TROUBLESHOOTING AND REPAIR OF BVS4/BVR4 ELECTRIC VALVES
In diagnosing malfunctioning valves, certain symptoms may be common not only to
valves, but often to hydraulic equipment in general. Before repairing the valve, mount a
VM-2 on the pump and verify that the problem is not with the pump.
Troubleshooting
1. Check electrical operation of valve. Make certain
pushbutton control station is in correct working
order. Check spool valve for "clicking" sound
which indicates operating solenoids.
2. In making observations, it is assumed that pilot
pressure has been correctly set, or can be
adjusted, and that valve has been checked for
external oil leakage.
3. Inability to obtain any pressure may be the result
of blown connector seals, jammed relief
components, or sticking solenoids.
4. Pressure leaks which are consistent and increase
proportionately with increasing pressure ranges
are usually the result of leaking gaskets or
threaded surfaces.
5. Ball seat leakage is often erratic and intermittent.
6. Become familiar with and use valve schematics.
7. Valve should operate identically in both directions.
If valve fails to operate in one direction, check
directional circuit involved.
8. If valve malfunction is identical in both directions,
check pilot circuit.
9. If valve operates to 1,200-1,500 PSI [82,8-103,5
Bar] in both directions, it usually indicates
excessive pilot pressure, with valve bypassing
through pilot relief.
10. If pilot setting cannot be adjusted down, it
indicates a severe leak in pilot ball seat.
11. If Valve fails to build to maximum pressure in both
directions, pilot pressure may be too low. This can
also be caused by inability to maintain sufficient
pilot pressure as a result of excessive leakage
through the spool valve, also through badly leaking
pilot relief ball seat in valve block.
12. If valve builds pressure simultaneously in both
directions, this may be the result of a broken pin in
the directional piston.
13. If valve fails to change direction immediately, this
may be due to worn spacers or bad spring
between balls of directional circuits.
Disassembly
1. Remove solenoid assembly (see Figure 3) by
removing cover and four screws that hold solenoid
assembly to valve block. NOTE: Do not
disassemble solenoid assembly.
2. Remove the adaptor block (Figure 1, item 11) by
removing the four screws (item 12), the connector
assembly (item 8) and gasket (item 6) from the
valve block.
3. Disassemble valve block (see Figure 2) by
removing the acorn nut (item 35), lock nut (item
32), adjusting screw (item 45), seven screws (item
41), cover (item 42) and gasket (item 57). Remove
the spacer (item 31), spring (item 27), piston
assembly (item 48), seat (item 38),gasket (item
43), ball (item 23), spacer (item 55) and spring
(item 37). The pilot piston section of valve is now
disassembled.
4. Disassemble the advance and retract piston
sections by removing the cover seals (item 46), (2)
pistons (item 51), the springs (item 26), upper
seats (item 39), gaskets (item 43), balls (item 24),
spring and spacer assemblies (item 39), balls
(item 24), lower seats (item 40) and gaskets (item
29). NOTE: Discard used copper gaskets and
replace with new items supplied with repair kit.
5. Disassemble the pilot relief section by removing
the screw (item 25), gasket (item 30), adjusting
screw (item 47), spring (item 44), ball guide (item
36) and ball (item 22).
6. Disassemble the high pressure relief sections for
both advance and retract by removing the (2)
screws (item 25), gaskets (item 30), adjusting
screws (item 34), slugs (discard), springs (item
28), ball guides (item 33) and balls (item 22).
7. It is not necessary to remove the pipe plugs
(item 20) from the valve body.
8. Body is now ready to be cleaned, inspected for
damage and reassembled.
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