Wind Speeds - Manitowoc Grove RT765E-2 Operator's Manual

SAFETY INFORMATION
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
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".
This 3-second wind gust is assumed to act on the entire
crane and the load. The wind effect on the load can be
conservatively estimated as:
a) If V(z) is ≤ 13.4 m/s (30 mph), then the allowable
load is the published rated capacity from the Load Chart.
b) If V(z) is > 13.4 m/s (30 mph) and is ≤ 20.1 m/s
(45 mph), the allowable load is the published rated
2-8
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 4-09-2021, Control # 364-11
RT765E-2 OPERATOR MANUAL
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.
capacity multiplied by the Capacity Reduction Factor
from Table 2-4 (metric) or (non-metric).
NOTE: This condition is limited to operation with the main
boom on fully extended outriggers only.
c) If V(z) is > 20.1 m/s (45 mph), then lifting is NOT
permitted. Cease lifting operations and lower and retract
the boom.
In both cases a) and b) above, the lift may also be limited by
the projected wind area of the load Ap and by the wind drag
coefficient Cd: This limit can be determined by comparing
the Actual wind resistance area with the Allowable wind
resistance area.
Refer to Figure 2-1 for a simplified calculation method to
determine permissible wind speed.