What the NN400 Conveyor Belt Is
The NN400 Conveyor Belt is a multi-ply fabric core belt built on nylon (NN) warp and weft canvas. The number 400 refers to the nominal tensile strength of the carcass, commonly expressed as 400 N/mm per ply in reference data. In everyday plant language it is an NN Conveyor Belt, and buyers also meet it as a nylon Fabric Core Conveyor Belt. Its construction sits between lighter NN grades and very high-strength designs, which makes it a practical choice for medium to heavy duty conveying lines in mines, cement works, power stations and aggregate yards.
How the Belt Is Built
The carcass is made from several plies of nylon fabric bonded with rubber skim compound. Nylon filaments give the belt high tensile strength, good fatigue resistance and the ability to absorb shock loads better than many stiff carcasses. A typical NN400 belt may use two to six plies depending on the required strength and the splice method. The top and bottom covers protect the carcass from abrasion, moisture and impact.
Cover thickness is stated as top plus bottom, for example 4+2 mm, 5+2 mm, 6+2 mm or 8+3 mm. A thicker top cover suits sharp rock, lump ore and repeated impact at transfer points. The belt can also be supplied with special compounds such as an Abrasion Resistant Conveyor Belt cover, a Heat Resistant Conveyor Belt cover, a Flame Retardant Conveyor Belt cover or an Oil Resistant Conveyor Belt cover, depending on the duty.
Reference Construction Data
The values below are indicative reference data only. Actual construction is confirmed by the manufacturer for each order.
- Belt type: NN400, nylon fabric core, multi-ply
- Carcass strength: 400 N/mm per ply (nominal reference)
- Common ply counts: 2 to 6 plies
- Cover combinations: 3+1.5 mm, 4+2 mm, 5+2 mm, 6+2 mm, 8+3 mm
- Common belt widths: B500, B650, B800, B1000, B1200, B1400, B1600, B1800, B2000
Where It Fits in the Plant
The NN400 belt is often found on main haulage and transfer conveyors in quarry and aggregate operations, on clinker and limestone lines in cement plants, and on coal handling systems in power stations. In mining, an NN Conveyor Belt may run alongside heavier Steel Cord Conveyor Belt installations on long overland routes, while the fabric belt serves shorter or more flexible sections. It also appears in sand and gravel plants, crushing circuits and port loading conveyors.
The belt works with the rest of the conveyor: idler rollers support the loaded strand, a drive pulley transmits power, a tail pulley returns the belt, and bend pulleys route it around curves. Conveyor brackets hold the idlers and pulleys in alignment. Proper alignment of these parts matters as much as belt quality.
Selecting an NN400 Belt
Selection starts with the duty. For abrasive rock or ore, a high abrasion resistant cover helps extend service life. For hot clinker or sinter, a heat resistant grade is needed. Underground coal work usually calls for flame retardant and anti-static properties. Cold climates may justify a cold resistant compound. The belt width should be matched to the lump size and required capacity, and the ply count to the calculated tension, not chosen from a single fixed rule.
Pulley diameters are selected from the belt construction and the manufacturer’s recommendations. A wider belt does not automatically dictate one shaft diameter, and pulley sizes should be checked against the carcass flexibility and the required wrap angle. Buyers should also confirm splice type, edge condition and whether an endless belt is preferred for a specific conveyor.
Buyer Checklist
- State the material, lump size, temperature and moisture level
- Provide belt width, center distance and incline angle
- Confirm required cover thickness and any flame, oil or heat resistance
- Check pulley and idler roller dimensions against the belt recommendation
- Ask for the actual ply count and splice data for the ordered NN400 belt
For more information on fabric core belts, visit NN Conveyor Belt and conveyor pulley guidance pages. A correctly specified NN400 Conveyor Belt, matched to its pulleys and idlers, gives reliable service in demanding industrial conveying.
