Dealer Service 27
29977 (Rev. 1/23/2009)
hammer. See Figure 19. Install snap ring and
repeat on opposite cup.
4. Repeat step 1 & step 2 to install remaining cups in
remaining yoke.
5. Move both yokes in all directions to check for free
movement. If movement is restricted, rap on yokes
sharply with a hammer to relieve any tension.
Repeat until both yokes move in all directions
without restriction.
SPRING-LOADED
WHEEL YOKE ADJUSTMENT
Tighten elastic stop nuts on spring bolts until 1/4" of
bolt thread extends through nut.
1-SPOOL, 3-WAY VALVE
This valve is an extremely closely-fitted unit. Great cau-
tion should be taken to keep all dirt and impurities out
of it. Any foreign matter could ruin sealing surfaces.
Open-Center or Closed-Center
This valve can be used with tractors having either a
closed-center or open-center hydraulic system. The
valve, as shipped, is ready for use with open-center
systems. To adapt it for use with closed-center sys-
tems, remove the plug adjacent to the outlet port and
replace with the power-beyond sleeve and plug
included in box of parts. Also, reset pressure relief
valve to a closed position by removing cap (45) and
turning adjustment screw (43) all the way in. Replace
cap (45).
In operation, an open-center system allows oil to flow
freely through valve when all spools are in neutral. it is
used on most tractor systems. The closed-center valve
is blocked, allowing no oil to circulate when spools are
in neutral. This system is used on late model John
Deere 3010, 4010, etc., Ford model 6000, and MF
models 1100 and 1130.
Operation
The valve spool is equipped to operate a single-acting
cylinder and has a float position detent. The spool will
automatically return to neutral when not in detent. With
spool in neutral, cylinder will be held in position.
Servicing
Spool Sticking
Any tendency of spools to stick in position is usually
caused when mounting bolts are pulled down too tight,
or the valve is mounted on an uneven surface. Also,
excessive pressure will make spools stick.
Lift Check Service
The load lift checks are used to prevent a load from
dropping prior to starting to raise when the spool is
being moved slowly to the raised position from neutral.
If these checks leak by, so that the load does not hold
properly, remove lift checks, inspect the check and
seats, and replace if necessary.
Spool Removal
The spool is selectively fitted in body and cannot be
interchanged or exchanged. However, it may be
removed to replace seals, but it is not necessary that it
be removed completely. To replace seals on any spool,
remove handle and snap ring, then push spool far
enough out back of valve to expose V-cup seal on han-
dle end. Remove and replace with new seal V-cup fac-
ing inward. Remove retaining screw from other end of
spool. Slide spool through the new seal, being careful
not to roll over the edge. Slide forward far enough to
expose the seal in back of valve. Replace it the same
way, slip spool back into its normal position, and reas-
semble.
Fitting leakage
Use a thread sealant on all fittings to prevent leakage.
