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Attachment to the control valve
2.3.3 Aligning and mounting the
cam disk
In rotary actuators with spring-return mech-
anism, the actuator springs determine the
fail-safe position and the direction of rota-
tion of the control valve.
With double-acting, springless rotary actua-
tors, the direction of rotation depends on
both the actuator and valve version used.
The initial position is always based on a
closed valve!
Whether the control valve should open or
close when the reference variable increases
must be set in the software (direction of ac-
tion increasing/increasing or increasing/de-
creasing).
1. Place the cam disk with scale on the
adapter (36) or coupling (34), and
fasten the screws loosely at first.
The cam disk has two cam sections. The
starting point of each section is marked by
a small hole.
Note!
When the valve is closed, the starting point
(hole) of the disk must be aligned so that the
pivot of the cam disk, the 0° position of the
scale and the arrow mark on the viewing
window are in one line.
The starting point for the closed valve posi-
tion should never be below the 0° position!
In actuators with fail-safe position "valve
OPEN", the maximum signal pressure must
be applied to the actuator prior to aligning
the cam disk.
In springless actuators, the supply air must
be connected.
20
EB 8383-1 EN
2. On aligning the cam disk, clip on the
double-sided scale disk so that the scale
matches the direction of rotation of the
control valve. 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:
There are four holes arranged around the
center hole on the cam disk. Select a suit-
able hole from the four holes to secure the
cam disk.
Drill a hole in the adapter (36) or coupling
(44) through the hole chosen and insert a
2 mm dowel pin.
3. Attach the positioner to the intermediate
piece (34) so that the lever (35) touches
the cam disk with its feeler roll.
To do so, insert a 2.5 mm Allen key or
screwdriver from the front into the bore
hole located below an oblong hole in
the cover plate and bring the positioner
lever in the required position.
4. Screw positioner to the intermediate
piece.
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