Great Plains 2S-2600 Installation Instructions - Manual (Page 7)

2/22/2005 195-300M
Great Plains Mfg., Inc.
7 Installation Instructions
ADJUSTING THE COUNTERBALANCE
VALVE(S).
On the stem of the valve (item 27, Figure 6) there
is a rubber cap that protects the threads of an ad-
justment 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 that the valve
will unlock even with no pilot pressure. The open-
ers will 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 and return the lever to neutral.
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 start-
ing 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.