Minimum pulley size depends on the belt pitch and whether back bending occurs in the drive layout. Each pitch has a specified minimum number of teeth for standard operation and a larger minimum for installations with back bending over idlers. See the table above for all 23 pitch profiles. For pulley selection, contact Texas Belting at 888-203-2358.

Back bending occurs when a timing belt wraps around an idler or pulley on its smooth (non-tooth) back side. This reverses the normal flex direction and creates additional stress. Back bending requires larger minimum pulley diameters than tooth-side engagement. ATN belts do not support back bending because snap-in profiles occupy the back surface.

A minimum of 6 teeth in mesh (approximately 60 degrees of wrap) is recommended for standard drives. High-torque or high-speed applications may require more teeth in mesh to distribute the load and prevent tooth jumping. For ATP high-power drives, consult Texas Belting for teeth-in-mesh requirements.

Pitch length is the total length measured along the pitch line (the neutral axis where the tension members sit inside the belt). It equals the number of teeth multiplied by the pitch. For example, a 100-tooth AT10 belt has a pitch length of 100 x 10mm = 1,000mm. Pitch length determines how the belt fits on a specific set of pulleys at a given center distance.

Belt pitch length = number of teeth x pitch. For open-ended belts, the length in meters equals the number of teeth times the pitch divided by 1,000. For example, 200 teeth at T5 pitch = 200 x 5mm = 1,000mm = 1.0 meter. Contact Texas Belting at 888-203-2358 for assistance calculating the correct pitch length for your drive layout.

A minimum wrap angle of 60 degrees (approximately 6 teeth in mesh) is recommended for standard drives. High-torque applications may require 90 degrees or more. Insufficient wrap angle can cause tooth jumping under load, especially during acceleration or shock loading. Adding an idler to increase wrap is a common solution.

At elevated temperatures, polyurethane becomes slightly softer, reducing load capacity by approximately 10% at +80°C. At low temperatures (-30°C), the material becomes stiffer but remains functional. Always derate belt capacity per the manufacturer's temperature correction factors when operating outside the +10°C to +30°C range. For extended high-temperature operation, GEN III compound is rated to +100°C continuous.

Standard pitch lengths for each belt series are listed on the individual series pages: T-Series, AT-Series, ATL, ATP, and Imperial. Custom pitch lengths are available for welded belts. Contact Texas Belting at 888-203-2358 for assistance.