FNW RP User Manual
Figure RP
ACTUATORS
PNEUMATIC RACK & PINION
www.fnw.com
TORQUE RANGES
The RP rack and pinion actuators are
available with output torques ranging
from 44 to 36,269 in-lbs depending on
air supply pressure and/or spring sets.
ACCESSORY MOUNTING
The accessory mounting pad meets
international NAMUR standards for
ease of directly attaching accessories
following the same standard.
ANTI BLOW-OUT PINION
The design of the pinion prevents
blow out by securing it with the piston
racks. The pinion is ground from
hardened steel and then nickel plated
for maximum corrosion and wear
resistance.
SPRINGS
For fail safe requirements,
reliable and high resistant
steel springs are included.
Springs are zinc phosphate
coated for corrosion
resistance.
SEALS
The standard
actuator is
supplied with NBR
seals at piston, pinion,
and end caps. Viton® is
available for high temperature
applications, and Silicon for low
temperature applications.
Standard Features
POSITION INDICATOR
High visibility position indicator with
snap on marks is easily converted to
indicate 3-way positions or can be
removed for other accessories.
END CAP SCREWS
End caps are secured with extra
length stainless steel screws for safe
disassembly.
ACTUATOR BODY
The body is a single piece extruded
aluminum housing with anodized
hard coat exterior nished to 45-50
microns. An optional nickel plated
exterior is available for added
corrosion resistance.
SOLENOID MOUNTING
Supply air connections follow the
international NAMUR standard for
direct mounting of like style solenoids
and is included on all sizes.
END CAPS
Ends caps are die cast aluminum with
polyester powder coating. Nickel
plated bodies also come with nickel
plated end cap. Double-acting
and spring-return actuators utilize
the same end caps, allowing quick
conversion by adding or removing
springs as needed.
TRAVEL STOPS
Each size actuator comes standard
with two travel stops for +/-5° of open
and close travel adjustment at
nominal positions of 0° and
90°. The stainless steel
adjustment screws and cam
are not located in the main
pressure containing
area of the body,
reducing the number
of possible leak
paths and necessary
seals.
PISTONS
Pistons are
constructed of die
cast aluminum and
designed for strength
and generous rack
engagement.
PISTON GUIDES
Piston guides, constructed from
POM materials, are designed with
a large contact area and long life.
The material offers low friction for self
lubrication.
VALVE MOUNTING
The valve mounting follows ISO 5211
for direct mounting to valves with the
same pattern. All output drive include
an 8-point female drive (except the
model 270 which has a single square
4-point female drive).
Travel Stops
The travel stop cam is located separate
from the pressure chamber of the
actuator. This design eliminates two
potential leak paths as well as the
associated seal components. The cam
is positively locked to the pinion and
easily installed during maintenance
via a guide in the cam chamber. The
cam chamber is a sealed compartment
that is protected from water and
dirt ingress, ensuring trouble free
operation.
Anti-Blowout Pinion
The RP actuators is designed with a
grooved pinion and a corresponding
at key cast in the piston rack. This
system creates an added mechanical
lock that prevents the pinion from
blowing out of the bottom of the
housing. In this design, lower pinion
clips and retainers that can wear out
are eliminated.
2
CAM STOP BOLT
GUIDE
PINION / PISTON GROOVE
Standard Materials
• Body - UNI 6060 Aluminum, Hard Anodized
(Optional Nickel Plating)
• End Caps - Die Cast Aluminum, Polyester
Powder Coated (Nickel plated with nickel plated
body)
• Pinion - Hardened Steel, Nickel Plated
• Pistons - Die Cast Aluminum
• Seals - NBR (Optional High Temperature Viton®
or Low Temperature Silicon)
• Guides/Spacers/Anti-Friction Rings - POM
(Acetal) (Model 270 uses PTFE and Graphite
Filled PTFE anti-friction rings)
• Travel Stops/Cam/End Cap Screws - Stainless
Steel
• Springs - Steel, Zinc Phosphate Coated (Spring
return models only)
• Position Indicator - Nylon
• Travel Stop Housing - GGG40 Ductile Iron
(Model 270 only)
• Upper Pinion Snap Ring - Steel, Nickel Plated
Standard Operation - Double Acting
AB AB
The RP rack and pinion actuator operates (turns) CCW by
supplying compressed air to port A. The pressure drives the
pistons outward, turning the drive pinion CCW. Air on the
outside of the pistons is exhausted out of port B.
Standard Operation - Spring Return
The RP rack and pinion actuator operates (turns) CW by
supplying compressed air to port B. The pressure drives the
pistons inward, turning the drive pinion CW. Air on the inside of
the pistons is exhausted out of port A.
AB
The RP rack and pinion actuator operates (turns) CCW by
supplying and holding compressed air at port A. The pressure
drives the pistons outward, turning the drive pinion CCW and
compressing the spring sets. Air on the outside of the pistons is
exhausted out of port B.
Reversible Operation
Standard Rotation Reversed Rotation
CWCCW
In the standard operation of the RP actuator, the output turns
CCW when the pistons are driven outwards. When the pistons
are driven inwards, the output turns CW. This is the typical
action of the majority of valves that open in the CCW direction,
and close in the CW direction.
Spring Return Spring Set Congurations
The RP rack and pinion
actuators are stocked with full
spring sets (spring set 05 for
models 52 to 140, spring set
06 for models 160 to 230, and
spring set 08 for the model
270).
Spring sets can be modied by
removal of springs, as indicated
in the spring set charts, to alter
the actuator’s torque curve as
shown on the torque charts.
Full spring sets provides the
maximum spring return torque
for a given size actuator, but
can be reduced for situations
where increased torque in the
air stroke is desired.
Spring
Set
01 1 1
02 2
03 1 2
04 2 1
05 2 2
Outer
Inner
Spring Quantity
Outer Inner
* Model 230 has maximum spring set of 06.
AB
The RP rack and pinion actuator operates (turns) CW by
releasing the compressed air at port A. This allows the spring
sets to decompress as they drive the pistons inward and the
pinion turns CW. Make-up air is drawn in through port B from
the atmosphere.
CCWCW
The RP actuator operation is eld reversible so the output turns
CW when the pistons are driven outwards, and CCW when they
are driven inwards. This conguration is used for spring return
actuators that require a mechanical fail in open position, or for
valves with reversed operation.
Models 160 to 200Models 52 to 140
Outer
Middle
Spring
Set
Spring Quantity
Outer Middle Inner
01 2
02 2
03 1 2
04 2 2
05 2 2
06 2 2 2
Inner
Models 230* & 270
Pre-tensioned
Spring
Set
Springs/Side
Side A Side B
01 2 3
02 3 3
03 3 4
04 4 4
05 4 5
06 5 5
07 5 6
08 6 6
Spring
3
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