MTS 256 User Manual

be certain.

m

Series 256 Servovalve
Product Information

Model 256.04
Model 256.05
Model 256.09
Model 256.18
Model 256.25
Model 256.40

011-209-602 G

Copyright information © 1992, 2000, 2002, 2008 MTS Systems Corporation. All rights reserved.

Trademark information MTS is a registered trademark of MTS Systems Corporation within the United

States. This trademark may be protected in other countries.

DTE is a registered trademark of Mobil Corporation.

Tellus is a registered trademark of Shell Oil Corporation

Publication information

Manual Part Number Publication Date

011-209-602 C December 1992

011-209-602 D March 2000

011-209-602 E October 2002

011-209-602 F March 2008

011-209-602 G April 2009

2

Series 256 Servovalve Product Information

Contents

Technical Support 5

How to Get Technical Support 5

Before You Contact MTS 5

If You Contact MTS by Phone 6

Problem Submittal Form in MTS Manuals 7

Preface 9

Before You Begin 9

Conventions 10

Documentation Conventions 10

Introduction 13

About the Servovalve 14

Servovalve Functional 14

Series 256 Servovalve—Multiple Stages 16

Specifications 17

Series 256 Servovalve General Specifications 17

Static Performance Specifications 18

Dynamic Performance Specifications 18

Series 256 Servovalve Performance Characteristics 19

Installation 23

How to Mount the Main Stage 23

How to Mount the Pilot Stage 24

How to Connect the Cables 26

Series 256 Servovalve Product Information Contents

3

4

Contents

Series 256 Servovalve Product Information

Technical Support

How to Get Technical Support

Start with your

manuals

Technical support

methods

MTS web site

www.mts.com

E-mail [e-mail]

Telephone MTS Call Center 800-328-2255

Fax [phone]

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.

MTS provides a full range of support services after your system is installed. If
you have any questions about a system or product, contact MTS in one of the
following ways.

The MTS web site gives you access to our technical support staff by means of a
Technical Support link:

www.mts.com > Contact Us > Service & Technical Support

Weekdays 7:00 A.M. to 5:00 P.M., Central Time

Please include “Technical Support” in the subject line.

Before You Contact MTS

MTS can help you more efficiently if you have the following information
available when you contact us for support.

Know your site

number and system

number

Series 256 Servovalve Product Information Technical Support

The site number contains your company number and identifies your equipment
type (material testing, simulation, and so forth). The number is usually written on
a label on your MTS equipment before the system leaves MTS. If you do not
have or do not know your MTS site number, contact your MTS sales engineer.

Example site number: 571167

When you have more than one MTS system, the system job number identifies
which system you are calling about. You can find your job number in the papers
sent to you when you ordered your system.

Example system number: US1.42460

5

Know information from

prior technical

If you have contacted MTS about this problem before, we can recall your file.
You will need to tell us the:

assistance

• MTS notification number

• Name of the person who helped you

Identify the problem Describe the problem you are experiencing and know the answers to the

following questions:

• How long and how often has the problem been occurring?

• Can you reproduce the problem?

• Were any hardware or software changes made to the system before the

problem started?

• What are the model numbers of the suspect equipment?

• What model controller are you using (if applicable)?

• What test configuration are you using?

Know relevant

computer information

Know relevant

software information

If you are experiencing a computer problem, have the following information
available:

• Manufacturer’s name and model number

• Operating software type and service patch information

• Amount of system memory

• Amount of free space on the hard drive in which the application resides

• Current status of hard-drive fragmentation

• Connection status to a corporate network

For software application problems, have the following information available:

• The software application’s name, version number, build number, and if

available, software patch number. This information is displayed briefly
when you launch the application, and can typically be found in the “About”
selection in the “Help” menu.

• It is also helpful if the names of other non-MTS applications that are

running on your computer, such as anti-virus software, screen savers,
keyboard enhancers, print spoolers, and so forth are known and available.

If You Contact MTS by Phone

Your call will be registered by a Call Center agent if you are calling within the
United States or Canada. Before connecting you with a technical support
specialist, the agent will ask you for your site number, name, company, company
address, and the phone number where you can normally be reached.

Technical Support

6

Series 256 Servovalve Product Information

If you are calling about an issue that has already been assigned a notification
number, please provide that number. You will be assigned a unique notification
number about any new issue.

Identify system type To assist the Call Center agent with connecting you to the most qualified

technical support specialist available, identify your system as one of the
following types:

• Electromechanical materials test system

• Hydromechanical materials test system

• Vehicle test system

• Vehicle component test system

• Aero test system

Be prepared to

Prepare yourself for troubleshooting while on the phone:

troubleshoot

• Call from a telephone when you are close to the system so that you can try

implementing suggestions made over the phone.

• Have the original operating and application software media available.

• If you are not familiar with all aspects of the equipment operation, have an

experienced user nearby to assist you.

Write down relevant

Prepare yourself in case we need to call you back:

information

• Remember to ask for the notification number.

• Record the name of the person who helped you.

• Write down any specific instructions to be followed, such as data recording

or performance monitoring.

After you call MTS logs and tracks all calls to ensure that you receive assistance and that action

is taken regarding your problem or request. If you have questions about the status
of your problem or have additional information to report, please contact MTS
again and provide your original notification number.

Problem Submittal Form in MTS Manuals

Use the Problem Submittal Form to communicate problems you are experiencing
with your MTS software, hardware, manuals, or service which have not been
resolved to your satisfaction through the technical support process. This form
includes check boxes that allow you to indicate the urgency of your problem and
your expectation of an acceptable response time. We guarantee a timely
response—your feedback is important to us.

The Problem Submittal Form can be accessed:

• In the back of many MTS manuals (postage paid form to be mailed to MTS)

• www.mts.com > Contact Us > Problem Submittal Form (electronic form to

be e-mailed to MTS)

Series 256 Servovalve Product Information Technical Support

7

Technical Support

8

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. It is very
important that you remain aware of hazards that apply to your system.

Other MTS manuals In addition to this manual, you may receive additional MTS manuals in paper or

electronic form.

If you have purchased a test system, it may include an MTS System
Documentation CD. This CD contains an electronic copy of the MTS manuals
that pertain to your test system, including hydraulic and mechanical component
manuals, assembly drawings and parts lists, and operation and preventive
maintenance manuals. Controller and application software manuals are typically
included on the software CD distribution disc(s).

Series 256 Servovalve Product Information Preface

9

Conventions

DANGER

WARNING

CAUTION

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.
Three different levels of hazard notices may appear in your manuals. Following
are examples of all three levels.

Note For general safety information, see the safety information provided with

your system.

Danger notices indicate the presence of a hazard with a high level of risk which,
if ignored, will result in death, severe personal injury, or substantial property
damage.

Warning notices indicate the presence of a hazard with a medium level of risk
which, if ignored, can result in death, severe personal injury, or substantial
property damage.

Caution notices indicate the presence of a hazard with a low level of risk which,
if ignored, could cause moderate or minor personal injury, equipment damage, or
endanger test integrity.

Notes Notes provide additional information about operating your system or highlight

easily overlooked items. For example:

Note Resources that are put back on the hardware lists show up at the end of

the list.

Special terms The first occurrence of special terms is shown in italics.

Illustrations Illustrations appear in this manual to clarify text. It is important for you to be

Electronic manual

conventions

Preface

10

aware that these illustrations are examples only and do not necessarily represent
your actual system configuration, test application, or software.

This manual is available as an electronic document in the Portable Document
File (PDF) format. It can be viewed on any computer that has Adobe Acrobat
Reader installed.

Series 256 Servovalve Product Information

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.

Series 256 Servovalve Product Information Preface

11

Conventions

12

Preface

Series 256 Servovalve Product Information

Introduction

Contents Servovalve Functional 14

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.

Series 256 Servovalve—Multiple Stages 16

Specifications 17

Series 256 Servovalve

What you need to

know

Series 256 Servovalve Product Information Introduction

MTS Systems Corporation assumes that you know how to use your controller.
See the appropriate manual for information about performing any controller­related step in this manual’s procedures. You are expected to know how to
perform the following procedures:

• Turn hydraulic pressure on and off.

• Select a control mode.

• Manually adjust the actuator position.

• You should have experience installing or servicing servohydraulic

equipment.

13

Related products The Series 256 Servovalves includes a Series 252 Servovalve. See the Series 252

Test

Command

Control

Signal

Inner
Loop

Outer
Loop

Manifold

Hydraulic

Power

Unit

Valve Driver

Feedback

Controller

Control
Mode

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. The servovalve responds to
command signals generated by the software and processed by the controller and
output through the valve driver module. The servovalve regulates the direction
and flow of the hydraulic fluid entering the actuator from the hydraulic pressure
ports. The direction that the spools move determines the direction of fluid flow to
the actuator. A pressure difference is what causes the fluid to move.

Servovalve Functional

Control signal In a closed-loop hydraulic system, the Product Name uses the control signal from

Typical Closed-Loop System

an electronic control device (controller) to operate a valve that regulates the
movement of a hydraulic actuator.

The control signal is created by comparing the program command signal (the
desired actuator position) and the feedback signal from a transducer (the actual
actuator position). Any difference between the two is called DC error, which is
the command to the servovalve to supply hydraulic fluid to the actuator until the
desired actuator position is achieved.

14

Introduction

Series 256 Servovalve Product Information

MP-G046H-2

Return

Pressure

Pilot

Pressure

Third

Stage

Second

Stage

First

Stage

Fixed Orifice

Feedback

Spring

Lower

Polepiece

Flapper

Core

Third (Main)
Stage Spool

LVDT

Transformer

Pilot

Return

Filter

Second (Pilot)

Stage Spool

Nozzle

Armature

Coil

Magnet

Upper Polepiece

Hydraulic

Actuator

Functional Diagram

Servovalve at rest The servovalve’s controlling element is the torque motor, which receives an

electrical input from the controller. A flapper is attached to the armature of the
torque motor. The flapper moves from side to side as the armature moves in
response to control signals from the controller. The flapper assembly is
mechanically attached to the armature. There are two nozzles, one on each side of
the flapper.

Because the nozzle-flapper valve is the first control point of hydraulic fluid, it is
called the first stage. As long as there is no command for actuator motion, the
flapper is centered between the two nozzles.

At the same time, pressurized hydraulic fluid entering the valve is applied
equally to both sides of the spool, which does not move. This is the second stage.

Series 256 Servovalve Product Information Introduction

15

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. The spool moves until the feedback wire

torque equals the torque from the magnetic forces. This causes the flapper to
move back toward the centered position. The spool stops at a position where the
feedback wire spring torque equals the torque input current of the command. The
spool position is proportional to the input command current.

Although the pressures are equal on both sides of the spool (so the spool is no
longer moving), control flow from the servovalve keeps the actuator moving.

Stopping actuator

movement

When the actuator has moved the desired amount, the valve drive command
decreases to zero. Hydraulic fluid flow to the actuator stops, and so does the
actuator.

Series 256 Servovalve—Multiple Stages

The Series 256 Servovalve contains three stages. The first and second stages are
formed by a Series 252 Servovalve. The first stage is a torque motor armature
that controls a flapper valve in the second stage. This valve, in turn, controls the
flow of hydraulic fluid (and therefore the movement of the spool) in the second
stage. The position of the spool in the second stage, in turn, controls the flow of
hydraulic fluid to the third stage. The third stage of the Series 256 Servovalve is
the main stage, which contains a larger four-way spool. The position of the third
stage spool is measured by a linear variable differential transformer (LVDT).

16

Introduction

Series 256 Servovalve Product Information

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.

ARAMETER SPECIFICATION

P

Temperature range -54°C to +135°C (-65°F to +275°F)

Specifications

Operating pressure*

Maximum

Minimum

Recommended hydraulic fluid

Pilot stage filtration

Main stage filtration

Seals

LVD T

Excitation

Impedance

Sensitivity

Pilot stage full flow current 25 mA (series)

Weight

256.04-01

256.05-01/02

256.09-01/02

256.18-01/02/05

256.25-01/02/05

256.40-01/02/05/10

‡

The normal operating pressure is 21 MPa (3000 psi)

21 MPa (3000 psi)

1.3 MPa (100 psi)

Mobil DTE 25 or Shell Tellus 46

3 microns absolute

12 microns absolute

Buna-N Standard

.

20 V p-p at 10 kHz

200 ¾ minimum at 10 kHz

0.21 V/V per 2.54 mm (0.100 inch) stroke

50 mA (differential)
50 mA (parallel)

6.3 kg (14 lb)

7.3 kg (16 lb)

7.3 kg (16 lb)

9.3 kg (12 lb)

20.4 kg (43 lb)

45.4 kg (100 lb)

†

* Higher operating supply pressures up to 41 MPa (6000 psi) are available on request (contact MTS for

information.
† Special seals are available on request on some 256 Models (contact MTS for information).
‡ For information on hydraulic fluid and hydraulic system care, see the Hydraulic Fluid Care Guide (MTS

part number 050-000-536).

Series 256 Servovalve Product Information Introduction

17

Specifications

Static Performance Specifications

Values are typical for Series 256 Servovalves operated at the recommended
hydraulic fluid filtration levels.

M

ODEL*RATED FLOW NOMINAL GAIN PRESSURE

G

AIN

PRESSURE
C

OEFFICIENT

NULL FLOW

L/MIN GPM L/MIN/

%

STROKE

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 3.1x10-3 21.0 5.5

256.25 950 250 16.0 4.2 160 1.38 5.9x10-3 23.8 6.3

256.40 1500 400 29.0 7.7 250 1.38 6.9x10-3 20.4 7.5

GPM

% STROKE

(% SUPPLY/
%

STROKE)

3

CM

/

KGF-SEC

3

IN

/SEC/PSI)

L/

MIN GPM

Dynamic Performance Specifications

The dynamic data is derived from typical Model 256 Servovalve driven with a
valve controller with “rate” compensation. A constant amplitude sine wave was
used as the input signal to the valve controller. The amplitude was plus-or-minus
the main stage, full-stroke, and LVDT voltage.

MODEL*RATED FLOW PILOT FLOW FULL FLOW

F

REQUENCY

90º PHASE

†

S

IGNAL

SPOOL STROKE RISE TIME (TR)

MILLISECONDS)

(

L/

MIN GPM L/MIN GPM HZ HZ 90% OPEN 10% OPEN

256.04A-01 150 40 3.8 1 80 130 4.8 3

256.09A-01

256.09A-02

256.18C-01

256.18C-02

256.18C-05

* Performance information is provided for the models listed. Contact MTS for performance information

for Models 256.18D and 256.xxB.
† At 10% spool stroke.
‡ These are estimated values. All other values are typical.

Introduction

18

340
340

680
680
680

90
90

180
180
180

3.8

9.5

3.8

9.5
19

1

2.5

1

2.5
5

30
80

20
30
50

120
130

90
100
100

Series 256 Servovalve Product Information

9

4.6

12
7

5.5

3.5

4.3

3

2.2

1.8

Specifications

MODEL*RATED FLOW PILOT FLOW FULL FLOW

F

REQUENCY

MIN GPM L/MIN GPM HZ HZ 90% OPEN 10% OPEN

L/

256.25A-01

256.25A-02

256.25A-05

256.40A-01

256.40A-02

256.40A-05

256.40A-10

950
950
950

1500
1500
1500
1500

250
250
250

400
400
400
400

3.8

9.5
19

3.8

9.5
19

3.8

1

2.5
5

1

2.5
5
10

10
18
25

4

9

12

15

‡

‡

‡

‡

90º PHASE

†

S

IGNAL

90
125
125

‡

40

‡

75
110
110

SPOOL STROKE RISE TIME (TR)
(

MILLISECONDS)

15
<10
8

‡

65

‡

26
13
10

* Performance information is provided for the models listed. Contact MTS for performance information

for Models 256.18D and 256.xxB.
† At 10% spool stroke.
‡ These are estimated values. All other values are typical.

Series 256 Servovalve Performance Characteristics

Note The servovalve flow at the higher frequencies depends on many system

characteristics that are unrelated to the Model 256 Servovalve (such as
hydraulic fluid compressibility, supply and return line lengths, actuator
characteristics, and specimen characteristics).

10
<10
4

20

‡

8
4

3.5

‡

The flow versus frequency performance curves shown in following figures
indicate the relative performance of the 256 Servovalves at various frequencies.
The curves are derived by driving the servovalve at the indicated frequency with
a sine wave control signal and ± full current to the coil. A 21 MPa (3000 psi)
pressure is supplied and there is a 7 MPa (1000 psi) pressure drop across the
servovalve.

Servovalve performance at higher frequencies is a function of variables
introduced by system components, actuator response, and specimen
characteristics.

Series 256 Servovalve Product Information Introduction

19

Specifications

Flow in Gallons Per Minute

256.40A

256.25A

256.09A

256.04A

-01

-01

-01

-01

-02

-02

-02

-05

-05

-10

Flow in Liters Per Minute

Frequency in Hz

1000

100

10

1

1

10 100 1000

3.8

38

380

3800

Series 256.xxA Flow vs. Frequency Servovalve Performance Curves

Note Performance is with 21 MPa (3000 psi) pressure supplied and 7 MPa

(1000 psi) pressure drop across the servovalve.

Introduction

20

Series 256 Servovalve Product Information

Specifications

1000

100

10

1

110100

1000

3.8

38

380

3800

Flow in Gallons Per Minute

Flow in Liters Per Minute

Frequency in Hz

256.40B Available on Request

256.25B

256.09B

256.04B

-01

-02

-05

-05-02-01

-01

Flow in Liters Per Minute

Frequency in Hz

1000

100

10

1

110100

1000

3.8

38

380

3800

-05

256.18C

-01 -02

Flow in Gallons Per Minute

Series 256.xxB Flow vs. Frequency Performance Curves

Series 256 Servovalve Product Information Introduction

Series 256.18C Flow vs. Frequency Performance Curves

21

Specifications

1000

100

10

1

1

10 100 10 00

3.8

38

380

3800

Flow in Liters Per Minute

Frequency in Hz

256.18D

-05

-01 -02

Flow in Gallons Per Minute

Main Stage

Spool Stroke

90%

Opening

10%

Opening

Time

t

r

t

r

Series 256.18D Flow vs. Frequency Performance Curves

Series 256 Servovalve - Rise Time

Introduction

22

Series 256 Servovalve Product Information

Installation

CAUTION

WARNING

Contents How to Mount the Main Stage 23

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.

How to Mount the Pilot Stage 24

How to Connect the Cables 26

Mixing different brands of hydraulic fluid can contaminate your system.

Contaminated hydraulic fluid can cause premature wear of the hydraulic
components in your system.

Do not mix different brands of hydraulic fluid. MTS Systems Corporation
recommends using Mobil DTE-25 or Shell Tellus 46 AW hydraulic fluid.

An active system has electrical or hydraulic power turned on.

Disturbing components of an active system can cause unexpected actuator
motion and result in injury to personnel and/or damage to equipment.

Before installing or replacing a servovalve, ensure that all electrical and hydraulic
power to the system is off, and residual hydraulic pressure in the system is at
zero.

How to Mount the Main Stage

To mount the main stage and manifold to an actuator:

1. Remove any cover plates from the main stage and actuator manifold ports.

2. Ensure that all O-rings are in good condition.

3. Lubricate all O-rings with a light film of hydraulic fluid and place in their
proper positions.

4. Mount the main stage body onto the actuator manifold and align the
mounting holes.

5. Lubricate the main stage mounting screws with a light film of hydraulic
fluid and tighten the mounting screws to:

Series 256 Servovalve Product Information Installation

23

• For Models 256.04/.09/.18, tighten the screws to 47.45 N·m

Spool Stop

Pilot Stage Mounting

Drain End Cap

LVDT End Cap

LVDT Adjustment

LVDT Locknut

Main Stage Mounting

(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.

How to Mount the Pilot Stage

To mount the pilot stage (a Series 252 Servovalve) to a main stage manifold:

1. Ensure that system hydraulic pressure has been reduced to zero before
proceeding. To do this, turn off the hydraulic power unit and exercise the
actuator until it stops moving.

2. Remove the cover plate or existing pilot stage from the manifold.

3. Ensure that the O-rings between the pilot stage and main stage manifold are
lubricated with a light film of hydraulic fluid and are correctly positioned.

Mounting Screw Locations

24

Installation

Series 256 Servovalve Product Information

The alignment pin ensures that the servovalve assembly is properly

WARNING

Pilot Stage

Manifold

Main Stage

Hole for

Pilot Stage

Locating Pin

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).

5. Lubricate the mounting screws with a light film of hydraulic fluid. Tighten
the mounting screws to 24.40 N·m (18 lbf·ft). As you tighten the screws,
those previously tightened will lose clamping force. Continue tightening
until all screws are at the specified torque.

6. Connect all hydraulic supply and return lines.

7. Connect control cables between the servovalve and the system controller,
including a valve drive cable to the pilot stage and a inner loop feedback
cable to the LVDT in the third stage.

8. Turn on system electrical power and hydraulic power.

9. Apply low hydraulic pressure to the servovalve so that the hydraulic fluid
will fill the filter cavities gradually.

Series 256 Servovalve Product Information Installation

25

10. Apply high pressure and check for leaks at the servovalve hydraulic

25 mA

Series

A

B

C
D

Differential

50 mA/0 mA

0 mA/50 mA

A

B

C

D

Coils

Connector

A

B

C

D

80

W

80W

A

BC

D

backshell

7

9

11

12

13

Drain

+Valve Command 1

- Valve Command 1

+Valve Command 2

- Valve Command 2

MTS Controller

Single

Servovalve

A

B

C

D

Parallel

50 mA Total

A

B

C
D

Output

-FB

-EX

A

B

D

C

Excitation

+FB

+EX

Note C and D leads may be reversed

for proper phasing.

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.)

connections and at the base of the servovalve.

Pilot Stage Coils and Connector

26

Installation

LVDT Coils and Connector

Series 256 Servovalve Product Information

m

MTS Systems Corporation

14000 Technology Drive
Eden Prairie, Minnesota 55344-2290 USA
Toll Free Phone: [phone]

(within the U.S. or Canada)

Phone: [phone]

(outside the U.S. or Canada)
Fax: [phone]
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Internet: www.mts.com

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