Page 58 - NSK_CAT_E1102m_A7-141

BEARING HANDLING

Although the bearing temperature can generally be mounting, or excessive friction of the seals. 14.4 Dismounting 14.4.2 Dismounting of Bearings with Cylindrical
estimated by the temperature of the outside surface of In the case of high speed operation, an incorrect Bores
the housing, it is more desirable to directly measure selection of bearing type or lubricating method may A bearing may be removed for periodic inspection or If the mounting design allows space to press out the
the temperature of the outer ring using oil holes for also cause an abnormal temperature rise. for other reasons. If the removed bearing is to be used inner ring, this is an easy and fast method. In this
access. The sound of a bearing may be checked with a noise again or it is removed only for inspection, it should be case, the withdrawal force should be imposed only on
The bearing temperature should rise gradually to locater or other instruments. Abnormal conditions are dismounted as carefully as when it was mounted. If the the inner ring (Fig. 14.12). Withdrawal tools like those
the steady state level within one to two hours after indicated by a loud metallic sound, or other irregular bearing has a tight fit, its removal may be difficult. The shown in Figs. 14.13 and 14.14 are often used.
the operation starts. If the bearing or its mounting noise, and the possible cause may include incorrect means for removal should be considered in the original
is improper, the bearing temperature may increase lubrication, poor alignment of the shaft and housing, design of the adjacent parts of the machine. When Bolt
rapidly and become abnormally high. The cause of this or the entry of foreign matter into the bearing. The dismounting, the procedure and sequence of removal
abnormal temperature may be an excessive amount possible causes and measures for irregularities are should first be studied using the machine drawing Plug
of lubricant, insufficient bearing clearance, incorrect listed in Table 14.2. and considering the type of mounting fit in order to Fig. 14.10 Removal of Outer Ring with Dismounting Bolts
perform the operation properly.
Table 14. 2 Causes of and Measures for Operating Irregularities
14.4.1 Dismounting of Outer Rings
Irregularities Possible Causes Measures
In order to remove an outer ring that is tightly fitted,
Abnormal Load Improve the fit, internal clearance, preload, position of housing first place bolts in the push-out holes in the housing
shoulder, etc. at several locations on its circumference as shown in
Fig. 14.10, and remove the outer ring by uniformly
Loud Metallic Incorrect mounting Improve the machining accuracy and alignment of shaft and housing, tightening the bolts. These bolt holes should always
Sound (1) Insufficient or improper Lubricant accuracy of mounting method. be fitted with blank plugs when not being used for
dismounting. In the case of separable bearings, such
Replenish the lubricant or select another lubricant. as tapered roller bearings, some notches should be
made at several positions in the housing shoulder, as
Contact of rotating parts Modify the labyrinth seal, etc. shown in Fig. 14.11, so the outer ring may be pressed
out using a dismounting tool or by tapping it.
Noise Flaws,corrosion,or scratches on Replace or clean the bearing, improve the seals, and use clean
raceways lubricant.
Loud Regular
Sound Brinelling Replace the bearing and use care when handling bearings.

Flaking on raceway Replace the bearing.

Excessive clearance Improve the fit, clearance and preload.

Irregular Penetration of foreign particles Replace or clean the bearing, improve the seals, and use clean
Sound lubricant.

Flaws or flaking on balls Replace the bearing.

Fig. 14.11 Removal Notches

Excessive amount of lubricant Reduce amount of lubricant, select stiffer grease.

Insufficient or improper lubricant Replenish lubricant or select a better one.

Abnormal Temperature Abnormal load Improve the fit, internal clearance, preload, position of housing
Rise Incorrect mounting shoulder.

Improve the machining accuracy and alignment of shaft and housing,
accuracy of mounting, or mounting method.

Creep on fitted surface, excessive seal Correct the seals, replace the bearing, correct the fitting or mounting.
friction

Brinelling Replace the bearing and use care when handling bearings.

Vibration Flaking Replace the bearing.
(Axial runout) Incorrect mounting
Correct the squareness between the shaft and housing shoulder or side
of spacer.

Penetration of foreign particles Replace or clean the bearing, improve the seals.

Leakage or Too much lubricant, Penetration by Reduce the amount of lubricant, select a stiffer grease. Replace the Fig. 14.12 Removal of Inner Fig. 14.13 Removal of Inner Ring Using Fig. 14.14 Removal of Inner Ring Using
Discoloration of foreign matter or abrasion chips bearing or lubricant. Clean the housing and adjacent parts. Fig. 14.1 2 Ring Using a Press Fig. 14.13 Withdrawal Tool (1) Fig. 14.14 Withdrawal Tool (2)

Lubricant

Note (1) Intermittent squeal or high-pitch noise may be heard in medium- to large-sized cylindrical roller bearings or ball A 121
A 120 bearings that are operating under grease lubrication in low-temperature environments. Under such low-temperature
conditions, bearing temperature will not rise resulting in fatigue nor is grease performance affected. Although
intermittent squeal or high-pitch noise may occur under these conditions, the bearing is fully functional and can
continue to be used. In the event that greater noise reduction or quieter running properties are needed, please contact
your nearest NSK branch office.