Bearings with a tapered bore
Dismounting bearing on a tapered journal
Small and medium-sized bearings on a tapered journal can be dismounted using conventional pullers, which engage the inner ring. Preferably a self-centring puller should be used to avoid damage to the bearing seat (fig 1). Bearings on tapered seats normally loosen very quickly. Therefore, it is necessary to provide a stop of some kind, a lock nut for example, to prevent the bearing from being completely withdrawn from the shaft.
The dismounting of large bearings from tapered journals is greatly eased if the oil injection method is employed. After injecting pressurised oil between the mating surfaces, the bearing will separate suddenly from its seat. A stop must therefore be provided, for example, a shaft nut or end plate, to limit the axial movement of the bearing to somewhat more than the drive-up distance (fig 2).
Dismounting bearing on an adapter sleeve
Small and medium-sized bearings on an adapter sleeve and smooth shafts can be dismounted by hammer blows directed to a drift (fig 3) until the bearing becomes free. But first the sleeve nut has to be loosened a few turns.
Small and medium-sized bearings on an adapter sleeve and stepped shafts against a support ring can be dismounted by using a dolly abutting the sleeve nut, which has been released by a few turns (fig 4).
Dismounting large bearings from an adapter sleeve with a hydraulic nut has proved easy to do. To use this technique however, the bearing must be mounted against a support ring (fig 5). If the sleeves are provided with oil supply ducts and distributor grooves the dismounting becomes easier because the oil injection method can be employed.
Dismounting bearing on a withdrawal sleeve
When dismounting bearings on withdrawal sleeves, the axial locking device - a locking nut, end cover etc. - has to be removed.
Small and medium-sized bearings can be dismounted using a lock nut and a hook or impact spanner to free the bearing (fig 6).
The preferred means of dismounting large bearings is by using a hydraulic nut (fig 7). If the threaded section of the sleeve protrudes beyond the shaft end or shaft shoulder, a support ring having the greatest possible wall thickness should be inserted in the sleeve bore to prevent distortion and damage to the thread when the hydraulic pressure is applied. SKF recommends providing a stop behind the hydraulic nut, e.g. through an end plate at the shaft end (fig 8). The use of a stop prevents the withdrawal sleeve together with the hydraulic nut from being completely withdrawn from the shaft if the sleeve would separate suddenly from its seat.
Withdrawal sleeves for large bearings are generally provided with distributor ducts and grooves for the oil injection method to save considerable time when mounting as well as dismounting large bearings (fig 9).
Detailed instructions for a selected bearing can be found at skf.com/mount.