EB 8331-3 EN 3-1
Design and principle of operation
3 Design and principle of oper-
ation
TheType3374ElectricActuatorisusedin
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
forform-tattachmenttovariousSAMSON
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
TheType3374ElectricActuatorisavailable
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
theelectromagnetisde-energized.
The direction of action depends on the actu-
ator version and cannot be reversed.
Testing according to DINEN14597
TheType3374ElectricActuatorwithfail-
safe action "actuator stem extends" is tested
bytheGermantechnicalsurveillanceassoci-
ationTÜVaccordingtoDINEN14597in
combination with different SAMSON valves
(the register number is available on request).
3.2 Versions
TheType3374Actuatorisoptionallyavail-
able with either integrated yoke (see
Fig.3-1)orusinganM30x1.5ringnut(see
Fig.3-2)includingthenecessarystemcon-
necting parts.
Fig.3-1: Construction with integrated yoke
(formB)
Fig.3-2: Construction for mounting with ring
nut (formA)