Page 48 - needle bearings

Lubrication
NTN

Table 8.5 Criteria for selection of lubrication oil (Reference)
Bearing operating dn value ISO viscosity grades for lubrication oil (VG)
temperature ˚C Ordinary load Heavy load or shock load
ʵ30ʙ0 up to allowable rotational speed 22 32 46
up to 15000 46 68 100
0ʙ60 15 000ʙ80 000 32 46 68
80 000ʙ150 000 22 32 32
up to 15000 150 220
60ʙ100 15 000ʙ80 000 100 150 Remarks:
1. Subject to oil bath lubrication or circulating
80 000ʙ150 000 68 100ɹ150 lubrication.
100ʙ150 up to allowable rotational speed 320 2. Apply to NTN for other operating conditions
other than those specified in this Table.

8.2.3 Oil quantity Where,
3
Under an forced oil lubrication system, heat value Q: Oil quantity per bearing cm /min
generating from bearing, etc. is equal to the sum of heat K: Coefficient being determined by operating
value radiated from housing and heat value carried away temperature rise of oil (Table 8.6)
by lubrication oil. q : Oil quantity that can be determined from the chart
3
Where a standard housing is used, the oil lubrication cm /min (Fig.8.6)
quantity as a guideline can be determined by formula
(8.2). The radiated heat value differs depending on the 8.2.4 Fresh oil refilling interval
shape /profile of a housing used. It is therefore desirable Although it depends on actual operating
to determine the lubrication quantity best-suited to an conditions, oil quantity and the kind of lubrication oil
actual equipment by adjusting it from a value used, the fresh oil refilling interval as a guideline is
approximately 1.5 to 2 times as much as the lubrication around one year where bearings are lubricated with
rate determined by formula (8.2). In addition, Where the oil of 50˚C and lower temperature by the oil bath
lubrication quantity is calculated assuming that the method and is at least 3 months where bearings are
generated heat value is all carried away by the oil, with no lubricated with oil of 80 to 100˚C.
heat radiation from the housing, the oil quantity q can be For an important equipment it is desirable to
determined, assuming that the shaft diameter on 2nd monitor periodically the lubrication performance,
vertical line from the right side in (Fig. 8.6) Chart for cleanliness deterioration, etc. of the lubrication oil in
Determination of Oil Quantity q is d=0. use and to specify the fresh oil refilling interval under
the monitor data.
Q= Kɾq ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯(8.2)

Table 8.6 K-value
Discharged oil temperature -
lubricating oil temperature ˚C K
Load Pr Lubricating oil
10ɹ ɹɹɹɹ1.5 quantity q
N
15ɹ ɹɹɹɹ1 300 000 cm /min
3
20ɹ ɹɹɹɹ0.75 200 000
100 000 d
25ɹ ɹɹɹɹ0.6 Shaft diameter 100
1 70 000 mm 200
60 000 160
2 40 000 140 300
30 000 100 400
dnʷ10 4 4 20 000 40 80 500
3
60
5 15 000 0 20 600
6
700
10 000
8
10 800
8 000
15 900
6 000
Needle roller bearing 30 4 000 1,000
20
Auxiliary line 40 Auxiliary line 2 000 Auxiliary line 1,100
1,200
Fig. 8.6 Chart for determination of lubricating oil quantity

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