4
Section I – Operating Characteristics
Type
Electrohydraulic two-stage servo valve
. . . . . . . . . . . .
Operating Fluid
Clean hydraulic fluid
. . . . . . . . . . . . . . . . . . .
Filtration
10 Micron
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Type Mounting
Sub-plate, manifold
. . . . . . . . . . . . . . . . . . .
Mounting Position
Optional
. . . . . . . . . . . . . . . . . . . . . . . . . .
Coil Resistance
OHMs Per Coil
(nominal)
Input
Differential
Current -ma
Deadband
Maximum
Null
Shift
Hysteresis
Power Required
– watts
(approx.)
20
400
25
360
40
300
.2%
L
th
100
175
.2%
open loop
ith dither
.03%/
°
F
Less than
2%
3
280
100
with dither
2%
2200
40
5300
25
Section II – Description
This manual contains operation, service and overhaul
information for the SA4 Series Servo Valve. Units are
identified on the nameplate. Figure 1 schematically illustrates
the construction in cross-section.
Servo valves are comprised of a rectangular body containing
four moving parts: a precision fitted pilot spool and sleeve,
main spool and mechanical feedback linkage. Each valve
uses a permanent magnet torque motor for pilot spool
actuation.
Section III – Model Code
002 – 20 OHMS
003 – 25 OHMS
004 – 40 OHMS
010 – 100 OHMS
028 – 280 OHMS
220 – 2200 OHMS
530 – 5300 OHMS
6
5
3
4
6
7
1
2
5
5.5 to 1
4.5 to 1
3.5 to 1
2.5 to 1
1.5 to 1
1
Servo Valve
2
Type A – Two Stage Sliding Spool
4-way
3
4
03 – 3/8
I
Nominal Pipe Size
06 – 3/4
I
Nominal Pipe Size
7
Design and Modification
Linkage Ratio
