
10 EB 8312-1 EN
Design and principle of operation
3 Design and principle of oper-
ation
The Type3273 Side-mounted Handwheel
with 60 and 120mm travel is suitable for
mounting on Series240, 250, 280, and
290 Valves or on suitable interfaces together
with the Type3271 Pneumatic Actuators with
effective areas of 1000, 1400-60, 1400-
120, 2800, and 2x2800cm². A special
version of the side-mounted handwheel can
also be used to move the valve on which a
pneumatic actuator is not mounted.
The side-mounted handwheel is mounted be-
tween the valve and actuator. The handwheel
can remain mounted on the valve during
maintenance and repair work or while ex-
changing the pneumatic actuator. The hand-
wheel can be used in this case to move the
valve manually to its closed or open position.
The handwheel can be used to move the
valve manually opposing the spring force of
the pneumatic actuator upon air supply fail-
ure.
The worm shaft unit, consisting of the worm
shaft and worm-geared wheel, is driven over
the handwheel. The spindle nut transfers the
rotary motion to the threaded rod, which
moves the valve. Depending on the direction
of rotation and mounted valve, the threaded
rod extends or retracts.
For mounted SAMSON globe valves
The handwheel is marked 'Open/Close' and
has directional arrows.
−Turn the handwheel clockwise: the globe
valve closes
−Turn the handwheel counterclockwise: the
globe valve opens
For mounted SAMSON three-way valves
A label is afxed to the handwheel, which
indicates in which direction the threaded rod
is moved by turning the handwheel (see
Fig.4).
The gear is locked by the locking bolt to pre-
vent accidental adjustment.