Siemens Sinumerik 840D Series Function Manual page 241

10.03
 Siemens AG, 2003. All rights reserved
SINUMERIK 840D/SIMODRIVE 611 digital, HLA Module (FBHLA) - 10.03 Edition
The symbol also illustrates the principle of position control applied to the valve
spool.
Reset spring
O B
P T
Fail-safe closed
O B
P T
Fig. A-3 Graphical symbol
A.1 Servo solenoid valves
Actuating solenoid
Position sensor
Setpoint
Valve amplifier U
with position
control
Fail-safe open
O B
P T
A Hydraulics
=0..."10 V
E
A-241