2-15
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The hydraulic capacity alert system is a hydrauli-
cally operated, maximum capacity sensing device that
will stop all of the normal crane functions that cause
overload when maximum capacity is exceeded. In the
event that an over capacity condition occurs, the hy-
draulic capacity alert system is actuated by sensing ex-
cessive pressure in the lift cylinder which causes the
boom down, extend out and winch up functions to be-
come inoperative. These are the functions that increase
the over capacity condition. This system allows for con-
tinued operation of the winch down, boom up and boom
retract functions, the functions that normally allow the
operator to bring the load to a shorter operating radius
or set the load down in order to eliminate an over ca-
pacity condition. Once the excessive cylinder pressure
has been reduced by bringing the load to a shorter ra-
dius or setting the load down, normal operation can be
resumed. This hydraulic capacity alert system uses the
work port unloader solenoids in the anti-two-block sys-
tem as the hydraulic system dump circuit.
The hydraulic capacity alert system has an over-
ride switch or button located on the operator’s console
that momentarily overrides the hydraulic capacity alert
and anti-two-block systems and restores power to crane
functions. Two indicator lights located near the override
alert the operator of function power loss and discrimi-
nate between the hydraulic capacity alert and the anti-
two-block systems as the cause of power loss. If crane
is equipped with optional audible alert, an audible alarm
will sound in an overload condition. $'$&
#%$$'3$$#7
%$45<%%$8
The hydraulic capacity alert system provides a load
range gauge at each operator station. This gauge has
three colors on the dial face: (1) Green – OK; (2) Yellow
– Caution; and (3) Red – Overload. The gauge is
plumbed directly to the lift cylinder and the indicator po-
+ !
sition can be used as an aid in determining the load
condition of the crane. The lift control lever must be
moved from boom up position to the neutral position to
get the most accurate reading when using load range
gauge. $'$&%'4$&(5.
!
The capacity alert system will operate as stated in
the System Description Section. Once an over-capacity
condition is reached, the system will not allow the op-
erator to move the load to a greater radius. The truck
may have to be repositioned closer to the load in order
to set the load at the desired location.
When trip pressure is reached, the pressure sens-
ing switch breaks electrical continuity to the work port
unloader solenoid in the main control valve. When power
is removed from this solenoid, the unloader valves al-
low the oil flowing to winch up, telescope out and boom
down to flow to tank. This path to tank will prevent fur-
ther operation of these functions. When the overload
condition is corrected by winching down, retracting the
boom, or raising the boom, the pressure sensing switch
allows the work port unloader solenoids to be powered
thereby allowing the crane to function normally.
During the operation at near capacity loads, care
must be taken to operate the controls smoothly or the
system may be shocked into the dump mode prema-
turely.
Caution should be exercised when operating near
80° of boom elevation. If the boom lift cylinder is fully
extended and pressurized above trip pressure, the sys-
tem solenoid will deactivate and the boom will remain
locked at 80°. To correct this condition, momentarily
actuate the override switch and boom down approxi-
mately 5°. Some units may be equipped with a Manual
Reset Valve Option that can be used to unlock the unit
from 80°. See Controls & Hydraulics Section for addi-
tional description of this system.
The override system consists of a key switch and a
momentary push button switch. The key switch provides
power to the momentary push button switch located on
the console. To momentarily override, activate key switch
and depress push button on console. This will activate
the anti-two-block solenoid and return power to winch
up, telescope out, and boom down functions. The over-
ride switch is not to be used during normal use of the
crane or as an aid in using the crane in an overload or
anti-two blocked condition.
The load range gauge is provided to aid the opera-
tor when operating near the rated capacity of the crane.
The gauge only provides accurate indication when the
lift control lever is in neutral. The gauge movement is
not proportional to the load on the hook. It is not un-
usual for the indicator to be in the red area at less than
rated load condition when operating the lift control, es-
pecially during boom down operation.
HYDRAULIC CAPACITY ALERT
ANTI–TWO–BLOCK
OVERRIDE
HOLDING THIS OVERRIDE TO
INCREASE LOADING OR TWO BLOCK
THE CRANE WILL RESULT IN
+x
TO CORRECT THE CONDITION CAUSING
THE CRANE SHUTDOWN REFER
TO OWNERS MANUAL
876452
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