Machinery's Handbook, 31st Edition
Thrust Bearings
2431
9) Pitch-line velocity.
. 12 377 3600 11 300ft per min # = = ,
U
10) Oil leakage factor.
. Y 275 L =
From Fig. 8,
11) Film-thickness factor.
. 11,300 2 75 18 5 75 10 404 4150 6 # # # # = = .
K
12) Minimum film thickness.
From Fig. 9, . h = 22mils 13) Friction power loss. From Fig. 10, J = 260, then . .
P 8 79 10 6 5 5 78 260 11,300 18 91 hp f 13 2 # # # # # # # = = −
14) Required oil flow.
. 35 50 424 91 220gpm # # . . =
=
Q
See footnote on page 2418. 15) Shape factor.
. 17 7 8 5 578 0963 . 2 2 =
# # = −
Y
S
16) Oil-flow factor.
From Fig. 11,
. Y 061 G =
where D 1 /D 2 = 0.41 17) Actual oil film flow. .
. 17 7 89 10 6 0005 17 3600 061 0963 267gpm F 4 3 2 # # # # # # # = − = − . . .
Q
Because calculated film flow exceeds required oil flow, chamfers are not necessary. However, if film flow were less than required, suitable chamfers would be needed. Table 2. Taper Values for Tapered Land Thrust Bearings Pad Dimensions, Inches Taper, Inch a × b δ 1 = h 2 − h 1 (at ID) δ 2 = h 2 − h 1 (at OD) 1 ⁄ 2 × 1 ⁄ 2 0.0025 0.0015 1 × 1 0.005 0.003 3 × 3 0.007 0.004 7 × 7 0.009 0.006 Tilting Pad Thrust Bearing Design.— The following steps define the performance of a tilting pad thrust bearing, one section of which is shown in Fig. 12. Although each bearing section is wedge shaped, as shown at the right below, for the purposes of design calcula tion, it is considered to be a rectangle with a length b equal to the circumferential length along the pitch line of the section being considered and a width a equal to the difference in the external and internal radii, as shown at left in Fig. 12. The location of the pivot shown in Fig. 12 is optimum. If shaft rotation in both directions is required, however, the pivot must be at the midpoint, which results in little or no detrimental effect on the performance.
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