An angular contact bearing of a lathe spindle is subjected to a cyclic radial load
during a manufacturing process in an automated plant. During the cycle, the
bearing experiences a radial load of 95 N for 30 s at 2 500 rpm, 75 N for 45 s at
3 500 rpm, and 115 N at 3 100 rpm for 15 s. Assume a shaft diameter of 15 mm.
Specify an appropriate bearing that will be used for 4 000 hours life with a 98 %
reliability. Give the bearing code as well as the relative ratings and dimensions.
Equivalent load (Pe)
Pe = 89.71N (Equivalent load/ mean cubic load)
Life of component = 4000h.
L10 Life = 6ON L10H/10⁶
N = N1 + N2 + N3 = 1250 + 2625 +775
N = 4650
+ ²N+IN = N
L10 Life = 60 × 4650 × 4000/10⁶
= 1116 milion revolutions
so, dynamic Load carrying capacity; (c)
c = Pe (L10)⅓
c = 89.71 (1116)⅓ = 930.52N