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6. Flow Control Cover:
Check the relief valve subassembly for free movement in the cover bore. Remove burrs from the valve
by polishing, but DO NOT round off the corners of the lands. Do not attempt to rework the valve bore. If
the bore is damaged, replace the cover.
7. Priority Valve Cover:
Inspect the priority valve spool and bore for burrs. Remove burrs from the spool by light polishing with
crocus or #500 grit paper. DO NOT round off sharp corners of the lands. Inspect the cover bore for
scratches, wear, and/or a pitted surface. DO NOT attempt to rework the bore. If the bore is damaged,
replace the cover. The priority valve spool must fit and move within the bore without evidence of bind.
Rotate the spool through 360
o
while inspecting for bind.
Integral Relief Valve:
Inspect the spring. The spring ends must be parallel to prevent cocking of the poppet. The poppet requires a
close inspection in the seat contact area. A slight wear pattern should exist around the poppet at the area of
seat contact. If the wear pattern is broken, a possible leakage path exists between the poppet and seat.
Inspect the seat for possible erosion or other defects. Refer to the seat removal procedure if the seat is
defective. (Paragraph VI. B. 3).
D. ASSEMBLY
D. ASSEMBLY
D. ASSEMBLY
D. ASSEMBLY
D. ASSEMBLY
Coat all parts with hydraulic fluid to facilitate assembly and provide initial lubrication. Use small amounts of
petroleum jelly to hold o-rings in place during assembly.
IMPORTANT: During handling and shipping of the precision machined cartridge parts, it is possible to raise
burrs on the sharp edges. All sharp edges on the parts of a new cartridges kit should be
stoned prior to installation.
1. Assembly of Flow Control Cover-See Figure 8. Assemble the snap ring in place within the bore, (early
design only) seat firmly in the groove. Insert the valve in the bore, small land first. Then install the spring
and both plugs. Use new o-rings if straight thread plugs are used.
2. Assembly of Priority Valve Cover-See Figure 8. If the relief valve seat was removed, a new seat must be
pressed into the body. Lubricate and insert the new seat chamfered end first into the cover opening.
Align square and press into place. Use a short length of brass rod as a pressing tool, to prevent seat
damage. Clean the relief valve bore to remove chips and filings. Insert the poppet into the bore, align
square and lightly tap the stem of the poppet to mate the poppet and seat. Install the spring, shims, and
plug into the cover. (Later design uses a spring guide and straight thread plug with o-rings). Be sure to
check the pressure setting of the relief valve against the model code. If the setting is out of tolerance,
readjust by removing or adding shims. (Removing shims reduces pressure while adding shims increases
pressure).
Priority Valve:
Install the snap ring within the priority valve cover bore, (early series only); make sure the snap ring is
seated within it’s groove. Insert the priority valve spool, small land first, into the bore. Install plugs at
each end of the bore and secure. Refer to Figure 8 for spool orientation.
3. Assembly of Pump-See Figure 8.
Begin assembly by pressing the shaft into the front bearing while supporting the bearing inner race. Install the
small snap ring on the shaft.
SERVO PUMP MAINTENANCE CONTINUED...
