USER
MANUAL
809NG
U
SE
B.44
7845469-01 03/20
subject to change without notice
B.8
USE UNDER SPECIAL SERVICE CONDITIONS
Exceptionally, the crane can be operated even if the service conditions are not met, i.e when:
- the stabilizers feet are deployed on a soft surface
- the crane is operated in low-temperature environments
- the inclination angle of the crane's base exceeds the max. permitted value
- the crane is operated in-service wind
In these events the entity of the unfavourable condition shall be estimated by skilled technicians.
If more conditions should be present at the same time, all the respective derating factors shall be
taken into account.
B.8.1
STABILIZERS ON SOFT SURFACE
It could happen that the stabilizers must be deployed on a soft or unstable surface. In this event, if
the user has not suitable support pads at disposal, a derating factor shall be applied to the max.
working pressure, as follows:
p
r
=
κ
s
· p
max
with
where:
κ
s
is the derating factor to apply if the support surface has insufficient bearing capacity
p
r
is the reduced pressure
p
max
is the max. working pressure under standard conditions
p
sur
is the effective bearing capacity of the surface supporting the stabilizers
p
stab
is the max. stabilizer pressure on the ground (see D.1)
The following table shows typical values of bearing capacity (p
sur
) for different soil types: these
values are only indicative and can change depending on material, humidity, granulometry, hardness,
inclination and other soil properties and conditions.
SOIL TYPE
BEARING CAPACITY
MPa
Natural, clearly virgin soils (mud, peat, marsh soil)
0
Fill soil, not compacted
0.0 ÷ 0.1
Not coherent, but compact soils (fine and medium sand)
0.15
Coarse sand and gravel
0.20
Coherent soils:
- doughy
0
- soft
0.04
- rigid
0.1
- half-solid
0.2
- solid
0.4
- rock
1.5
- solid rock
3.0