
A sheave is the grooved wheel a V-belt runs in, and every listing here answers four questions about one: which belt section its grooves are cut for, how many grooves it has, how big it is, and how it attaches to the shaft. The group splits three ways. V-belt sheaves cover the classical and narrow sections in one to eight grooves, finished bore or bushed. Fractional horsepower sheaves cover the light 3L, 4L and 5L drives in one and two grooves. Synchronous belt pulleys are the toothed alternative where the drive must not slip at all, listed by tooth count and belt section rather than by diameter. Variable pitch types sit inside the first two groups and let the ratio be adjusted by opening the groove.
Also known as: sheaves, v-belt pulleys, drive pulleys, belt pulleys
Series in this category
Related guides: V-belt sheave sizes, FHP V-belt sizes, Split taper bushing sizes, Q-D bushing sizes, Cross-reference help
| Specification | What it means |
|---|---|
| Belt section | The groove profile: 3L, A, B, C, 3V, 5V or 8V, or a combination groove such as A and B or B and 5V that takes more than one. |
| Number of grooves | From one to eight. It must equal the belt count in the drive and match the other sheave. |
| Bore type | Finished bore, finished with keyway and setscrew, rough bore, Split Taper bushed or Q-D bushed. |
| Bushing used and bushing bore range | Which bushing letter the hub takes and the span of shaft sizes that bushing covers, such as 0.500 to 1.625 inch. |
| Pitch diameter and datum diameter | The effective diameter for each section the sheave is grooved for. The drive ratio is worked out on these, not on the outside diameter. |
| Material | Cast iron, G3000 gray iron, ductile iron or steel. Cast iron sets the 6,500 feet per minute belt speed limit. |
In this group a sheave is grooved for a V-belt and drives through the sides of the belt wedging into the groove, while a synchronous pulley is toothed and drives through teeth meshing with the belt. The words are often used interchangeably in the trade, but the parts are not interchangeable: a V-belt will not drive on a toothed pulley and a synchronous belt will not drive in a V groove.
Some can, and the listing says so. A combination groove is cut to accept more than one section: a B5V sheave takes A, B and 5V belts, and the AK and BK families are listed for both 4L or A and, where the table marks it, 3L. Where a sheave is not listed as a combination groove it takes one section only, and TB and B sheaves in particular cannot be used with 5V belts.
They have to be grooved for the same belt section and carry the same number of grooves, but they do not have to mount the same way. It is common for the motor sheave to be a finished bore and the driven sheave to be bushed, or for the two to take different bushing letters, because the shafts they sit on are different sizes.
When the grooves have worn. A worn groove lets the belt ride lower and touch the bottom, so a new belt cannot wedge properly, slips, and fails early. Fitting new belts to worn sheaves is one of the most common causes of premature belt failure, so the sheave is replaced along with the set.
| Pulley construction | Solid, web or arm and spoke. Heavy shock loads call for a web type rather than a standard arm type. |
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