V Belts

Hothersal Trading has a national reputation for being a leader in the sale of V belts of all sizes and sections for a wide range of industrial and manufacturing establishments. Our staff is experienced in determining the section of the belt required and in making correct the measurement.  In the rare case that a customer’s belt specification is not in stock, Hothersal will source the required belts to order right away.  We carry the world renowned brand, Fenner.

Design Hints

Installation and Maintenance

Correct design of drives using Optibelt V-Belts ensures long belt life and a high degree of safety. Premature failure can often be traced back to faulty installation or maintenance, thus the following recommendations are very important

  • Pulleys

The grooves should be in good condition, free from scores or sharp edges, and all dimensions should conform to the relevant standard

  • Alignment

Shafts and pulleys should be correctly aligned prior to belt installation

We recommend a maximum tolerance of + 1° in both planes

  • Multiple V-Belt Drives

For multiple V-belt drives it is necessary to assemble the belts in matched sets either by measurement or by examination of the manufacturer’s code numbers or other markings. It may also be necessary to remeasure the belts if they have been stored for any length of time. Optibelt V-Belts in S=C plus construction may be used in matched sets without the need for reference to codemarks, measurement, or measurement after storage.

  • Installation of the V-Belts

The drive centre distance should be reduced prior to the installation of belts so that they may be fitted without undue force. The severe stresses placed upon V-Belts if they are forced over the pulley flanges can damage the cover fabric and the high quality, low stretch tension members.

  • Belt Tensioning

The drive should be tensioned correctly and retensioned as advised on the opposite page to compensate for the small initial belt stretch and “bedding” into the pulley grooves.

  • Idler Pulleys

Where possible the use of idler pulleys should be avoided. If for design reasons, such an arrangement is necessary, then an inside idler should be used in preference to an outside idler. For other details refer to “The Optibelt Technical Manual”.

  • Maintenance

It is recommended that V-Belt drives should be regularly inspected for loss of belt tension, unusual heat build up or wear. Retension or replace when necessary.

Should an individual belt in a matched set require replacement for any reason, a complete new set must be fitted.


Belts from different manufacturers must not be mixed on the same drive.

Adapted from Optibelt Manual p5




 Belt breaking after fitting Forcing belt over pulley when fitting, damaging cord and cover
Ingress of a foreign body, e.g. a stone, during running
Insufficient belts, or wrong section, for driveDrive stalled
Reduce drive centre distance to fit belt
Fit an effective guardCheck drive details and fit correct number or section of belts
Ascertain cause and put right
Cuts and splits in the base of the belt Outside idler pulley in use 


Pulley Diameter too small


Ambient temperatures too high (above + 70 °C/+ 158 °F)


Ambient temperatures too low (below -40 °C/ -40 °F)

Abnormal belt slip



Contamination by oil or chemicals

Replace with inside idler pulley on the slack side if the drive. Increase the size of the existing idler.Redesign using recommended minimum pulley pitch diameters.

Ensure good ventilation and protect the belts from direct heat.

Warm area surrounding drive.

Check drive design to ensure correct number of belts, redesign if necessary. Check drive tension

Protect drive from contamination

Belts turn over in pulleys Poor drive alignment
Incorrect pulley groove section or excessive wear in grooves
Excessive belt flapLow belt tension
Worn out belts
Ingress of foreign body
Renew PulleysUse an inside idler on drive slack side
Renew belts
Use a more effective drive guard
Excessive wear on belt flanks Incorrect pulley groove angleIncorrect pulley section
Excessive wear in pulley grooves

Poor Drive alignment

Small pulley diameter below
recommended minimum


Belt catching on protruding parts

Renew or remachine pulleysRenew pulleys
Renew or remachine pulleys


Redesign using correct pulley diameters.

Remove protrusions or move drive away

Adapted from Optibelt Manual pp6&7