Design And Principle Of Operation; Fail-Safe Action; Versions - Samson 3374 Mounting And Operation Instructions

3 Design and principle of oper-
ation
The Type 3374 Electric Actuator is used in
industrial plants as well as in heating, venti-
lation and air-conditioning systems.
The actuator is a linear actuator which is
controlled by a three-step signal. It is suitable
for form-fit attachment to various SAMSON
valve series, depending on the version with
or without fail-safe action.
Principle of operation
The synchronous motor is switched off by
torque switches in the end positions and in
case of overload. The force of the motor is
transmitted to the actuator stem over gearing
and ball screw drive.

3.1 Fail-safe action

The Type 3374 Electric Actuator is available
with or without fail-safe action.
Type 3374-2x and Type 3374-3x Actuators
are able to perform a fail-safe action and
contain a spring assembly and an electro-
magnet. The actuator is moved by the force
of the spring to the fail-safe position when
the electromagnet is de-energized.
The direction of action depends on the actu-
ator version and cannot be reversed.
Testing according to DIN EN 14597
The Type 3374 Electric Actuator with fail-
safe action "actuator stem extends" is tested
by the German technical surveillance associ-
ation TÜV according to DIN EN 14597 in
combination with different SAMSON valves
(the register number is available on request).
EB 8331-3 EN

Design and principle of operation

3.2 Versions

The Type 3374 Actuator is optionally avail-
able with either integrated yoke (see
Fig. 3-1) or using an M30x1.5 ring nut (see
Fig. 3-2) including the necessary stem con-
necting parts.
Fig. 3-1: Construction with integrated yoke
(form B)
Fig. 3-2: Construction for mounting with ring
nut (form A)
3-1