ConCar Variable Speed Belts 70x18 - 1550 Li

ConCar Variable Speed Belts 70x18 – 1,550 mm inner length – DIN 7719 / ISO 1604

The ConCar Variable Speed Belts 70x18 x 1.550 Li is a flank-driven variator belt according to DIN 7719 and ISO 1604 with a molded toothed underside. The transversely molded teeth are not a tooth profile in the sense of a toothed belt; they do not engage with the pulley. Their purpose is to reduce bending stiffness so that the belt can be bent even on small running diameters without the flanks tearing or the belt heating up due to internal flexing.

This length in the drive

The inner length of 1,550 mm is a short version for the 70x18 profile. This means a compact center distance and a correspondingly small drive volume, but at the same time a high bending frequency. At a belt speed of 20 m/s, this equates to approximately 12.2 revolutions per second. With short belts, check whether the tapered pulleys meet the minimum running diameter specified by the manufacturer, as the bending stress has the greatest impact on service life at this point.

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 1,550 mm; it is measured at the inner circumference of the belt and is the standard ordering dimension in Germany. The effective length (Ld) of 1,635 mm refers to the neutral axis and is the dimension used in many catalogs and drive calculations. The outer length (La) of 1,663 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): 1,550 mm

• Effective length (Ld): 1,635 mm

• External length (La): 1,663 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: 2.124 kg

• Article number: G470181550

• EAN: 4059213024736

• 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 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

Variable Speed Belts are supplied as continuous, single belts and cannot be shortened or joined. Before installation, the tapered pulleys must be fully opened so that the belt can be positioned at its smallest effective diameter. Tensioning is then achieved via the pulley's adjustment range or the motor rocker arm. Prying the belt open by the pulley edge is particularly damaging with Variable Speed Belts , as this can damage the exposed flanks and the tension member without any visible external damage.

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 70x18 profile and a 1,550 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.