SKF timing belts: pitches, lengths and widths

In PHG 60-3M-6 the middle block, 3M, is the pitch; the first number is the length and the last one the width, both in millimetres. PHG 145-H-075 and PHG 44-XL-025 follow the same order, but H and XL are inch pitches, and length and width are also expressed in that unit. A 075 is not 75 millimetres.

In PHG S8M-480-20 the profile comes first: S8M, then the length and finally the width. Although it shares the 8 millimetre pitch with other families, the tooth has a different shape and needs its own pulley. When a D appears before the length, the belt has teeth on both faces, and it is another reference.

A timing belt only meshes properly with pulleys of its own pitch and profile. Two tooth forms of similar pitch may look compatible when placed together by hand and fail within hours of running, with teeth sheared at the root. Before ordering, count the teeth of the removed belt and measure the distance across three or four teeth to confirm the pitch.

The belt width must not exceed that of the pulley, and at least one of the two pulleys must have flanges so the belt does not run off. If the teeth are worn on one side only, the pulleys are misaligned: correct it before fitting the new belt. Tension is set according to the drive; a timing belt is not tensioned like a V-belt.

Give us the complete PHG part number and the quantity. If the marking has worn off, state the pitch, the number of teeth and the width of the belt, and the number of teeth of each pulley. A photo of the teeth seen from the side lets us tell the profile apart. Saying whether the belt was double-sided and which machine it runs on completes the reference.