Kohler K91 Owner's Manual page 316

IO
SPRING
TENSION ADJUSTER
(IMPLEMENT CIRCUIT PRESSURE)
FIG. 7.
Implement Relief Valve Removed
( 108494/ 109679
Va Ives)
5 .
Remove the bolts securing the valve together.
Separate the sections one at a time, carefully
noting the location and quantity of mylar shims
around the bolt holes (if used).
CHECK FOR
SHIMS
FIG. 8. Separate Valve Sections
6. Remove and discard the O-rings and shims from
each section. Thoroughly clean and inspect all
parts. Generally, any deep scratches or scoring
of the spool valve or bore, or other visible
damage will make the valve unserviceable.
FIG. 9.
Single Valve Disassembled
3 -
FIG. 10.
Double Valve Disassembled
7 . Reassemble the valve in reverse order, using
the new parts supplied in the overhaul kit. The
following assembly notes apply:
a. Use care not to pinch O-rings between sec-
tions. Torque bolts to
72-75
in. Ibs.
b.
Install an O-ring in valve body. Insert spool
valve from spool cap end, then install valve
handle.
c.
Install an O-ring in the groove at the spool
cap end of the valve body.
If
the valve was
made before
6-75
(see "Manufacturing Date
Code"), use the special oversize O-ring,
which is slightly thicker than the standard
ring.
d. When securing the shoulder screw (Fig.
5),
be sure the shoulder passes through the
center of the special washer, or the spool
valve will operate in only one direction.
e. The float detent, on valves so equipped
(Fig.
5B),
i s adjusted using the set screw on
the bottom of the valve. Properly adjusted,
the spool valve w i l l lock into the float posi-
tion when engaged, yet release easily when
light
pressure is applied to the handle.
VALVE DESCRIPTION (VICTOR)
The hydraulic control valves are made up of one
or two spool valves and a cast iron valve body.
Normal working pressure is 500-700 PSI. An imple-
ment relief valve is part of the control valve and
is
factory set at
700 PSI
-
do not attempt to alter this
setting. Severe transmission damage may r e s u l t . Refer
to the applicable repair manual for system pressure
tests and adjustments.
There are two ports for each spool. When spool is
moved into valve, one port is pressurized and one port
becomes an outlet. When spool is moved out of valve,
ports are reversed. Spool valve is spring loaded to
return to a middle, "neutral" position, where both
lift cylinder ports are sealed off from the pressure and
outlet ports. These are open-center valves, so hydraulic
oil is
free to flow from the pressure port to the outlet
port when the spool i s in neutral. Attachment float is
accomplished mechanically by the tractor's
lift
link-
age, or through a detented
float
position provided on
one spool of the two-spool control valve.