Wire Ropes Under Tensile Load - Wire Ropes: Tension, Endurance, Reliability - page 115

Fig. 2.28 Rotation of a
bottom sheave

r 1 r 1

d
rope

diameter

h

h o

L

bottom
sheave

r 2

a

M rev ¼ r 1 r 2 sin u
h 0

Q tot ¼ r 1 r 2 sin u
h 0

ð Q 0 þ Q þ G rope = 2 Þ ð 2 : 79 Þ

with
Q 0 + Q weight force of the bottom sheave and the load
G rope weight force of all wire rope traces
These weight forces will be reduced by the buoyancy, if the installation is
situated under water.
The torque of all the wire rope traces can be calculated with Eq. ( 2.77 ) and the
constants of Table 2.6 . Then for untwisted ropes (x 0 = 0) the mean torque of the
bearing wire rope traces is

:

M rope ; 50 ¼ c 1 d Q 0 þ Q þ G rope = 2 ð 2 : 80 Þ

The torque, that is not exceeded in 90 % of the cases, is

M rope ; 90 ¼ ð c 1 þ 1 ; 282s 1 Þ d Q 0 þ Q þ G rope = 2 ð 2 : 80a Þ

with
c 1 from Table 2.6

s 1 from Table 2.6 .

The bottom sheave rotated with the angle u is in equilibriom for