Timing Pulleys

Timing Pulleys - Standard

Timing Belt Drive Pulleys are drive components that transmit rotary motion between parallel axes.  Pulleys require very little maintenance, and the only maintenance that is generally required is periodic adjustment of belt tension.  Timing belt drive pulleys can be used for speed reduction, speed increase, or simply to transfer rotary motion from one axis to another.  Just like gears, the ratio is determined by dividing the number of grooves of the two pulleys in the pair.  Timing belt drive pulleys belong to the synchronous drives category of components because they maintain relative positions and do not slip or creep, unlike flat, v-shaped and ribbed belts.  However, it is possible for a belt to jump or skip a groove, causing the assembly to lose indexing  This will happen if the system is not properly tensioned, is angularly misaligned, or too much torque is attempted to be transmitted.  Timing pulleys are able to transfer power as well as precise position.  How precise this positioning is will depend on the groove profile, type of belt, and pulley quality.

Standard pulleys are made with no flanges, a single flange, or double flanges to hold the belt’s position and have one or two set screws to fix onto a shaft.  Generally, a pair of pulleys would require a minimum of two flanges and proper alignment to ensure the timing belt will stay in position and not run off the pulley.  Which pulley and how many flanges will depend on the system’s design, including orientation, size, and distance between pulleys.

Timing Pulleys - CustomTiming belt drive pulleys can be made from many different materials, and the most common are made from lightweight aluminum, steel or plastic.  Standard pulleys may be modified into custom timing belt pulleys to suit specific application requirements:

  • Keyway in bore
  • D shaped bore
  • Custom timing pulley bore size
  • Clamp style hub instead of standard set screw
  • Two pulleys on one part
  • Different materials such as Acetal with a brass hub
  • Addition of plating or finishes

The custom pulleys shown to the right are cluster pulleys, have weight-reduction on the larger pulley, and are made from steel with zinc plating.

Various pulley groove and belt profiles exist, and they are not interchangeable due to differences in pitch, size, and tooth shape.  MXL, XL, L, 40DP, and T have a trapezoidal shape, while HTD and GT2 have a curvilinear groove profile.

Ondrives.US can supply standard pulleys, replacement pulleys to match your existing system and is also capable of making fully custom pulleys to your specifications up to 16” outer diameter.  Send us a request for quote with your requirements to receive a prompt quote, or contact Ondrives.US applications engineers for assistance in selecting timing pulleys and belts for your application.