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4.4 2006 plus GFS Controls
GFS kits from 2006 and later have a different cab
control box and GFS control box with 2 additional
features:
1. A cab buzzer will signal the operator whenever
the GFS master switch is turned on and one
side of the GFS system has been off for more
than 10 seconds. Operators sometimes lift a
boom to carry the GFS gauge wheel over a
water hole, and forget to turn that side of the
GFS on after the hole is past. Later in the field,
when the ground comes up to raise the wheel,
there is no GFS hydraulic assist. The gauge
wheel must act as a ground wheel and this
could cause reduced life in some boom and
GFS parts. After 2005, the operator has a
audible reminder to keep both sides of the
GFS engaged during normal operation.
2. For users with open center systems only,
the open center output now has a delay time
adjustment after the low pressure signal is
received. On an open center hydraulic system
when the system pressure drops below the
preset level, an optional pressure switch
closes, which in turn closes the open center by
pass valve. In pre 2006 units, the pressure
would build up and instantly turn off the open
center bypass, allowing a situation where the
system could turn on and off several times per
hill or lift cycle. With the later than 2005
model, the pressure switch signals the start of
the closed cycle and that cycle can be field
adjusted to extend the closed time for up to 5
seconds. This will reduce the number of cycles
on the valves and switches, resulting in
greater dependability over the long term.
Although there is additional features, the same basic
functionality and part numbers have been retained,
and either of the in cab or rear GFS control boxes may
be substituted back into 2005 machines. If both are
substituted, then both new features will be available.
4.4.1 Adjusting the GFS time delay
The GFS time delay will be factory set to have an on
time of 2.5 seconds each time a low pressure is
detected. The delay is easily checked by timing the red
light on cycle in the cab. If the unit is being operated in
extremely rolling terrain, and the red indicator light on
the cab box is staying on for 2.5 seconds, then
flashing off and instantly back on, the cycle could be
increased to 4-5 seconds.
If the hydraulic oil system is getting hotter than 160
degree F or 60 degree C, shorten the cycle to reduce
oil flow over the relief valve when the open center by
pass is closed.
1. Turn on the cab box, engage the hydraulics if
necessary, have a person lift a boom tip to
decrease GFS system pressure.
2. Watch the red open center output light,
record the open center output time,
3. Turn off the GFS cab switch to power down
the GFS box
4. Use a 3/16 wide blade driver to remove the
external screw.
5. Reach through the threaded hole with a 1/16
wide blade driver, gently rotate the slot inside
approximately 1/3 clockwise to adjust from 2.5
up to 5 seconds per cycle, or 1/3 turn counter
clockwise to adjust to .5 seconds per cycle.
6. Turn on the cab box, engage the hydraulics if
necessary, have a person lift a boom to
decrease pressure.
7. Record the open center output time, and
compare to time written down in step one.
8. If the change in time is satisfactory, replace
the external screw and gasket to seal the box
again.
FIGURE 13 2006 GFS ADJUSTABLE CONTROL
VALVE
23
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