LGH Technical User Guide - Page 152



ACRA Enterprises, Inc. 800-992-0689 www.acratech.com
ACRA Enterprises, Inc. 800-992-0689 www.acratech.com
Load Share - LEFT end
Load Share
- LEFT end
(D2 /SPAN)
x TW = LEFT
RIGHT
RIGHT
Lift Point
Lin
e
SPAN
SPAN
Angle
RIGHT
LiftRIGHT
Point
LiftCenter
Point of
ll
Pu
LEFT
Lift Point
LEFT
D2
D2
e
Lin
D1
D1
Total Load
A single sheave block used to
change load line direction can
be subjected to total loads
weight being lifted or pulled.
The total load value varies with
the angle between the incoming and departing lines to the
block.
(D2 /SPAN) x TW = LEFT
LEFT
LEFT
Blocking
Load
Block Loading
Pu
ll
Determine Load Share /
Find the centre of gravity
-- Page 42 --
Total Load
2000 kg
NOTE: The total load at the pulley
attachment point is always greater
than the weight of the load being
lifted!
Gravity
Center of
Gravity

Locate the CG from the LEFT lift point (D1)
Locate the(WR
CG from
thex LEFT
lift=point
/ TW)
SPAN
D1 (D1)
WL
WL
(WR / TW) x SPAN = D1
D1
D1
LEFT
Lift Point
LEFT
SPAN
SPAN
Lift Point
Line pull
requires
1000 kg
D2
D2
CG = Center of Gravity
D1 = Distance from LEFT lift point to CG
CG =
= Distance
Center offrom
Gravity
D2
RIGHT lift point to CG
D1 =
= Distance
Distance between
from LEFTlift
liftpoints
point to CG
SPAN
D2
= LEFT
Distance
RIGHT lift point to CG
WL =
End from
Weight
SPAN
=
Distance
between
WR = RIGHT End Weight lift points
WL
=
LEFT
End
Weight
TW = Total Weight (WL+WR)
WR = RIGHT End Weight
WL + WR = TW
TW =WL
Total
Weight
(WL+WR)(of load share )
/ TW
= Percentage
RIGHT
LiftRIGHT
Point
LiftCenter
Point of
Line pull
requires
1000 kg
WL + WR = TW
WL / TW = Percentage (of load share )
Gravity
Center of
Gravity
-- Page 41 --- Page 41 --
Total Load = Line Pull x Angle Factor
TECHNICAL INFO
Example: 5000 kg line pull at 40° (5000 x 1.87) a total load of 9,350 kg
Angle
100°
110°
120°
130°
135°
140°
150°
160°
170°
180°
--
Factor
1.29
1.15
1.00
0.84
0.76
0.68
0.52
0.35
0.17
0
--
Mechanical Advantage
Weight to be lifted
Pull Required =
Mechanical Advantage
1 part of line
To move a load
on a LEVEL plane
F= CF x W
F
F
To move a load on an
UPHILL incline
L
R
To move a load on a DOWNHILL incline:
W = Weight of load
Coefficient
CF =
of friction
F = Force required
to move load
H = HEIGHT
Never include the “pulling
end” of the line
0
0 1
2
Line pull
500 kg
Line pull
1,000 kg
H
2 parts of line
ONLY the parts of line
supporting the load are
considered.
0
v5 - 5/16
Pulling
Forces
Pulling Force
LEGEND
1
1000 kg
-- Page 44 --
ACRA Enterprises, Inc. 800-992-0689 www.acratech.com
Factor
2.00
1.99
1.97
1.93
1.87
1.84
1.81
1.73
1.64
1.53
1.41
40º
©2016 ACRA Enterprises, Inc - all rights reserved
Block Loading
Angle

10°
20°
30°
40°
45°
50°
60°
70°
80°
90°
Total Load
1870 kg
1000 kg
WR
WR
1000 kg
1000 kg
-- Page 43 --
(Vertical distance in feet)
R = RUN
(Horizontal distance in feet)
These coefficient of friction values
apply to hard, clean surfaces sliding
against each other. These may not
directly relate to your application due
to actual surface conditions.
CF
0.05
0.10
0.30
0.50
0.50
0.60
0.65
0.74
Materials
Load on wheels/rollers
Steel on Steel (wet)
Metal on Wood (wet)
Wood on Wood (dry)
Wood on Concrete (dry)
Metal on Wood (dry)
Concrete on Concrete (dry)
Steel on Steel (dry)
©2016 ACRA Enterprises, Inc - all rights reserved
152 All our equipment is tested and certied to the highest standard
v5 - 5/16





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