Page 59 - NSK_CAT_E1102m_A7-141

BEARING HANDLING

In both cases, the claws of the tools must substantially 14.4.3 Dismounting of Bearings with Tapered Bores 14.5 Inspection of Bearings 14.5.2 Inspection and Evaluation of Bearings
engage the face of the inner ring; therefore, it is
advisable to consider the size of the shaft shoulder When dismounting relatively small bearings with 14.5.1 Bearing Cleaning After being thoroughly cleaned, bearings should be
or to cut grooves in the shoulder to accommodate the adapters, the inner ring is held by a stop fastened to When bearings are inspected, the appearance of the examined for the condition of their raceways and
withdrawal tools (Fig. 14.14). the shaft and the nut is loosened several turns. This is bearings should first be recorded and the amount and external surfaces, the amount of cage wear, the
The oil injection method is usually used for the followed by hammering on the sleeve using a suitable condition of the residual lubricant should be checked. increase in internal clearance, and degradation of
withdrawal of large bearings. The withdrawal tool as shown in Fig. 14.18. Fig. 14.16 shows one After the lubricant has been sampled for examination, tolerances. These should be carefully checked, in
is achieved easily by mean of oil pressure applied procedure for dismounting a withdrawal sleeve by the bearings should be cleaned. In general, light oil or addition to examination for possible damage or other
through holes in the shaft. In the case of extra wide tightening the removal nut. If this procedure is difficult, kerosene may be used as a cleaning solution. abnormalities, in order to determine the possibility for
bearings, the oil injection method is used together with it may be possible to drill and tap bolt holes in the nut Dismounted bearings should first be given a its reuse.
a withdrawal tool. and withdraw the sleeve by tightening the bolts as preliminary cleaning followed by a finishing rinse. Each In the case of small non-separable ball bearings, hold
Induction heating is used to remove the inner rings shown in Fig. 14.17. bath should be provided with a metal net to support the bearing horizontally in one hand, and then rotate
of NU and NJ types of cylindrical roller bearings. The Large bearings may be withdrawn easily using oil the bearings in the oil without touching the sides or the outer ring to confirm that it turns smoothly.
inner rings are expanded by brief local heating, and pressure. Fig. 14.19 illustrates the removal of a bottom of the tank. If the bearings are rotated with Separable bearings such as tapered roller bearings
then withdrawn (Fig. 14.15). Induction heating is also bearing by forcing oil under pressure through a hole foreign matter in them during preliminary cleaning, the may be checked by individually examining their rolling
used to mount several bearings of these types on a and groove in a tapered shaft to expand the inner raceways may be damaged. The lubricant and other elements and the outer ring raceway.
shaft. ring. The bearing may suddenly move axially when the deposits should be removed in the oil bath during the Large bearings cannot be rotated manually; however,
interference is relieved during this procedure so a stop initial rough cleaning with a brush or other means. the rolling elements, raceway surfaces, cages,
nut is recommended for protection. Fig. 14.20 shows a After the bearing is relatively clean, it is given the and contact surface of the ribs should be carefully
withdrawal using a hydraulic nut. finishing rinse. The finishing rinse should be done examined visually. The more important a bearing is,
carefully with the bearing being rotated while immersed the more carefully it should be inspected.
Inner Ring in the rinsing oil. It is necessary to always keep the The determination to reuse a bearing should be made
rinsing oil clean. only after considering the degree of bearing wear,
Withdrawal Claw the function of the machine, the importance of the
Oil bearings in the machine, operating conditions, and
Fig. 14.16 Removal of Withdrawal Fig. 14.17 Removal of Withdrawal the time until the next inspection. However, if any of
Fig. 14.20 Removal Using Hydraulic Nut the following defects exist, reuse is impossible and
Fig. 14.15 Removal of Inner Ring Using Fig. 14 .16 Sleeve Using Withdrawal Nut (1) Fig. 14.17 Sleeve Using Withdrawal Nut (2) replacement is necessary.
Fig. 14. 15 Induction Heater
(a) When there are cracks in the inner or outer rings,
rolling elements, or cage.

(b) When there is flaking of the raceway or rolling
elements.

(c) When there is significant smearing of the raceway
surfaces, ribs, or rolling elements.

(d) When the cage is significantly worn or rivets are
loose.

(e) When there is rust or scoring on the raceway
surfaces or rolling elements.

(f) When there are any significant impact or brinell
traces on the raceway surfaces or rolling elements.

(g) When there is significant evidence of creep on the
bore or the periphery of the outer ring.

(h) When discoloration by heat is evident.
( i ) When significant damage to the seals or shields of

grease sealed bearings has occurred.

Fig. 14.18 Removal of Adapter with Stop and Axial Pressure Fig. 14.19 Removal Using Oil Injection Hydraulic Pump A 123
A 122