Timing belts are essentially flat belts with the addition of evenly spaced teeth along the surface that contacts toothed pulleys. Power is transmitted smoothly and without slippage. Pulley pitch diameters are larger than their outside diameters and the belt pitch lines lie within the flat portion. Tension members are moulded in the flat portion to serve as load-carrying elements. Miniature HTD timing belts have deep curvilinear tooth forms, as contrasted to trapezoidal for conventional timing belts. Greater strength, lower tooth pressures and decreased stress concentration result in superior performance.
The following general guidelines apply to selection of miniature HTD timing belts and pulleys:
Design with ample reserve horsepower capacity and apply the proper service factors.The belt must have six or more teeth in engagement with the smaller pulley to carry rated horsepower. Avoid smaller timing pulley diameters where practical to assure satisfactory timing belt life. Timing belt speed should not exceed 6500 feet per minute. At least one pulley in the drive should be flanged and for vertical shafts or where centre distance exceeds eight times the smaller timing pulley diameter, both pulleys should be flanged.