The hydraulic controller has been programmed to
supply these output signals to the electrically-oper-
ated control valve depending on the following varia-
bles:
• Input signals
• Programmed functions
• Settings
A.
CAB AND FRAME CONTROLLER INPUTS
B.
SOFTWARE LOGIC CONTROLS
C.
CAB AND FRAME CONTROLLER OUTPUTS
Figure 2. Control Flow
Output signals can be Pulse Width Modulation
(PWM) signals for proportional hydraulic functions,
digital signals for ON/OFF functions, or CAN Bus
messages for other linked controllers.
Both hydraulic controllers continually monitor the
system for fault conditions, display appropriate
fault codes, and take action when necessary.
Each controller requires a 24 volt power supply for
operation. Power is provided through the ignition
switch, the hydraulic controller relay, and a 30
amp fuse. There is a Red and Green LED next to
the main connector of each controller. The Green
LED is ON when the controller is powered. The
Red LED is ON when a hydraulic control system
fault condition is detected, and blinks when the
fault is related to a CAN Bus message.
CONTROL VALVE
The flow of hydraulic oil through the electrically-
operated control valve is determined by the position
of the spools. The position of each spool depends on
the electrical controller signal received at the ac-
tuation module for that spool.
For hydraulic functions that just require hydraulic
supply to be ON or OFF, the electrical signal is ON
or OFF as well. Operating voltage is ±24 volts (Sys-
tem Voltage).
For hydraulic functions that require flow control,
the desired spool position is obtained by a voltage-
controlled PWM (Pulse Width Modulation) signal.
Depending on the hydraulic function, the average
voltage varies in relation to the PWM duty cycle be-
tween ±8% and ±50% of the truck supply voltage at
the solenoid.
ANALOG INPUTS
Joysticks/Levers
Joysticks/Levers are used to proportionally control
the following functions:
• Lift and Lower
• Tilt Forward and Tilt Backward
• Aux0 (Power Pile Slope)
• Aux1 (Rotate)
Depending on the position of the joystick/lever, the
5-volt sensor supply signal from the controller is
converted to a signal between 0.5 volts and 4.5
volts. The neutral position of the joystick/lever
translates to a signal of 2.5 volts.
The controller monitors the signals provided by the
joystick/lever and if the signals are out of range,
the controller activates a fault code and enters a
fail safe mode. Joysticks/levers must be calibrated
before being put into service.
Calibration of the joystick/lever provides a refer-
ence to the controller for the two extreme and neu-
tral joystick/lever positions. The controller converts
the joystick/lever position input signal into a PWM-
output signal and sends it to the control valve.
Description
1900 SRM 1561
2