SKF power transmission components: PHH hubs

The letters after the prefix name the shape of the hub. PHH W12 and PHH WH12 are weld-on hubs, with different outside geometry; PHH SM12 and PHH BF12 are bolt-on hubs, with a flange. The number is the size of the taper bushing it takes, and it is the same detail to use when ordering the bushing.

The hub does not include the bushing. The bushing is chosen afterwards, with that size and the bore that suits the shaft. The same line lists other references that do not follow this logic, such as BT 515-0-13, which is a ball unit for transfer tables: they are identified by their complete code.

The weld-on hub is used when the part is made in the workshop: it is centred, tacked and welded evenly so the taper does not distort. Welding on one side only or with a heavy bead twists the seat, and the bushing then does not close properly. It is worth checking the centring before the final bead.

The bolt-on hub is chosen when the part cannot be welded or has to be removable. There the bolt circle, the number of bolts and the spigot diameter matter. In both cases the hub must sit square to the shaft: any error shows up later as wobble of the mounted part.

Send us the complete PHH code and the quantity. If you do not have it, state whether the hub is welded or bolted, which taper bushing size you want to use and the shaft diameter. Tell us which part will be mounted, its diameter and weight, and the space there is for the hub. If you also need the bushing, give us the shaft and keyway dimensions.