BELTING GLOSSARY

Our conveyor belt glossary explains common terms in plain words. Need help choosing a belt? Try the Belt Selector or send us your details.

Abrasion loss

Volume of rubber (mm³) lost in a standard abrasion test. Lower is better. IS 1891 allows up to 150 mm³ for M-24 and 200 mm³ for N-17 covers.

Belt rating

Written like EP 800/4: fabric type (EP), full-thickness breaking strength in N/mm (800) and number of plies (4).

Bottom cover

Rubber layer on the pulley side of the belt, usually thinner than the top cover.

Carcass

The fabric (or steel cord) layers inside the belt that carry the tension.

Carry-back

Fine material that sticks to the belt after the head pulley and falls along the return side.

Chevron belt

Belt with moulded V-shaped cleats on the top cover that stop material sliding back on inclines.

Cleat

A raised bar or profile on the belt surface that holds material on an incline.

Cold vulcanizing

Joining or repairing a belt with a bonding solution and hardener at site temperature, without a heated press.

Cover grade

The rubber compound of the covers, chosen for the duty: M-24, N-17, HR, UHR, FR, OR, SAR and others.

Cut edge / moulded edge

Cut edge belts are slit from a wider slab; moulded edge belts have rubber sealed along both edges.

Elongation at break

How far the cover rubber stretches before breaking in a test, as a percentage. M-24 needs at least 450%.

Endless belt

A belt joined into a loop by hot vulcanizing and supplied to the exact length of the conveyor.

EP fabric

Polyester warp and nylon weft fabric. Low stretch and good strength – the most common carcass today.

FR belt

Fire resistant belt whose cover stops burning when the flame is removed. Tested to IS 1891 Part V.

FRAS

Fire resistant and anti-static belting, used where both fire and static sparks are a risk, such as underground coal mines.

HR / SHR / UHR

Heat resistant cover grades. T1, T2 and T3 classes have rising temperature limits; UHR is for the hottest duties.

Hot vulcanizing

Joining belt ends with uncured rubber under heat and pressure in a vulcanizing press. Gives the strongest joint.

Idler

The rollers that support the belt on the carrying and return sides.

M-24

IS 1891 cover grade for heavy, abrasive duty: tensile strength 24 MPa or more and elongation 450% or more.

N-17

IS 1891 cover grade for lighter, less abrasive duty: tensile strength 17 MPa or more.

NN fabric

Nylon warp and nylon weft fabric. Flexible and impact-tolerant, but stretches more than EP.

Ply

One layer of fabric in the carcass. A 4-ply belt has four fabric layers.

Pulley lagging

Rubber sheet bonded to a pulley shell to improve grip on the belt and protect the pulley.

SAR

Super abrasion resistant cover for sharp, highly abrasive material such as granite, slag and iron ore fines.

Sidewall belt

Belt with corrugated walls along both edges and cleats across the width, used for very steep or vertical lifts.

Splice (joint)

Where two belt ends are joined – by hot vulcanizing, cold vulcanizing or mechanical fasteners.

Take-up

The screw or gravity device that keeps the belt tight and takes up stretch.

Tensile strength

For cover rubber: the stress it withstands in a test, in MPa. For the whole belt: breaking strength per mm of width, in N/mm.

Top cover

Rubber layer on the carrying side, which takes the wear and impact from the material.

Tracking

Keeping the belt running centrally on idlers and pulleys. Poor tracking wears the belt edges.

Troughing angle

The angle of the side idlers (commonly 20, 30, 35 or 45 degrees) that forms the belt into a trough.