SERVO VALVES
3-STAGE FLOW CONTROL
79 SERIES
FOR DEPENDABLE, LONG LIFE OPERATION WHERE
POSITION, SPEED, PRESSURE OR FORCE CONTROL
SYSTEMS HAVE HIGH DYNAMIC RESPONSE
REQUIREMENTS
WHAT MOVES YOUR WORLD
Rev. L, September, 2019
The actual flow is dependent
upon electrical command signal
and valve pressure drop. The
flow for a given valve pressure
drop can be calculated using
the square root function for
sharp edge orifices.
The flow value Q calculated in
this way should not exceed an
average flow velocity of 100
ft/s in ports P, A, B and T.
∆p
Q = Q
N
∆p
N
Q [gpm] = calculated flow
Q
N
[gpm] = rated flow
∆p [psi] = actual valve
pressure drop
∆p
N
[psi] = rated valve
pressure drop
If large flow rates with high
valve pressure drops are
required, an appropriate higher
pilot pressure has to be chosen
to overcome the flow forces.
An approximate value can be
calculated as follows:
p
x
≥ 5.6 • 10
-2
• • ∆p
Q [gpm] = max. flow
∆p [psi] = valve pressure
drop with Q
A
k
[in
2
] = spool drive area
p
x
[psi] = pilot pressure
The pilot pressure p
x
has
to be at least 215 psi above
the return pressure of the
pilot stage.
This catalog is for users with technical
knowledge. To ensure that all
necessary characteristics for function
and safety of the system are given, the
user has to check the suitability of the
products described here. In case
of doubt, please contact Moog Inc.
79 SERIES SERVO VALVES
The 79 Series flow control
servo valves are throttle valves
for 3 and preferably 4-way
applications. These three stage
servo valves were developed
for applications that require
high flow rates and high
performance. The 79 series
covers the range of rated
flow from 30 to 200 gpm at
1,000 psi valve drop. These
valves are offered with 76X
Series pilot valves, in either
Standard, High, or Very High
performance configurations.
These valves are suitable for
electrohydraulic position,
speed, pressure or force
control systems with
high dynamic response
requirements.
Principle of operation
An electrical command signal
(set point, input signal) is
applied to the external control
amplifier which drives a
current through the pilot valve
coils. The pilot valve produces
differential pressure in its
control ports. This pressure
difference results in a pilot
flow which causes main
spool displacement.
The position transducer, which
is excited via an oscillator,
measures the position of
the main spool (actual value,
position voltage). The signal
then is demodulated and fed
back to the control amplifier
where it is compared with
the command signal. The
control amplifier drives the
pilot valve until the error
between command signal and
feedback signal is zero. Thus,
the position of the main spool
is proportional to the electrical
command signal.
2
VALVE FEATURES
n Electrical feedback on the main spool for low hysteresis
and excellent linearity
n Optional external pilot supply and return connections
n High spool control forces
n High dynamics
n Rugged, long-life design
n High resolution, low hysteresis
n Completely set-up at the factory
n Excellent null stability
79 SERIES
THREE STAGE SERVO VALVES
Q
A
K
3
79 SERIES
GENERAL TECHNICAL DATA
Operating Pressure
Main Stage*
Ports P, A and B
with X internal up to 5,000 psi with High Pressure Pilot
with X external up to 5,000 psi
Port T with Y internal up to 3,000 psi
Port T with Y external up to 5,000 psi
Pilot valve (76X series)*
Ports P, A and B up to 5,000 psi
Port T up to 3,000 psi
Temperature Range
Fluid 0°F to 180°F
Ambient 0°F to 180°F
Seal Material Viton, others on request
Operating Fluid Mineral oil based hydraulic fluid
(to DIN 51524), others on request
Recommended viscosity 60-450 SUS @ 100°F
Class of Cleanliness: The cleanliness of the hydraulic
fluid greatly effects the performance
(spool positioning, high resolution)
and wear (metering edges, pressure
gain, leakage) of the valve.
* Maximum special order is 5,000 psi
Recommended Cleanliness Class
For normal operation ISO 4406 < 14/11
For longer life ISO 4406 < 13/10
System Filtration
Pilot valve: High pressure filter (without
bypass, but with dirt alarm)
mounted in the main flow
and if possible, directly
upstream of the servo valve.
Main stage: High pressure filter as for the pilot
stage. In combination with a fast
regulating VD-pump, a bypass filter
is possible.
Filter Rating recommended
For normal operation ß
10
≥ 75 (10 µm absolute)
For longer life ß
5
≥ 75 (5 µm absolute)
Installation Options Any position, fixed or moveable.
Vibration 30 g, 3 axes
Weight
Shipping Plate Delivered with an oil sealed
shipping plate.
P B T A
3 stage Servo Valve
79-1XXX Series with a
76X Series pilot valve
4
79-1XXX SERIES
TECHNICAL DATA
M
odel . . . Type 79-1XXX
Mounting Pattern ISO, but X and Y do not correspond to ISO ISO 10372-06-05-0-92
Valve Body Version 4-way
3-stage with spool-bushing assembly
Pilot Valve 2-stage, 76X series
Pilot Connection Optional, internal or external X and Y
Mass 24 lbs [10.9 kg]
Rated Flow (± 10%) at ∆p
N
= 1,000 psi [gpm] 30 60
Response Time* for 0 to 100% stroke [ms] 14 14
Threshold* [%] < 0.5%
Hysteresis* [%] < 1.0%
Null Shift with ∆T = 50°C [%] < 2.5%
Null Leakage Flow* total, max. [gpm] 0.8 1.6
Main Spool Stroke [in] .075
Main Spool Drive Area [in
2
] 0.442
* measured at 3,000 psi pilot or operating pressure, respectively, and fluid viscosity 32 mm
2
/s
4
2
0
-2
-4
-6
-8
-12
-14
-16
Amplitude Ratio (dB)
Phase Lag (degrees)
100 200 300
0
20
40
60
80
100
120
140
160
Frequency (Hz)
Optional High Response Frequency Response
5710 20 30 40 50 70
Supply pressure 3000 psi
Loop gain 700 sec
-1
±10% Spool travel
±100% Spool travel
4
2
0
-2
-4
-6
-8
-12
-14
-16
Amplitude Ratio (dB)
Phase Lag (degrees)
100 200 300
0
20
40
60
80
100
120
140
160
Frequency (Hz)
Standard Response Frequency Response
5710 20 30 40 50 70
Supply pressure 3000 psi
Loop gain 425 sec
-1
±100% Spool travel
±10% Spool travel
60 gpm
30 gpm
500
100
100 1000 5000
10
5
Flow Rate Q (gpm)
Rated pressure drop ∆pN= 1,000 psi Valve pressure drop ∆pN [psi]
Valve flow for maximum valve opening (100% command signal) as a
function of the valve pressure drop.
Typical Characteristic
Curves measured at 3,000 psi
pilot or operating pressure,
respectively, and fluid kinematic
viscosity of 32 mm
2
/s.
Valve Flow Diagram
Frequency Response
for valves with different rated
flows and different pilot valvesSet-up and Operation
1.2
1.0
0.8
0.6
Phase Angle (degrees)
5
-50
-25
0
+25
Excitation Frequency (kilohertz)
.4 .5 .7 11.5 234
(volts/inch)
Sensitivity
volt
Sensitivity
Phase
Note: Individual units may vary ±10%
Figure 1
79-2XXX SERIES
TECHNICAL DATA
Model . . . Type 79-2XXX
Mounting Pattern Moog Standard
Valve Body Version 4-way
3-stage with spool-bushing assembly
Pilot Valve 2-stage, 76X series
Pilot Connection Optional, internal or external X and Y
Mass 35.5 lbs. [16.1 kg]
Rated Flow (± 10%) at ∆p
N
= 1,000 psi [gpm] 100 200 250
Response Time* for 0 to 100% stroke Standard [ms] 15 15 15
High Response [ms] 6 6 6
Threshold* [%] < 0.5%
Hysteresis* [%] < 0.5%
Null Shift with ∆T = 50°C [%] < 2.0%
Null Leakage Flow* total, max. [gpm] 2.5 2.5 2.5
Main Spool Stroke [in] 0.130
Main Spool Drive Area Standard [in
2
] 1.107
High Response [in
2
] 0.442
* measured at 3,000 psi pilot or operating pressure, respectively, and fluid viscosity 32 mm
2
/s
4
2
0
-2
-4
-6
-8
-12
-14
-16
Amplitude Ratio (dB)
Phase Lag (degrees)
100 200 300
0
20
40
60
80
100
120
140
160
Frequency (Hz)
Frequency Response
200 gpm
5710 20 30 40 50 70
Supply pressure 3000 psi
Loop gain 590 sec
-1
±10% Spool travel
±100% Spool travel
4
2
0
-2
-4
-6
-8
-12
-14
-16
Amplitude Ratio (dB)
Phase Lag (degrees)
100 200 300
0
20
40
60
80
100
120
140
160
Frequency (Hz)
Frequency Response
100 gpm
5710 20 30 40 50 70
Supply pressure 3000 psi
Loop gain 700 sec
-1
±10% Spool travel
±100% Spool travel
200 gpm
130 gpm
100 gpm
60 gpm
500
100
100 1000 5000
10
Flow Rate Q (gpm)
Rated pressure drop ∆pN = 1,000 psi Valve pressure drop ∆pN [psi]
Valve flow for maximum valve opening (100% command signal)
as a function of the valve pressure drop.
30 gpm
5
Typical Characteristic
Curves measured at 3,000 psi
pilot or operating pressure,
respectively, and fluid kinematic
viscosity of 32 mm
2
/s.
Valve Flow Diagram
Frequency Response
for valves with different rated
flows and different pilot valves.
4
2
0
-2
-4
-6
-8
-12
-14
-16
Amplitude Ratio (dB)
Phase lag (degrees)
100 200 300
0
20
40
60
80
100
120
140
160
Frequency (Hz)
Frequency Response
60 and 100 gpm
5710 20 30 40 50 70
Supply pressure 3000 psi
Loop gain 280 sec
-1
±10% Spool travel
±100% Spool travel
High Response Valves
4
2
0
-2
-4
-6
-8
-12
-14
-16
Amplitude Ratio (dB)
Phase Lag (degrees)
100 200 300
0
20
40
60
80
100
120
140
160
Frequency (Hz)
Frequency Response
130 and 200 gpm
5710 20 30 40 50 70
Supply pressure 3000 psi
Loop gain 620 sec
-1
±10% Spool travel
±100% Spool travel
Standard Valves
The mounting Manifold must
conform to
ISO 10372-06-05-0-92.
Note: The X port to ISO
Standard must not be
machined. The X and Y ports
of Moog valve body do not
correspond to ISO Standard.
Surface to which valve is
mounted requires a
32
[∆∆]
finish, flat within 0.001[0.03] TIR.
79-1XXX SERIES
INSTALLATION DRAWINGS WITH
PILOT VALVES 76X SERIES
6
.005
5.00
1.790
PORT PER SAE J1926
1.000 [25.4]
4X
4X
DASH 20 STR. THD. ORING BOSS
PILOT RETURN
PRESSURE PORT
RETURN PORT
SURFACE
VALVE MOUNTS
1.437
4.250
PORT PER SAE J1926
.406 [10.3] THRU
1.000
.688
NOTES:
5.00
MANIFOLD P/N 22236AM3 IS NOT PROVIDED WITH PORTS.
2.500
.156
3.375
NEAR AND FAR SIDE
2.000
DASH 20 STR. THD. ORING BOSS
ON THIS MANIFOLD
4X .375-16 UNC-2B
1.625-12 UNC-2B
2.125
.609 [15.4]
EXTERNAL PILOT SUPPLY AND RETURN PORTS SHOWN FOR REFERENCE ONLY.
PILOT PRESSURE
2.50
1.790
.50 [12.7]
NEAR AND FAR SIDE
1.625-12 UNC-2B
2.125
2.875
(1.20 O.D. TUBE)
.31 [7.8]
1.250
.156 [3.9]
2.500
4.250
1.687
.005
(1.20 O.D. TUBE)
2.000
TRANSDUCER
ELECTRICAL
CONNECTOR
P
PIN B
PIN D
PIN C
PIN A
3.57
[90.7]
[36.1]
1.42
6.00
[152.4]
1.46
[37.1]
3.79
[96.3]
.83
[21.0]
10.29
[261.4]
2.68
[68.1]
OPTIONAL ADAPTER PLATE
FOR EXTERNAL PILOT VALVE
PRESSURE AND RETURN.
SAE STR THD O-RING
FOR .50 O.D. TUBE FITTING
PORTS ARE .750-16
PILOT VALVE
PIN A
PIN B
PIN E
PIN D
PIN C
5.51
[140.0]
2.875
[73.03]
1.437
[36.50]
1.687
[42.85]
3.375
[85.73]
1.89
[48.0]
3.78 MAX
[96.0]
TO DEPTH SHOWN
.67 [17.0]
.009
M
.41 [10.5] THRU
.25
1.24
[31.5]
1.61
[40.9]
2.95
[74.9]
2.17
[55.1]
.26
[6.6]
2.17
[55.1]
4.33
[110.0]
1.72 MAX
[43.7]
3.83 MAX
[97.3]
[6.4]
2.85 MAX
[72.4]
NULL ADJUST
HEX SOCKET
EXTERNAL
3/32 IN.
TWO STAGE PILOT VALVE
760 SERIES SERVOVALVE
ELECTRICAL CONNECTOR
[53.9]
[107.9]
[50.8]
[55.4]
[45.4]
[45.4]
[127.0]
[63.5]
[50.8]
[85.7]
[107.9]
[53.9]
[42.8]
[3.9]
[73.0]
[36.4]
[127.0]
[63.5]
[31.7]
[.127]
[.127]
[63.5]
[17.4]
X
X
P
G
AB
T
Y
Y
F1
3.62
[92]
4.09
[104]
F2
F4 F3
79-1XXX SERIES
TYPICAL SUBPLATE MANIFOLD
7
US P A T B G X* Y* F1 F2 F3 F4
Ø.63 Ø.63 Ø.63 Ø.63 Ø.32 Ø.156 Ø.156 3/8-16 3/8-16 3/8-16 3/8-16
X 1.44 0.44 1.44 2.44 0.44 1.44 1.44 0 2.87 2.87 0
Y 0.69 1.69 2.69 1.69 0.94 - 0.1 3.48 0 0 3.37 3.37
METRIC P A T B G X* Y* F1 F2 F3 F4
Ø16 Ø16 Ø16 Ø16 Ø8 Ø4 Ø4 M10 M10 M10 M10
X 36,5 11,1 36,5 61,9 11,1 36,5 36,5 0 73 73 0
Y 17,5 42,9 68,3 42,9 23,8 -2,5 88,3 0 0 85,7 85,7
THE MOUNTING MANIFOLD MUST CONFORM TO ISO 10372-06-05-0-92
* NOTE: The X port to the ISO standard must not be machined.
The X and Y ports of the Moog valve do not correspond to ISO standard.
Surface to which the valve is mounted requires a 32 finish [∆∆], flat within .0001 [.03] TIR.
O-rings (included in delivery)
for P, T, A, B 4 pieces ID 0.800 x 0.070 42082-040
for X, Y 2 pieces ID 0.301 x 0.070 42082-012
Mating connector, waterproof IP 65 (not included in delivery) pilot valve -49054F014S002S (MS3106F14S-2S)
LVDT -49054F014S005S (MS3106F14S-5S)
Flushing plate G4321AM001
Mounting bolts (not included in delivery)
3/8 - 16 UNC x 2.25 4 pieces required torque 50 lb.-ft. A31324-336B
SPARE PARTS AND ACCESSORIES FOR 79-1XXX SERIES
79-2XXX SERIES (STANDARD)
INSTALLATION DRAWING
WITH PILOT VALVE 76X SERIES
M
EXTERNAL NULL
ADJUST
3/32 IN. HEX SOCKET
.940
[23.88]
1.880
[47.75]
2.181
[55.40]
4.362
[110.79]
4.25
[108.0]
2.310
[58.67]
4.620
[117.35]
5.72
[145.3]
1.89
[48.0]
5.61 MAX
[142.5]
3.78 MAX
[96.0]
3.12 DIA
MAX
[79.2]
3.75 DIA
[95.3]
2 PL
PIN B
PIN A
PIN E
PIN C
.28
[7.1]
PIN D
2.17
[55.1]
2.85 MAX
[72.4]
4.69 MAX
[119.1]
.28
[7.1]
1.50
[38.1]
2.56
[65.0]
3.83 MAX
[97.3]
1.72
MAX
[43.7]
3.54
[89.9]
7.09
[180.1]
4.43
[112.5]
2.38 MAX
[60.5]
4.64 MAX
[117.9]
5.32 MAX
[135.1]
* TRANSDUCER
ELECTRICAL
CONNECTOR
TWO STAGE PILOT VALVE
760 SERIES SERVOVALVE
ELECTRICAL CONNECTOR
FOR EXTERNAL PILOT VALV E
PRESSURE AND RETURN
PORTS ARE .750-16 SAE
STR THD O-RING PORTS
FOR .50 O.D. TUBE FITTING
OPTIONAL ADAPTER PLATE
STR THD O-RING PORTS
OPTIONAL EXTERNAL PILOT
VALVE PRESSURE AND RETURN
PORTS ARE .5625-18 SAE
FOR .375 O.D. TUBE FITTING
PIN B
PIN C
PIN D
PIN A
1.24
[31.5]
.26 MAX DIA
[6.5]
Note: The X and Y tubes have to be
connected to the Moog valve body
by fittings.
Surface to which valve is
mounted requires a
32
[∆∆]
finish, flat within 0.001 [0.03] TIR.
TYPICAL SUBPLATE MANIFOLD
8
RETURN PORT
PRESSURE PORT
CONTROL PORT B
.31 DIA X .33 DEEP
63
2.250
1.125
3.120
1.560
4.620
2.310
7.88
4.376
2.181
.940
1.880
3.88
5.88
2.940
6.620
3.310
3.940
1
PRESS
-2 MANIFOLD:
1-1/2 - 11-1/2 NPTF
4 PLACES
1.125 DIA PORT
4 PLACES
2.38
4 PL
.656 DIA THRU
CBORE 1.00 DIA x .88 DP
4 MOUNTING HOLES
.002
.625-11 UNC-2B THD
8 VALVE MTG HOLES
-1 MANIFOLD:
PORT PER SAE J1926
1.875-12 UN-2B DASH 24
STR THD O-RING BOSS
(1.50 TUBE OD REF)
4 PLACES
CONTROL PORT A
9
79-2XXX SERIES (HIGH RESPONSE)
INSTALLATION DRAWINGS
WITH PILOT VALVES 76X SERIES
O-rings (included in delivery)
for P, T, A, B 4 pieces ID 1.418 x 0.138 42082-264
Mating connector, waterproof IP 65 (not included in delivery) pilot valve -49054F014S002S (MS3106F14S-2S)
LVDT -49054F014S005S (MS3106F14S-5S)
Flushing Block Kit -43949-001K002
Mounting bolts (not included in delivery)
5/8 - 11 UNC x 2.25 8 pieces required torque 215 lb.-ft. B40052-218B
SPARE PARTS AND ACCESSORIES FOR 79-2XXX SERIES
3.37
[85.6]
1.69
[42.9]
PILOT VALVE
NULL ADJUST
INTERNAL HEX
.28
[7.1]
2.56
[65.0]
.256 [6.50]
MAX DIA
1.25 [31.8]
HEX LOCKNUT
[72.4]
2.85 MAX
[31.5]
1.24
4.69 MAX
[119.1]
[38.1]
1.50
LVDT NULL ADJUST
.250 [6.35]
INTERNAL HEX
EXTERNAL
OPTIONAL
RETURN PORT
PRESSURE PORT
CONTROL PORT B
.31 DIA X .33 DEEP
63
2.250
1.125
3.120
1.560
4.620
2.310
7.88
4.362
2.181
.940
1.880
3.88
5.88
2.940
6.620
3.310
3.940
1
PRESS
CONTROL PORT A
-2 MANIFOLD:
1-1/2 - 11-1/2 NPTF
4 PLACES
1.125 DIA PORT
4 PLACES
2.38
4 PL
.656 DIA THRU
CBORE 1.00 DIA x .88 DP
4 MOUNTING HOLES
.002
.625-11 UNC-2B THD
8 VALVE MTG HOLES
-1 MANIFOLD:
PORT PER SAE J1926
1.875-12 UN-2B DASH 24
STR THD O-RING BOSS
(1.50 TUBE OD REF)
4 PLACES
P
R
PIN A
PIN E
PIN D
PIN C
PIN B
4.25
[108.0]
5.72
[145.3]
[47.75]
1.880
[110.79]
4.362
[23.88]
.940
.671 [17.04] DIA THRU
[48.0]
1.89
[96.0]
3.78 MAX
2.181
[55.40]
2.310
[58.67]
LEAKAGE PORT PER SAE J1926
.437-20 UNF-2B
DASH 4 STR THD O-RING BOSS
(0.250 O.D. TUBE REF)
4.620
[117.35]
[16.8]
OPTIONAL EXTERNAL PILOT
VALVE PRESSURE AND RETURN
PORTS ARE SAE J1926 .562-18 UNF-2B
DASH 6 STR THD ORING BOSS
(0.375 O.D. TUBE REF)
P
2.11
[53.6]
1.89
[48.0]
TWO STAGE PILOT VALVE
ELECTRICAL CONNECTOR
760 SERIES SERVOVALVE
TRANSDUCER
ELECTRICAL
CONNECTOR
4.55
[115.6]
.28
[7.1]
5.81
[147.6]
.66 MAX
3.90 DIA
[99.1]
2 PL
4.15
[105.4]
2 PL
8 PLACES
OPTIONAL ADAPTER PLATE
FOR EXTERNAL PILOT VALVE
PRESSURE AND RETURN.
STR THD O-RING PORTS
FOR .50 O.D. TUBE FITTING
PORTS ARE .750-16 SAE
A
10
79 SERIES
ELECTRICAL CONNECTIONS
SET-UP AND OPERATION
Servo Controller
The Moog Model N121-132A is a convenient servo controller
for use with 79 Series servo valves. The Model N123-134
exciter/demodulator is available for operation of the spool
position LVDT.
The AC excitation is adjustable between ±10 and ±14 volts
peak-to-peak. The recommended frequency is 2000 Hz (N123-
134) to achieve good servo valve response; however, a lower
frequency may be necessary if a long cable run is required.
The sensitivity of the spool position LVDT can be determined
from Figure 1; the demodulated gain of the N123-134 can be
determined from its data sheet.
Inner Loop Gain Set-up
• Connect the pilot valve coils to servo controller terminals
12 and 13 per the schematic below.
• Ground servo controller terminal 7 and apply a +1.0 VDC
signal to servo controller terminal 6 (with the LVDT
demodulated signal from the N123-134 disconnected).
• Monitor the valve current by measuring the voltage drop
across the 20 Ω sensing resistor R31 (test point lsv to
TP11). The valve current scale factor is 50 mA per volt
measured at lsv.
• Adjust the GAIN 2 pot to obtain the desired servocon-
troller gain (see equations to the right). It may not be
possible to operate with satisfactory valve stability at the
maximum servo controller gain as both the pilot valve and
LVDT have ±10% gain tolerances. It is recommended that
the servo controller gain be turned down the first time
pressure is applied.
Standard Electrical Configuration
Servo Valve Loop Gain
The inner loop gain of the 79 Series Servo Valves, when operating
with 3,000 psi pilot supply pressure and with the pilot valve coils
wired in parallel, can be determined by:
K
IL
=
K
A
K
PV
K
D
K
X
∆
X
where:
K
IL
= servo valve inner loop gain (sec
-1
)
K
A
= servo controller gain (mA/VDC)
K
PV
= pilot valve gain in
3
/sec
( mA )
Z gpm x 3.85
in
3
/sec 3000 psi
=
gpm 1000 psi
15 mA
where Z = 2.5 for 79-100, 5.0 for 79-200 standard, and
4.0 for 79-200 High Response.
K
D
= demodulator gain (VDC/vrms)
K
x
= LVDT gain (vrms/inch)
∆
X
= power spool end area = 1.107 in
2
for 79-200 standard
= 0.442 in
2
for 79-200 High
Response and 79-100
The required servo controller gain can be found by:
K
IL
A
S
K
A
=
K
PV
K
D
K
X
Outer Servoloop Gain
The nominal gain of the 79 Series for the outer loop will be:
K
S
K
VAL
=
K
D
K
X
where:
K
VAL
= overall valve gain in
3
/sec
(
VDC
)
K
S
= power spool flow gain (see specifications)
K
D
= demodulator gain (VDC/vrms)
K
X
= LVDT gain (vrms/inch)
Note that the power spool flow gain is specified for operation at
1000 psi supply. This gain must be corrected for operation at other
supply pressures by multiplying it by a correction factor of the square
root of the available hydraulic pressure divided by 1000 psi.
The summing section of the model N121-132A servo controller
can be used for summing the load servo command and
feedback signals. The GAIN 1 pot provides a convenient
loop gain adjustment.
Typical Valve Schematic*
*Refer to specific model installation for wiring details.
A
B
C
D
A
B
C
D
E
P
R
PR
C
1
C
2
OPTIONAL
PILOT SUPPLY
PILOT VALVE
LVDT
PRIMARY
SECONDARY
}
}
4
7
COMMAND
FEEDBACK
SCALE
INNER LOOP
GAIN-2
+E
-E
GAIN
+E
-E
PHASE
AMPLITUDE
+E
R
R
P
s
s
P
U5
IC1
26
27
28
29
3
17
21
1
12
13
6
21
19
17
6
7
8
12
11
10
9
3
4
OUTER LOOP
GAIN-1
SERVO
VALVE
115 vac
50 - 60 Hz
17
21
MODEL N121-132A
SERVOCONTROLLER
MODEL N123-134
EXCITER-
DEMODULATOR
Insert R45
Remove R20
On Model N121-132A:
CIRCUIT CARD MODIFICATIONS
*
*
value determined by system gain requirements
Signal for 100% Spool Stroke
Command
H ±15 mA (single coil)
L ±40 mA (single coil)
79-1, 79-2 • • •
Model Designation
Assigned at the factory
Model Number Type Designation
Preferred configurations highlighted.
All combinations may not be available.
Options may increase price and delivery.
Technical changes are reserved.
11
• • • • • • • • • • • •
Valve Version
S Standard response
H High response (200 only)
Rated Flow
Q
N
[gpm] at ∆p
N
= 1,000 psi
Standard (gpm) Series
10 30 (100 only)
25 60 (100 only)
40 100 (200 only)
80 200 (200 only)
99 260 (200 only)
Maximum Operating Pressure p
p
and Body Material
F 3,000 psi
J 4,500 psi at p
x
≤ 4,000 psi (X and Y external) operating pressure in ports
P, A, B and T up to 5,000 psi possible
K 5,000 psi steel
Seal Material
V FPM (Fluorocarbon)
Others on request*
Valve Electronics
7 Customer Supplied Electronics
79 SERIES
ORDERING INFORMATION
Pilot Stage
P 76X Standard
Q 76X High response
76X Super high response
Main Spool Type
O 4-way / axis cut / linear characteristic
X Special spool*
B 3 way/A port active
Spool Position without Electrical Signal
Position Pilot Pressure [psi]
O Undefined ≥215
A P º B, A º T ≥215
B P º A, B º T ≥215
Pilot Connections and Pressure
Supply [X] Return [Y]
0 internal internal
1 external internal (adapter plate)
2 external external (adapter plate)
6 external external (ports in body)
* Optional designs are available with special spool bushing lap configuration.
Available seal materials: Fluorocarbon (Std.), BUNA or EPR.
LVDT Electrical Connector
4 4 pin XDCR: 4 pin Pilot
5 5 pin XDCR: 4 pin Pilot
K
TAKE A CLOSER LOOK
Motion Control solutions from Moog are available around the world.
For more information, visit our web site or contact one of the locations below.
Argentina
+54 11 4326 5916
info.argentina@moog.com
Australia
+61 3 9561 6044
info.australia@moog.com
Brazil
+55 11 3572 0400
info.brazil@moog.com
Canada
+1 716 652 2000
info.canada@moog.com
China
+86 21 2893 1600
info.china@moog.com
Finland
+358 9 2517 2730
info.finland@moog.com
France
+33 1 4560 7000
info.france@moog.com
Germany
+49 7031 622 0
info.germany@moog.com
Hong Kong
+852 2 635 3200
info.hongkong@moog.com
India
+91 80 4057 6605
info.india@moog.com
Ireland
+353 21 451 9000
info.ireland@moog.com
Italy
+39 0332 421 111
info.italy@moog.com
Japan
+81 46 355 3767
info.japan@moog.com
Korea
+82 31 764 6711
info.korea@moog.com
Luxembourg
+352 40 46 401
info.luxembourg@moog.com
The Netherlands
+31 252 462 000
simulation@moog.com
Norway
+47 6494 1948
info.norway@moog.com
Russia
+7 8 31 713 1811
info.russia@moog.com
Singapore
+65 677 36238
info.singapore@moog.com
South Africa
+27 12 653 6768
info.southafrica@moog.com
Spain
+34 902 133 240
info.spain@moog.com
Sweden
+46 31 680 060
info.sweden@moog.com
Switzerland
+41 71 394 5010
info.switzerland@moog.com
United Kingdom
+44 168 429 6600
info.uk@moog.com
USA
+1 716 687 7600
info.usa@moog.com
www.moog.com/industrial
Moog is a registered trademark of Moog Inc. All trademarks as indicated herein are the
property of Moog Inc. and its subsidiaries.
©2019 Moog Inc. All rights reserved.
79 Series Servo Valve CDL6198 Rev. L 0919
TJW/PDF
WHAT MOVES YOUR WORLD
