m be certain. Series 256 Servovalve Product Information Model 256.04 Model 256.05 Model 256.09 Model 256.18 Model 256.25 Model 256.
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Contents Technical Support 5 How to Get Technical Support Before You Contact MTS 5 5 If You Contact MTS by Phone 6 Problem Submittal Form in MTS Manuals 7 Preface 9 Before You Begin Conventions 9 10 Documentation Conventions 10 Introduction 13 About the Servovalve Servovalve Functional 14 14 Series 256 Servovalve—Multiple Stages Specifications 16 17 Series 256 Servovalve General Specifications Static Performance Specifications 17 18 Dynamic Performance Specifications 18 Series 256 Serv
Contents Series 256 Servovalve Product Information
Technical Support How to Get Technical Support Start with your manuals The manuals supplied by MTS provide most of the information you need to use and maintain your equipment. If your equipment includes MTS software, look for online help and README files that contain additional product information. If you cannot find answers to your technical questions from these sources, you can use the internet, e-mail, telephone, or fax to contact MTS for assistance. Technical support methods MTS web site www.mts.
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Technical Support Series 256 Servovalve Product Information
Preface Before You Begin Safety first! Before you attempt to use your MTS product or system, read and understand the Safety manual and any other safety information provided with your system. Improper installation, operation, or maintenance of MTS equipment in your test facility can result in hazardous conditions that can cause severe personal injury or death and damage to your equipment and specimen. Again, read and understand the safety information provided with your system before you continue.
Conventions Conventions Documentation Conventions The following paragraphs describe some of the conventions that are used in your MTS manuals. Hazard conventions As necessary, hazard notices may be embedded in this manual. These notices contain safety information that is specific to the task to be performed. Hazard notices immediately precede the step or procedure that may lead to an associated hazard. Read all hazard notices carefully and follow the directions that are given.
Conventions Hypertext links The electronic document has many hypertext links displayed in a blue font. All blue words in the body text, along with all contents entries and index page numbers, are hypertext links. When you click a hypertext link, the application jumps to the corresponding topic.
Conventions 12 Preface Series 256 Servovalve Product Information
Introduction MTS Series 256 Servovalves regulate the rate and direction of hydraulic fluid flow to and from hydraulic actuators requiring from 113–1500 L/min (30–400 gpm) of fluid flow. Contents Servovalve Functional 14 Series 256 Servovalve—Multiple Stages Specifications 16 17 Series 256 Servovalve What you need to know MTS Systems Corporation assumes that you know how to use your controller.
Related products The Series 256 Servovalves includes a Series 252 Servovalve. See the Series 252 Servovalve Product Information manual (part number 011-182-906) for productspecific information and maintenance procedures for the Series 252 Servovalve. About the Servovalve The heart of a servohydraulic system is the servovalve. It is the final control element in most MTS closed-loop systems.
Coil Magnet Upper Polepiece Armature Lower Polepiece Nozzle Flapper Second (Pilot) Stage Spool Feedback Spring Filter Fixed Orifice Pilot Return LVDT Transformer Pressure Core Third (Main) Stage Spool First Stage Second Stage Pilot Pressure Third Stage Return Hydraulic Actuator MP-G046H-2 Functional Diagram Servovalve at rest The servovalve’s controlling element is the torque motor, which receives an electrical input from the controller.
Moving the spool A command from the controller causes the armature to rotate clockwise or counterclockwise (depending on the polarity of the command). The command causes the flapper to block one of the nozzles which diverts hydraulic flow to that end of the spool. The spool moves and opens hydraulic pressure to one control port and the return line to the other control port. The control ports are connected to each end of the actuator. Stopping the spool The feedback wire works like a spring.
Specifications Specifications The following subsections list the general specifications, performance specifications, and performance characteristics of the Series 256 Servovalve. Series 256 Servovalve General Specifications The following table shows the specifications that are common to all Series 256 Servovalves. PARAMETER SPECIFICATION Temperature range -54°C to +135°C (-65°F to +275°F) Operating pressure* The normal operating pressure is 21 MPa (3000 psi) Maximum 21 MPa (3000 psi) Minimum 1.
Specifications Static Performance Specifications Values are typical for Series 256 Servovalves operated at the recommended hydraulic fluid filtration levels. MODEL* RATED FLOW NOMINAL GAIN PRESSURE GAIN PRESSURE COEFFICIENT NULL FLOW L/MIN L/MIN/ % STROKE GPM (% SUPPLY/ % STROKE) CM3/ IN3/SEC/PSI) L/MIN GPM % STROKE GPM KGF-SEC 256.04 150 40 2.2 0.58 100 0.30 1.3x10-3 9.5 2.5 256.09 340 90 6.0 1.6 150 0.56 2.4x10-3 13.0 3.5 256.18 680 180 10.6 2.8 200 0.73 3.
Specifications MODEL* RATED FLOW PILOT FLOW FULL FLOW FREQUENCY 90º PHASE SIGNAL† SPOOL STROKE RISE TIME (TR) (MILLISECONDS) L/MIN GPM L/MIN GPM HZ HZ 90% OPEN 10% OPEN 256.25A-01 256.25A-02 256.25A-05 950 950 950 250 250 250 3.8 9.5 19 1 2.5 5 10 18 25 90 125 125 15 <10 8 10 <10 4 256.40A-01 256.40A-02 256.40A-05 256.40A-10 1500 1500 1500 1500 400 400 400 400 3.8 9.5 19 3.8 1 2.5 5 10 4‡ 9‡ 12‡ 15‡ 40‡ 75‡ 110 110 65‡ 26‡ 13 10 20‡ 8‡ 4 3.
Specifications 1000 3800 256.40A -01 -02 -05 -10 -01 -02 100 -05 380 256.09A -01 -02 256.04A -01 38 10 1 1 10 100 1000 Flow in Liters Per Minute Flow in Gallons Per Minute 256.25A 3.8 Frequency in Hz Series 256.xxA Flow vs. Frequency Servovalve Performance Curves Note 20 Introduction Performance is with 21 MPa (3000 psi) pressure supplied and 7 MPa (1000 psi) pressure drop across the servovalve.
Specifications 3800 1000 Available on Request -02 Flow in Gallons Per Minute 256.25B -05 -01 100 380 256.09B -01 -02 -05 256.04B -01 10 38 Flow in Liters Per Minute 256.40B 3.8 1 1 10 100 1000 Frequency in Hz Series 256.xxB Flow vs. Frequency Performance Curves 1000 3800 -01 100 -02 -05 380 10 38 1 Flow in Liters Per Minute Flow in Gallons Per Minute 256.18C 3.8 1 10 100 1000 Frequency in Hz Series 256.18C Flow vs.
Specifications 1000 3800 -01 100 -05 -02 380 10 38 1 Flow in Liters Per Minute Flow in Gallons Per Minute 256.18D 3.8 10 1 100 1000 Frequency in Hz Series 256.18D Flow vs.
Installation This section describes how to install a Series 256 Servovalve. This procedure assumes that all electrical and hydraulic power to the system is off, and that the residual hydraulic pressure in the system is at zero. Contents How to Mount the Main Stage 23 How to Mount the Pilot Stage 24 How to Connect the Cables 26 CAUTION Mixing different brands of hydraulic fluid can contaminate your system.
• For Models 256.04/.09/.18, tighten the screws to 47.45 N·m (35 lbf·ft) • For Models 256.25/.40, tighten the screws to 146 N·m (108 lbf·ft). 6. As you tighten the screws, those previously tightened will lose clamping force. Continue tightening until all screws are at the specified torque. 7. Mount the main stage manifold onto the main stage body and line up the mounting holes. 8. See the procedure for mounting the pilot stage in order to continue the installation procedure.
WARNING The alignment pin ensures that the servovalve assembly is properly positioned over the hydraulic ports. Failure to correctly align the locating pin and locating hole can result in injury to personnel, or damage to equipment. Ensure that the locating pin on the bottom of the servovalve is correctly positioned within the locating hole of the actuator, manifold, or secondary servovalve. 4. Install the pilot stage onto the manifold, aligning the locating pin (as shown in the following figure).
10. Apply high pressure and check for leaks at the servovalve hydraulic connections and at the base of the servovalve. How to Connect the Cables The following figures show the pilot stage internal coils and connector wiring and the three cable wiring variations that can be used. (The main stage LVDT internal coils and connector wiring.
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