Bush Hog CBH60, CBH80, CBH70 manual Model CBH 70, CBH Valve Repair Disassembly

MODEL CBH 70, CBH 80

VALVE REPAIR - DISASSEMBLY

Replace Center Section Assemblies:

Note: For the purpo se of t hese instruct ions we will consider the section cont aining the INLET PORT as the left side of the valve.

NOTE: If it is de cided that an o verhaul o f comp o- nents or pressure adjustments are necessary to cor- rect m alfunct ioning , it is re comme nded tha t you r dealer make these repairs. He i s equipped to do this work.

1.Remove control valve from the backhoe.

2.Thoroughly clean the exteri or of the valve before beginning disassembly procedures.

3.Sinc e the valve wil l be asse mbled in the same order, each section should be marked numerically so that th ey ca n be reassembled in the same sequence.

4.Mount the valve vertically in a vise to facilitate dis- assembly and assembly.

5.Remove the t hree tie rod nuts f rom the right end section, using a thin-wall so cket. Tools required for basic valve d isassembly and rea ssembly in clude 1/2” and 9/ 16” op en or box en d w renches an d a torque wrench with thin wall sockets.

6.Valve sections can now be removed by sliding the sections along the tie rods.

7.Lay out valve components on a clean, flat working surface. The inl et assembly will include an O-ring, and th e spool section (s) include an O-ring, a load check poppet and a load check spring.

8. Assemble tie rod nuts to one e nd of each tie rod
with on e or two threa ds showing. Insert tie ro ds
through tie ro d holes	of inlet (la rger t ie r od at top) .
Lay inle t on end with	tie rods up, place O- ring into
position.

9.Place first spool section (O-ring side up) on inlet section, position O-ring and insert load check poppet (nose down) and spring (behind poppet) into loade r check cavity. Repeat t his procedure f or e ach spoo l section; the load check springs are compresse d by the following sections during assembly.

10.Position end s ection o n last sp ool se ction and hand tighten tie rod nuts. The end s ection does not have O-ring grooves.

11.Position valve a ssembly with the m ounting pads

of the end sections on a flat surface. To obtain prop - er alignment of end sections relative to the spool sec- tions apply d ownward pressure to the end sections; snug tie rod nuts to about 10 ft. lbs.

Finally torque t he two 1/2” nuts to 14 ft. lbs. ; finally torque the 9/16” nut to 3 3 ft. lbs. C heck for proper spool movement.

12.As required, install auxiliary valves and plugs and torque to proper specifications.

Replacing Spools Seals:

Note: For the purp ose of t hese instru ctions we will
consider the control handle side of the valve as th e
FRONT, and the opposite side as the BACK.
1.	Remove control valve from the backhoe.
2.	Thor oughly clean the exterior of	the valve before
beginning disassembly procedures.
3.	At t he BACK of the valve remov	e al l bo nnet
assembly parts whi ck are conn ected to the spool.
Keep p arts in the order of dis assembly . See each
valve section parts breakdown for the par ts involved
in the make-up of the bonnet assembly.

IMPORTANT: DO NOT remove the spool from the
val ve. The seals can be replace d e xtern all y.
Prevent spools from turning or moving by	insert-
ing a scre w driver through the clevis slot,	or by

running a rod through the pin hole and using the rod as a handle.

DO N OT hold the spool w ith a wrench. This will destroy the finish.

4.At the BACK of the va lve, remove seal ret ainer, back-up wa sher, and spool O-ring seal, or retaining sleeve, bonnet O-ring seal and spool O-ring.

5.Thoroughly clean counter bores.

6.Install new seals:

A. Spring-Centered Bonnet Assembly Only:

Lightly oil new O- ring seal. S lide O-r ing over valve spool and insert in seal counter bore. R eplace back- up washer and seal retainer.

B. Float Bonnet Assembly Only:

Lightly oil ne w O- rings. I nstall O -rings into space r. Slide spacer with O-rings over spool being careful to orient as shown in boom valve section breakdown.

7. At the BACK of the valve replace bonnet assembly parts, reversing the ord er in which they w ere disas- sembled in step 3. Use 6 - 8 ft. lbs torque to tighten

26 assembly screw on spring centered bo nnet assem -