3 step 3: partial duration of service, s, Hours, Tk s ∗ ∗ = 2 . 1 – R&M Materials Handling WIRE ROPE HOISTS Service User Manual
Page 125: 4 step 4: actual duration of service, s [hours
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8.3.1 STEP 1: Operating hours per inspection interval, T
i
60
2
∗
∗
∗
∗
∗
=
V
J
T
N
H
T
i
-
H = average hoisting height [m]
-
N = number of work cycles per hour [cycles/h]
-
T = daily working time [h]
-
V = hoisting speed [m/min]
-
J = working days during inspection interval [days]
8.3.2 STEP 2: Actual load spectrum factor per inspection interval, K
mi
Load spectrum factor can be calculated using following table:
Load %
Lifting time %
Factor k
3
Load spectrum
factor
100 %
*
1
=
+
+
80 %
*
0.51
=
+
+
60 %
*
0.22
=
+
+
40 %
*
0.06
=
+
+
20 %
*
0.01
=
+
+
0 %
*
0
=
=
=
Sum: 100%
Sum:
Divide by 100:
/100 =
Load spectrum factor, K
mi
:
8.3.3 STEP 3: Partial duration of service, S
i
[hours]
When the load spectrum factor of inspection interval K
mi
and the operating hours per inspection interval T
i
are identified, the Partial duration of service, S
i
can be calculated as follow:
i
mi
i
T
K
S
∗
∗
= 2
.
1
8.3.4 STEP 4: Actual duration of service, S [hours]
Actual duration of service can be calculated when the earlier partial duration of inspection intervals is
known.
i
S
S
S
S
+
+
+
=
...
2
1