Formula for calculating COUNTERWEIGHT & LENGTH of
back beam,
(La) 4
(La) 4
W =
or
b =
b
W
W = L x a x 4 ÷ b
or
b = L x a x 4 ÷ W
W = Counterweight in Pounds
L = Load in Pounds (Rated capacity of Hoist)
a = Reach (from center front frame to the suspension wire
rope in feet)
b = Back Span - (Distance between front frame and
back frame in feet center to center)
4 = Safety Factor
Severe injury or death can result from improper use or
assembly. Assemble in accordance to this manual. Check
and recheck counterweight chart and formula. Minor
changes could cause complete system failure. Consult your
GRIPHOIST dealer for additional information.
Counterweights must be a nonflowable material, and they
must be attached to the outrigger beam.
Always use tieback wire ropes capable of holding the full
load.
© 2013 Tractel Ltd. All Rights Reserved.
20
5.2
CALCULATION OF COUNTERWEIGHTS
COUNTERWEIGHT FORMULA CALCULATIONS
Provided only as a reference. If you are using the two beam version of the 4’ Skybeam 28 counterweights
are required. The three beam version requires 16 counterweights. Both beams have a 4’ reach and a
1,000lb. (454 kg) Maximum capacity.
Example Calculations:
W= ?
L = 1000 lbs.
a = 4 foot
b = 11’ 6"
(1000x4) x4
W =
11.5
W = 1391 lbs of Counterweights
(26 pcs.) or more, must be added.
Only have 990 lbs. in Counterweights
then
W= 990
L = 1000 lbs.
a = 4 foot
b = ?
(1000x4) x4
b =
990
b = 16’ 2" Therefore the distance
between A and B must be 16 foot and
2 inches or greater.