Liebherr LHM 420 - Manual (Page 24)

24
8
Tubular tower design: exterior view
Tower and Boom
Tubular Tower Design
The submerged-arc welded pipe construction, a torsion-
ally rigid design, is part of a unique stress-flow system
absorbing all static and dynamic demands and distribut-
ing the load as best as possible onto the slew ring bear-
ing. The spiral staircase is well lit with handrails and kick-
plates, leading to the tower cabin. Access to the upper
tower platform and rope pulleys is also gained through
this route.
s¬ $ECREASE¬OF¬TORSIONAL¬STRAIN
s¬ ,OW¬STRESS¬FOR¬WELDING¬SEAMS
s¬ ,ONGER¬LIFETIME¬OF¬SLEWING¬GEARS¬AND¬UNDERCARRIAGE
s¬ 3AFE¬AND¬CONVENIENT¬ACCESS¬TO¬THE¬TOWER¬CABIN¬INSIDE¬
the tower
Luffing Cylinder
The cylinder rod is completely protected while in crane
parking position. Due to the fact that the luffing ram is a
tension cylinder, collisions between swinging loads and
the cylinder during crane operation are impossible.
s¬ -AINTENANCE¬FREE
s¬ ,ESS¬CORROSION
s¬ ,UFlNG¬CYLINDER¬IS¬PROTECTED¬AGAINST¬DAMAGE
s¬ .O¬RISK¬OF¬BUCKLING¬ONLY¬TENSION¬FORCE
Boom
The boom is of lattice construction featuring three main
chords and consisting of 2 sections (fulcrum section,
boom head). The boom head can be laid down on the
ground. Seamless high strength tubular steel ensures op-
eration without difficulty down to -40°C.
s¬ -ORE¬STABILITY¬¬HIGH¬LEVEL¬OF¬STIFFNESS
s¬ 0RECISE¬CRANE¬MOVEMENT
s¬ 0IVOT¬POINT¬UP¬TO¬¬M