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Farmer 400
Fav 700
Fav 900
Power lift / Electrohydraulic control EPC
Rear power lift - functional description
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General
Fav 900 chassis number 23/3001 and up
29.11.2000
8610
000001
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4/8
Capitel
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Rear power lift - functional description
Fav 700 twin ECU
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The ECU A002 is responsible for actuating the electrohydraulic control valves; the command to the
valve comes via the special valve bus (=V-bus).
b) Hydraulically
Bullet-List
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Load power / LS connection is active when main piston is deflected to lift or lower.
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If LS pump PR is not yet active, current LS pressure (= standby pressure of LS pump) is transmitted
as maximum pressure to LS pump as a command via shuttle valves (1.2 valve, 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.
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Should LS pump already be active elsewhere with higher pressure demand, "surplus" pressure at
electrohydraulic control valve's pressure governor is limited to power lift load level.
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Lifting and lowering speed (flow rate) is taken from currently set value of second valve at terminal.
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Hydraulic oil for lifting or lowering then goes directly to lift system cylinders from electrohydraulic
control valve 1.2 output.
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Displaced oil returns to tank via multiway valve AV3 and AV4.
c) Mechano-hydraulically
Bullet-List
●
Power lift moves to mechanical end stop in lift cylinder with external command "Lift" or "Lower" and
generates 200 bar there (= max. standby pressure).
Safety systems:
Bullet-List
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Max. pressure protection of LS pump with pressure-relief valve DBV-A in central control block
Text-module
Operational statuses
Text-module
6. Floating position
Bullet-List
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EPC valve has no special floating position.
Explanation of functions:
a) General
Bullet-List
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Floating position is activated - as previously - by max. depth setting.
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However, "floating" is also active at higher power lift position as soon as no more weight is available
for lowering or if implement is on ground before lowest position is reached.
b) Electrically:
Bullet-List
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ECU A005 receives voltage of 10 scale graduations setting from depth-setting potentiometer.
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Any control commands, e.g. to lift slightly, are suppressed, i.e.
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"Lower" valve receives constant power.
c) Hydraulically
Bullet-List
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With "Lower" valve active and "Lift" valve inactive (i.e. in neutral), connection is made between both
load powers and tank line - as with previous floating position.
Text-module
7. Shock load damping
Bullet-List
●
This is automatically active after upper end position (B030) has been reached when lifting
implement.
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Speed at which shock load damping is enabled can be set at terminal in rear power lift menu (see
Operating Manual).
Background:
Oscillation of mounted implement while driving results in pressure peaks which cannot be brought
smoothly under control in 230 bar pressure-relief valve of EPC valve.
Function / principle of shock load damping system:
Based on draft-sensing pin signals (B030 / B031), downward oscillations of implement are damped by
specific opening and closing of "Lower" valve. This prevents further escalation.