Rev. C, April 2020

DIRECT DRIVE

ANALOG CONTROL

SERVO VALVES

HIGH PRODUCTIVITY FOR DEMANDING APPLICATIONS

THAT REQUIRE A HIGHLY DYNAMIC RESPONSE AND

FLEXIBLE INTEGRATION.

D634 SIZE 05

D633 SIZE 03

WHAT MOVES YOUR WORLD

2Rev. C, April 2020

Whenever the highest levels of motion control performance

and design ﬂexibility are required, you’ll ﬁnd Moog expertise

at work. Through collaboration, creativity and world-class

technological solutions, we help you overcome your tough-

est engineering obstacles. Enhance your machine’s perfor-

mance, and help take your thinking further than you ever

thought possible.

INTRODUCTION

Direct Drive Analog Control Servo Valves

This catalog is for users with technical knowledge. To ensure all necessary characteristics for function and safety of the system, the user has

to check the suitability of the products described herein. The products described herein are subject to change without notice. In case of doubt,

please contact Moog.

Moog is a registered trademark of Moog Inc. and its subsidiaries.

All trademarks as indicated herein are the property of Moog Inc. and its subsidiaries.

For the full disclaimer refer to www.moog.com/literature/disclaimers.

For the most current information, visit www.moog.com/industrial or contact your local Moog ofﬁce.

INTRODUCTION .............................................................................. 2

Product Overview ..................................................................... 3

Description of Operation ....................................................... 5

Features and Beneﬁts ............................................................ 6

TECHNICAL DATA .......................................................................... 7

Size 03 - D633 Servo Valve .................................................. 7

Size 05 - D634 Servo Valve ................................................12

BACKGROUND ..............................................................................17

Electronics ................................................................................17

Flow Calculation .....................................................................19

ORDERING INFORMATION .......................................................20

Accessories and Spare Parts .............................................20

Moog Global Support ............................................................24

Ordering Code..........................................................................25

Rev. C, April 2020 3

PRODUCT OVERVIEW

The D633 and D634 Series are Direct Drive Valves (DDV)

with electric closed loop spool position control.

These valves are throttle valves for 3-, 4-, and 2x2-way ap-

plications. They are suitable for electrohydraulic position,

velocity, pressure or force control systems including those

with high dynamic response requirements.

The spool drive device is a permanent magnet linear force

motor, which can actively stroke the spool from its spring

centred position in both directions. This is an advantage

compared with proportional solenoids with one force

direction only. The closed loop spool position control and

pulse width modulated (PWM) drive electronics are inte-

grated into the valve.

The integrated electronics of the valves features SMD

technology with pulse width modulated (PWM) current

output stage, and requires a 24 V

power supply.

INTRODUCTION

Direct Drive Analog Control Servo Valves

D633 D634

Valve design 1 stage, with spool and bushing

Size according ISO 4401 Size 03 Size 05

Mounting pattern ISO 4401-03-03-0-05 (with or without leakage

oil connection Y)

ISO 4401-05-05-0-05 (with or

without leakage oil connection Y)

Rated ﬂow at Δp

35 bar (500

psi) per spool land

5 l/min

(1.3 gpm)

10 l/min

(2.6 gpm)

20 l/min

(5.3 gpm)

40 l/min

(10.6 gpm)

60 l/min

(15.9 gpm)

100 l/min

(26.4 gpm)

Maximum ﬂow 75 l/min (19.8 gpm) 180 l/min (47.6 gpm)

Maximum operating pressure -

Port P, A, B

350 bar (5000 psi)

Step response time for 0 to

100 % stroke

≤ 12 ms ≤ 20 ms

D634

D633

4Rev. C, April 2020

PRODUCT OVERVIEW

Design and Application

A permanent magnet linear force motor is used to drive

the spool. In contrast to proportional solenoid drives, the

linear force motor drives the spool in both working direc-

tions from the spring-centered middle position. The strong

actuating force of the spool, provides Moog Servo Valves

with excellent static and dynamic characteristics.

Spool Position Control

In this operating mode of the servo valve, the spool

position is controlled. The command signal is proportional

to a desired spool position. A position transducer (LVDT)

measures the spool‘s actual position, and forwards this

information to the valve electronics. The system electron-

ics compare the actual spool position with the command

signal. This generates a signal that drives the linear force

motor and brings the spool to the correct position.

Optional Valve Features

Moog offers a range of optional features. These include

options to ruggedize valves for operation in extremely

demanding environments, and valves designed for special

applications and ﬂuids. The following sections provide

short overviews of these functions. Please contact Moog

for more detailed information.

Valves for Operation with Ester Based Fluids

Standard hydraulic seal materials such as HNBR and FKM,

are frequently incompatible with ﬁre resistant phosphate

ester based ﬂuids. In order to use valves with this type of

ﬂuid, Moog offers them as special seal versions that are

mineral oil and phosphate ester resistant. Please note:

These valve types are tested by Moog using mineral oil,

remnants of which will remain in the valve after testing.

Explosion Protection

Valves D633K and D634K available with explosion

protection for Gas:

• Ex II 2G Ex db eb IIB+H2 T* Gb

according to EN 60079-0, EN 60079-1 and EN 60079-7.

• Ex db eb IIB+H2 T* Gb

according to IEC 60079-0, IEC 60079-1, IEC 60079-7.

Valves D633D available with explosion protection for

Dust:

• Ex II 2D Ex tb IIIC T155°C Db

• Ex II 3D Ex tc IIIC T155°C Dc

according to EN 60079-31, EN 600079-0.

Note: Installation dimensions and electric connection

altered.

INTRODUCTION

Direct Drive Analog Control Servo Valves

Rev. C, April 2020 5

DESCRIPTION OF OPERATION

INTRODUCTION

Direct Drive Analog Control Servo Valves

Main Features

• Direct drive with permanent magnet linear force motor

that provides high actuating force, works in 2 direc-

tions.

• Direct operated - no pilot oil required.

• Pressure-independent dynamic response.

• Low hysteresis and high response characteristics.

• Lower power demand in and around the spool center

position. This results in lower energy consumption

during the majority of operating and stand by times.

• If the electrical supply fails, a cable breaks or emer-

gency stop is activated, the spool returns to the

predeﬁned spring-centered position without passing a

fully open control port position increasing safety.

1 Null adjust cover plug

2 Valve connector

3 Spool

4 Bushing

5 Centering spring

6 Linear force motor

7 Position transducer

8 Integrated electronics

87 65

PTA YB

Permanent Magnet Linear Force Motor

The Linear Force Motor (LFM) is a permanent magnet

excited differential motor.

The LFM’s armature (4) is connected to the valve spool

via a rod. Also connected to this rod are the centering

springs (2), which keep the LFM in its center position. The

permanent magnets (1) supply part of the motor’s force.

In combination with the force created by the coil (5), the

force level of a Linear Force Motor is higher than that of a

proportional solenoid of similar size.

The LFM has a neutral mid-position from which it gen-

erates force and stroke in both directions. This is an

advantage over a proportional solenoid drive, which can

only operate in one direction. The LFM’s force is roughly

proportional to the coil current. To move out of the center

position, a PWM current is applied to the coil and the spool

is deﬂected against the centering springs. To move back

towards the center position, a reverted PWM current is

applied to the coil, which causes the LFM to actively move

the spool towards the center. This movement is supported

by the centering springs.

Due to the high force levels of the LFM it is able to

overcome ﬂow and frictional forces, and still guarantee a

precise and dynamic positioning of the spool.

1 Permanent magnets

2 Centering springs

3 Screw plug

4 Armature

5 Coil

6 Bearing

3564

6Rev. C, April 2020

FEATURES AND BENEFITS

Features Beneﬁts

D633 and D634 Series Servo Valves

Direct operated servo valves No pilot oil required, valve dynamics are not dependent on

pilot pressure

Linear Force Motor with high force level and push-pull

operation

Precise and dynamic valve operation even at high pressure

drops

Precise spool positioning with low hysteresis and thresh-

old

High control accuracy for demanding closed loop control

tasks

High valve dynamics Supports highly dynamic control tasks

Spool slides in precisely manufactured and fully hardened

steel bushing

Low internal leakage, high control accuracy and high wear

resistance

INTRODUCTION

Direct Drive Analog Control Servo Valves

Rev. C, April 2020 7

Hydraulic Data

Maximum operating pressure - Port P, A, B 350 bar (5000 psi)

Maximum operating pressure - Port T without Y 50 bar (725 psi)

Maximum operating pressure - Port T with Y 350 bar (5000 psi)

Maximum operating pressure - Port Y Depressurized to tank

Rated ﬂow at Δp

35 bar (500 psi) per spool land 5 l/min

(1.3 gpm)

10 l/min

(2.6 gpm)

20 l/min

(5.3 gpm)

40 l/min

(10.6 gpm)

Maximum ﬂow 75 l/min (19.8 gpm)

Hydraulic ﬂuid Hydraulic oil as per DIN 52524 parts 1 to 3 and ISO 11158.

Other ﬂuids upon request.

Leakage ﬂow (rate) (≈ zero lap)

0.15 l/min

(0.04 gpm)

0.3 l/min

(0.08 gpm)

0.6 l/min

(0.16 gpm)

1.2 l/min

(0.32 gpm)

Temperature range -20 - +80 °C (-4 - +176 °F)

Recommended viscosity range at 38 °C (100 °F) 15 - 100 mm

/s (cSt)

Maximum permissible viscosity range at 38 °C (100 °F) 5 - 400 mm

/s (cSt)

Recommended cleanliness class as per ISO 4406 for

functional safety

18/15/12

Recommended cleanliness class as per ISO 4406 for

longer service life

17/14/11

Measured at 140 bar (2,000 psi) system pressure, oil viscosity 32 mm

/s and oil temperature 40 °C (104 °F).

In order to avoid an emptying of the return line, a back-pressure of 2 bar (29 psi) should be maintained on the T, T1

and Y connections.

SIZE 03 - D633

General Technical Data

Valve design 1 stage, with spool and bushing

Mounting pattern ISO 4401-03-03-0-05

(with or without leakage oil connection Y)

Installation position Any

Weight 2.5 kg (5.51 lb)

Storage temperature range -40 - +80 °C (-40 - +176 °F)

Ambient temperature range -20 - +60 °C (-4 - +140 °F)

Vibration resistance 30 g, 3 axis, 10 Hz to 2 kHz

Shock resistance 50 g, 6 directions, 3 ms

MTTF

value according to EN ISO 13849-1 150 years

Typical Static and Dynamic Data

Step response time for 0 to 100 % stroke ≤ 12 ms

Threshold, typical 0.05 %

Threshold, maximum < 0.1 %

Hysteresis, typical 0.1 %

Hysteresis, maximum < 0.2 %

Null shift at ΔT = 55 K (131 °F) < 1.5 %

Sample deviation of rated ﬂow < 10 %

Measured at 140 bar (2,000 psi) system pressure, oil viscosity 32 mm

/s and oil temperature 40 °C (104 °F).

TECHNICAL DATA

Direct Drive Analog Control Servo Valves

8Rev. C, April 2020

SIZE 03 - D633

TECHNICAL DATA

Direct Drive Analog Control Servo Valves

Electrical Data

Duty cycle 100 %

Degree of protection according to IEC/EN 60529 IP65 with mounted mating plugs

Supply voltage

24 V

, min. 19 V

, max. 32 V

Permissible ripple of supply voltage

±3 V

RMS

Maximum current consumption

1.2 A

Power consumption of the motor in middle position 9.6 W (0.4 A @ 24 V

)

Power consumption maximum 28.8 W (1.2 A @ 24 V

)

Fuse protection, external, per valve 1.6 A (slow)

EM compatibility Immunity to interference as per DIN EN 61000-6-2 (evalu-

ation criterion A)

All connected circuits must be isolated from the main supply by „electrical separation” in accordance with IEC/EN

61558-1 and IEC/EN 61558-2-6. Voltages must be limited to the safety extra-low voltage range in accordance with EN

60204-1. We recommend the use of SELV/PELV power packs.

Frequency from 50 Hz to 10 kHz.

Measured at ambient temperature 25 °C (77 °F) and supply voltage 24 V.

Rev. C, April 2020 9

INSTALLATION DRAWING SIZE 03 - D633

TECHNICAL DATA

Direct Drive Analog Control Servo Valves

APE

(2.80)

(0.79)

(0.98)

(1.97)

101

(3.98)

235

(9.25)

113

(4.45)

(3.46)

(1.85)

1,3

(0.05)

Mating connector

Removal space

(0.43)

(4x)Ø

12.4

(0.48)

9.5

(0.37)

5.4

(0.21)

Port Pattern of Mounting Surface

The mounting surface must conform to ISO 4401-03-03-

0-05. Observe mounting length of minimum 77 mm (3.0 in)

and O-ring recesses for Y.

For maximum ﬂow the ports for P, T, A and B must be

designed with Ø 7.5 mm (0.3 in), not according to the

standard.

Evenness of connecting surface has to be 0.01 mm (0.0004

in) over 100 mm (3.94 in), average surface ﬁnish R

better

than 0.8 μm (0.0000314 in).

Designation P A B T Y F1 F2 F3 F4 G

Size Ø mm

7.5

0.30

7.5

0.30

7.5

0.30

7.5

0.30

3.3

0.13

4.0

0.16

Position X mm

21.5

0.846

12.7

0.5

30.2

1.189

21.5

0.846

40.5

1.594

40.5

1.594

40.5

1.594

1.299

Position Y mm

25.9

1.02

15.5

0.61

15.5

0.61

5.1

0.201

0.354

-0.75

-0.03

31.75

1.25

1.22

31.75

1.25

(0.7)

(3.0)

9,5

(0.4)

(2.0)

(0.7)

(3.0)

9.5

(0.4)

(2.0)

10Rev. C, April 2020

CHARACTERISTIC CURVES SIZE 03 - D633

Measured with system pressure p

of 140 bar (2,000 psi), oil viscosity 32 mm

/s and oil temperature of 40 °C (104 °F).

TECHNICAL DATA

Direct Drive Analog Control Servo Valves

Step Response

Frequency Response

020406080 100

R02

R04

R08

R16

Q [l/min (gpm)]

Signal [%]

20 (5.3)

10 (2.7)

30 (8)

40 (10.6)

Flow signal curves at Δp

= 35 bar (500 psi) per

spool land

Flow Signal

Pressure Signal

Rev. C, April 2020 11

TECHNICAL DATA

Direct Drive Analog Control Servo Valves

HYDRAULIC SYMBOLS - D633 2-WAY AND 2X2-WAY OPERATION

2-way and 2x2-way operation

In 2-way and 2x2-way operation the servo valves can be

used to control the ﬂow in one direction (used as 2-way

throttle valves). In 2x2-way operation the valve can be

used in 2-way applications for higher ﬂows. It is necessary

to connect ports P with B and A with T externally for this

purpose.

2-way operation 2x2-way operation

TPY

4-way and 3-way operation

In 4-way operation the servo valves can be used to control

the ﬂow in ports A and B (used as 4/3-way throttle valves).

Port A or B must be closed in order to obtain 3-way

operation. Leakage port Y must be used if the pressure in

tank port T exceeds a value of 50 bar (725 psi). The valves

are available with zero lap, less than 3 % or 10 % positive

overlap.

Note: The speciﬁed ﬂow directions must be observed.

3-way operation with failsafe

option F

4-way operation with failsafe

option F

TPY

12Rev. C, April 2020

Hydraulic Data

Maximum operating pressure - Port P, A, B 350 bar (5000 psi)

Maximum operating pressure - Port T without Y 50 bar (725 psi)

Maximum operating pressure - Port T with Y 210 bar (3000 psi)

Maximum operating pressure - Port Y Depressurized to tank

Rated ﬂow at Δp

35 bar (500 psi) per spool land 60 l/min (15.9 gpm) 100 l/min (26.4 gpm)

Maximum ﬂow 180 l/min (47.6 gpm)

Hydraulic ﬂuid Hydraulic oil as per DIN 52524 parts 1 to 3 and ISO 11158.

Other ﬂuids upon request.

Leakage ﬂow (rate) (≈ zero lap)

1.2 l/min (0.32 gpm) 2.0 l/min (0.53 gpm)

Temperature range -20 - +80 °C (-4 - +176 °F)

Recommended viscosity range at 38 °C (100 °F) 15 - 100 mm

/s (cSt)

Maximum permissible viscosity range at 38 °C (100 °F) 5 - 400 mm

/s (cSt)

Recommended cleanliness class as per ISO 4406 for

functional safety

18/15/12

Recommended cleanliness class as per ISO 4406 for

longer service life

17/14/11

Measured at 140 bar (2,000 psi) system pressure, oil viscosity 32 mm

/s and oil temperature 40 °C (104 °F).

In order to avoid an emptying of the return line, a back-pressure of 2 bar (29 psi) should be maintained on the T, T1

and Y connections.

SIZE 05 - D634

General Technical Data

Valve design 1 stage, with spool and bushing

Mounting pattern ISO 4401-05-05-0-05

(with or without leakage oil connection Y)

Installation position Any

Weight 7.9 kg (17.42 lb)

Storage temperature range -40 - +80 °C (-40 - +176 °F)

Ambient temperature range -20 - +60 °C (-4 - +140 °F)

Vibration resistance 30 g, 3 axis, 10 Hz to 2 kHz

Shock resistance 50 g, 6 directions, 3 ms

MTTF

value according to EN ISO 13849-1 150 years

Typical Static and Dynamic Data

Step response time for 0 to 100 % stroke ≤ 20 ms

Threshold, typical 0.05 %

Threshold, maximum < 0.1 %

Hysteresis, typical 0.1 %

Hysteresis, maximum < 0.2 %

Null shift at ΔT = 55 K (131 °F) < 1.5 %

Sample deviation of rated ﬂow < 10 %

Measured at 140 bar (2,000 psi) system pressure, oil viscosity 32 mm

/s and oil temperature 40 °C (104 °F).

TECHNICAL DATA

Direct Drive Analog Control Servo Valves

Rev. C, April 2020 13

SIZE 05 - D634

Electrical Data

Duty cycle 100 %

Degree of protection according to IEC/EN 60529 IP65 with mounted mating plugs

Supply voltage

24 V

, min. 18 V

, max. 32 V

Permissible ripple of supply voltage

±3 V

RMS

Maximum current consumption

3.0 A

Power consumption of the motor in middle position 9.6 W (0.4 A @ 24 V

)

Power consumption maximum 55.2 W (2.3 A @ 24 V

)

Fuse protection, external, per valve 3.15 A (slow)

EM compatibility Immunity to interference as per DIN EN 61000-6-2 (evalu-

ation criterion A)

All connected circuits must be isolated from the main supply by „electrical separation” in accordance with IEC/EN

61558-1 and IEC/EN 61558-2-6. Voltages must be limited to the safety extra-low voltage range in accordance with EN

60204-1. We recommend the use of SELV/PELV power packs.

Frequency from 50 Hz to 10 kHz.

Measured at ambient temperature 25 °C (77 °F) and supply voltage 24 V.

TECHNICAL DATA

Direct Drive Analog Control Servo Valves

14Rev. C, April 2020

INSTALLATION DRAWING SIZE 05 - D634

TECHNICAL DATA

Direct Drive Analog Control Servo Valves

(2.80)

(0.43)

6.5

(0.26)

(0.79)

36.5

(1.44)

(2.87)

290

(11.42)

146

(5.75)

120

(4.72)

(1.85)

1,3

(0.05)

(2x)Ø

18.7

(0.74)

18.7

(0.74)

115

(4.53)

(5x)Ø

15.7

(0.62)

Mating connector

Removal space

Port Pattern of Mounting Surface

The mounting pattern must conﬁrm to ISO 4401-05-

05-0-05 with additional T1. Observe mounting length of

minimum 100 mm (3.94 in) and O-ring recesses for Y. For

4-way valves with Q > 60l/min (15.9 gpm) the second tank

port T1 is required.

For maximum ﬂow the ports for P, T, T1, A and B must be

designed with Ø 11.5 mm (0.45 in), not according to the

standard.

Evenness of connecting surface has to be 0.01 mm (0.0004

in) over 100 mm (3.94 in), average surface ﬁnish R

better

than 0.8 μm (0.0000314 in).

Designation P A B T T1 Y F1 F2 F3 F4

Size Ø mm

11.2

0.44

11.2

0.44

11.2

0.44

11.2

0.44

11.2

0.44

6.3

0.25

Position X mm

1.063

16.7

0.657

37.3

1.469

3.2

0.126

50.8

2.441

2.126

Position Y mm

6.3

0.248

21.4

0.843

21.4

0.843

23.5

1.28

23.5

1.28

0.433

1.811

(0.9)

100

(3.9)

14.5

(0.6)

(3.0)

Rev. C, April 2020 15

CHARACTERISTIC CURVES SIZE 05 - D634

Measured with system pressure p

of 140 bar (2,000 psi), oil viscosity 32 mm

/s and oil temperature of 40 °C (104 °F).

TECHNICAL DATA

Direct Drive Analog Control Servo Valves

Step Response

Frequency Response

020406080 100

R24

R40

Q [l/min (gpm)]

Signal [%]

20 (5.3)

40 (10.6)

60 (15.9)

80 (21.1)

100 (26.4)

Flow signal curves at Δp

= 35 bar (500 psi) per

spool land

Flow Signal

Pressure Signal

16Rev. C, April 2020

HYDRAULIC SYMBOLS SIZE 05 - D634

TECHNICAL DATA

Direct Drive Analog Control Servo Valves

2-way and 2x2-way operation

In 2-way and 2x2-way operation the servo valves can be

used to control the ﬂow in one direction (used as 2-way

throttle valves). In 2x2-way operation the valve can be

used in 2-way applications for higher ﬂows. It is necessary

to connect ports P with B and A with T externally for this

purpose.

2-way operation 2x2-way operation

TPY

4-way and 3-way operation

In 4-way operation the servo valves can be used to control

the ﬂow in ports A and B (used as 4/3-way throttle valves).

Port A or B must be closed in order to obtain 3-way

operation. Leakage port Y must be used if the pressure in

tank port T exceeds a value of 50 bar (725 psi). The valves

are available with zero lap, less than 3 % or 10 % positive

overlap.

3-way operation with failsafe

option F

4-way operation with failsafe

option F

TPY

Note: The speciﬁed ﬂow directions must be observed.

Rev. C, April 2020 17

ELECTRONICS

Pin Assignment for Valves with 6-pole + PE Connector, Pin Contacts (X1)

According to EN 175201-804, mating connector (type R or S, metal) with preleading protective earth pin (W)

Pin Pin Assignment Signal type

Voltage ﬂoating Current ﬂoating

A Supply voltage U

Supply

= 24 V

(18 to 32 V

) referenced to GND (reverse

polarity protected against GND)

B GND Power ground/signal ground

C Enable input U

> 8.5 to 32 V

referenced to GND: Valve ready for op-

eration (enabled) UCB < 6.5 V

referenced to GND: Valve

disabled

The input resistance is 10 kΩ

D Command signal - spool

position

= U

= 10 k Ω

= I

= -I

= 200 Ω

max

= ±25 mA

E Reference point Input

rated command

Reference for pin D

F Actual value - spool posi-

tion

F-B

= 2 to 10 V; U

F-B

proportional to the spool

position; 6 V corresponds to

the spool center position; R

= 500 Ω

out

= 4 to 20 mA referenced

to GND; I

out

is proportional

to the spool position; 12 mA

corresponds to the spool

center position; the output

is short-circuit-proof;

= 0 to 500 Ω

Protective earth (PE) Connected with valve body

Signal ranges see next page.

The potential difference between pins D or E referenced to pin B must be between -15 and +32 V.

Command signals I

< 3 mA (due to cable break, for example) indicates a failure of 4 to 20 mA signals.

The valve reaction to this failure may be customized and activated by the customer.

BACKGROUND

Direct Drive Analog Control Servo Valves

18Rev. C, April 2020

ELECTRONICS

Ordering Codes and Signals for Valves with 6-pole + PE Connector (X1)

Note: For more information see Technical Notes TN 353 „Protective Grounding and Electrical Shielding of Valves“

and TN 494 „Maximum Permissible Length of Electric Cables for Valves with Integrated Electronics“.

Visit www.moog.com/industrial/literature to download document.

Ordering Code Command signal ±100% spool position Actual value ±100 % spool position

M U

- U

-10 to +10 V I

4 to 20 mA

X I

-10 to +10 mA I

4 to 20 mA

E I

4 to 20 mA I

4 to 20 mA

D U

- U

-10 to +10 V U

- U

2 to 10 V

Note: See inside back cover for complete ordering information.

BACKGROUND

Actual Value 2 to 10 V, Ordering Code D

The signal can be used for monitoring and fault detection

purposes. The spool position is proportional to U

out

. The

spool position corresponds to 2 to 10 V. At 6 V the spool

is in center position. 10 V corresponds to 100 % valve

opening P → A and B → T. A cable fault is detected by U

out

0 V. R

= 500 Ω (0.25 W).

out

(GND)

Valve Spool

position

Actual Value 4 to 20 mA, Ordering Code M, X or E

The signal can be used for monitoring and fault detection

purposes. The spool position is proportional to I

out

. The

spool position corresponds to 4 to 20 mA. At 12 mA the

spool is in center position. 20 mA corresponds to 100 %

valve opening P → A and B → T. A cable fault is detected by

out

= 0 mA. Optional use: Actual value U

out

= 2 to 10 V with

resistor R

= 500 Ω (0.25 W) provided by customer.

out

(GND)

Valve Spool

position

Command Signal Voltage Floating, Ordering Code D

or M

The spool position is proportional to U

− U

. For a com-

mand signal U

− U

= +10 V the spool moves to 100 % P →

A and B → T. For a command signal U

− U

= 0 V the spool

is in the deﬁned center position.

GND

0 V +24 V

Supply

Control

Command signal

Signal

Valve

Command signal p

Command Signal Current Floating, Ordering Code X

or E

The spool position is proportional to I

= - I

. For a com-

mand signal I

= 20 mA (code E) or +10 mA (code X) the

spool moves to 100 % P → A and B → T. For a command

signal I

= 12 mA (code E) or 0 mA (code X) the spool is in

the deﬁned center position.

0 V +24 V

Valve

Control

Command signal

Supply

Command signal p I

Direct Drive Analog Control Servo Valves

Rev. C, April 2020 19

Direct Drive Analog Control Servo Valves

FLOW CALCULATION

When the valve is open, the prevailing ﬂow is dependent

not only on the spool position, (i.e. the opening cross

section of the valve), but also on the pressure drop at the

individual lands. When the valve is deﬂected at 100 %, it

delivers the rated ﬂow with the rated pressure drop.

The rated ﬂow of a servo valve corresponds to a pressure

drop of 35 bar (500 psi) per land, equating to 70 bar (1,000

psi) for two lands. When a valve is opened at 100 %, the

ﬂow can be calculated as a function of the actual pressure

drop with the aid of the formula below or taken from the

diagram.

The actual ﬂow in the valve ports must not exceed a mean

ﬂow velocity of approximately 30 m/s (96.5 ft/s) due to

the risk of cavitation. When operating the valves close to

these application limits, it is necessary to drill the ports to

the maximum possible diameters (see speciﬁcations for

the respective valve).

For ISO 4401 size 05 mounting surfaces the second tank

port must additionally be connected starting from a ﬂow Q

exceeding 60 l/min (15.9 gpm).

BACKGROUND

Q [l/min (gpm)] actual ﬂow

[l/min (gpm)] rated ﬂow

Δp [bar (psi)] actual pressure drop per spool land

Δp

[bar (psi)] rated pressure drop per spool land

Flow Diagram

100

(1,450)

200

(2,900)

350

(5,000)

p [bar (psi)]

Q [l/min (gpm)]

150 (39.6)

200 (52.8)

100 (26.4)

60(15.9)

80 (21.1)

40 (10.6)

30 (7.9)

20 (5.3)

15 (4.0)

10 (2.6)

8 (2.1)

5 (1.3)

3 (0.8)

2 (0.5)

(725)

(290)

(435)

(145)

(15)

(1,000)

60 (15.9)

40 (10.6)

100 (26,4)

20 (5.3)

10 (2.7)

5 (1.3)

D633-

R02

D633-

R04

D633-

R08

D633-

R16

D634-

R24

D634-

R40

max

= 180 l/min (47.6 gqm)

max

= 75 l/min (19.8 gqm)

20Rev. C, April 2020

ACCESSORIES AND SPARE PARTS

Series-speciﬁc

Spare Parts Size 03 - D633

Part designation Description Material Part number

Service sealing set Contains the following

O-rings:

• 4 pieces for P, T, A, B

inner Ø 9.25 mm (0.36

in) x Ø 1.8 mm (0.07 in)

• 1 piece for Y inner Ø

7.65 mm (0.3 in) x Ø 1.8

mm (0.07 in)

FKM 90 Shore B97215-V630F63

HNBR 90 Shore B97215-H630F63

Accessories Size 03 - D633

Part designation Description Image Part number

Flushing plate P, A, B, T , X, Y

AP BYTX

B46634-002

Shipping plate 1 piece B46035-001

Mounting screws 4 pieces M5x55, ISO 4762-

10.9, tightening torque 6.8

Nm (60 Ibf in)

ORDERING INFORMATION

Direct Drive Analog Control Servo Valves

Documents Size 03 - D633

Part designation Description Image Part number

ATEX manual Operating Instructions for

Proportional Valves D633D

Series ISO 4401 Size 03 for

category 2D

B97264-002 (German)

ATEX manual Operating Instructions for

Proportional Valves D633D

Series ISO 4401 Size 03 for

category 3D

B97256-002 (German)

Rev. C, April 2020 21

ACCESSORIES AND SPARE PARTS

Series-speciﬁc

Spare Parts Size 05 - D634

Part designation Description Material Part number

Service sealing set Contains the following

O-rings:

• 5 pieces for P, T, T

, A, B

inner Ø 12.4 mm (0.49

in) x Ø 1.8 mm (0.07 in)

• 2 pieces for X, Y

inner Ø 15.6 mm (0.61

in) x Ø 1.8 mm (0.07 in)

• 1 piece for ﬁlter

inner Ø 12.0 mm (0.47

in) x Ø 2.0 mm (0.08 in)

• 1 piece for ﬁlter cover

inner Ø 17.1 mm (0.67

in) x Ø 2.6 mm (0.10 in)

FKM 90 Shore B97215-V681-10

HNBR 90 Shore B97215-H681-10

Accessories Size 05 - D634

Part designation Description Image Part number

Flushing plate P, A, B, T, T

, X, Y

AP YTX

B67728-001

Flushing plate P, A, B, T, T

, X, Y

AP YTX

B67728-002

Flushing plate P, A, B, T, T

, X, Y

AP YTX

B67728-003

Shipping plate 1 piece A40503

Mounting screws 4 pieces M6x60, ISO 4762-

10.9, tightening torque 11

Nm (97 Ibf in)

ORDERING INFORMATION

Direct Drive Analog Control Servo Valves

22Rev. C, April 2020

ACCESSORIES AND SPARE PARTS

Series-independent

Accessories Size 04 - D633 and Size 05 - D634

Part designation Description Image Part number

Cable with straight mating

connector 6-pole + PE

5, 10, 20 or 25 m, e.g. for 5

m specify 005, other length

upon request

C21033-xxx-001

Mating connector, elbow

6-pole + PE

In accordance with EN

175201-804, type S, metal,

IP65, cable Ø 8 to 12 mm

(0.31 to 0.47 in)

(2.53)

Ø 22

(0.86)

(0.39)

(2.45)

(2.64)

Ø 28.8

(1.13)

22, max. 20 Nm

(177 lbf in)

(0.79)

B97069-061

Mating connector, straight

6-pole + PE

In accordance with EN

175201-804, type R, metal,

IP65, crimp contact Ø 0.75

to 1.5 mm

(0.0012 to

0.0023 in

), conus Ø 12.2

mm (0.48 in), cable Ø 9 to

12 mm (0.35 to 0.47 in),

sealing element Ø 9 to 13

mm (0.35 to 0.51 in)

22, max. 20 Nm

(177 lbf in)

Ø 22

(0.86)

Ø 29

(1.13)

(2.60)

(0.79)

(2.76)

B97007-061

Mains power connection Power supply cable, length

2 m (6.4 ft)

B95924-002

Mains power connection SELV power pack 24 V

10 A

D137-003-001

ORDERING INFORMATION

Direct Drive Analog Control Servo Valves

Rev. C, April 2020 23

ACCESORIES AND SPARE PARTS

Series-speciﬁc

Documents Size 04 - D633 and Size 05 - D634

Part designation Description Part number

ATEX and IECEx manual Operating Instructions for Proportional Valves D633K,

D634K and D635K Series ISO 4401 Size 03 and 05

CA49304-200

Technical note TN 353 Protective Grounding and Electrical Shielding of Hydraulic

Valves with Integrated Electronics

CA58437

Technical note TN 494 Maximum Permissible Length of Electric Cables for Valves

with Integrated Electronics

CA48851

ORDERING INFORMATION

Direct Drive Analog Control Servo Valves

24Rev. C, April 2020

MOOG GLOBAL SUPPORT

ORDERING INFORMATION

Direct Drive Analog Control Servo Valves

Moog Global Support is our promise to offer world-class

Repair and Maintenance Services delivered expertly by our

trained technicians. With the reliability only available from

a leading manufacturer with facilities around the world,

Moog offers you service and expertise you can count on to

keep your equipment operating as it should.

This promise offers many beneﬁts to our customers

including:

• Reduce your downtime by keeping critical machines

running in peak performance

• Protect your investment by ensuring reliability, versa-

tility and long-life of products

• Better plan your maintenance activities and make

systematic upgrades

• Leverage our ﬂexible programs to meet the unique

service requirements of your facility

• Look to Moog for global support including:

• Repair services using OEM parts are performed by

trained technicians to the latest speciﬁcations

• Stock management of spare parts and products to

prevent unplanned downtime

• Flexible programs, tailored to your needs such as

upgrades, preventative maintenance and annual/multi-

year contracts

• On-site services bring the expertise to you, providing

quicker commissioning, set-up and diagnostics

• Access to reliable services that are guaranteed to

offer consistent quality anywhere in the world

For more information on Moog Global Support visit

www.moog.com/industrial/service.

Rev. C, April 2020 25

ORDERING CODE

ORDERING INFORMATION

Direct Drive Analog Control Servo Valves

NBR (Buna)

FKM

Other seal material upon request

Model designation

(

assigned at the factory)

12345678910 11

350

D 63 KRS2

–

Command signal Actual valve

±10 V

6+PE pole EN 175201-804

4 to 20 mA

4 to 20 mA 4 to 20 mA

±10

to 10 mA

10 mA, ﬂoating

deadband compensation on request

4 to 20 mA

Signals for position control

Explosion proof version

for dust upon request

Size

Factory identiﬁcation

Valve type

Rated ﬂow per spool land [l/min (gpm)]

Pressure range [bar (psi)]

Maximum operating pressure

Bushing/spool design

(5,000)

Seal material

Closed with screw plug p

Tmax

= 50 bar (725 psi)

Open, with ﬁlter insert p

> 50 bar (725 psi)

Y-port

StandardD633

StandardD634

Linear motorSeries

Spool position without electrical signal

Center position

A, B

T connected (approximately 10 % open)

A, B

T connected (approximately 10 % open)

Other openings on request

= 35 bar (500 psi)

Series p

Valve connector

Model number (assigned at the factory) Type designation

(1.3) 2D633

(2.6) 4D633

(5.3) 8D633

(10.6) 16D633

(15.8) 24D634

100

(26.3) 40D634

= 5 bar per land

For

Standard response

4-way:

2x2-way:

axis cut, linear characteristic

1.5 to 3 % overlap, linear characteristic

10 % overlap, linear characteristic

P A, B T, with Y-port only

Special spool on request

Size 03

Size 05

Supply voltage

Input voltage limited, see section "ELECTRONICS"

Speciﬁcation status

Series speciﬁcation

Preseries speciﬁcation

Special speciﬁcation

Explosion proof version

for gas upon request

24 V

, for more information,

see section on "Electronics"

WHAT MOVES YOUR WORLD

MORE PRODUCTS. MORE SUPPORT.

Moog designs a range of motion control products to complement those featured in this document.

Moog also provides service and support for all of our products. For more information, contact the Moog facility closest to you.

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Service + 61 3 8545 2140

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Service +49 7031 622 197

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Service 800 815 692

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Service +7 8 31 764 5540

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+44 (0) 1684 858000

Service +44 (0) 1684 278369

info.uk@moog.com

service.uk@moog.com

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+1 716 652 2000

info.usa@moog.com

service.usa@moog.com

For product information, visit www.moog.com/industrial

Moog is a registered trademark of Moog Inc. and its subsidiaries.

All trademarks as indicated herein are the property of Moog Inc. and its subsidiaries.

For the full disclaimer refer to www.moog.com/literature/disclaimers.

D633, D634 Direct Drive Analog Control Servo Valve

PIM/Rev. C, April 2020, CDL 59872-en