Wind Forces; Wind Speeds - Manitowoc Grove RT770E Operator's Manual

RT770E OPERATOR MANUAL
operate. Be sure that the surfaces will support a load greater
than the crane's weight and maximum capacity.
Be aware of all conditions that could adversely effect the
stability of the crane.
Be aware of the danger for people entering the working area.
Do not allow unnecessary personnel in the vicinity of the
crane while operating.

WIND FORCES

There are basic principles that must be followed while
operating in windy conditions. This information has been
provided to assist in determining safe operation in windy
conditions.
Always use extreme caution when windy conditions exist.
NEVER exceed the rated capacity shown on the Load Chart.
Always check the Load Chart to ensure the load to be
lifted is within the rated capacity of the crane.
Table 2-1 Beaufort Wind Scale
Beaufort
Description
Number
Zero (0) Calm
1 Light Air
2 Light Breeze
Gentle
3
Breeze
Moderate
4
Breeze
Fresh
5
Breeze
Strong
6
Breeze
7 High Wind
8 Gale
9 Strong Gale
10 Storm

Wind Speeds

The maximum permissible wind speed referred to in the load
charts is the 3-second wind gust speed measured at the
boom tip height and is designated as V(z). This value is
either recorded at boom tip or calculated based on mean
Grove
Maximum Wind Speed
m/s km/h mph
0.3 1.1 0.7
1.5 5.4 3.4
3.3 11.9 7.4
5.4 19.4 12.1
7.9 28.4 17.7
10.7 38.5 23.9
13.8 49.7 30.9
17.1 61.6 38.3
20.7 74.5 46.3
24.4 87.8 54.6
28.4 102.2 63.5
Published 04-04-2017, Control # 446-09
Wind can have a significant effect on loads that may be lifted
by a crane. Wind forces act differently on a crane depending
upon the direction from which the wind is blowing (e.g., wind
on the rear of the boom can result in decreased forward
stability, wind on the underside of the boom can result in
decreased backward stability, wind on the side of the boom
can result in structural damages, etc.)
Wind forces can exert extreme dynamic loads. Manitowoc
recommends that a lift not be made if the wind can cause a
loss of control in handling the load.
Wind forces can be determined by typical visible effects on
the landscape.To assist you in determining prevailing wind
conditions, refer to (Table 2-1).
NOTE: The wind speed corresponding to the Beaufort
scale in the table is mean wind speed at 10 m
(33 ft) elevation over a period of 10 minutes.
Visible Indicator
Effects of wind as observed on land
Calm; smoke rises vertically
Smoke drift indicates wind direction. Leaves and wind vanes
are stationary.
Wind felt on exposed skin. Leaves rustle. Wind vanes begin to
move.
Leaves and small twigs constantly moving. Light flags
extended.
Dust and loose paper raised. Small branches begin to move.
Branches of a moderate size move. Small trees in leaf begin to
sway.
Large branches in motion. Whistling heard in overhead wires.
Umbrella use becomes difficult. Empty plastic bins tip over.
Whole trees in motion. Effort needed to walk against the wind.
Some twigs broken from trees. Cars veer on road. Progress on
foot is seriously impeded.
Some branches break off trees, and some small trees blow
over. Construction/temporary signs and barricades blow over.
Trees are broken off or uprooted, structural damage likely.
wind speed recorded at crane operation site. For lift planning
purposes only, the 3-second wind gust speed, V(z), may be
calculated based on mean wind speed reported at http://
www.windfinder.com "Super Forecast".
SAFETY INFORMATION
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