Wire Ropes Under Bending and Tensile Stresses - Wire Ropes: Tension, Endurance, Reliability - page 305

Balance rope mass s b = 653 kg

Speed v = 5 m/s

Traction sheave diameter D = 40 d

Deflection sheave diam D = 40 d

Steel, groove radius r = 0.53 d

Analysis:
The load sequence is shown for a rope piece running over
the sheaves when the car drives from or to the ground floor.
Instead of the unknown rope force changing from both of
the traction sheaves at the beginning and the end of the trip,
the smallest occurring tensile force will be set in. As shown
in the figure on the left, the loading elements (bendings per
trip) is
The rope bending length is l = 8m.

loading sequence

3 x

loading elements

Rope tensile forces:
Force factors from Table 3.12
For roller guidance f s1 = 1.05
For rope efficiency g = 0.995 4 = 0.98 (Table 3.21 f S2 = (1 + 1/g)/2 = 1.01
For unequal forces in the parallel bearing ropes f S3 = 1.25
For acceleration or deceleration (on the whole bending length) f S4 = 1.15.
When the car starts from the ground floor, the rope tensile force (for a mean
loading of half of the nominal load) in the rope piece running over the sheaves is

f 1 f 2 f 3 f 4 þ G T g S ¼ ð F þ 0 : 5 Q þ s Þ g

n 2 n ¼ 3953 9 : 81

1 : 524 þ 400 9 : 81
2 5

:

5

S ¼ 12,220 N :

ð 3 : 96 Þ

When the counterweight is standing at its lowest position later on, the smallest
tensile force in the same rope piece is

S 0 ¼ G g
n

þ G T g

2 n ¼ 3,300 9 : 81

þ 400 9 : 81
2 : 5 5

S 0 ¼ 6,870 N

The difference in tensile force is

DS ¼ S S 0 ¼ 5 ; 350 N
DS = S ¼ 0 : 4378 :