HEIDENHAIN Length Gauges - Manual (Page 20)

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Pneumatic plunger actuation
The pneumatically actuated plungers of
the AT 1217, AT 3017, MT 1287, MT 2587,
ST 12x7 and ST 30x7 length gauges are
extended by the application of compressed
air. When the air connection is ventilated,
the integral spring retracts the plunger. to a
protected resting position within the
housing.
The gauging force can be adjusted to the
measuring task through the level of air
pressure. At constant pressure, it depends
on the operating attitude and the plunger
position.
The diagrams show the respective measur-
ing force for a horizontal operating attitude
depending on the working pressure applied
with the plunger fully extended and fully re-
tracted. These are approximate values that
are subject to changes due to tolerances
and depend on seal wear.
Note
The compressed air introduced directly into
the length gauges must be properly
conditioned and must comply with the
following quality classes as per ISO 8573-1
(1995 edition):
• Solid contaminants Class 1
(max. particle size 0.1 µm and max.
particle density 0.1 mg/m
3
at 1 · 10
5
Pa)
• Total oil content: Class 1
(max. oil concentration 0.01 mg/m
3
at 1 · 10
5
Pa)
• Max. pressure dew point: Class 4,
but with reference conditions of
+3 °C at 2 · 10
5
Pa
HEIDENHAIN offers the DA 400 com-
pressed air unit for purifying compressed
air. The minimum flow rate is 10 l/min.
For more information, ask for our DA 400
Product Information Sheet.
Gauging f
or
ce [N]

Pressure [bars] 
MT 12x7 retracted
MT 12x7 extended
ST 12x7 retracted
ST 12x7 extended
AT 1217 retracted
AT 1217 extended
Gauging f
or
ce [N]

Pressure [bars] 
MT 2587 retracted
MT 2587 extended
ST 30x7 retracted
ST 30x7 extended
AT 3017 retracted
AT 3017 extended
The working pressure defines the pressure
range of the first complete plunger exten-
sion up to the maximum specified range.
Except for special variants, the diagrams
apply for the horizontal operating
attitude. The following compensation
values are to be taken into account for
other operating attitudes.
Type Operating attitude vertical
North South
AT 121x
AT 301x – 0.12 N
– 0.18 N
+ 0.12 N
+ 0.18 N
MT 12xx
MT 25x1
MT 2587 – 0.13 N
– 0.17 N
– 0.19 N
+ 0.13 N
+ 0.17 N
+ 0.19 N
ST 12x7
ST 12x8
ST 30xx – 0.07 N
– 0.08 N
– 0.11 N
+ 0.07 N
+ 0.08 N
+ 0.11 N
12 mm measuring range
(pneumatically actuated)
25 mm/30 mm measuring range
(pneumatically actuated)