Bulletin HY14-1450-M1/US
Bul 1450-M1pgs.p65, dd
Flow Control Servovalves
12
Parker Hannifin Corporation
Hydraulic Valve Division
Elyria, Ohio, USA
Troubleshooting
Series BD15 and BD30
Table 2. Service Suggestions
Symptom
Possible Cause
To Verify or Correct
1. Open coil wire or open coil lead to
connector pin.
1. Check lead and coil resistance. If there is
an "open", remove the connector and
check it's solder joints. Resolder if
required.
2. Totally plugged supply orifice or
filter.
2. Remove and inspect filter and orifice per
Maintenance Section.
3. Spool stuck.
3. Return to factory.
1. Partially plugged:
1. Clear the blockage
a. Filter element
a. Inspect filter per Maintenance Section
b. Orifice
b. Inspect orifice per Maintenance
Section.
c. Pilot Valve
c. Return to factory.
2. Leaky sleeve o-rings.
2. Investigate excessive internal leakage to
tank (bypassing flow sound)
3. Low pilot supply pressure.
3. Check pilot supply pressure per
Maintenance Section.
4. Cylinder piston ring failure.
4. Check cylinder (listen for bypassing
sound.)
5. Shorted coil.
5. Check coil resistance in accordance with
Maintenance Section, Electrical Checkout.
6. Low supply pressure.
6. Verify that the supply pressure to the
valve falls within the range noted on the
valve nameplate.
1. Incorrect null adjust.
1. Adjust null per Servovalve Maintenance
Section.
2. Partially plugged receiver.
2. Return valve to factory.
1. Valve improperly phased.
1. Swap the two leads to the valve coil to
change the polarity of the current to the
coil.
2. Plugged pilot valve receiver port.
2. Return valve to factory.
3. Spool stuck.
3. Return valve to factory.
Very high flow to cyl.
port with little or no
current input.
1. Pilot valve malfunction.
1. Return to factory.
1. Valve drive electronics gain set too
high or some other misadjustment.
1. Reset the electronics. See electronics
installation manual.
2. Partially plugged orifice or filter.
2. Check pilot pressure at test port and/or
remove, inspect, and clean orifice/filter per
Servovalve Maintenance Section.
3. Sticky spool.
3. Return valve to factory.
High null bias. (high
input current required to
maintain actuator or
motor stationary.)
Output flow obtained
from one port. (Actuator
hard over no response to
servo command.)
Oscillation or hunting
motion of actuator in the
closed loop system.
Servovalve does not
follow input command.
(Actuator or motor is
stopped.)
Sluggish valve.
(Servovalve output lags
electrical command
signal or it fails to meet
its rated output.)
