Wire Ropes Under Bending and Tensile Stresses - Wire Ropes: Tension, Endurance, Reliability - page 315

Table 3.21 Wire rope efficiency in %
D/d S/d 2 = in N/mm 2
10 50 100 150 200 250
10 92.8 96.8 97.3 97.4 97.5 97.6
12.5 94.6 97.6 98.0 98.1 98.2 98.2
16 96.1 98.3 98.5 98.6 98.7 98.7
20 97.1 98.7 98.9 99.0 99.0 99.0
25 97.9 99.0 99.2 99.2 99.3 99.3
32 98.5 99.3 99.4 99.5 99.5 99.5
40 98.9 99.5 99.6 99.6 99.6 99.6
50 99.2 99.6 99.7 99.7 99.7 99.7
63 99.4 99.7 99.8 99.8 99.8 99.8
Rope efficiency is in 90 % of the cases even for the unfavourablest rope construction higher than
that of the table for ropes lubricated with diameter d C 5 mm; for not too deep temperature for
metallic sheaves with roller bearings and sliding seals

temperatures between 20 and -50 C with various lubricants. They found that
appropriate lubricants had less than a double rope force loss in contrast to room
temperature. However, when inappropriate lubricants were used, a multiple rope
force loss had to be expected. No research has yet been done on the rope force loss
for sheaves with grooves made of synthetic material and for rope side deflection.

3.5.2 Rope Drive, Efficiency

3.5.2.1 Stationary Sheaves

For a rope running over n stationary sheaves (that means with the same peripheral
speed) the efficiency is

g stat ¼ g n : ð 3 : 107 Þ

3.5.2.2 Hanging Sheave

The efficiency for a rope running over a hanging sheave—as seen in Fig. 3.85 —is
by definition the ratio of the half force Q and the rope force S

g h ¼ Q = 2
S 1

¼ S 1 þ S 2
2 S 1

: