Environmental Engineering Reference
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vertical factor, and the distance factor, while increasing the effect of frequency
and adding reduction factors for couplings and asymmetry.
2.4.1 Revised Lifting Equations
The revised lifting equations are as follows (Waters et al. 1994):
RWL
=
×
×
×
×
×
×
LC
HM
VM
DM
AM
FM
CM
(5)
=
(
Load weight
)/(
RWL
)
LI
Table 2.4 lists the metrics for the variables in equation (5).
2.4.2 Definition and Constraints of the Factors in the Revised Guide
As in the 1981 guide, factors (multipliers) are defined and limitations are pre-
sented for each factor (Waters et al. 1994):
•
Horizontal location
. Measured from the midpoint of the line joining the
inner ankle bones to a point projected on the floor directly below the
midpoint of the hand grasps (i.e., load center) as defined by the large middle
knuckle of the hand. If significant control is required at the destination,
then
H
should be measured at both the origin and destination.
HM
=
(
25
/H )
in cm, or
HM
(
10
/H )
in inches
When
H
cannot be measured, it can be approximated using Table 2.5.
If
H
=
25 cm (10 in.), and the horizontal mul-
tiplier becomes 1.0. If
H >
63 cm (25 in.), then the horizontal multiplier
becomes 0.0.
≤
25 cm (10 in.), then set
H
=
Ta b l e 2 . 4
Factors for Revised Lifting Equations
Metric
U.S. Customary
Load Constant
LC
23 kg
51 lb
Horizontal Multiplier
HM
(25/H)
(10/H)
Vertical Multiplier
VM
1
−
(
0
.
003
|
V
−
75
|
)
1
−
(
0
.
0075
|
V
−
30
|
)
Distance Multiplier
DM
0
.
82
+
(
4
.
5
/
D
)
0
.
82
+
(
1
.
8
/
D
)
Asymmetric Multiplier
AM
1
−
(
0
.
0032 A
)
1
−
(
0
.
0032 A
)
Frequency Multiplier
FM
From Table 2.11
From Table 2.11
Coupling Multiplier
CM
From Table 2.12
From Table 2.12
Ta b l e 2 . 5
Horizontal Factor Calculations (
H
Cannot Be Measured)
Metric (Distances in cm)
U.S. Customary (Distances in inches)
H
=
+
W/
2For
V
≥
H
=
+
W/
2For
V
≥
20
25 cm
8
10 in.
H
=
+
W/
2For
V<
25 cm
H
=
+
W/
2For
V<
10 in.
25
10
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