Farmer 400
Fav 700
Fav 900
Power lift / Electrohydraulic control EPC
Rear power lift - functional description
A
General
Fav 900 chassis number 23/3001 and up
29.11.2000
8610
000001
A
a
2/8
Capitel
Docu-No.
Index
Date
Version
Page
Rear power lift - functional description
Explanation of functions:
a) Electrical
Bullet-List
●
Block multiway valve, consisting of AV3 and AV4, is in "EPC" position
●
This position is detected by solenoid switch S048 and transmitted to EPC box A005 pin 12, i.e. EPC
box is active.
●
"Lift" solenoid Y021 of EPC valve is supplied with power by EPC box A005 pin 55 (12 volts).
Text-module
b) Hydraulically
Bullet-List
●
Load power/load-sensing system connection is active when "Lift" valve is active.
●
If LS pump PR is not yet active, current load pressure (= standby pressure of LS pump) is transmitted
as maximum pressure to LS pump as a command via shuttle valves (EPC valve, 1.1 valve, WLS-2,
WLS-1).
●
LS pump PR then goes automatically to pumping and pressure regulation, i.e. it pumps required
volume at required pressure.
●
Should LS pump already be active elsewhere with higher pressure demand, "surplus" pressure at
EPC valve's pressure governor is limited to power lift load level.
●
Max. lifting speed is defined as cross-section (= fixed aperture) in EPC valve.
●
Hydraulic oil then comes from EPC valve output directly to lift side of power lift cylinders.
●
Displaced oil returns to tank via multiway valve AV4.
Text-module
c) Mechano-hydraulically
Bullet-List
●
Lifting of largest possible implement to full height is primarily limited by three-point linkage setting
(top link length and coupling point) and,
●
for maximum safety, by working pressure of LS pump PR (this pressure is fixed and must never be
increased!).
Safety system:
Bullet-List
●
Max. pressure protection of LS pump with pressure-relief valve DBV-A in central control block
●
During every lift operation - except with external buttons S027 and S029 - max. height is activated by
safety end shutoff, i.e. "Lift" process is automatically shut off.
Text-module
2. "EPC lower / regulate"
The "Lower" command can be triggered by
Bullet-List
●
rapid lift control at control console with command "Lower = regulate", or
●
depth setting (= setpoint potentiometer), or
●
"END" rocker switch on joystick, when in automatic mode, or
●
external buttons (S028 and S030) at cab on right and left
●
Any external commands immediately lock all other EPC functions.
Explanation of functions:
a) Electrical
Bullet-List
●
Block multiway valve, consisting of AV3 and AV4, is in "EPC" position.
●
This position is detected by solenoid switch S048 and transmitted to EPC box A005 pin 12, i.e. EPC
box is active.
●
"Lower" solenoid Y022 of EPC valve is supplied with power by EPC box A005 pin 19 (12 volts).
●
Lowering speed is set as infinitely variable setpoint in terminal's "Rear power lift" control menu and
●
transmitted by EPC box as pulse-width-modulated (PWM) power signal to electrically proportional
"Lower" valve.
b) Hydraulically
Bullet-List
●
"EPC lower" works without LS command and without active intervention of LS pump PR.
●
Displaced oil from lift cylinder moves to open "Lower" valve.
●
"Lower" valve opens its cross-section in accordance with setpoint flow rate.
●
If lowering is activated by external button S028 or S030, "Lower" valve automatically moves to
medium lowering speed, i.e.to medium flow rate.