Maeda MK0003, Service Manual, Page: 87 / 348

2-59
6.3 INSPECTION AND ADJUSTMENT
[1] Parts inspection
Subject area Judgment criteria Remedy
･ Housing
･
Block body
･ Scratch and blemish, stain or corrosion of spool sliding area
･
Scratch and blemish, stain or corrosion of the seal pocket of
spool insertion area
･
Scratch and blemish, stain or corrosion of the port seal in
contact with the O-ring
･ Scratch and blemish, stain or corrosion of the sealing area of
relief valve
･
Any other damage that may spoil normal functions
･ Replacement
･
Replacement
･
Replacement
･ Replacement
･
Replacement
･
Spool
･ Scar that catches a finger nail of the circumferential sliding
surface when touched
･
Blemishes on the sliding surface mating with an end seal
･
Spool action is not smooth.
･ Replacement
･
Replacement
･
Repair or replace
･ Load check valve
･
Imperfect sealing due to damage of valve or spring
･ When inserted in a block body and allowed to operate, it
should move smoothly without being caught.
･
Repair or replace
･ Normal
･ Spring and its periphery
･
Significant damage such as stain, corrosion, deformation or
breakage of spring, holder, and cover
･
Replacement
･
Spool sealing area
･ Outward oil leakage
･
Stain, corrosion or deformation of seal holder
･ Repair or replace
･
Repair or replace
･
Main relief valve
･ Port relief valve
･
Anti-cavitation valve
･
Stain or damage in appearance
･
Damage on the valve seat mating surface
･
Damage on the poppet mating surface
･
Fault in spring
･ O-ring, backup ring, and seals
･
Replacement
･
Replacement
･
Replacement
･
Replacement
･ Total replacement
is required in
principle.
[2] Pressure adjustment of main relief valve
1. Attach a pressure gauge to the pressure detection port.
2. Run the pump at its rated revolution speed.
3. Allow the control valve spool to move to its full stroke and read the
pressure gauge value.
4. Loosen the lock nut (2) of main relief valve.
5. While watching the pressure gauge, turn set screw (1) to adjust the
pressure.
･ Clockwise direction (turning rightward): To raise the set
pressure.
･
Counterclockwise direction (turning leftward):
To lower the set pressure.
6. After completing the pressure adjustment, tighten the lock nut (2)
while preventing the set screw (1) from turning.
7. Run the pump again at its rated revolution speed to ensure that the
pressure is stabilized.