Conveyor belt terms, in plain words

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Abrasion loss

The volume of cover rubber lost when a test piece is rubbed against a standard abrasive drum, in mm³ (IS 10066 / ISO 4649). The lower the figure, the longer the cover lasts under wear. Cover grades →

Antistatic belt

A belt whose covers conduct enough to drain static charge, so it cannot spark in a dusty or explosive atmosphere. Fire resistant (FR) belts are antistatic. Fire resistant belts →

Belt ratingBreaking strength, kN/m

The breaking strength of one metre of belt width, in kN/m. A 630 kN/m belt holds 630 N for each millimetre of width. It is the first number in a designation such as EP 630/4. Choosing the rating →

Bias (splice)

The angle across the belt at which a splice is cut, usually around 20°, so the joint passes over pulleys gradually rather than all at once.

Bottom coverPulley side cover

The rubber layer on the underside of the belt that runs on the pulleys and return idlers. It is thinner than the top cover, typically 1.5 to 3 mm.

Breaker ply

An open-weave fabric layer placed just under the top cover of some belts to protect the carcass from impact and cuts.

Carcass

The fabric core of a belt: the plies and the skim rubber that bonds them. The carcass carries the tension; the covers protect it.

Centre distance

The distance between the centres of the head and tail pulleys of a conveyor, the main input to the belt length. Belt length →

Cleated belt

A belt with raised rubber profiles across its top cover that stop material sliding back on steep inclines.

Cold spliceCold bonded joint

A belt joint made with a cold-curing adhesive instead of a vulcanising press. Quicker to make in the field, but weaker than a hot splice. Splicing compared →

Compound

The rubber recipe: polymer, carbon black, oils and chemicals mixed in fixed amounts. The compound decides the cover grade.

Cover grade

The type of rubber on the belt, named for what it resists: general purpose (N17, DIN-Y), abrasion (M24, DIN-X, DIN-W), heat (T1, T2, T3), oil (G), fire (FR) or food contact (FG). Cover grades →

Designation

The name that specifies a belt completely, for example EP 630/4 6+2 X: fabric, rating in kN/m, plies, top and bottom cover in mm, and cover grade. The catalogue →

DIN 22102

The German standard for textile conveyor belts, which defines the cover grades W, X, Y, Z and others and is widely used in export specifications. Standards →

Drive pulleyHead pulley

The powered pulley that moves the belt, usually at the discharge end. It is often lagged with rubber for grip.

EE belt

A belt whose fabric plies have polyester in both the warp and the weft: very stable in length and when wet, stiffer across the width. EP vs EE vs NN →

Elongation at break

How far a cover test piece stretches before it breaks, as a percentage of its length. N17 needs 400%, M24 450%.

Endless belt

A belt joined into a continuous loop, either in the factory or on site by splicing.

EP belt

A belt whose fabric plies have a polyester (E) warp and a polyamide or nylon (P) weft. The most common conveyor belt fabric: low stretch and good troughing. EP vs EE vs NN →

FG beltFood grade

A belt with white, hygienic covers for food contact, used for sugar, grain, salt, spices and packaged food. Food grade belts →

Fire resistant beltFR belt

A belt that self-extinguishes in the ISO 340 flame test and is antistatic, for coal handling, power plants and underground conveyors. Fire resistant belts →

Heat resistant belt

A belt with covers compounded to keep their properties at temperature: T1 to 100°C, T2 to 125°C, T3 to 150°C continuous. Heat resistant belts →

Hot spliceHot vulcanised joint

A belt joint in which stepped ends are overlapped with uncured rubber and cured in a press under heat and pressure. The strongest and longest-lasting joint. Splicing compared →

Idler

A free-running roller that supports the belt. Carrying idlers support the loaded side, return idlers the empty side, impact idlers the loading point.

Impact bed

A row of low-friction bars or rubber-cushioned rollers under the loading point that absorbs the impact of falling material and protects the belt.

IS 1891

The Indian standard for conveyor belting. Part 1 covers general use (N17 and M24 grades), Part 2 heat resistant, Part 4 oil resistant and Part 5 fire resistant belts. Standards →

ISO 14890

The international specification for rubber or plastics covered textile conveyor belts, with grades H, D and L.

ISO 340

The laboratory flame test for conveyor belts: test pieces must stop burning within set limits once the flame is removed.

Lagging

A rubber or ceramic covering on a pulley that improves grip between the pulley and the belt and reduces slip.

M24

The high abrasion cover grade of IS 1891: 24 MPa minimum tensile strength, 450% elongation, abrasion loss up to 150 mm³. Equivalent duty to DIN-X. Abrasion resistant belts →

Mechanical fastener

A metal plate or hinge joint bolted or riveted across the belt ends. Fast to fit but weaker than a vulcanised joint and lets fines through.

N17

The general purpose cover grade of IS 1891: 17 MPa minimum tensile strength, 400% elongation, abrasion loss up to 200 mm³. Equivalent duty to DIN-Y. General purpose belts →

NN belt

A belt with nylon fabric in both the warp and the weft. Stretches more than polyester but takes impact well. EP vs EE vs NN →

Oil resistant beltDIN-G

A belt with covers that keep their shape and strength against mineral and vegetable oils, used for oil seeds, oily scrap and chemicals. Oil resistant belts →

Ply

One layer of woven fabric in the carcass. A 4 ply belt has four layers; plies × fabric strength gives the rating. Fabric chart →

Ply adhesion

The force needed to peel one ply from the next, or the cover from the ply, in N/mm. At least 3.5 N/mm between plies.

Safety factor

The ratio of the belt’s breaking strength to its running tension, usually 8 to 10 for textile belts, allowing for splices, starts and ageing.

Shore A hardness

The hardness of rubber on the Shore A scale, measured with a durometer. Cover hardness is held within ±5 of the declared value.

Skim rubber

The thin layer of rubber between plies that bonds the carcass together.

Skirting

Rubber strips along the sides of the loading point that keep material on the belt. Made from rubber sheet. Rubber sheet →

Take-up

The device that keeps the belt tight: a screw, gravity weight or winch that moves a pulley to take up stretch.

Tensile strength

The stress at which a cover test piece breaks when pulled, in MPa. N17 needs 17 MPa, M24 24 MPa.

Top coverCarrying side cover

The rubber layer on the carrying side of the belt, which takes the wear. Thicker on abrasive duties: 3 to 10 mm.

Tracking

How straight the belt runs. A belt that runs to one side is mis-tracking, usually because of a crooked idler, off-centre loading or a joint not cut square. Belt care →

Troughing

The shape of the loaded belt when its side idlers are angled up (20° to 45°), forming a trough that carries more material.

Warp

The threads that run along the length of the belt in a fabric ply. They carry the belt’s tension.

Weft

The threads that run across the belt in a fabric ply. They give troughability and impact resistance.