Maeda CC1908S-1 - Page 138

5.4 CRANE OPERATION M A E D A Crawler Crane
5-22 5/2020 CC1908S-1
PAY ATTENTION TO WEATHER
INFORMATION
• During a thunderstorm, there is a risk of
lightning strikes, so stop operating the crane,
unload immediately, and retract the boom.
• Wind can cause the hoisted load to sway,
making the machine unstable. If the hoisted
load sways in the wind, unload immediately,
and retract the boom.
• If the maximum instantaneous wind speed is
10 m/s or greater, stop operating the crane,
unload immediately, and retract the boom.
• Care is needed when working even when the
maximum instantaneous wind speed is below
10 m/s, as larger hoisted loads, higher hoisted
load positions, and longer boom extension can
all increase the effects from the wind.
• Take care when operating with the boom
extended, as the winch wire rope and electric
signal cables are susceptible to being blown by
the wind. Care is also required near high-rise
buildings, as the wind speed may be increased
by wind blowing along the building.
• Take care when hoisting a load such as steel
plate with a large area exposed to wind, as the
wind from the front/rear/side of the boom may
cause the machine to topple or damage the
boom.
• Take care when raising the boom, as this
increases the probability of toppling backward
when the wind blows from the front.
• If an earthquake occurs, stop operations and
wait for the earthquake to subside.
• The following table indicates the approximate
correlation between wind speed and its effects.
The wind speed given in weather forecasts is
the 10-minute mean wind velocity (m/s) at a
height of 10 m above ground level.
Wind
force
Wind velocity
(m/s)
Effect on land
0 Less than 0.3 Smoke rises vertically.
1
0.3 to less
than 1.6
Wind motion visible in
smoke.
2
1.6 to less
than 3.4
Wind felt on exposed skin.
3
3.4 to less
than 5.5
Leaves and small branches
move constantly.
4
5.5 to less
than 8.0
Dust and loose paper is
stirred up. Small branches
sway.
5
8.0 to less
than 10.8
Bushes with leaves start to
sway. Waves form on the
surface of ponds and
marshes.
6
10.8 to less
than 13.9
Large branches sway.
Electrical cables whistle.
Use of an umbrella
becomes difficult.
7
13.9 to less
than 17.2
Whole trees sway. Effort is
needed to walk into the
wind.
8
17.2 to less
than 20.8
Small branches break. It is
difficult to walk into the
wind.
9
20.8 to less
than 24.5
Houses sustain minor
damage. Tiles become
dislodged.
10
24.5 to less
than 28.5
Trees are uprooted.
Houses sustain major
damage.
11
28.5 to less
than 32.7
Widespread structural
damage occurs.