2.3.3 Aligning and mounting the
cam disk
In rotary actuators with spring-return mech-
anism, the built-in actuator springs deter-
mine the fail-safe position and the direction
of rotation of the control valve.
With double-acting, springless rotary actua-
tors, the direction of rotation depends on
both the actuator and the valve model used.
Any adjustments are only permitted when
the valve has been closed.
The positioner’s direction of action, i.e.
whether the valve shall either open or close
when the reference variable increases, has
to be software adjusted via the communica-
tion (increasing/increasing or increas-
ing/decreasing).
1. Position the cam disk with the scale on
the adapter (36) or the coupling (34),
and fasten the screw loosely at first.
The cam disk carries two cam sections. The
starting point of each section is marked by
a small bore.
NOTE
With the valve closed, the starting point
(bore hole) of the respective characteristic is
to be aligned so that the center of rotation
of the cam disk, the 0° position on the
scale, and the arrow mark on the plate are
aligned.
The starting point for the closing position
must not be below the 0° position!
In actuators with fail-safe position "Control
valve open" (OPEN), the actuator must
therefore be loaded with max. signal press-
ure prior to aligning the cam disk.
In springless actuators, the supply air must
be connected.
2. In aligning the cam disk, the double-
sided scaled disk must be installed in
such a way that the value on the scale
corresponds to the control valve’s direc-
tion of rotation. Only then secure the
cam disk with the fastening screws.
Securing the aligned cam disk
If you want to additionally secure the cam
disk to prevent it from being turned, pro-
ceed as follows:
Four bore holes are located centrically
around the center bore on the cam disk. Se-
lect a suitable one of the four holes to se-
cure the cam disk.
Through this hole, drill a hole in the adapter
(36) or coupling (44), and insert a 2 mm
dowel pin.
3. Attach the positioner to the intermediate
piece (34) so that the lever (35) con-
tacts the cam disk with its cam follower
roll. To do so, insert a 2.5 mm hexagon
socket key or a screwdriver from the
front into the bore hole which can be
seen below an oblong hole on the
cover plate and bring the positioner
lever in the required position.
4. Screw positioner to the intermediate
piece.
20
EB 8382-1 EN
Attaching the positioner
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