Moog 760K Series Owner's manual

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.760K Series Installation and
Operation Instruction
Electrohydraulic Servovalve
Intrinsic Safety Protected
1. INTRODUCTION
This manual provides instructions and procedures necessary to install,
operate and troubleshoot the Moog -760K, D760K and E760K Series Industrial
Servovalves. The .760K series valves are electrical equipment for hazardous
areas requiring intrinsic safety or non-incendive protection. The approved
hazardous location markings include:
1G Ex ia IIC/IIB T4 Ga KEMA 02ATEX1015 X
II 3G Ex ec II T3 Gc KEMA 02ATEX1016 X
0344 per ATEX directive 2014/34/EU
Ex ia IIB/IIC T4 Ga IECEx KEM 10.0041X
Ex ec IIC T4 Gc IECEx KEM 10.0041X
per IECEx certification scheme.
The 760K servovalves are also approved by FM, CSA, and TIIS for hazardous
locations. They are intended for directional, position, velocity, pressure and
force control in hydraulic control systems that operate with mineral oil based
fluids. Others on request.
2. OPERATION
The Moog .760K Series Industrial Servovalve consists of a polarized
electrical torque motor and two stages of hydraulic power amplification. The
motor armature extends into the air gaps of the magnetic flux circuit and is
supported in this position by a flexure tube member. The flexure tube acts as a
seal between the electromagnetic and hydraulic sections of the valve. The two
motor coils surround the armature, one on each side of the flexure tube.
The flapper of the first stage hydraulic amplifier is rigidly attached to the
midpoint of the armature. The flapper extends through the flexure tube and
passes between two nozzles, creating two variable orifices between the nozzle
tips and the flapper. The pressure controlled by the flapper and nozzle variable
orifice is fed to the end areas of the second stage spool.
The second stage is a conventional 4-way spool design in which output flow
from the valve, at a fixed valve pressure drop, is proportional to spool displacement
from the null position. A cantilever feedback spring is fixed to the flapper and
engages a slot at the center of the spool. Displacement of the spool deflects the
feedback spring which creates a force on the armature/flapper assembly.
Input signal induces a magnetic charge in the armature and causes a deflection
of the armature and flapper. This assembly pivots about the flexure tube and
increases the size of one nozzle orifice and decreases the size of the other.
This action creates a differential pressure from one end of the spool to
the other and results in spool displacement. The spool displacement causes a
force in the feedback wire which opposes the original input signal torque. Spool
movement continues until the feedback wire force equals the input signal force.
ELECTROHYDRAULIC VALVE CUT-AWAY
CAUTION
DISASSEMBLY, MAINTENANCE, OR REPAIR OTHER THAN IN ACCORDANCE WITH THE
INSTRUCTIONS HEREIN OR OTHER SPECIFIC WRITTEN DIRECTIONS FROM MOOG WILL
INVALIDATE MOOG’S OBLIGATIONS UNDER ITS WARRANTY AND YIELD THE INTRINSICALLY
SAFE PROTECTION PERMIT NULL AND VOID.
Figure 1 Moog Series .760K
Upper Polepiece
Flexure Tube
Flapper
Lower Polepiece
Feedback Wire
Inlet Orifice
Magnet
Coil
Armature
Nozzle
Spool
Control Port B
Tank
Control Port A
Pressure
Filter

5. HYDRAULIC SYSTEM PREPARATION
To prolong servovalve operational life and to reduce hydraulic system
maintenance, it is recommended that the hydraulic fluid be kept at a
cleanliness level of ISO DIS 4406 Code 16/13 maximum, 14/11 recommended.
The most effective filtration scheme incorporates the use of a kidney loop
or “off-line” filtration as one of the major filtration components. The filter
for the “off-line” filtration scheme should be a B3≥75 filter for maximum
effectiveness.
Upon system startup, and prior to mounting the servovalve, the entire
hydraulic system should be purged of built-in contaminating particles by an
adequate flushing. The servovalve should be replaced by a flushing manifold
and the hydraulic circuit powered up under conditions of fluid temperature
and fluid velocity reasonably simulating normal operating conditions. New
system filters are installed during the flushing process whenever the pressure
drop across the filter element becomes excessive. The flushing processes
should turn over the fluid in the reservoir between fifty to one hundred
times.
To maintain a clean hydraulic system, the filters must be replaced on
a periodic basis. It is best to monitor the pressure drop across the filter
assembly and replace the filter element when the pressure drop becomes
excessive. In addition to other filters that are installed in the hydraulic
circuit, it is recommended that a large capacity, low pressure ß3≥75 filter be
installed in the return line. This filter will increase the interval between filter
element replacement and greatly reduce the system contamination level.
6. INSTALLATION
The Moog .760K Series Industrial Servovalve may be mounted in any
position, provided the servovalve pressure, control, and tank ports match
respective manifold ports. The mounting pattern and port location of the
servovalve is shown on figure 4. The servovalve should be mounted with
5/16-18 x 1.75 inch long, socket head cap screws. Apply a light film of oil to
the screw threads and torque to 96 inch pounds. Wire mating connector for
desired coil configuration and polarity. Thread connector to valve.
7. MECHANICAL NULL ADJUSTMENT
It is often desirable to adjust the flow null of a servovalve independent
of other system parameters. The “mechanical null adjustment” on the Moog
.760K Series servovalve allows at least ±20% adjustment of flow null.
The “mechanical null adjustor” is an eccentric bushing retainer pin, located
above the “tank” port designation on the valve body (see Figure 2) which, when
rotated, provides control of the bushing position. Mechanical feedback elements
position the spool relative to the valve body for a given input signal. Therefore, a
movement of the bushing relative to the body changes the flow null.
Adjustment Procedure
Using a 3/8inch offset box wrench, loosen the self-locking fitting until the
null adjustor pin can be rotated. (This should usually be less than 1/2 turn).
DO NOT remove self-locking fitting. Insert a 3/32 inch Allen wrench in null
adjustor pin. Use the 3/32 Allen wrench to rotate the mechanical null adjustor
pin to obtain desired flow null. Torque self-locking fitting to 57 inch lbs.
Note: Clockwise rotation of null adjustor pin produces flow from port P to port B.
3. ELECTRICAL INFORMATION AND INTRINSICALLY SAFE
CIRCUIT SAFETY PARAMETERS
a. A wide choice of coils is available for a variety of rated current
requirements. The torque motor coil leads are attached to the connector
so external connections can provide series, parallel or single coil operation.
The valves are equipped either with an MS type connector or with pigtail
leads for electrical wiring. Refer to installation drawings of the specific
model for details. Servovalve coils should be driven with current to
provide consistency throughout the temperature range.
b. The .760K valves are approved for intrinsically safe protection per EN IEC
60079-0 : 2018, EN 60079-7 : 2015, and EN 60079-11 : 2012 for ATEX, and
IEC 60079-0 : 2017, IEC 60079-7 : 2017, and IEC 60079-11 : 2011 for IECEx.
The approved safety parameters are listed in the following table for all the
coils used by .760K series. Coil number is marked on the valve nameplate.
Coil Configuration Marking Ui(MAX) Ii(MAX)
G4220-031 (single, series, parallel) Ex ia IIB T4 12 V 120 mA
G4220-051/098 (single, series, parallel) Ex ia IIB T4 12 V 240 mA
G4221-001 G4220-042 (single) Ex ia IIC T4 16 V 160 mA
G4221-001 G4220-042 (single) Ex ia IIC T4 24.4 V 85 mA
G4220-031 (single, parallel) Ex ia IIC T4 30 V 26 mA
G4220-031 (series) Ex ia IIC T4 30 V 18 mA
G4220-051/098 (single, parallel) Ex ia IIC T4 30 V 19 mA
G4220-051/098 (series) Ex ia IIC T4 30 V 12.7 mA
G4220-042 (single) Ex ia IIC T4 30 V 37 mA
G4220-042 (parallel) Ex ia IIC T4 30 V 20 mA
G4220-042 (series) Ex ia IIC T4 30 V 10 mA
G4221-001 (single) Ex ia IIC T4 30 V 28 mA
c. The .760K valves are approved for non-incendive operation for supply
current not to exceed 50 mA dc.
d. When making electric connections to the valve, appropriate measures
must be taken to ensure that locally different earth potential do not
result in excessive ground currents. When barriers are required for
the hazardous location, hazardous area (field) wiring must meet the
requirements of the barrier manufacturer. All barriers must be mounted
and installed in compliance with the barrier manufacturer’s requirements.
Twisted pairs of 18-20 gage wire are recommended. If shielded wire is
used, connect shield wire to earth ground only at the barrier strip.
4. SPECIAL CONDITIONS FOR SAFE USE
Because the enclosure of the apparatus is made of aluminum, if it is
mounted in an area where the use of category 1 G apparatus is required, it
must be installed such that even in the event of rare incidents, ignition sources
due to impact and friction sparks are excluded.
When the electrohydraulic servovalve is used in an application for type of
explosion protection intrinsic safety “i”, the appropriate box on the data label
must be scored. When the electrohydraulic servovalve is used in an application
for type of explosion protection “n”, the appropriate box on the data label
must be scored.
After use in an application for type of explosion protection “n”, the
servovalve cannot abe safely used in a intrinsically safe application.
The screwed cable connector may only be disconnected when the circuit
is de-energized or when the location is known to be non-hazardous.
When used at an ambient temperature ≥70°C, heat resistant cable must
be used with a continuous operating temperature in accordance with the
application.
When the electrohydraulic servovalve is used in type of protection “n”
or “ec”, the equipment shall only be used in an area of not more than Pollution
Degree 2, as defined in IEC 60664-1.
The cable gland shall be installed such that impact is not possible.
When the electrohydraulic servovalve is used in type of protection “n”
or “ec”, the user shall provide additional clamping of the cable to ensure that
pulling is not transmitted to the terminations.
Figure 2
Mechanical Null Adjustment

Table 1. Replacement Parts
Part Description Qty. Part Number
.760K Series Filter Replacement Kit 1 B52555RK004K001
Inlet Orifice - Body O-Ring (1) 2 -42082-059
Filter Plug - Body O-Ring (1) 2 -42082-060
End Cap - body O-Ring (1) 2 -42082-042
End Cap - Body O-ring (1) 2 -42082-001
Filter Tube (1) 1 -23020
Base O-Rings (1) 4 -42082-022
(1) Included in Filter Replacement Kit
Potential Trouble
Servovalve does not follow input command
signal. (Actuator or components are
stationary or creeping slowly).
High threshold. (Jerky, possible oscillatory
or “hunting” motion in closed loop system).
Poor response. (Servovalve output lags
electrical command signal).
High Null Bias, (High input current
required to maintain hydraulic cylinder or
motor stationary).
Probable Cause
1. Plugged inlet filter element.
1. Plugged filter element.
1. Partially plugged filter element.
1. Incorrect null adjustment.
2. Partially plugged filter element.
Remedy
1. Replace filter element.
1. Replace filter element.
1. Replace filter element.
Check for dirty hydraulic fluid in system.
1. Readjust null.
2. Replace filter element and check for
dirty hydraulic fluid in system.
9. TROUBLESHOOTING CHART
The following troubleshooting chart list potential troubles encountered, probable causes, and remedies.
10. FILTER ASSEMBLY REPLACEMENT
a. Remove eight socket head cap screws and lockwashers using a 5/32 inch
Allen wrench. Remove end caps.
b. Remove O-Rings from end caps.
c. Remove filter plug and inlet orifice assembly from both sides of body.
Note: 2-56 screw threads into the filter plug and inlet orifice assembly.
Remove filter. The inlet orifice assemblies are matched to each other and
are therefore interchangeable.
Note: These assemblies seat in body and cannot go through bore during
removal.
d. Remove O-Rings from filter plugs and O-Rings from inlet orifice
assemblies.
e. Visually inspect filter orifice assemblies for damage or foreign matter.
f. Discard O-Rings and filters.
g. Install O-Rings on filter plugs, and O-Rings on inlet orifices.
h. Install filter, inlet orifice assembly, and a filter plug in body. Inlet
orifice assembly pilots into filter. Install the other inlet orifice assembly
and filter plug into other end of filter. Inlet orifice assemblies are
interchangeable.
i. Install O-Rings on end caps.
j. Install end caps on body and install eight socket head cap screws and
lockwashers. Torque the screws to 57 inch-pounds.
11. FUNCTIONAL CHECKOUT AND CENTERING
a. Install servovalve on hydraulic system or test fixture, but do not connect
electrical lead.
b. Apply required system pressure to servovalve and visually examine for
evidence of external leakage. If leakage is present and cannot be rectified
by replacing O-Rings, remove the discrepant component and return for
repair or replacement.
Note: If the system components are drifting or hardover, adjust
the mechanical null of the servovalve.
c. Connect electrical lead to servovalve and check phasing in accordance
with system requirements.
12. AUTHORIZED REPAIR FACILITIES
Moog does not authorize any facilities other than Moog or Moog subsidiaries
to repair its servovalves. It is recommended you contact Moog at
[phone] to locate your closest Moog repair facility. Repair by an
independent (unauthorized) repair house will result in voiding the Moog
warranty and could lead to performance degradation or safety problems.
13. DECLARATION OF MANUFACTURER
An EU Declaration of Conformity according to Council Directive
2014/34/EU is supplied with each servovalve.
Figure 3
Inlet Orifice Assemblies
(one each end of body)
End Plate
Filter Tube
Orifice Assembly
End Cap-Body
O-Rings
Filter Plug
Filter Plug
O-Ring Inlet Orifice O-Ring
8.GENERAL SERVICING RECOMMENDATIONS
a. Disconnect the electrical lead to the servovalve.
b. Relieve the hydraulic system of residual pressure.
c. Remove the servovalve.

STANDARD -760K SERIES INSTALLATION DIMENSIONS
(Consult factory for specific model dimensions)
Moog Inc., East Aurora, NY 14052-0018
Telephone: [phone]
Fax: [phone]
Toll Free: 1-800-272-MOOG
www.moog.com
TJW/PDF RevD, January 2023, Id. CDS7155
NOTES
TYPICAL WIRING SCHEMATIC
The products described herein are subject to change at any time without notice, including, but not limited to, product features, specifications, and designs.
1 Valve Weight:
1.1 lbs (0.5 kg)
2 Polarity:
A&C (+), B&D (-) produces flow out
port B
3 Manifold O-Rings
0.070 (1.78) sect x 0.426 (10.82) I.D.
(Universal dash No. 13)
0.070 (1.78) sect x 0.364 (9.25) I.D.
(Universal dash No. 12) for optional
X-port
4 Surface:
Surface to which valve is
mounted requires 32 ( ) finish, flat
within .001 [0.025] TIR
5 Electrical Connector:
Mates with MS3106-14S-2S or equivalent;
others on request
6 Null Adjust:
Flow out of port B will increase with
clockwise rotations of null adjust pin
7 Compressed Oil Volume
for one control port: 0.229 in3
(3.75 cm3)
8 Suggested Mounting Screws:
0.312-18 x 1.750 lg (M8 x 45)
socket head screw (4 req’d)
Dimensions in parenthesis are in millimeters.
2
A B C D
Figure 4
DD
TANK PORT T
PRESSURE PORT P
CONTROL PORT B
3.88
1.94
1.750
.875
.670
.875
.437
CONTROL PORT A
1.500
.500
3.000
1.750 .390
3.500
VALVE MOUNTS ON THIS
MANIFOLD SURFACE
.437
.875
.670
1.281
2.562
1
PORT PER SAE J1926
1.0625-12 UN-2B DASH 12
STR THD O-RING BOSS
(.75 [19.05] TUBE OD REF)
4 PLACES
1.00
4 PL
1.25
63
2.00
2.11
4.22
RET AUX PRESS
760
PORT PER SAE J1926
.4375-20 UNF-2B DASH 4
STR THD O-RING BOSS
(.25 TUBE OD REF)
.001
.156 (3.96) AUXILIARY
PILOT PRESSURE PORT
.008 M
4X .312 [7.92]
.014 M
4X .3125-18 UNC-2B THD
.007 M
.015 M
.136 .20
.014 M
.50 .63
4X .344 [8.74] THRU
[50.8]
[53.6]
[107.19]
[31.75]
[44.45]
[22.23]
[50.8]
[17.02]
[11.1]
[38.1]
[76.2]
[12.7]
[9.91]
[44.45]
[88.9]
[98.55]
[49.28]
[65.07]
[32.54]
[49.28]
[11.1]
[17.02]
[25.4] CERTIFICATION CONTROLLED RELATED DOCUMENT
THIS INSTALLATION INSTRUCTION IS CERTIFICATION CONTROLLED.
REVISION SHALL BE APPROVED BY THE MOOG ICD Ex/ATEX
AUTHORIZED PERSON AND MAY REQUIRE APPROVAL BY THE ATEX
NOTIFIED BODY.
APPLICABLE CERTIFICATE(S):
KEMA 02ATEX1015 X
KEMA 02ATEX1016 X