Great Plains 2S-2600F Operator Manual v2 - Manual (Page 19)

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Section 2 Operating Instructions
9/26/13 2S-2600 and 2S-2600F Two-Section Folding Drill 195-200M-A
Great Plains Mfg., Inc.
Adjusting the Counter Balance 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 pis-
ton. More spring force will let the valve open with a low pi-
lot 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 sys-
tem 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.