This Rigger's Handbook is dedicated to Theodore C - Igor Chudov

Lift Engineering
FINDING THE HYPOTENUSE
c
b
LOAD ANGLE FACTORS
5,000 lbs. 5,000 lbs.
H
TENSION IN OVERHEAD HOISTS
OFF-SET CENTER OF GRAVITY (SHARE OF THE LOAD)
OFF-LEVEL LIFT POINTS
a
L
10,000 lbs.
H = 10' L = 15'
A B
2'
6'
6,000 lbs.
A B
L1
3' 7'
H1
10,000 lbs.
H2
D1 D2
L2
6'
To find c (hypotenuse)
Given: a2 + b2 = c2 Example: 42 + 32 = c2; 16 + 9 = c2; 25 = 5
—
L
= LAF (Load Angle Factor)
H
Example:
15
— = 1.5 (LAF)
10
Tension in L = —
L
x L's share of the load
H
Tension in L =
15
— x 5,000;
10
1.5 x 5,000 Ten. = 7,500 lbs.
6
Ten. in A = — x 3,000 Ten. in A = 9,000 lbs.
2
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142
(As load moves, tension changes)
Inverse Proportion To Distance
Lift Point A
Lift Point B
7 + 3 = 10, — = .70
10
7 + 3 = 10, — = .30
10
.70 x 10,000 = 7,000 lbs. .30 x 10,000 = 3,000 lbs.
W x D2 x L1
TL1 = (D2 x H1) + (D1 x H2)
W x 1 x L2
TL2 = (D2 x H1) + (D1 x H2)
YOUR SLING AND RIGGING SPECIALIST
LEGEND
W = Load Weight
L1 = Length Leg 1
L2 = Length Leg 2
H1 = Vertical Height 1
H2 = Vertical Height 2
D1 = Horizontal Distance 1
D2 = Horizontal Distance 2