Description Of The System
© Hirschmann Rev. I 05/22/17
190154_I.DOC
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3.3
DESCRIPTION OF THE SYSTEM COMPONENTS
Pressure Transducer:
The pressure transducer converts hydraulic pressure into an electric signal.
A pressure transducer block houses two transducers, CAN bus converter board, and two bus
connectors. One pressure transducer is connected to the piston side of the lift cylinder and the other
to the rod side.
The Length-Angle Transducer:
The length-
angle sensor (LWG), often referred to as the “cable reel”,
is a combination of two transducers in one box, installed on the base section of the boom. It
measures the length and the angle of the boom.
A reeling drum drives a potentiometer, which is the length transducer. Part of the length transducer
circuit is the length cable on the drum, which is a multi-conductor cable. It is connected to the anti-
two-block switch at the boom head and to a slip ring body in the LWG.
The angle transducer is a potentiometer driven by a weighted pendulum that is oil damped. Both
length and angle transducer are connected to a CAN bus controller board, which is connected to the
bus system.
Anti-Two-Block Switch:
The anti-two-
block switch monitors the load block and it’s relationship with
the head of the boom. In working condition the switch is closed. When the load block strikes the
weight the circuit opens, disengaging a relay output to the lock out solenoid valves, where applicable.
To check the cable for damage, (short circuit to ground) there is a 4.7k resistor between ground and
the contact of the switch, to give a signal back to the central unit. The weight at the anti-two-block
switch keeps the switch closed until the load block strikes it.
Console:
The graphic console displays all geometrical information such as length and angle of main
boom, working radius and head height of the boom. It also displays the actual load and the maximum
load permitted by load chart. Furthermore, it has an alarm horn, a warning light for overload, and a
pre-warning light. The graphic display allows for a simple interactive configuration setup, as well as
sensor calibration (zero adjustment), and troubleshooting sensor output screen. The console has a
warning light for anti-two-block conditions and an override switch for overload or anti-block condition.
Refer to Operator’s Handbook for detailed operation of the console.
Central Unit:
Inside the central unit there is a CPU and connection board. The board has a hard
mounted connector for power, ground, bus controller, and slew indication. The board has a green
LED, indicating relay energized and a communication LED that flashes through red, yellow, and green
colors.
Slew Potentiometer:
This component is not supplied by PAT/Hirschmann. It is part of the electrical
swivel (slip ring assembly). The potentiometer has two wipers which are used to determine the
slewing angle (rotational positioning) of the super structure in relation to the carrier. The slew input to
the central unit is not a CAN signal, but rather two 4..20mA analog signals.
