Page 21 - The Tribology Handbook

A2 Selection of journal bearings

V, ft/min
'0 lop 1000 10000
1000
I I I 1100 000
10 000
' O O m

1000
.-
2
d
n
3
100

' \ I
0.1 I I
0 5 10
MAX. DEFLECTION I ,CH WAY, DEGREES
Selection of rubbing plain bearing materials for Selection of flexure bearings by external load
bushes with oscillatory movement, by maximum pressure and the required deflection. If the
pressure and maximum value of average sliding speed. centre of rotation does not have to be Held constant,
Rolling bearings in an equivalent arrangement usually single strips or cables can be used
can carry about IO MNIm2

Selection of journal bearings with oscillating movement for special environments
or performance

Dirt and External Wet and Type of
Type of bearing Low friction High temp. Low temp. dust Vibration humid bearang
Rubbing plain Good with Good to Very good Good but Very good Good but
bearings PTFE the temp. sealing shaft must
limit of helps be incor-
material rodible
Porous metal Good Poor since Fair; Sealing is Good Good
plain bearings lubricant friction essential
oil oxidises can be
impregnated high
Rolling bearings Very good Consult Good Sealing is Poor Good with
makers essential seals
above
150°C
Rubber bushes Elastically Poor Poor Excellent Excellent Excellent
stiff

Strip flexures Excellent Good Very good Excellent Good ; @
Excellent watch
corrosion

Knife edge Verygood Good Good Good Poor Good ;
pivots watch

A2.3