Urethane Round Belting
Urethane Round Belting
Urethane round belting is solid, elastic polyurethane cord, supplied as endless O-ring drive belts, used to power live roller conveyors and light to medium power transmission drives. Because the belts stretch to fit, they run without tensioners, idlers, or take-ups, and they seat in round or V grooved pulleys. Texas Belting cuts and welds round belting to your exact length in a wide range of cross sections, durometers, and colors, with same day shipping on stock cord from our Houston warehouse.
- Cross sections: 1/16 in to 3/4 in (2 mm to 18 mm)
- Durometers: 60A to 100A, plus 53D
- Length: endless, cut to your center distance
- Colors: clear, orange, red, green, blue, white, black
- Surface: smooth or rough / matte finish
- Food grade: FDA and USDA options available
- Tensioner: none required, belts stretch to fit
- Stock cord: same day shipping from Houston
What Is Urethane Round Belting?
Round belting, also called O-ring belting, endless round belts, or urethane drive belts, is extruded polyurethane cord with a circular cross section. It is an elastomeric belt, which means it is designed to stretch. The cord is cut to length and the ends are fused into a continuous loop, producing an endless belt with no buckles, clips, or hooks.
That elasticity is the reason round belts are so widely used on conveyors and small drives. The belt is made slightly shorter than the path it travels, then stretched into place. The built in stretch supplies running tension, so there is no need for spring tensioners, take-up assemblies, or adjustable idlers. A round belt seats naturally in round grooves and also runs in V grooved pulleys.
- No tensioners or take-ups, the belt provides its own tension
- High resilience and recovery, the cord springs back after shock loads
- Resistant to cuts, abrasion, and most oils
- Non-marking and easy to clean, will not fray at the joint
- Quiet, smooth running on round and V pulleys
- Most grades are FDA and USDA recognized for food contact
Round Belting Specifications
| Property | Range and Options |
|---|---|
| Cross section (diameter) | 1/16 in to 3/4 in, plus metric 2 mm to 18 mm and standard O-ring sizes |
| Length | Endless, cut and welded to your exact center distance (typically any length above about 3 in) |
| Durometer (hardness) | 60A, 70A, 75A, 80A, 83A, 85A, 88A, 90A, 92A, 95A, 100A, and 53D |
| Surface texture | Smooth (standard) or rough / matte for higher abrasion resistance |
| Colors | Clear, orange, red, green, blue, light blue, white, yellow, brown, black |
| Food grade | Most standard urethane grades are FDA and USDA recognized; metal detectable versions available |
| Special properties | Static dissipative (anti-static), UV resistant, low temperature, and anti-vibration options |
| Pulley fit | Runs in round grooves and V grooved pulleys |
Durometer and Material Options
Durometer is the hardness of the urethane on the Shore A scale. Softer cord grips well, runs quietly, and absorbs shock. Harder cord transmits more drive force and resists abrasion, which is what you want for heavier loads, curves, and accumulation. Beyond hardness, the base material can be tuned for temperature, static control, washdown, or metal detection.
| Material | Typical durometers | Key properties |
|---|---|---|
| Standard thermoplastic urethane (TPU) | 70A to 95A | Food grade (FDA), excellent oil and abrasion resistance, the default for most drives |
| High tension TPU | 85A | Long life, accepts higher stretch for more drive tension, food grade |
| All weather TPU | 85A, 90A | Food grade (FDA and NSF), humidity and mold resistant, UV stabilized for outdoor and wet areas |
| Static dissipative TPU | 90A | Bleeds off static charge for electronics and dusty environments, not food grade |
| Low temperature TPU | 85A | Stays flexible down to about -10 F, good abrasion resistance, food grade |
| Rough / matte surface TPU | 88A, 90A | Lower friction matte finish, more abuse resistant, suited to high speed and curves |
| Anti-vibration TPU | 85A | Runs on bare or misaligned shafts and stays seated in pulleys |
| Polyester cord reinforced urethane | 83A to 100A | Tension member adds pull capacity with much less stretch |
| Polyester (high performance) | 92A, 100A, 53D | Works to about -40 F, strong chemical resistance, FDA for dry food |
| Metal detectable urethane | 83A, 90A | Food grade and detectable by inline metal detectors for food and pharma lines |
All of our polyurethane cord is RoHS and REACH compliant and supported by Proposition 65 documentation. If you are not sure which material fits, send us your temperature range, washdown chemistry, speed, and load and we will recommend a grade.
Round Belting by Application
The two largest uses for urethane round belting are live roller conveyors and general power transmission. Live roller conveyors split into two drive styles, line shaft and powered roller, and each one uses a different family of round belt grades.
Line shaft (shaft driven) live roller conveyors
On a line shaft conveyor, a single rotating shaft runs the length of the conveyor. Each roller is driven by a round belt looped over a urethane spool on the shaft and held in position with C clips. Choosing a higher durometer or higher tension belt increases the drive force and the box weight each roller can move. The figures below are typical for a 3/16 in belt unless noted.
| Belt grade | Durometer | Common diameters | Stretch | Approx capacity |
|---|---|---|---|---|
| Standard | 83A | 1/8 in to 3/8 in | 10 to 12% | Up to about 20 lb per roller |
| High tension | 85A | 3/16 in to 5/16 in | 15 to 20% | About 30% more drive, up to 25 lb per roller |
| Highly elastic, high tension | 88A | 7/32 in (necks into a 3/16 in groove) | 15 to 30% | 70 to 90% more drive, 40 lb per roller (55 lb in 1/4 in) |
| High drive | 90A | 1/8 in to 1/4 in | 12 to 15% | 70 to 100% more drive, 36 lb per roller (50 lb in 1/4 in) |
| Rough / matte (high speed) | 88A | 3 mm to 6 mm | 9 to 11% | About 30% more drive than 83A, best for curves and high speed |
We supply replacement line shaft belts and spools for live roller conveyors from major builders, including Hytrol, Omni-Metalcraft, Roach, Lewco, MHS Conveyor, Metzgar, and Automated Conveyor Systems. Send your roller centers, groove size, and box weight and we will size the belt.
Powered roller and motor driven roller (MDR) conveyors
Powered roller conveyors use a motor driven roller, also called an MDR or motorized roller, to drive a zone of six to ten slave rollers through round belts. Select the belt by the heaviest box you need to move. Four groove rollers roughly double the box weight a zone can carry.
| Diameter | Durometer / type | Max box weight | Approx per roller | Stretch |
|---|---|---|---|---|
| 3/16 in (4.8 mm) | 83A standard | Up to 50 lb | 6 lb | 14% |
| 3/16 in (4.8 mm) | 85A high tension | Up to 80 lb | 9 lb | 20% |
| 0.210 in (5.3 mm) | 85A high tension | Up to 100 lb | 12 lb | 20% |
| 0.216 in (5.5 mm) | 88A highly elastic, high tension | Up to 130 lb | 16 lb | 15 to 30% |
| 0.235 in (6 mm) | 85A high tension | Up to 120 lb | 15 lb | 20% |
| 1/4 in (6.4 mm) | 85A high tension | Up to 140 lb | 17 lb | 20% |
| 5/16 in (8 mm) | 85A high tension | Up to 200 lb | 26 lb | 20% |
| 5 mm | 88A rough / matte (abuse resistant) | Up to 60 lb | 7 lb | 16% |
| 6 mm | 88A rough / matte (abuse resistant) | Up to 70 lb | 8 lb | 16% |
We carry replacement belts for powered roller systems from Interroll, Itoh Denki, Holjeron, and Pulse Roller. Rough or matte belts are the right choice where boxes jam against a powered zone, because a lower friction surface slips with less heat and survives the abuse better than a smooth belt. Smooth belts move the heaviest boxes but should be paired with controls that clear jams quickly.
General power transmission and machinery drives
Beyond conveyors, round belting drives countless light to medium power transmission jobs where a slip-fit, maintenance free belt is preferred over a chain or timing belt. Common uses include packaging and bottling machinery, printing and mailing equipment, food processing lines, vending and dispensing units, exercise and medical equipment, and small fan or pump drives. The belt is simply sized to the pulley centers and stretched into place, which makes field replacement fast.
Choosing the Right Round Belt
Four decisions size a round belt: cross section, durometer, surface, and material. Work through them in this order:
- Cross section: match the existing pulley or roller groove. Larger diameters carry more load and more drive tension.
- Durometer: softer (60A to 80A) for grip, quiet running, and shock absorption; harder (85A to 95A) for more drive force, heavier loads, and abrasion resistance.
- Surface: smooth for maximum grip and drive; rough or matte for high speed, curves, and jam-prone zones where the belt needs to slip cleanly.
- Material: standard TPU covers most jobs; choose all weather for UV and washdown, static dissipative for electronics, low temperature for freezers, or metal detectable for food and pharma.
If you can give us the conveyor or machine, the groove or pulley size, the center distance, and the load, we will calculate the correct stretched length and recommend a grade. For reusable joints on machines where belts are changed often, ask about connectable twisted belts.
Frequently Asked Questions
Urethane round belting drives live roller conveyors (both line shaft and powered roller systems) and serves as an elastic drive belt on packaging machinery, small power transmission drives, and equipment that uses round or V grooved pulleys. Because the belts stretch to fit, they run without tensioners or take-ups.
No. Urethane round belts are elastomeric, so they are made slightly shorter than the path they run and stretched into place. The built in stretch supplies running tension, which removes the need for spring tensioners or take-up assemblies.
Standard cross sections run from 1/16 in to 3/4 in, plus common metric diameters from 2 mm to 18 mm and standard O-ring sizes. Endless belts can be made to almost any length above roughly 3 in, cut and welded to your exact center distance.
The cord is cut to length and the ends are fused into a continuous loop with a heat weld. A properly welded joint carries most of the strength of the base material and will not fray. Belts can also be welded on site with a splicing kit for fast in plant replacement.
Softer durometers (60A to 80A) grip well, run quietly, and absorb shock. Harder durometers (85A to 95A and above) transmit more drive force and resist abrasion, which suits higher loads, curves, and accumulation. On live roller conveyors, a higher durometer or higher tension belt moves heavier boxes per roller.
Most standard thermoplastic urethane round belts are FDA and USDA recognized for food contact. Metal detectable and static dissipative versions are also available for food, pharmaceutical, and electronics handling. Tell us the environment and we will confirm the right material.
Yes. Line shaft conveyors drive each roller with a round belt looped over a spool on the line shaft and held by C clips. Standard 83A belts move lighter loads, while high tension and high drive grades move 40 to 55 lb per roller or more. Keep at least 5 in (130 mm) between the shaft and the roller.
Round belting is solid elastic urethane cord that stretches to fit and needs no tensioner. Reinforced live roller belts use an aramid or polyester tension member with a finger splice for higher pull and minimal stretch. For those, see our live roller belts page. We stock both and can match either to your conveyor.
Need Urethane Round Belting?
Send your cross section, length or roller centers, durometer, and color. We cut and weld round belting to your exact length and ship stock cord the same day from Houston.