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Plastic Pulley Specs Data Sheet

Composite Nylon Pulleys
Reinforced with Fiberglass


  1. Rugged. Our plastic pulleys are used in the hostile environment experienced by commercial lawn mowers where high speeds (3600 rpm) and high temperatures (170°F) far exceed stresses encountered in most conveyors. Even under such severe conditions, our molded-in bearings and drive adapters will not separate from the fiberglass-reinforced nylon rim.

  2. Molded-in bearings extend belt life. Molded-in bearings on our composite idler pulleys are more precise than pressed-in bearings and drive adapters. Pressed-in bearings may slip from side to side by as much as 1/16", meaning adjacent idlers can be out of line by 1/8". The resulting misalignment can cause premature belt wear. Our bearings and drive adapters do not slip. True-running idlers extend belt life.

  3. Higher Quality and Lower Prices. The production of molded-in bearings requires fewer steps. This facilitates automation, improves quality, and reduces costs. Consequently, our prices are very competitive.

  4. TIR (Total Indicated Readout) for idler pulleys is 0.014" (0.4mm) maximum because they have molded-in bearings. TIR for drive pulleys is .020" (.5mm) maximum because we have to press in drive adapters.


plastic composite nylon idler pulley sheave

Plastic Composite
Nylon Idler Pulley

Radial Load Ratings for
Standard Pulleys (Sheaves)
Based on a 1500 hour L10 life.

RPM Maximum (lbs.)
32 1,600
100 1,140
300 790
600 630
1,200 500
1,500 465
1,800 436
2,400 395
3,600 345
5,000 310
7,200 275
10,000 245
12,500 230

Printable Version

For pulley sizes click on
round, flat and vee pulleys.


High-grade plastic composite nylon pulley (sheaves) are reinforced with 33% fiberglass -- operating temperature range -20°F to 230°F (-29°C to 110°C). Our 1.9" poly-v endcaps are anti-static, but our other nylon pulleys are not anti-static.

Bore adapters are sintered powdered metal.

Standard bearings are imported 6203-2RS that are rated A.B.E.C.-1 precision and have radial seals. U.S. made bearings are also available. Bearing grease is Chevron SRI-2 or the equivalent (30% grease fill) -- operating temperature range -20°F to 350°F (-29°C to 177°C), complies with Mil-Spec MILG3545G.

Bearings with seals are standard and are better for dirty environments, but seals can be tight, making the bearing difficult to turn, so most conveyors use shielded bearings.

Bearings with shields are available but must be specified when ordering. Shielded bearing turn easier, so they put less strain on motor and belts. They are also more energy efficient. Most roller conveyors use shielded bearings.

Chemical Resistance

Chemicals that damage Nylon

Other chemicals may also attack nylon, but these are the most common. Damage depends on concentration, temperature and exposure time.

Acetic Acid
Ammonium Chloride
Ammonium Hydroxide
Antimony Trichloride
Aqua Regia
Barium Chloride
Benzoic Acid
Boric acid
Butyric Acid
Calcium Chloride
Calcium Hypochlorite
Calcium Thiocyanate
Chloroacetic Acid
Chlorosulfonic Acid
Chromic Acid
Formic Acid
Glycolic Acid
Hydrochloric Acid
Nitric Acid
Perchloric Acid
Potassium Permanganate
Potassium thiocyanate
Stannic Chloride
Stannic Sulfate
Sulfuric Acid

For the best in plastic composite nylon pulleys and sheaves, insist on DuraBelt.
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