Great Plains P12720 - Manual (Page 30)

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Operating Instructions
30
4. Adjustment / Operation
4.7 Disc Frame Cushioning
The cylinders have an additional rod and
piston. These are linked to accumulators and
act as shock absorbers in work.
The cushioned rod end of the cylinders is
intended to operate fully extended under
normal conditions and retract, absorbing the
shock loadings, as obstructions are
encountered.
Operation of the system is limited to setting
and maintaining the cushioning pressure in
this normally closed part of the circuit. Pitch
adjustment via the removable rod stop shims
is carried out in the normal way thereafter.
During operation the tap fitted should be
CLOSED at all times. Only open the tap to
make a pressure adjustment (factory setting
pressure is 30 bar).
Maintain the tap in the CLOSED setting at all
times in work even when altering disc frame
pitch via the rod stops
4.6 Adjusting Disc Frame
Depth
4.6.1 Manual Adjustment
Adjustment of the disc frame depth is
achieved by lengthening or shortening the
adjusters as required in combination with
raising or lowering the disc frames relative to
the DD roller by adding or removing drawbar
shims (for example, to increase disc depth
remove drawbar shims and adjust the
turnbuckle as required). Once set, the
adjusters should be locked by adding shims
to the lower end thread and tightening.
To change the settings it is advisable to lift
the disc frames just clear of the ground so that
the adjusters can be lengthened enough to fit
the amount of shims required. When the
shims have been fitted the machine can be
lowered, making it easier to tighten the
adjuster against the shims.
4.6.2 Hydraulic Adjustment
Adjustment of the disc frame depth is
achieved by adding or removing shims from
the cylinder rod. To make an adjustment the
tap on the at the front of the system (see page
35) must be turned to the open position
(handle in line with the pipe). The cylinders
can now be worked. Only the bottom end of
the cylinder will operate as the top end of the
cylinder is the cushioning end and is a closed
separate circuit. Extend the shimmed ends
of the cylinders and add or subtract shims until
the desired depth is achieved. Retract the
cylinder rods to the shim length and close the
tap. This locks the disc wings and prevents
the cylinders from being ‘sucked out’ in work.
Fig. 4.04: Cushioning Cylinder