding at the end positions. Simultaneously, the large upper width of 28 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 cover the classic field of industrial variators: feed and grinding belt control in woodworking machines, demand-controlled piston and screw compressors, spinning and drawing units in textile machines, industrial mixers and kneaders with soft start, take-off and screw drives on plastic extruders, as well as boring mills and lathes with stepless control.

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.

Before you classify a belt as worn, it's worth taking a look at the pulley. A worn groove allows the belt to sink deeper, causing it to sit on the bottom of the groove and lose contact with the belt flanks. This manifests as a sudden loss of power, even with a seemingly new belt. This can be checked in a minute using a groove feeler gauge.

Similar names for other brands

Variable Speed Belts are standardized according to DIN 7719 and ISO 1604. A belt with a 28x8 profile and an inner length of 2,240 mm 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 28x8 / VARIO POWER 28x8

• GATES: Multi-Speed ​​28x8 / Predator V Variable Speed

• CONTITECH: VARIO Speed ​​28x8 / CONTI-V VARISPEED

• MEGADYNE: VARISECT 28x8

• MITSUBOSHI: VARI-SPEED 28x8

• BANDO: Variable Speed ​​28x8

• PIX: Variable Speed ​​28x8

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.