Actuator Guide - Norgren Pneumatics. Motion Control Equipment ...

Another form of rotary actuator is the rack and pinion design.
The basic double acting rack and pinion design is shown in
(Figure 10). These larger actuators are often used in the
process industry to operate quarter turn valves.
Figure 10: Rack and pinion
The torque output can be doubled by adding a second actuator
to drive the same pinion (Figure 11).
Figure 11: Double rack and pinion
CLAMPING CYLINDERS
For use in confined spaces where only a short stroke is
required these cylinders have a small axial overall dimension
for their bore size. They are mostly used in single acting
versions (Figure 12), but are also available as double acting
through-rod styles (Figure 13). They are usually used in light
duty applications.
Figure 12: Figure 13:
Single acting clamp cylinder Double acting clamp cylinder
7
BELLOWS
Bellows are durable single acting concertina like actuators
which extend when inflated and are similar to the air
suspension units seen on
large trucks. They provide
powerful short strokes and
have all round compliance
allowing them to bend in
any direction (Figure 14).
Single, double and triple
convolution types provide a
range of strokes with power Figure 14: Bellows
developed from nominal
diameters in the range 70mm to 546mm. Loads varying in
angle up to a maximum of 30° from the actuator axis can be
accommodated.
These actuators can be used as air springs and are ideal for
isolating the vibration of supported loads from the actuators
base mounting. To avoid the accumulation of moisture if used
with wet air, bellows should be installed with the port facing
down, to assist expulsion with the exhaust on each cycle.
Caution: The maximum extension and compression of the
bellows must be limited by external restraints. The bellows
must never be pressurised while unrestrained as it will over
extend and the end plate is likely to be blown free and could
cause serious injuries. When the bellows are exhausted the
load must be prevented from crushing it by means of external
stops.