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Welcome
to the widest range of standard racks & pinions in the
World! Consisting of both helical & straight (spur) tooth
versions, in an assortment of sizes, materials and quality levels, to meet
almost any axis drive requirements.
These
drives are perfect for a wide range of applications,
including axis drives requiring precise positioning & repeatability, traveling
gantries & columns, pick & place robots, and
material handling systems. Heavy load capacities and duty cycles
can also be easily handled with this drives. Industries served
include Material Handling,
Automation, Automotive, Aerospace, Machine Tool and
Robotics.
Typical delivery time for these
standard components is 2 to 3 weeks, which is ideal for OEM's requiring just-in-time delivery schedules.
Special and/or modified components are always possible - please consult
the factory.
Complete Range |
Selection |
Ratings |
Accuracy |
Lubrication |
PDF Files
| Application Sheet
There are four
basic quality levels of gear racks available, each of which is well suited for certain types of
applications:
Rack
Type: |
Tooth
Quality: |
Tooth
Hardness: |
Tooth
Pitches: |
Segment
Lengths: |
Typical
Applications: |
| Soft
Rack |
~AGMA
9
(DIN 9) |
~28
Rc |
Module
1.0 to 10.0 |
Up
to
3.0 Meters |
Light
Loads
Medium Accuracy |
Quenched
&
Tempered Rack |
~AGMA
10
(DIN 8) |
~28
Rc |
Module
2.0 to 5.0 |
Up
to
2.0 Meter |
Medium
Loads
Medium Accuracy |
Induction
Hardened Rack |
~AGMA
8
(DIN 10) |
50 - 55
Rc |
Module
2.0 to 10.0 |
Up
to
2.0 Meters |
Heavy
Loads
Low Accuracy |
Hardened
&
Ground Rack |
~AGMA
12
(DIN 6) |
60
Rc |
Module
2.0 to 10.0 |
Up
to
2.0 Meters |
Heavy
Loads
High Accuracy |
The quality
levels denote the accuracy of the teeth, which affects the positioning
accuracy, backlash and noise level of the rack & pinion set. We
always recommend a hardened & ground pinion regardless of the rack
type used.
Don't let the
rack segment lengths above deceive you - unlimited travel
lengths can easily be achieved by mounting the racks end-to-end, using a
companion rack to properly space each segment.
What is a
Module? Module is a metric pitch, inversely related to
diametral pitch, e.g. Module = 25.4 / Diametral Pitch.
The most recent addition to this range is our
Integrated
Rack & Rail,
for mounting directly to linear guides, simplifying alignment and
machining.
Selecting
the right gear rack depends on many things, including accuracy and load
requirements, design constraints, and cost. Sometimes it is possible
that two different racks would work for the same application, but each
having it's own advantages and disadvantages.
Rack
& pinions are typically selected based on the peak cycle forces, which
usually happen during accelerations and decelerations. These cycle
forces depend on the weight being moved, the speed vs. time profile for
the cycle, the friction of the axis bearings, and any other external
forces acting on the axis.
Maximum
tangential force ratings for the various racks can be seen in the
following table:
Rack
& Pinion
Size |
Maximum
Tangential
Force Ratings * |
Hardened
& Ground
Rack |
Induction-Hardened
Rack |
Quenched
& Tempered Rack
Soft Rack |
| Module
2.0 |
1,900
lb. |
1,500
lb. |
up
to 1,000 lb. |
| Module
3.0 |
3,400
lb. |
2,800
lb. |
up
to 2,300 lb. |
| Module
4.0 |
6,500
lb. |
5,300
lb. |
up
to 4,300 lb. |
| Module
5.0 |
7,700
lb. |
7,000
lb. |
up
to 4,200 lb. |
| Module
6.0 |
11,000
lb. |
10,000
lb. |
up
to 4,400 lb. |
| Module
8.0 |
21,000
lb. |
16,000
lb. |
up
to 7,600 lb. |
| Module
10.0 |
31,000
lb. |
22,500
lb. |
9,000
lb. |
* Ratings
depend on size and material of mating pinion, and are based on fatigue
strength; breaking strength ratings are much higher. Service factors need to be
applied to these ratings to make a proper selection.
Helical
versus Straight. There are two styles of gear racks we offer -
Straight tooth, where the teeth are perpendicular to rack length, and
Helical tooth, where the teeth are at an angle to the rack length.
The helical style provides several key benefits over the straight style,
including:
-
Helical
rack & pinions runs quieter than the straight, especially at high speeds
-
Helical
rack & pinions has a higher contact ratio (the number of effective teeth
engaged) than straight, which increases the load carrying capacity
-
Helical
rack lengths are nice round numbers, e.g. 500.0 mm and 1,000.0 mm, for
easy integration with machine bed lengths; Straight racks lengths are
always a multiple of pi., e.g. 502.65 mm and 1005.31 mm.
-
In most
cases, helical rack & pinions cost the same as the straight rack &
pinions!
The only real
disadvantage to using helical rack & pinions is it requires more time to set up
and align properly.
For
application & selection assistance, please call us or fill out our
Application Sheet. Your application
data will be reviewed by our engineers, who will recommend the best
solution for your application.
Rack
& Pinion
Ratings |
Rack
& Pinion
Selection Procedure |
Application Sheet
When
talking about rack & pinion accuracy, it can be broken down into three
components: Backlash, Pitch Deviation and Tooth Quality.
-
Backlash is the amount of clearance between the rack & pinion tooth
flanks, and will depend on the type of rack selected and alignment
accuracy between the rack and pinion. The backlash can be eliminated
completely by using a preloaded split-pinion or
dual pinion drive system.
-
Pitch
Deviation is the difference between the theoretical rack length and its
actual length. This varies depending on the rack quality selected
and is shown in the catalog as GTf per 300 mm length. Some servo
systems can compensate for this error by using a laser interferometer to map
out the errors. Zero cumulative pitch deviation for long travels is
available - please consult the factory.
-
Tooth
Quality is the accuracy that the tooth flanks are manufactured
to, which affects the running precision and smoothness of the axis
drive. Soft rack & pinions have a quality level of ~AGMA 9
(DIN 9) *. Induction-hardened rack & pinions have a quality
level of ~AGMA 8 (DIN 10) *, due to deformation from the heat
treatment process. Quenched & Tempered rack & pinions have a
quality level of ~AGMA 10 (DIN 8) *. Finally, Hardened &
Ground rack & pinions have a quality level of ~AGMA 12 (DIN 6) *,
since the teeth are precision ground. For high accuracy
applications, a precision rack, such as the Hardened & Ground,
should be used.
*AGMA quality level numbers increase with higher precision; DIN
quality level numbers decrease with higher precision.
With
open gearing such as rack & pinions, lubrication is critical! A
thin film of grease or oil should always be on the contacting tooth flanks
to ensure there is no metal-to-metal contact, which can damage the teeth.
It
is recommended to use our Automatic Lubrication System, which pumps grease
through a felt gear applicator and meshes directly to the pinion or the
rack. This provides continuous lubrication at the tooth flanks,
extending the lifetime and maintaining the quality of the gearing.
For more information
on our Automatic Lubrication System, please follow this link:
Automatic
Lubrication Systems.
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Other Products Available: |
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Servo-Worm Reducers are available
in four levels of precision to meet any application needs. Perfect for use in applications that
demand high performance, precise positioning and repeatability.
Angular backlash levels down to less than 1 arc-minutes are
available as standard. Optional integral pinion shafts are
also available to mount directly to hollow output
shaft.
-
Zero-Backlash Rack & Pinion Drives,
for applications requiring ultra-precise positioning
and repeatability, the system backlash can be eliminated by using a
split-pinion or dual pinions.
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Helical
Flanged Pinions, are provided with ISO 9409-1 flanges
to mount directly
to our High-Torque (HT) Servo-Worm Reducers
and popular planetary gearboxes, such as
Alpha TP, Stober PH, Apex AD and Neugart
PLF. This interface provides a tight
integration of the pinion to the gearbox output, reducing overhung loading and
backlash between the components. The
pinions are easily mounted and replaceable if future repair is needed.
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Helical Splined Pinions,
are provided with DIN 5480 internal splines to mount directly to
popular planetary gearboxes, such as Alpha and Stober. This
interface provides a tight integration of the pinion to the gearbox
output, reducing overhung loading and backlash between the
components.
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Integrated
Rack & Rail mounts
directly
to most standard linear guides (HIWIN, IKO, INA, NSK, SKF, Star,
THK, etc.), eliminating the need for additional machining and
alignment, saving time and money.
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