Great Plains 2S-2600 Assembly Instructions - Manual (Page 6)

195-298M 4/19/2007
Great Plains Mfg., Inc.
Counterbalance Update 6
Adjusting the Valve
On the stem of the valve there is a rubber cap that
protects the threads of an adjustment stem. This
stem is locked in place with a hex nut. To adjust
the valve, loosen the nut and turn the stem using
an Allen wrench.
Screwing the stem in (clockwise) pushes on a
spring which supplements the pilot line’s force on
an internal piston. More spring force will let the
valve open with a low pilot pressure. Less spring
force will require higher pilot pressure to open the
valve.
Note: With the screw turned in fully, the spring will
develop enough force on the piston to unlock the
valve, even with no pilot pressure, causing the
openers to settle.
Raise and lower the drill several times then hold
hydraulic down pressure on the openers to purge
air from the system and to warm the oil. Repeat.
Raise the openers. Observe the openers closely
to detect settling. If the openers remain up, no
valve adjustment is needed.
If the openers settle, the stem is screwed in too far.
Gently back the stem out until it stops, then screw
it in one turn. Generally this is a good starting
point. Check for settling.
Backing the stem out will lock the valve, screwing
it in too far can cause it to unlock.
A small increase in lowering speed can be
achieved by screwing the stem in.
2S-2600 November 2003 and later Plumbing Diagram. (no point row or open center kit)
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