2019-09-18
72 SERIES
TWO STAGE SERVOVALVES
72 SERIES SERVOVALVES
The 72 Series flow control servovalves are throttle valves for 3 and preferably 4-way applications.They are a high performance, two-stage design that covers the range of rated flows from 25 to 60 gpm at 1000 psi valve drop.The output stage is a closed center, four-way sliding spool.The pilot stage is a symmetrical double-nozzle and flapper, driven by a double air gap, dry torque motor. Mechanical feedback of spool position is provided by a cantilever spring.The valve design is simple and rugged for dependable, long life operation.
These valves are suitable for electrohydraulic position, speed, pressure or force con-trol systems with high dynamic response requirements.
Principle of operation
An electrical command signal (flow rate set point) is applied to the torque motor coils, and creates a magnetic force which acts on the ends of the pilot stage armature.This causes a deflection of armature/flapper assembly within the flexure tube. Deflection of the flapper restricts fluid flow through one nozzle which is carried through to one spool end, displacing the spool.
Movement of the spool opens the supply pressure port (P) to one control port, while simul-taneously opening the tank port (T) to the other control port.The spool motion also applies a force to the cantilever spring, creating a restoring torque on the armature/flapper assembly. Once the restoring torque becomes equal to the torque from the magnetic forces, the armature/flapper assembly moves back to the neutral position, and the spool is held open in a state of equi-librium until the command sig-nal changes to a new level.
In summary, the spool position is proportional to the input current and with constant pressure drop across the valve, flow to the load is proportional to the spool position.
VALVE FEATURES |
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2-stage design with dry torque motor | Rugged, long-life design |
Low friction double nozzle pilot stage | High resolution, low hysteresis |
High spool control forces | Completely set-up at the factory |
High dynamics | Optional fifth port for separate pilot supply |
Field replaceable pilot stage filter |
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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:
Q [gpm] = calculated flow
QN [gpm] = rated flow
∆ p [psi] = actual valve pressure drop
∆ pN [psi] = rated valve pressure drop
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.
72 SERIES
GENERAL TECHNICAL DATA
Operating Pressure | up to 3,000 psi* |
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ports P, X,A and B |
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port T | up to 3,000 psi |
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Temperature Range |
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Fluid | -40°F to 275°F |
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Ambient | -40°F to 275°F |
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Seal Material | Viton ** |
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Operating Fluid | Compatible with common |
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| hydraulic fluids, other fluids |
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| on request. |
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Recommended viscosity | 60-450 SUS @ 100°F |
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System Filtration: High pressure filter (without bypass, but with dirt alarm) mounted in the main flow and if possible, directly upstream of the valve.
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 servovalve.
Recommended Cleanliness Class |
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For normal operation | ISO 4406 < 14/11 |
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For longer life | ISO 4406 < 13/10 |
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Filter Rating recommended |
| ≥ |
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For normal operation | ß10 | 75 (10 µm absolute) |
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For longer life | ß5 | ≥ | 75 (5 µm absolute) |
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Installation Operations | Any position, fixed or moveable. |
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Vibration | 30 g, 3 axes |
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Weight | 7.75 lb. (3.52 kg) |
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Shipping Plate | Delivered with an oil sealed |
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| shipping plate. |
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72 SERIES
TECHNICAL DATA
Model . . .Type |
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| 72 . . . . . |
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Mounting Pattern |
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| ISO 10372 - 06 - 05 - 0 -92 |
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Valve Body Version |
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| 4-way |
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| 2-stage with spool-bushing assembly | ||
Pilot Stage |
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| Nozzle/Flapper, High flow |
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Pilot Connection | Optional Internal or External |
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Rated Flow | (± 10%) at ∆ pN = 1,000 psi | [gpm] | 25 | 40 | 60 |
Response Time* |
| [ms] | 16 | 26 | 40 |
Threshold* |
| [%] |
| < 1.5% |
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Hysteresis* |
| [%] |
| < 4.0% |
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Null Shift | at ∆ T = 100°F | [%] |
| < 4.0% |
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Null Leakage Flow* | max. | [gpm] |
| 0.55 to 1.30 |
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* Measured at 1,000 psi pilot or operating pressure
Step Response
Typical characteristic curves
with ±40% and ±100% input signal, measured at 3,000 pilot or operating pressure.
Stand ard Valves
72 SERIES
INSTALLATION DRAWINGS
TYPICAL SUBPLATE MANIFOLD
Null Adjust: Flow out of Control Port B will increase with clockwise rotation of null adjust screw (3/32 hex key).
The mounting manifold must conform to ISO 10372-06-05-0-92.
Surface to which valve is mounted requires a √32 [∆∆ ] finish, flat within 0.002[0.05] TIR.
Standard electrical connector mates with MS3106F14S-2S or equivalent.
Note: Before applying electrical signals, the pilot stage has to be pressurized.
Procedure to Configure a 72 Series Servovalve for External Pilot Operation
72 SERIES
ORDERING INFORMATION
SPARE PARTS AND ACCESSORIES
Preferred configurations highlighted.
All combinations may not be available.
Options may increase price and delivery.
Technical changes are reserved.
SPARE PARTS AND ACCESSORIES
O-Rings (included in delivery), | FPM 85 Shore | Moog P/N |
for P,T, A and B | ID 0.801 x 0.070 | 42082-040 |
for X | ID 0.364 x 0.070 | 42082-013 |
Mating Connector, waterproof IP 65 (not included in delivery) |
| 49054F014S002S (MS3106F14S-2S) |
Flushing Block |
| G4321AM001 |
Mounting Bolts (not included in delivery) |
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3/8 - 16 NC x 2 long (4 pieces) |
| A31324-332B |
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Replaceable Filter Cartridge |
| 22050K002 |
Field Replaceable Filter Kit |
| B52555RK099K001 |
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