Page 339 - Analysis and Design of Machine Elements

Solution Rolling Contact Bearings 317
Since the bearing has not been selected, bearing parameters C , e, X, Y are unknown.
0
Here a simple trial-and-error method is used. We initially selected bearings 6215 and
6315.

Steps Computation Results
6215 6315

1. Decide the basic From a manufacturer’s catalogue or C = 66 000 N C = 113 000 N
dynamic and static load Table 11.2, the basic dynamic and
0
0
rating of selected static load rating of selected bearings C = 49 500 N C = 76 800 N
bearings can be obtained.
A 2880
2. Decide the ratio of Bearing 6215 = = 0.058 A/C = 0.058 A/C = 0.0375
0
0
A/C C 0 49500
0
A 2880
Bearing 6315 = = 0.0375
C 76800
0
3. The value of e The value of e can be obtained from e = 0.261 e = 0.234
Table 11.1 by interpolating.
A 2880
4. Calculate the ratio of = = 0.576 0.576 > e 0.576 > e
A/R R 5000
5. Decide X and Y X and Y canbeselectedfrom X = 0.56 X = 0.56
Table 11.1 by interpolating.
Y = 1.699 Y = 1.895
6. Calculate equivalent From Eq. (11.14) P = 7693 N P = 8258 N
load P
P = XR + YA
Bearing 6215
P = XR + YA =0.56 × 5000 +
1.699 × 2880 = 7693 N
Bearing 6315

P = XR + YA =0.56 × 5000 +
1.895 × 2880 = 8258 N
7. Compute the bearing For light-to-moderate impact, select 4060 h 16 475 h
life f = 1.2. < 5000 h > 5000 h
p
From Eq. (11.15), the design life of
bearing 6215 is
( )
10 6 f C
t
L = =
10h 60n f P
p
10 6 ( 1 × 66000 ) 3
= 4060 h
60 × 1500 1.2 × 7693