Civil Engineering Reference
In-Depth Information
TABLE 46.1 Horizontal Multiplier
H (in.)
HM
H (cm)
HM
10
1.00
25
1.00
11
0.91
28
0.89
12
0.83
30
0.83
13
0.77
32
0.78
14
0.71
34
0.74
15
0.67
36
0.69
16
0.63
38
0.66
17
0.59
40
0.63
18
0.56
42
0.60
19
0.53
44
0.57
20
0.50
46
0.54
21
0.48
48
0.52
22
0.46
50
0.50
23
0.44
52
0.48
24
0.42
54
0.46
25
0.40
56
0.45
.
25
0.00
58
0.43
60
0.42
63
0.40
63
0.00
.
46.4.2 Vertical Component
46.4.2.1 Definition and Measurement
Vertical location (V) is defined as the vertical height of the hands above the floor. V is measured vertically
from the floor to the midpoint between the hand grasps, as defined by the large middle knuckle. The
coordinate system is illustrated in Figure 46.1.
46.4.2.2 Vertical Restrictions
The vertical location (V) is limited by the floor surface and the upper limit of vertical reach for lifting
(i.e., 70 in. or 175 cm). The vertical location should be measured at the origin and the destination of
the lift to determine the travel distance (D).
46.4.2.3 Vertical Multiplier
To determine the vertical multiplier (VM), the absolute value or deviation of V from an optimum height
of 30 in. (75 cm) is calculated. A height of 30 in. above the floor level is considered “knuckle height” for a
worker of average height (66 in. or 165 cm). The VM is (1
(0.0075
j
V
30
j
)) for V measured in
2
2
inches, and VM is (1
)) for V measured in centimeters.
When V is at 30 in. (75 cm), the VM is 1.0. The value of VM decreases linearly with an increase or
decrease in height from this position. At floor level, VM is 0.78, and at 70 in. (175 cm) height VM is
0.7. If V is greater than 70 in., then VM
(0.003
j
V
75
j
2
2
0. The VM value can be computed directly or determined
¼
from Table 46.2.
46.4.3 Distance Component
46.4.3.1 Definition and Measurement
The distance variable (D) is defined as the vertical travel distance of the hands between the origin and
destination of the lift. For lifting, D can be computed by subtracting the vertical location (V) at the
origin of the lift from the corresponding V at the destination of the lift (i.e., D is equal to V at the desti-
nation minus Vat the origin). For a lowering task, D is equal to Vat the origin minus Vat the destination.
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