Design And Principle Of Operation; Versions - Samson 3274 Mounting And Operating Instructions

3 Design and principle of oper-
ation
The electrohydraulic actuator is used to posi-
tion Series 240, 250, and 280 Control
Valves.
The actuator is fastened to the valve bonnet
with a ring nut. The actuator and plug stems
are fastened together by a stem connector.
The actuator mainly consists of the actuator
housing, motor with oil pump, and cylinder
housing with piston.
Pilot valves regulate the flow of oil to and
from the piston. The actuator is equipped
with compression springs which determine
the positioning forces. Actuator versions with
spring mechanism also serve to move valve
to the fail-safe position "actuator stem re-
tracts" or "actuator stem extends" in the
event of a power supply failure.

3.1 Versions

The following versions (see technical data on
page 5 for details) are available:
With electric override:
Manual override with two pushbuttons
− Type 3274-11
− Type 3274-12
− Type 3274-13
− Type 3274-14
EB 8340 EN

Design and principle of operation

With mechanical override:
Mechanical override implemented using an
Allen key (width across flats 24 mm) at the
additional gear housing
− Type 3274-15
− Type 3274-16
− Type 3274-17
− Type 3274-18
Versions with fail-safe action and with
electric override:
− Type 3274-21
− Type 3274-22
− Type 3274-23
Testing according to DIN EN 14597
The Type 3274-21 and Type 3274-23 Actu-
ators are tested by the German technical
surveillance association (TÜV) according to
DIN EN 14597 in combination with various
SAMSON valves (registration number on re-
quest).
7