Page 90 - The Tribology Handbook

Plain thrust bearings A15

Plain thrust washers are simple and occupy little axial
space. Their performance cannot be predicted with
W accuracy because their operation depends upon small-scale
surface undulations and small dimensional changes arising
from thermal expansion whilst running.
Thrust washers with radial grooves (to encourage hydro-
dynamic action) are suitable for light loads up to 0.5 MN/
m2 (75 lbf/in2), provided the mean runner speed is not less
than the minimum recommended below according to
lubricant viscosity.

Minimum sliding speeds to achieve
quoted load capacity

Minimum sliding speed = nnd,
Viscosity grade
IS0 3448 mls in/s
100 2.5 100
68 4 160
46 6 240

32 8 320

Suitable materials
0.5 mm (approx) white metal on a steel backing, overall
thickness 2-5 mm, with a Mild Steel Collar.
or
Lead bronze washer with a hardened steel collar.

Recommended surface finish for both combinations
Bearing 0.2-0.8 pm Ra
(8-32 pin cla)
Collar 0.1-0.4 pm Ra
(4- 16 pin cla)

I OVER IN EVENT OF OVERLOAD)

GROOVES OF UNIFORM CROSS-SECTION
SHOULD BE OPEN-ENDED UNLESS FED
WITH LUBRICANT AT HIGH PRESSURE
AI 5.1