BOOM RT9130E SERVICE MANUAL
4-2 Published 08-25-09, Control # 077-04
The hydraulic fluid for the first stage of the lower cylinder is
supplied by hoses from the turntable. The hydraulic fluid for
the second stage of the lower cylinder and the upper cylinder
is routed through the hose reel that is mounted in the
turntable into a manifold that is attached at the rear of the
center mid section. There are two cam operated check
valves mounted at the rear of the center mid which control
flow to the second stage of the lower cylinder and the upper
telescope cylinder. With both cylinders retracted, the check
valve for the second stage of the lower telescope cylinder is
open and the check valve for the upper cylinder is closed
allowing the second stage of the lower cylinder to extend.
When the lower cylinder is fully extended, the check valve for
the upper cylinder opens allowing the upper cylinder to
extend. The check valve for the lower cylinder closes after
the upper cylinder starts to extend and shuts off the flow to
the lower cylinder. As the upper telescope cylinder barrel
extends, the extend cables around the extend sheaves on
the end of the cylinder barrel push on the extend cables to
pull the fly section out at the same time the outer mid is
extending.
Boom Retraction
The upper telescope cylinder retracts the outer-mid and two
retract cables pull the fly section in at the same time. When
the upper cylinder is fully retracted, the check valve for the
lower telescope cylinder is opened and the lower cylinder
starts to retract. The check valve for the upper cylinder is
closed as the lower cylinder starts to retract. The outer mid
and fly retract first and then the center mid and lastly the
inner mid.
LMI SYSTEM (WITH BOOM CONTROL
SYSTEM)
General
The crane has a 5-section sequence synchronized boom
assembly. The electronic control system interfaces with the
actuating systems, and provides the necessary controls,
according to the following system standards.
Telescoping Control System Description
Boom Configuration
The boom is a five section configuration (i.e. one fixed
section and four telescoping sections). The fully retracted
length of the boom is 12.8 m (42 ft) and the fully extended
length is 48.5 m (159.33 ft). The full extension value of all
four telescoping sections is the same (i.e. 48,564 - 12,805)/4
or 8,940mm (29.33 ft).
Extension/Retraction Modes
The boom telescoping system operates in either of two
modes selected by the operator, Automatic or Manual.
a. In Automatic (AUTO) mode, a single telescope
controller extends or retracts the boom at the
correct speeds, in the correct sequence of section
movements, with no action by the operator other
than to actuate the controller and to cease actuating
it when the desired boom length is achieved. The
system also automatically enforces a “soft”
transition at each section changeover point in the
sequence, resulting in smooth changes from section
to section without the need for the operator to
“feather” the telescope control.
b. In Manual (MANUAL) mode, the operator has the
selective capability to adjust the extension of the
inner mid and center mid sections independently.
Manual mode adjustment is utilized only to
reconfigure the boom sections into a synchronized
relationship according to the programmed criteria
for automatic mode operation (if the boom has for
any reason become unsynchronized during
operation in the Automatic mode), or to extend the
boom intentionally in non-synchronized mode, so
that access holes in the boom sections align, and
serviceable internal components of the boom are
made accessible for maintenance. To prevent
overloading of the boom while the sections are
unsynchronized, when the Manual mode has been
selected, the LMI electronic controller limits the
allowable gross load to 10,000kg, or 50% of the load
chart allowable capacity at the applicable measured
boom length, whichever figure is less. In the Manual
mode, the smoothness of the changeover from
section to section is entirely under the control of the
operator.
Extension/Retraction Sequence (Automatic
Mode)
Boom extension in the Automatic mode does not follow the
customary sequence whereby all the boom sections are
extended by the same proportion for any given boom length.
Instead, in order to optimize the crane structural and/or
stability limitations, the sections extend in particular
proportions according to the following sequences (as
directed by the particular load chart/crane configuration
selected by the operator; i.e. these sequences reside in the
system data software, not in the control software):
To Next Page
Loading...
