What Is an SPB Belt

The most widely used SP wedge-belt section — the practical middle ground between compact drives and heavy-tonnage plant.

The SPB belt is a wrapped metric V-belt with a 16 mm top width, 13.5 mm section height and a 40° wedge angle. It sits in the middle of the SP series: smaller than an SPC, larger than an SPA, and that is exactly why it is the section most often specified. Where an SPC would be oversized and a 5V or B-section would need more width, the SPB lands on the right belt for the job.

The 40° wedge is the technical story. A narrower wedge sinks deeper into the sheave groove and develops more grip per millimetre of belt width than a classical V-belt. The result is a smaller sheave, a lighter shaft load and less bearing wear for the same transmitted power — a real saving that shows up on the capital cost of the drive, not just the running cost.

Our SPB belts are moulded rather than cut, so every belt of the same specification leaves production with an identical datum length. In a matched multi-belt drive that means every belt carries the same share of load from the first hour. No one belt runs tight and takes the punishment, no flank wears out early, and no unexpected break stops production.

Every belt is manufactured to ISO 4184, the international standard covering dimensional tolerances and performance requirements for V-belts. Order with confidence: every belt seats correctly in any ISO 4184-compliant SP sheave.

Complete Technical Specifications

Verified under ISO 4184 test conditions. Supplied in matched datum lengths for multi-belt drives.

Materials & Construction

Three layers, each doing one job properly. Built on chloroprene rubber for genuine resistance to oil, heat, ozone and static.

Why Choose Our SPB Belt

Every claim below is measurable on the drive, not just on a spec sheet.

Industries & Equipment Served

The SPB belt is the most broadly applicable of the SP family — specified across ten industries and their auxiliary drives.

Printing

Offset printing presses and their auxiliary equipment, where smooth, stable running and compact drive layout protect print quality and machine life.

Grain & Oil Processing

Oil presses and all auxiliary equipment, including conveying, elevating and processing drives running long hours in dusty conditions.

Construction & Building Materials

Concrete mixers and milling-planing machines. Heavy shock loads, jobsite debris and long run hours are the conditions that expose a weak belt fast.

Mining & Aggregates

Sand makers, crushers, grinders, screening machines, conveyors, brick machines and rock drills. A wrapped belt with stable cords earns its keep in abrasive environments.

Agricultural Machinery

Seed drills, rotary tillers, mowers, rice mills, micro-tillers, fertiliser spreaders, paddy de-huskers, grain grading screens, cleaning screens, ditch openers and pruning machines.

Steel & Metallurgy

Forging presses, grinders, planers, drilling machines, sawing machines, plate shears, forming machines, conveyors, crushers, mixers, distributors, belt conveyors, separators, feeders, continuous casters, cutting equipment, bundling machines, marking machines and full auxiliary systems.

Textiles

Auxiliary equipment across spinning, weaving and finishing lines, where quiet, stable running protects product quality.

Paper & Pulp

Pulpers, washers, bleach washers, breakers, separators, refiners, flotation cells, beaters, disc refiners, washing machines, straw cutters, reed cutters and wood chippers. Continuous running makes belt life a direct maintenance cost.

Ceramics & Building Materials

Ball mills, grinding mills and shaker screens. High-inertia loads with long run hours, where a belt that holds its tension pays back every month.

Petrochemical & Plastics

Oil pumping and extraction units, dryers, industrial refrigeration, dehumidifiers, mixers, pulverizers, vacuum formers, blow moulders, extruders, forming machines and pelletisers.

Auxiliary Equipment Across All Sectors

Fans, electric motors, gear reducers, mixers, air compressors, pumps and pulverizers. If a machine needs to turn reliably for years, the SPB belt is on the bill of materials.

How to Select Length & Matched Sets

An SPB belt code reads as SPB followed by the datum length in millimetres. The number is the datum length; the outside circumference is longer by the standard profile offset and is listed in the downloadable chart below.

For any drive using more than one belt, install a matched set. Because our belts are moulded to a consistent datum length, every belt in the set carries the same share of load. A common failure pattern is one new belt paired with several worn belts: the new belt runs tight, takes almost all the tension and fails in days. Replacing the full set is always the lower-cost choice over the life of the drive.

If you are unsure of the correct length, send us the centre distance, both sheave diameters and the service factor you want to apply. Our engineering team will return a recommended belt code, normally within one working day. MOQ: 50 pcs per size  |  Delivery: 15-20 days

SPB Size Chart & PDF Download

The table below groups the full SPB range into practical datum length bands. Every size is available through the product options on this page. For the complete dimensional chart — datum length, outside circumference conversion, sheave groove dimensions per ISO 4184 and the full length-by-length listing — download the PDF.

Installation & Maintenance

Correct Installation Procedure

1. Loosen the driven-unit mounting bolts and reduce the centre distance before fitting the belt. Never lever a belt over a sheave rim — the forced bend will break tension cords at one point along the belt.
2. Seat the belt in the grooves, then increase the centre distance gradually to apply tension.
3. Tension to the specified value with a proper tension gauge. Too tight overloads the bearings; too loose causes slip, heat and rapid wear.
4. Run the drive 15–30 minutes under light load so the belt beds into the grooves, then re-check and adjust tension once.
5. Check sheave alignment with a straightedge. Misalignment wears one belt sidewall quickly and shortens belt life.

Maintenance Guidelines

• Inspect belts every 500 operating hours for glazing, cracking or exposed cords.
• Keep sheaves clean and free of oil, grease and embedded debris.
• Replace all belts in a matched set together — never replace one belt alone.
• Store spares in a cool, dry place away from direct sunlight and ozone sources such as electric motors.

Troubleshooting Guide

The belt cannot be tensioned

Possible causes: the centre-distance adjustment range is too small; the belt has stretched beyond recovery or the drive frame is undersized and overloaded; the belt length is wrong.
Remedies: re-design the drive with a larger adjustment range; re-calculate the drive data and resize the drive; select the correct SPB length.

The belt wears out too quickly

Possible causes: the belt has exceeded its service life and the compound has aged; the drive imposes excessive tension; poor installation causes misalignment, uneven wear or vibration.
Remedies: replace on a fixed schedule, correct the drive design, and align and seat the belt properly at installation.

The belt breaks after a short time

Possible causes: it was pried onto the sheave and cords were damaged; a foreign object entered the drive and snapped it; the driven system seized; severe shock loading or a load applied too suddenly.
Remedies: loosen the mounting bolts and reduce centre distance to fit the belt with no forced leverage; fit a guard to keep debris out; stop and clear the fault before restarting; re-design for the actual shock load and ramp loads up gradually.

Black powder is coming off the belt

Cause: on a new installation the sheave surface finish is too rough, so the belt rubs off fine black rubber dust.
Remedy: improve the sheave surface finish.

The belt slips

Possible causes: insufficient tension, worn or contaminated sheave grooves, or a drive ratio that no longer matches the requirement.
Remedies: adjust tension to the specified value with a tension gauge; inspect and replace worn or contaminated grooves; correct or replace the drive so the ratio matches.

Frequently Asked Questions