Page 52 - The Tribology Handbook

Ring and disc fed journal bearings A8

1.5 2.0
1.5
1.0 Specific Load = I .5 MN/m2
0.9
0.8 1 .o Bearing length/diameter = I
3 0.7 0.9 Ambient temperature = 2ooC (for ambient temperature
:0.6 0.8 4ooC take 80% of losses shown)
20.5 0.7 Clearance ratio = 0.001 mm/mm (for clearance ratio of
0.6 P
20.4 0.0015 mm/mm take 95% of losses shown)
0.5= Heavy turbine oil (IS0 VG68 or SAE 20) (for light
$0.3 0.4
g turbine oil take 85% of losses shown)
P 0.3 Heat dissipating factor as Fig. 8.9 (for erect of heat
0.2
dissipating factor see Fig. 8.4)
0.2 The power loss will be higher for assemblies incorporating
thrust location - see Fig. 8.6
0.1
100 2010 300 400500 8001000 2000 3000
JOURNAL SPEED, rev/min
Fig. 8.3. Guide for power loss in self-contained bear-
-
ings

8 9 10 15 Ibf/in2 20 25 30 35 40

0.15
0.2
0.25 0.30
I9 0.1
a= LOCATING THRUST SPECIFIC LOAD, MN/rnZ
4
2
W
Fig. 8.5. Reduced limiting speed where assembly
includes thrust location
Ibf/in2

Fig. 8.4. Showing how power loss in self-
contained bearings (without thrust) is affected
by heat dissipating factor KA

The heat dissipating casing area A and/or the heat trans-
fer coefficient K may both differ from the values used to
derive the load capacity and power loss design charts.
Figure 8.4 shows how change in KA affects power loss.
*The ratio
New heat dissipating factor KA .
in Fig. 8.4
Heat dissipating factor
is given by Fig. 8.6. Increased power loss with thrust location
K for actual air velocity (Fig. 8.9(b)) actual casing area {single thrust plain washer - for typical dimensions
-X
18 (for still air) casing area (Fig. 8.9(a)) see Fig, 8.7)
A8.3