CONTROL VALVE
Hydraulic oil flow through the control valve is de-
termined by the position of the spools. The position
of each spool depends on the electrical controller
signal received at the actuation module for that
spool.
Depending on the hydraulic function, different
types of solenoid are used: PVEO, PVEH, or PVEA.
For hydraulic functions that just require hydraulic
supply to be ON or OFF, the electrical signal is ON
or OFF as well. The solenoid used is PVEO. Oper-
ating voltage is 24 volts.
For hydraulic functions that require more precise
control, the actual spool position is regulated ac-
cording to a PWM (Pulse Width Modulation) signal
of 6–12–18 volts at the solenoid.
The solenoids used are PVEH or PVEA.
PVEH affords more precise control of the spool po-
sition and is used for the lift and lower functions.
PVEA affords less precise control of the spool posi-
tion and is used for the tilt and auxiliary functions.
The actuation module has an integrated circuit (IC)
that compares the controller signal/desired spool
position with the actual spool position, and at-
tempts to adjust the spool position accordingly.
A fault code will be displayed in the form of an LED
light if the actual spool position cannot be matched
with the desired spool position. In addition, each
electrical actuation module has an LED:
• OFF
indicates no power signal.
• Green indicates normal operation of the con-
trol valve section.
• Red indicates a sticking spool or an internal
error in the actuation module.
• Flashing Red indicates an input signal fault.
Cycling the ignition key resets the LED to Green.
The LED will immediately turn Red if the fault
condition continues.
ANALOG INPUTS
Levers and Joysticks
Levers and joysticks are used to proportionally con-
trol the movement of the following functions:
• Lifting and lowering
• Tilting forward and backward
• Aux0 (often sideshift)
• Aux1 (often fork positioning)
Depending on the position of the lever, the 5-volt
signal from the controller is converted to a signal
between 0.5 volts and 4.5 volts. The neutral posi-
tion of the lever translates to a signal of 2.5 volts.
The controller monitors the signals provided by the
levers and if the signals are out of range, the con-
troller activates a fault code and enters a fail safe
mode.
Levers must be calibrated before being put into
service. This provides a reference to the controller
for the two extreme and neutral lever positions.
The controller converts the lever position input sig-
nal into a PWM-output signal and sends it to the
control valve.
For backward lever movements, the lever output
signals are linked with flow direction A.
For forward lever movements, the lever output sig-
nals are linked with flow direction B. The specific
lever position and connector orientation assures
lever directions cannot inadvertently result in in-
correct oil flow directions.
Sensors
Additional analog input is provided by a tempera-
ture sensor and a pressure sensor.
2200 SRM 1481
Description
3
