403 OF ENGINEERING FOHMULÆ.
Coefficients of Friction in Axles.
Bearing.
097
Bell-metal
07
05
18
l . .1 — — !
vitæ j — — j
Bell.aietal ..
Cast iron ..
Wrought iron
Cast iron
Bell metal
Lignum vitie
Cast iron
Lignum >
Frictional Resistance ok Shaftixo. (Webber.)
•09
•h ; -
— -of
•049
Cast iron ..
Wrought iron
Cast jron ..
Lignum vitæ
II :
I) :
R :
K = Coefficient of friction.
w—Work absorbed in ioot-lbs.
p = Weight of shafting and pulleys + resultant stress
of belts.
Horse-power absorbed.
Diameter of journals in inches.
Number of revolutions per minute.
Ordinary oiling. .
. -0182 P D
Continuous oiling.
•0112 P i>.
•000000339 PDB.
■044.
AVj — • __________ ■
H = -OC0000556 PDH
As a ron-h approximation, 100 feet of shafting, 3 inches dm-
mtK Xking 120 revulutions per minute, requires 1 ijQjse-
power' Pkessure on Bbabums of Shafting.
Pressure on bearings should not exceed 750 lbs. per square
lnFÖr™S of uprS shafts, Fairbairn limits the pressure
tOCast-konPteMtog^ wear well if the pressure does not
exceed 100 lbs. per square inch, or velocity 150 feet per
minute. n o
& 1) Ä