Technical support

Operation and maintenance instruction for electrohydraulic servo valve

1.Double nozzle flapper and jet pipe valves normally have 2 coils, which can work in single, series and parallel connection. Parallel connection is recommended.

 2.Dither is an additional signal input applied to servo valve to improve the threshold of servo valve and system performance. It is recommended dither frequency be a little higher and peak to peak amplitude be less than 5%.

 3.For linear direct servo valves return reverse pressure of hydraulic source should be less than 5MPa.

 4.Alternating signal should not be applied to servo valves in case no pressure is supplied to servo valves. But direct drive servo valve is an exception.

 5.Air bleed hole should be properly set on the oil circuit of servo valve and actuator to make servo control system stable, especially for position and force systems.

 6.Should lower pressure gain and internal leakage of servo valve is spotted after the system is in operation for some time, it indicates there is an increase in the wear of sharp edge of sliding spool. In case of slow response in system, filter to protect nozzle-flapper stage may be clogged, causing performance degrade in the nozzle-flapper stage. Should these problems occur, please return the valve to factory for repairs or replace a new one.

7. Surface to which valve is mounted requiresServo valve use safeguarding manualfinish, flat within 0.02mm.
8.Please strive to avoid installing servo valve on components with strong vibration or sharp movement change. Should servo valves have to be installed on components with sharp movement change, please ensure that axis direction of spool doesn’t match movement direction of components.

9.Please strive to control fluid temperature and ambient temperature of servo valve. Big temperature change or high temperature will affect the performance and operational life of servo valve.

10.Instruction for hydraulic oil source used for servo valve:

(1)Hydraulic system to which valve is mounted must be cleaned thoroughly.Oil tank should be sealed.
(2)Hydraulic fluid should be kept at a cleanliness level of GJB420 7/A.
(3)Working fluid should be tested on a periodic base to ensure it is as per technical specifications. Otherwise it should be filtered or changed.
(4)A filter with absolute filtration rate ≤10 μ should be provided before supply port of servo valve. It is recommended filter with absolute filtration rate ≤5μbe used to prolong servo valve operational life.
(5)Fluid pressure impulse amplitude of servo valve hydraulic power should be kept as small as possible.

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