Great Plains P12720 - Manual (Page 34)

X-Press
Operating Instructions
34
5. Servicing and Maintenance
5.5 To Adjust the System
Pressure
A low oil flow should be used, i.e.,
tractor tickover or low flow
selected.
The wing circuit is controlled by an
overcentre valve contained within
the manifold block which positively
locks oil flow until pressurised by
the tractor. System pressure can
be retained in the circuit even after
depressurisation of the tractor
quick release couplings.
Exercise extreme care when
checking the valve or circuits, and
under no circumstances attempt
to adjust or loosen fittings without
prior reference to your authorised
simba dealer, and detailed
maintenance instructions.
It is normal to operate at 10-20 bar. This can
be increased to 40-50 bar max, or reduced
to 5 bar as conditions determine. Higher
pressure will cause the wing tips to dig in
causing the centre of the machine to lift it out.
Too little pressure will cause the wing tips to
lift out & the centre of the machine to dig in.
When towing another implement behind the
X-Press, the pressure may need increasing
to compensate.
In all cases the normal adjustment method is
to minimise system pressure & then increase
by adjusting the pressure valve until the
desired pressure is achieved.
In all cases, regardless of tractor make,
adjustment should start from zero (minimum
pressure) and gradually increase up to
desired pressure value.
With the machine off the ground,
1. Pressurise the wings to unfold. As the
unfolding begins the pressure reading
on the gauge will drop. When the wings
have fully unfolded the pressure reading
will start to climb. Keep pressurising the
wings until the gauge has stabilised at
the pre-set pressure. The standard
factory setting is 15 bar.
2. If the system needs adjusting:- Partially
fold the wings & hold them in this
position. To adjust the pressure utilise
valve 3 (shown in Fig. 5.04). Unscrew
the adjusting screw until no resistance
can be felt (almost fully unscrewed
position). Unfold the wings fully as
before, checking the gauge reading.
Maintain hydraulic pressure unfolding
wings & adjust the screw whilst
pressurising.
• Turning adjuster clockwise increases
pressure.
• Turning adjuster anti-clockwise
decreases pressure.
Once the desired pressure is achieved lock
the valve. As a check, partially fold the wings,
stop, and then unfold again maintaining
pressure until the gauge stabilises at your
desired setting.
Fig. 5.04: Manifold Block