Timing Pulley Flanges

Timing pulley flanges are press on rims that keep a synchronous belt tracking on the pulley teeth instead of walking off the edge. This collection stocks 770 flange sizes from 0.42 to 14.6 in outside diameter in aluminum, steel, and stainless steel, covering the pitch families in the pulley and bar stock collections.

Flanges are required when shaft parallelism cannot be held exactly: long center distances, vertical shafts, and reversing drives all push the belt sideways. Standard practice is to flange at least one pulley in the drive, usually the smaller one, or both pulleys on long unsupported spans.

Frequently Asked Questions

When does a timing pulley drive need flanges?

Whenever the belt can drift axially. Misaligned or non parallel shafts, vertical drives, long center distances, and reversing loads all walk the belt sideways. Flanging one pulley, typically the smaller, contains the drift; severe cases flange both.

How do I size a flange for a pulley?

Match the flange inside diameter to the pulley flange seat diameter, and check the flange outside diameter clears the belt back by a comfortable margin. Product pages list inside diameter, outside diameter, and thickness for each size.

How are flanges attached to a pulley?

Press fit onto a machined seat, then typically staked or spun over to lock. On bar stock pulleys, machine the seat as part of finishing the blank, press the flange square, and stake in three or more places.