Bearing dismounting

After dismounting bearings, handling of the bearings and the various methods available for this should be considered.
If the bearing is to be disposed of, any simple method such as torch cutting can be employed. If the bearing is to be reused or checked for the causes of its failure, the same amount of care as in mounting should be taken in dismounting so as not to damage the bearing and other parts.
Since bearings with interference fits are easily damaged during dismounting, measures to prevent damage during dismounting must be incorporated into the design.

It is recommended that dismounting devices be designed and manufactured, if necessary.
It is useful for discovering the causes of failures when the conditions of bearings, including mounting direction and location, are recorded prior to dismounting.

Dismounting method

"Table 15-7 Dismounting of cylindrical bore bearings"
"Table 15-8 Dismounting tapered bore bearings"
"Table 15-9 Dismounting of outer rings"
describe dismounting methods for interference fit bearings intended for reuse or for failure analysis.

The force necessary to remove bearings can be calculated using the equations given on "参考：軸受の圧入又は引抜きに要する力".

Table 15-7 Dismounting of cylindrical bore bearings

Inner ring dismounting methods

Descriptions

(a) Dismounting by use of a press (b) Dismounting by use of special tools (c) Dismounting by use of special tools (d) Dismounting using induction heater

Non-separable bearings should be treated carefully during dismounting so as to minimize external force, which affects their rolling elements. The easiest way to remove bearings is by using a press as shown in Fig. (a). It is recommended that the fixture be prepared so that the inner ring can receive the removal force. Figs. (b) and (c) show a dismounting method in which special tools are employed. In both cases, the jaws of the tool should firmly hold the side of the inner ring. Fig. (d) shows an example of removal by use of an induction heater : this method can be adapted to both mounting and dismounting of the inner rings of NU and NJ type cylindrical roller bearings. The heater can be used for heating and expanding inner rings in a short time.

Table 15-8 Dismounting tapered bore bearings

Inner ring dismounting methods

Descriptions

(a) Dismounting by use of a wedge (b) Dismounting by use of oil pressure (c) Dismounting by use of clamps (d) Dismounting by use of hydraulic nuts (e) Dismounting by use of locknuts (f) Dismounting by use of bolts (g) Dismounting by use of hydraulic nuts

Fig. (a) shows the dismounting of an inner ring by means of driving wedges into notches at the back of the labyrinth. Fig. (b) shows dismounting by means of feeding high pressure oil to the fitting surfaces. In both cases, it is recommended that a stopper (ex. shaft nuts) be provided to prevent bearings from suddenly dropping out. For bearings with an adapter sleeve, the following two methods are suitable. As shown in Fig. (c), fix bearings with clamps, loosen locknuts, then hammer off the adapter sleeve. This method is mainly used for small size bearings. Fig. (d) shows the method using hydraulic nuts. Small size bearings with withdrawal sleeves can be removed by tightening locknuts as shown in Fig. (e). For large size bearings, provide several bolt holes on locknuts as shown in Fig. (f ), and tighten bolts. The bearings can then be removed as easily as small size bearings. Fig. (g) shows the method using hydraulic nuts.

Table 15-9 Dismounting of outer rings

Outer ring dismounting methods	Description
(a) Notchs for dismounting (b) Bolt holes and bolts for dismounting	To dismount outer rings with interference fits, it is recommended that notches or bolt holes be provided on the shoulder of the housings.