Gear Rack,

Gears, Pinions,
& Related Products

from

Schlenker Enterprises, Ltd.

Standard & Custom

Components
Nov 2003
 Linear Products Associated Products

Quality system

Reliance operations are controlled by a quality management

system approved to BS EN ISO 9001:2000.

Standard products and assemblies

Accurate positioning from modifiable standards for

instrumentation, measurement and light actuation
applications.

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Index Linear Products

Page Title Page

Ground round rack ..................................................24

Actuation rack ..........................................................27
Ground helicoidal rack ............................................28
Rack pinions ............................................................30
Hardened rack pinions ............................................34
PEEK™ polymer pinions..........................................36

Tubular rack actuator ..............................................38

Spline shafts ............................................................40
Linear motion shafting..............................................42
Hollow linear motion shafting ..................................43

Technical information .............................................. 52

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 Tubular Rack Ground Round Rack

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Stainless steel
Grade 316 series.
Pressure angle 20°

Part number selection table

Part Circular Outer Dia Bore Dia Pitch Height Rack
Number Pitch (mm) ØD Ød P Thrust (N)
RRT06-1M-500 6 3.4 5.682
RRT08-1M-500 1 8 5 7.682 20*
Notes RRT10-1M-500 10 6 9.682
(1):
0.5 module not
available on Ø6 tube. * Rack thrust based on a mesh with a 50 tooth stainless steel pinion, 3N if used with a
50 tooth PEEK™ polymer pinion.

• Cumulative pitch error less than 0.050mm.

• Ground teeth, standard accuracy grade 2.
• Hollow shaft allows for the passage of fluids, fibre-
optics and gasses etc.
• Highly stainless material resists pitting corrosion.
• Ideal for medical and scientific applications.
• Bearing surface and drive in one.

Non-standard options, please enquire....

• Modifications :
ie. flats, journals, end modifications.
• Shorter lengths.
(1)
• Alternative pitches, including 0.3 and 0.5
module.
• Higher accuracy grades.

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Ground Round Rack Soft Round Rack

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Stainless steel
Grade 300 series
Pressure angle 20°

Part number selection table

Part Circular Outer Dia Pitch Height Rack
Number Pitch (mm) ØD P Thrust (N)
RRS06-1M-500 6 5.682
RRS08-1M-500 1 8 7.682 20*
RRS10-1M-500 10 9.682

* Rack thrust based on a mesh with a 50 tooth stainless steel pinion, 3N if used with a
50 tooth PEEK™ polymer pinion.

• Cumulative pitch error less than 0.050mm.

• Ground teeth, standard accuracy grade 2.
• Highly stainless material resists pitting corrosion.
• Ideal for medical and scientific applications.
• Bearing surface and drive in one.

Non-standard options, please enquire....

• Modifications :
ie. flats, journals, end modifications.
• Shorter lengths.
• Alternative pitches, including 0.3 and 0.5
module.
• Higher accuracy grades.

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 Round Bar Rack Hardened Round Rack

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
linear brg shaft
St steel, Grade 440C
or X90CrMoV18.
Treatment:
Case hardened to
55HRc min.
Pressure angle 20°

Part number selection table

Part Circular Outer Dia Pitch Height Rack
Number Pitch (mm) ØD P Thrust (N)
RR10-1M-500 10 9.682
RR12-1M-500 12 11.682
1 60*
RR16-1M-500 16 15.682
RR20-1M-500 20 19.682

* Rack thrust based on a mesh with a 60 tooth hardened rack pinion.

• Cumulative pitch error less than 0.025mm.

• Ground teeth, standard accuracy grade 3.
• Manufactured from a linear bearing stainless steel.
• Can be used with both open and closed linear
bearings with either 4, 5 or 6 ball tracks. (The
bearing must be positioned so the balls do not run
on the edges of the teeth. See technical section.)
• Bearing surface and drive in one.

Non-standard options, please enquire....

• Modifications :
ie. flats, journals, end modifications.
• Shorter lengths.
• Alternative pitches, including 0.3 and 0.5
module.
• Higher accuracy grades.

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Actuation Rack Rectangular Rack

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Stainless steel
Grade 416
Treatment:
Hardened to
35-45 HRc.
Pressure angle 20°

Part number selection table

Part Circular Pitch Height Rack Number of
Number Pitch (mm) P Thrust (N) Holes
24.601
RH79-25M-300 2.5 130* 6
24.576

* Quoted rack thrust based on meshing with a 76 tooth pinion.

• Cumulative pitch error 0.015mm.

• Ground teeth, standard accuracy grade 3.
• Manufactured from stainless steel.
• High load capacity.
• Unlimited axis lengths possible by setting individual racks together.

Non-standard options, please enquire....

• Alternative lengths available, to a

maximum of 500mm.
• Shorter lengths.
• Alternative pitches, including module.
• 25° pressure angle available.

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 Rectangular Rack Ground Helicoidal Rack

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Stainless steel
Grade 416
Treatment:
Hardened to
35-45 HRc.
Pressure angle 20°

Part number selection table

Part Circular Length Pitch Height Number of
Number Pitch (mm) L P Holes
R9-1M-300 1 11.869
R9-2M-300 2 300 11.550 6
R9-25M-300 2.5 11.391
R11-1M-600 1 11.869
R11-2M-600 2 600 11.550 12
R11-25M-600 2.5 11.391

• Cumulative pitch error less than 0.008mm per 300mm.

• Ground teeth, standard accuracy grade 4.
• Manufactured from a stainless steel.
• Unlimited axis lengths possible by setting individual racks together.

Non-standard options, please enquire....

• Shorter lengths.
• Alternative pitches, including module.
• Higher accuracy grades.
• See technical data, page 56 for alternative
grades.

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Ground Helicoidal Rack Rectangular Rack

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Stainless steel
Grade 416
Treatment:
Hardened to
35-45 HRc.
Pressure angle 20°

Part number selection table

Part Circular Pitch Height Number of
Number Pitch (mm) P Holes
R5-1M-300 1 10.679 6

• Cumulative pitch error less than 0.008mm per 300mm.

• Ground teeth, standard accuracy grade 4.
• Manufactured from a stainless steel.
• Unlimited axis lengths possible by setting individual racks together.

Non-standard options, please enquire....

• Shorter lengths.
• Alternative pitches, including module.
• Higher accuracy grades.
• See technical data, page 56 for alternative
grades.

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 Plain Rack Pinions 6mm & 1/4" Bore

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Stainless steel
Grade 316
Pressure angle 20°

Part number selection table

Example Part No:- SH25MS2B6F7A- 32

Basic Part Circular Bore Size No. of Teeth

Number Pitch (mm) ØB Min Max
SH1MS2B6F7A- 1 43 111
SH2MS2B6F7A- 2 6 23 54
SH25MS2B6F7A- 2.5 19 43
SH1MS2B250F7A- 1 43 111
SH2MS2B250F7A- 2 1/4" 23 54
SH25MS2B250F7A- 2.5 19 43

• Standard accuracy AQ10.

• Higher accuracy & zero backlash when used with Flexplate
assemblies.
• Ideal for use with Reliance soft & hardened, round & rectangular
rack.
Non-standard options, please enquire....

• Higher accuracy grades.

• Alternative pitches, including module.
• Alternative bore sizes.

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6mm & 1/4" Bore Anti-backlash Rack Pinions

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Stainless steel
Grade 316
Pressure angle 20°

Part number selection table

Example Part No:- AH25MS2B6F89A- 20

Basic Part Circular Bore Size No. of Teeth

Number Pitch (mm) ØB Min Max
AH1MS2B6F89A- 1 46 54
AH2MS2B6F89A- 2 6 24 26
AH25MS2B6F89A- 2.5 20 20
AH1MS2B250F89A- 1 46 54
AH2MS2B250F89A- 2 1/4" 24 26
AH25MS2B250F89A- 2.5 20 20

• Standard accuracy AQ10.

• Ideal for use with Reliance soft & hardened, round & rectangular
rack.
• Ideal for lightly loaded measurement applications.

Non-standard options, please enquire....

• Higher accuracy grades.

• Alternative pitches, including module.
• Alternative bore sizes.

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 Plain Rack Pinions 10mm & 3/8" Bore

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Stainless steel
Grade 316
Pressure angle 20°

Part number selection table

Example Part No:- SH25MS2B10F7A- 32

Basic Part Circular Bore Size No. of Teeth

Number Pitch (mm) ØB Min Max
SH1MS2B10F7A- 1 63 104
SH2MS2B10F7A- 2 10 33 51
SH25MS2B10F7A- 2.5 27 40
SH1MS2B375F7A- 1 63 104
SH2MS2B375F7A- 2 3/8" 33 51
SH25MS2B375F7A- 2.5 27 40

• Standard accuracy AQ10.

• Higher accuracy when used with Flexplate assemblies.
• Ideal for use with Reliance soft & hardened, round & rectangular
rack.

Non-standard options, please enquire....

• Higher accuracy grades.

• Alternative pitches, including module.
• Alternative bore sizes.

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10mm & 3/8" Bore Anti-backlash Rack Pinions

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Stainless steel
Grade 316
Pressure angle 20°

Part number selection table

Example Part No:- AH25MS2B10F89A- 40

Basic Part Circular Bore Size No. of Teeth

Number Pitch (mm) ØB Min Max
AH1MS2B10F89A- 1 87 104
AH2MS2B10F89A- 2 10 45 51
AH25MS2B10F89A- 2.5 37 40
AH1MS2B375F89A- 1 87 104
AH2MS2B375F89A- 2 3/8" 45 51
AH25MS2B375F89A- 2.5 37 40

• Standard accuracy AQ10.

• Ideal for use with Reliance soft & hardened, round & rectangular
rack.
• Ideal for lightly loaded measurement applications.

Non-standard options, please enquire....

• Higher accuracy grades.

• Alternative pitches, including module.
• Alternative bore sizes.

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 Hardened Rack Pinions 6mm & 1/4" Bore

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Stainless steel,
17-4PH
Hardened to:
36/40 HRc.
Pressure angle 20°

Part number selection table

Example Part No:- SH25MS9B6F7A- 35

Basic Part Circular Bore Size No. of Teeth

Number Pitch (mm) ØB Min Max
SH1MS9B6F7A- 1 43 111
SH2MS9B6F7A- 2 6 23 54
SH25MS9B6F7A- 2.5 19 43
SH1MS9B250F7A- 1 43 111
SH2MS9B250F7A- 2 1/4" 23 54
SH25MS9B250F7A- 2.5 19 43

• Standard accuracy AQ10.

• Suitable for light actuation applications.
• Longer pinion life, higher load and provides higher thrust.
• Ideal for use with Reliance hardened round and rectangular rack.

Non-standard options, please enquire....

• Higher accuracies.
• Alternative pitches, including module.
• Alternative bore sizes.
• Alternative materials.
• Special wear resistant coating.

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10mm & 3/8" Bore Hardened Rack Pinions

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Stainless steel,
17-4PH
Hardened to:
36/40HRc.
Pressure angle 20°

Part number selection table

Example Part No:- SH25MS9B10F7A- 35

Basic Part Circular Bore Size No. of Teeth

Number Pitch (mm) ØB Min Max
SH1MS9B10F7A- 1 63 104
SH2MS9B10F7A- 2 10 33 51
SH25MS9B10F7A- 2.5 27 40
SH1MS9B375F7A- 1 63 104
SH2MS9B375F7A- 2 3/8" 33 51
SH25MS9B375F7A- 2.5 27 40

• Standard accuracy AQ10.

• Suitable for light actuation applications.
• Longer pinion life, higher load and provides higher thrust.
• Ideal for use with Reliance hardened round and rectangular rack.

Non-standard options, please enquire....

• Higher accuracies.
• Alternative pitches, including module.
• Alternative bore sizes.
• Alternative materials.
• Special wear resistant coating.

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 PEEK™ Polymer Rack Pinions 4 & 5mm Bore

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
PEEK™ 450G pinion
with
Stainless steel 303
hub.
Pressure angle 20°

Part number selection table

Example Part No:- SH1MP1B4F6A- 35

Notes Basic Part Circular Bore Size Boss Dia Screw Standard
PEEK™ is a trademark Number Pitch (mm) ØB ØD T No. of Teeth
of Victrex PLC.
SH1MP1B4F6A- 1 4 10 SS-M2.5-3 35

SH1MP1B5F6A- 1 5 12 SS-M3-3 40 50

• Standard accuracy AQ10.

• Unique stainless steel insert for accurate non-slip attachment to
shafts.
• Ideal for driving Reliance tubular rack - see page 24.

Non-standard options, please enquire....

• Other numbers of teeth.

• Higher accuracies.
• Alternative pitches, including module.
• Alternative bore sizes.

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 Tubular Rack Actuator Size 17

General
Information
All dimensions in mm
General tolerances:
±0.13mm

Part number selection table

Part Number Rack Length Rack Dia Axial Load

RRA17-6-250 250 ±1 6 3N

Technical specification*
• Drive: NEMA size 17 stepper motor, see technical section, pages
61 - 62.
• Tubular rack: 6mm OD, 3.4mm bore, 250mm length, 316 stainless
steel.
• Travel range: 200mm.
• Max continuous axial load: 3N.
• Max momentary load: 12N.
• Max speed: 300mm/sec.
• Resolution: 0.21mm with 200 steps/rev.
0.0033mm with microstepping (12800 steps/rev).
• Temperature range: -10ºC to +80ºC.
• Repeatability: 0.025mm.
• Life: in excess of 5 million cycles.
• Side wobble, fully extended: ±0.2mm.
• Backlash: equivalent to less than 0.08 linear movement.
• No lubricant required.
• Smooth quiet operation - no metal to metal contact.

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Size 17 Tubular Rack Actuator

General
Information
All dimensions in mm
General tolerances:
±0.13mm

* This actuator is supplied pre-assembled. Technical specification

figures are only valid if the actuator has not been dismantled.
If required, suitable customer supplied motors may be incorporated
in the actuator assembly.

Non-standard options, please enquire....

• Longer or shorter lengths of rack. Maximum

length 500mm.
• Tubular rack end modifications.
• Custom designs.
• Size 11 stepper motor assembly.

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 Spline Shafts RSS Series

RSSBP
(Basic)
General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Spline shaft -
Aluminium alloy, TFE
coated.
Bushing - Graphite and
PTFE filled
thermoplastic, with
brass collar.

RSSBY
(Basic)

RSSZP
(Anti-backlash)

RSSZY
(Anti-backlash)

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RSS Series Spline Shafts
Part number selection table

Example Part No:- RSS B P 6 T 1 - 100mm

Shaft length
Number of bushings
TFE coating (standard)
General
Basic Bushing Mount Size Shaft Bushing Bushing Thread Thread Information
Part Style Code Dia Outside Dia Length Length
All dimensions in mm
No. ØA ØB C M* N* General tolerances:
±0.05mm ±0.025mm ±0.25mm (Inch) ±0.13mm ±0.13mm
Material:
Spline shaft -
Aluminium alloy, TFE
6 6.35 12.70 19.1 7/16"-20 6.35 coated.
Bushing - Graphite and
B P PTFE filled
(Basic) (Plain Dia) thermoplastic, with
brass collar.
RSS 10 9.53 15.88 25.4 9/16"-20 9.53
Z Y
(Anti- (Thread)
backlash) 13 12.70 20.65 38.1 3/4"-20 12.70

* Only on thread mounting spline shafts.

• For spline shaft lengths of up to 1000mm, add required length to

basic part number.
• Standard shaft straightness is 0.076mm per 300mm.
• Typical radial and torsional clearance between shaft and bushing
for basic assembly is 0.05 to 0.076mm. Anti-backlash assemblies
provide additional system stiffness.
• Designed for light load applications.
• Maximum twist 3º/305mm.
• Torsional clearance (basic) 3º Bushing to shaft.
• Drag force 170g.

Non-standard options, please enquire....

• Longer lengths available.

• Larger number of bushings.
• Modified ends.

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 Linear Motion Induction Hardened
Shafting

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Bearing steel SUJ2
Stainless steel 440C
Surface finish:
1.5Mm Rz
Straightness: L/D (Mm)
Hardness: 58-63HRc

Part number selection table

Example Part No.- RS-3-400

Basic Outside Outside Dia Available Lengths

Part Dia Tol L
Number ØD Max Min 100 200 300 400 500 600 800 1000 1200 1500
RS-3 3 •# •# •# •#
RS-4 4 -0.009 -0.017 •# •# •# •#
RS-5 5 •# •# •# •#
RS-6 6 •# •# •# •# •# •# •# •#
RS-8 8 •# •# •# •# •# •# •# •#
-0.010 -0.019
RS-10 10 •# •# •# •# •# •# •# •# # •#
RS-12 12 • •# •# •# •# •# •# •# # •#
• SUJ2 bearing steel.
# SUS440C stainless steel.

• Standard material = SUJ2 bearing steel, for stainless steel, add -SS
to the part number.

Non-standard options, please enquire....

• Hard chrome plating (0.01mm deep) available on SUJ2 shafts.

• Ultra precision (straightness 0.5 L/D) on both SUJ2 and 440C
shafts.
• Reduced clearance shafts manufactured to h6 tolerance.
• Custom end machining available to order.
• Non-standard lengths available.

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Induction Hardened Hollow Linear Motion
Shafting

General
Information
All dimensions in mm
General tolerances:
±0.13mm
Material:
Bearing steel SUJ2
Surface finish:
1.5Mm Rz
Straightness: L/D (Mm)
Hardness: 58-63HRc

Part number selection table

Example Part No.- RPS-10-500

Basic Outside Outside Dia Inside Available Lengths

Part Dia Tol Dia L
Number ØD Max Min Ød 500 700 1000 1200 1500
RPS-10 10 4 • • • • •
-0.010 -0.019
RPS-12 12 6 • • • • •
• SUJ2 bearing steel.

Non-standard options, please enquire....

• Hard chrome plating (0.01mm deep).

• Ultra precision (straightness 0.5 L/D).
• Reduced clearance shafts manufactured to h6 tolerance.
• Custom end machining available to order.
• Non-standard lengths available.

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Technical Information Linear Products

Technical section index Page

Rack manufacture ..................................................56

Engineering data (racks & pinions) ........................57
Installation (racks & pinions) ..................................59
Rack applications ....................................................61

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 Racks & Pinions Technical Information
RACK MANUFACTURE

Reliance standard precision racks are produced by a thread grinding process, which
generates teeth of helicoidal form. This provides two distinct advantages: very good pitch
accuracy and sufficient tolerance of meshing conditions (within 0.25º) to make high
precision alignment of the pinion unnecessary.

This feature will be appreciated from the diagram below. Slight misalignment of the
straight-tooth pinion, in terms of deviation from a true right-angle between the axis and
rack in either plane, results merely in a change of position of the contact points across
the face.

Mesh geometry

Points of contact.
Standard pressure angle is 20º
25º pressure angle available on
request.

RACK STANDARDS AND TOLERANCES

Reliance precision racks are offered in four basic grades of accuracy through most of
the range, please see the individual product pages for details. Grade 4b has been
introduced to offer a lower cost grade 4 where a single rack is to be used in a non-
butting application.
The tooth form is generally in accordance with BS 4582 part 1. fig 1. for metric racks.

Rack Grade 5 4 4b 3 2 1
Max pitch error between any two
0.005 0.008 0.008 0.015 0.025 0.050
points per 300mm of rack

Max end to end pitch error up to

±0.004 ±0.004 ±0.008 ±0.008 ±0.013 ±0.025
300mm of track*

Adjacent Tooth Error 0.0025 0.0025 0.0025 0.005 0.010 0.013

+0 +0 +0 +0 +0 +0
Pitch Height Variation
-0.013 -0.013 -0.013 -0.013 -0.018 -0.025

* Applies pro rata to length >300mm All dimensions in mm

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Technical Information Racks & Pinions
ENGINEERING DATA

1. Linear Speed
Linear speeds of up to 10 metres/second can be achieved with correctly installed rack
and pinion systems. When specifying a system, care needs to be taken to ensure that
the transducer count rates are not exceeded. With grease lubrication, care should be
taken to ensure that the lubrication is not thrown off the pinion

2. Load Capacity
The following analysis is intended to give a guide to the load capacity of a rack system.
To simplify the calculation a number of assumptions have to be made. In many
applications this will give a conservative estimate of the gear capacity, therefore in
critical applications an exact analysis must be completed. Please consult the relevant
gear standards or Technical Sales.
The basic load capacity (Fb) of a rack and pinion is defined as the maximum linear force
at which they can operate indefinitely.
Fb has two values: one calculated from tooth strength, (Fbs) and one for tooth flank wear
(Fbw). The useful or transmitted load capacity, Ft, is usually less than Fb due to transient
or dynamic loads generated within the mechanism.

For tooth root strength Fts = Fbs/Ka Ka&Ca = application factors

For tooth flank pitting (wear) Ftw = Fbw/Ca

Both calculations should be made and the lower value used.

The application factors Ka and Ca make allowance for any externally applied loads in
excess of the nominal linear force Fb. These are most accurately determined by direct
measurement application factors, consideration should be given to the fact that many
prime movers develop momentary peak torques appreciably greater than those
determined by the nominal ratings of either the prime mover or the driven equipment.
There are many possible sources of overload which should be considered, including
system vibrations, acceleration torques, overspeeds, variations in system operation and
changes in process load conditions. Impact loads due to reversing across backlash can
be significant in servo systems.
As a general guide application factors for a motor gear system range from 1.0 for
uniform loads up to 1.75 where heavy shock loads are anticipated.

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 Racks & Pinions Technical Information
The previous graph has been calculated in accordance with AGMA 2001-B88 for a life of
at least 108 load cycles, and a rack hardness exceeding 50HRc and pinion material 17-
4PH. For alternative pitches and materials the graph values need to be modified as
shown in the table below.

Pitch and Rack/Pinion material modification factors

Rack Pinion Pitch Strength Wear
17-4PH 1 0.50 0.50
Hardened Round Rack
316 1 0.23 0.10
(hardness>50HRc)
PEEK™ polymer 1 0.04 0.01
1 0.38 0.28
17-4PH 2 0.75 0.56
2.5 0.94 0.70
Rectangular Rack #
1 0.23 0.10
(hardness 35-45HRc)
316 2 0.47 0.20
2.5 0.59 0.25
PEEK™ polymer 1 0.04 0.01
17-4PH 1 0.23 0.10
Tubular and Round
316 1 0.23 0.10
Rack
PEEK™ polymer 1 0.04 0.01
# For R5 a further reduction of 50% is required due to the thin face width

Example:
A 40 tooth, 1mm CP pinion material 316 meshing with rack of hardness <50HRc.
The application factors should be applied after the reduction for material and pitch.

Fbw = 175 x 0.10 =17.5N

Fbs = 170 x 0.23 = 39.1N

3. Bearing Capacity
When linear bearings are used with the hardened round bar racks the capacity of the
support bearings needs to be considered. Where possible the bearings should be
positioned with all the ball rows running on the rack shaft. However, it is important that
the balls do not run on the edges of the teeth. If necessary the 5 and 6 row bearings can
be used with 1 row above the teeth. In this scenario, the manufacturer’s ratings apply
with a modification for the direction of the load application. The factors given in the
following charts should be substituted for the bearing manufacturer’s load reduction.

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Technical Information Racks & Pinions
Closed bearing 5 rows of balls Closed bearing 6 rows of balls

4. Lubrication
Lubrication is not required when using PEEK™ polymer pinions. For other combinations
unlubricated systems are not recommended. Measurement applications should use a
very thin coat of light oil, in many machine tool applications stray cutting oil is sufficient.
Grease lubrication is recommended for higher loads, but care should be taken to ensure
the lubrication is not thrown off the pinion at speed.

INSTALLATION

The installation techniques differ according to the type of rack. All racks should be
mounted with teeth pointing downwards wherever possible so that dust etc cannot settle
in them.

1. Soft Round and Tubular Rack

Plastic moulded bearings are recommended for use with soft round and tubular rack,
these can be found in the Bearings and Spacers section of the Reliance catalogue.
Round racks are not recommended for multi section use.

2. Hardened Round Rack

Bearings for the round bar rack should be fitted in accordance with the manufacturer's
instructions. It is important that the balls do not run on the edge of the teeth. Suitable
bearings can be found in the Linear Bearings section of the Reliance catalogue. Round
racks are not recommended for multi section use.

3. Rectangular Rack
Reliance rectangular section rack is manufactured to enable butting to form infinite
lengths. Socket head cap screws, plain washers and a thread locking adhesive are
preferred for mounting. Dowels are not recommended. The pitch line of the rack must be
constrained to be straight to obtain maximum accuracy. To avoid distortion, racks should
be screwed to a machined flat surface.

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 Racks & Pinions Technical Information
Machining requirements for rack location
1. Pinion clearance
2. Clearance required if:
a) anti-backlash pinions are used
b) full face of rack is to be used
3. Abutment
4. Mounting face

To align racks, two adjustments need to be made, pitch line alignment and pitch
adjustment. The pitch line straightness is not critical (see drawing below) but steps at the
joints should be avoided as they can lead to excessive noise and wear.

1. Pitch line alignment

2. Pitch adjustment and error
compensation

Pitch Line Alignment

There are three methods of setting the pitch line at a joint.These are:
i) Setting the base of the racks against an abutment perpendicular to the mounting face.
The misalignment is then governed by the rack pitch line to base tolerance.
ii) Using the tops of the rack teeth as a reference. These are parallel to the pitch line
within 0.008mm. Use a short straight edge (eg. slip block) as shown below.
iii) The best measurement of the pitch line is with the pinion installed on a Flexplate. A
dial indicator fitted as shown gives a direct reading of the pitch line straightness.

Pitch line alignment using slip block Dial indicator carried with Flexplate

The Flexplate spring loads the pinion into mesh on both flanks of the teeth, ensuring
complete backlash elimination. For more information on the Flexplate assembly please
refer to the Rack Systems section of the Reliance catalogue.

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Technical Information Racks & Pinions
Pitch Adjustment and Error Correction
Pitch accuracy can be obtained by one of three methods depending upon accuracy
required.

GRADE 1 (and for the initial setting of all grades)

For pitch accuracy across the joint of ±0.020mm the Rack Setting Piece is the simplest
method.

GRADE 2, 3 or 4
After initial setting and with the measuring system functioning, length bars may be used
as references. Checks made against these allow adjustment to be made within the
system resolution.

GRADE 3, 4 or 5
After initial setting and with the measuring system functioning, comparison should be
made with a laser measuring system. This allows pitch adjustment and machine error
compensation within the system resolution over the full travel of the axis.

RACK APPLICATIONS

Reliance precision rack is manufactured in both round and rectangular section, and can
be used for both measurement and actuation. In general the smaller pitches (1mm) are
ideal for measurement, as the smaller pinion diameter gives higher linear resolutions.
The larger pitches (2mm and 2.5mm) allow a higher load capacity.

For most applications the rack can be used for both the feedback and the actuation. In
very precise applications we recommend that an unused section of the actuation rack is
used for feedback. Alternatively a separate rack can be used.

All Reliance racks are calibrated to measure correct at 20ºC using a temperature
compensated laser. Calibration graphs can be supplied if required.

RACK ACTUATOR

The rack actuator is supplied pre-assembled and should not be dismantled. The rack
should not be removed from the housing. Any tampering with the assembly may result in
the technical specification becoming invalid.

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 Racks & Pinions Technical Information
STEPPER MOTOR

The rack actuator is supplied as standard with a NEMA size 17 stepper motor, which
conforms to the following specification:

Motor Voltage Current Resistance Inductance

Size V A/phase Ω/phase mH/phase

17 4.0 0.95 4.2 2.8

Direction of rotation of motor resulting in downward movement of rack as shown:

This stepper motor has a minimum cable length of 200mm.

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 Linear Products Notes

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ISO 9001
Quality assured to BS/EN/ISO 9001, Reliance specialises in gears, gearboxes,
assemblies and associated components which are used in instrumentation,
measurement, diagnostic equipment and light actuation systems. Reliance aims to
provide its customers with a single source for the design, production, assembly and
testing of high quality mechanical components and electro-mechanical assemblies.

Standard Products
For over thirty years, Reliance has provided a standard range of precision mechanical
components from stock or on short delivery. This service allows design engineers to
order in small quantities at stock prices in order to develop prototypes effectively.
Dedicated manufacturing facilities enable larger quantities to be supplied for full
production requirements.

Dust Free Assembly

Reliance also has over 350 square metres of clean room space for the assembly,
wiring and testing of precision gearboxes, optical equipment and scientific
instruments to customers' specifications. Particle counts in the clean rooms meet ISO
14644-1 Class ISO 7, but are readily adaptable to more stringent standards if
required.

For engineering assistance

and to place an order
please contact us at:

Schlenker Enterprises, Ltd.

P.O. Box 9277, Lombard, IL 60148-9277, USA

Phone: (USA)708.449.5700
Fax: (USA)708.449.5703
www.schlenkent.com
e-mail: sales@schlenkent.com