TEL : +81 48 254 1744

"Easy" Gear Selection Screen

- Choose a gear by pitch, # of teeth, or bore size.
- 2D/3D Drawings Available
- PDF Catalog Available
- Strength Calculation Available

Go to Gear Selection Screen

CLOSE

Gear Rack and Pinion

What is a rack and pinion ?

image of rack and pinion

Gear racks are utilized to convert rotating movement into linear motion. A gear rack has straight teeth cut into one surface of a square or round section of rod and operates with a pinion, which is a small cylindrical gear meshing with the gear rack. Generally, gear rack and pinion are collectively called “rack and pinion”. There are many ways to use gears. For example, as shown in the picture, a gear is used with the gear rack to rotate a parallel shaft.

To provide many variations of rack and pinion, KHK has many types of gear racks in stock. If the application requires a long length requiring multiple gear racks in series, we have racks with the tooth forms correctly configured at the ends. These are described as “gear racks with machined ends”. When a gear rack is produced, the tooth cutting process and the heat treatment process can cause it to try & go out of true. We can control this with special presses & remedial processes.

There are applications where the gear rack is stationary, while the pinion traverses and others where the pinion rotates on a fixed axis while the gear rack moves. The former is used widely in conveying systems while the latter can be used in extrusion systems and lifting/lowering applications.

As a mechanical element to transfer rotary into linear motion, gear racks are often compared to ball screws. There are pros and cons for using racks in place of ball screws. The advantages of a gear rack are its mechanical simplicity, large load carrying capacity, and no limit to the length, etc. One disadvantage though is the backlash. The advantages of a ball screw are the high precision and lower backlash while its shortcomings include the limit in length due to deflection.

Rack and pinions are used for lifting mechanisms (vertical movement), horizontal movement, positioning mechanisms, stoppers and to permit the synchronous rotation of several shafts in general industrial machinery. On the other hand, they are also used in steering systems to change the direction of cars. The characteristics of rack and pinion systems in steering are as follows: simple structure, high rigidity, small and lightweight, and excellent responsiveness. With this mechanism, the pinion, mounted to the steering shaft, is meshed with a steering rack to transmit rotary motion laterlly (converting it to linear motion) so that you can control the wheel. In addition, rack and pinions are used for various other purposes, such as toys and lateral slide gates.

How to Buy
button to gear select page
Please enter part number here for a price and a drawing of the gear
Technical Information

Technical Information of
Gear Racks

With this technical data you can view comprehensive information regarding KHK gear racks such as their features and advice and warnings when selecting and using them.

SRF_Racks

SRF

Steel Racks with Machined Ends

Module : 0.5 – 10
Length : 300-2000mm
Material : S45C
Hardening : None
Tooth finish : Cut (non-ground)
Grade : KHK R001 4

Large selection of modules and lengths, low cost allows many applications.

Recommended mating pinion
SS, SSS, SSA

Click Here to Select Gear Rack
SRFD SRFK_Racks

SRFD / SRFK

Steel Racks with Bolts Holes

Module : 0.5 – 6
Length : 300-2000mm
Material : S45C
Hardening : None
Tooth finish : Cut (non-ground)
Grade : KHK R001 4

Large selection of modules and lengths, low cost allows many applications.

Recommended mating pinion
SS, SSS, SSA

Click Here to Select Gear Rack
SRAF SRAFD SRAFK_Racks

SRAF / SRAFD / SRAFK

Steel Racks with Machined Ends

Module : 1.5 – 4
Length : 1000mm-2000mm
Material : S45C
Hardening : None
Tooth finish : Cut (non-ground)
Grade : KHK R001 4

Compared to SRF rack, has the same tooth height and width and is a low cost compact size rack.

Recommended mating pinion
SS, SSS, SSA

Click Here to Select Gear Rack
SR_Racks1

SR

Steel Racks

Module : 0.5 – 10
Length : 100-500mm
Material : S45C
Hardening : None
Tooth finish : Cut (non-ground)
Grade : KHK R001 4

Large selection of modules and lengths, low cost allows many applications.

Recommended mating pinion
SS, SSS, SSA

Click Here to Select Gear Rack
SRG SRGF SRGFD SRGFK_Racks

SRG / SRGF / SRGFD / SRGFK

Hardened Ground Racks

Module : 0.5 – 6
Length : 100,300,500,1000mm
Material : S45C
Hardening : Induction hardening
Tooth finish : Ground teeth
Grade : KHK R001 3

Wear resistant, reasonably priced ground rack.

Recommended mating pinion
SSG, SSGS

Click Here to Select Gear Rack
SRF H SRFD H_Racks

SRF-H / SRFD-H

Hardened Racks

Module : 1.5 – 4
Length : 1000mm
Material : S45C
Hardening : Induction hardening
Tooth finish : Cut (non-ground)
Grade : KHK R001 5

High strength and durable, safe for long term use and low cost rack, heat treated.

Recommended mating pinion
SSG, SSGS, SS/SSS/SSA (with hardening)

Click Here to Select Gear Rack
SRF-HL and SRFD-HL Racks

SRF-HL / SRFD-HL

Laser Hardened Racks

Module : 1.5 – 6
Length : 1000,1500,2000mm
Material : S45C
Hardening : Gear teeth laser hardened
Tooth finish : Cut (non-ground)
Grade : KHK R001 4

Hardened racks with high strength due to the laser hardened tooth surfaces and with a low price tag. Finished J series products are also available.

Recommended mating pinion
SSG

Click Here to Select Gear Rack
SRO SROS_Racks

SRO / SROS

Steel Round Racks

Module : 1 – 6
Length : 500,1000mm
Material : S45C
Hardening : None
Tooth finish : Cut (non-ground)
Grade : KHK R001 4

Convenient in applications when the rack needs to be used in reciprocal motion. Easily attachable type is also available.

Recommended mating pinion
SS, SSS, SSA

Click Here to Select Gear Rack
SRH steel helical rack

SRH / SRHF / SRHFD

Steel Helical Racks

Module : 2 – 3
Length : 100,500,1000mm
Material : S45C
Hardening : None
Tooth finish : Cut (non-ground)
Grade : KHK R001 5

Large contact ratio of helical rack is effective in reducing noise and vibration.

Recommended mating pinion
SH

Click Here to Select Gear Rack
KRHG KRHGF KRHGFD_Racks

KRHG / KRHGF / KRHGFD

Ground Helical Racks

Module : 1 – 3
Length : 100,500,1000mm
Material : SCM440
Hardening : Thermal refined
Tooth finish : Ground teeth
Grade : KHK R001 1

High precision, high strength, quiet operation and good wear resistance make this a very high quality product.

Recommended mating pinion
KHG

Click Here to Select Gear Rack
SUR SURF SURFD_Racks

SUR / SURF / SURFD

Stainless Steel Racks

Module : 1 – 4
Length : 500,1000mm
Material : SUS304
Hardening : Solution treated
Tooth finish : Cut (non-ground)
Grade : KHK R001 5

Using SUS304, its rust resistance makes it suitable for food machinery.

Recommended mating pinion
SUS, SUSA

Click Here to Select Gear Rack
SURO_Racks

SURO

Stainless Steel Round Racks

Module : 1 – 3
Length : 500,1000mm
Material : SUS303
Hardening : None
Tooth finish : Cut (non-ground)
Grade : KHK R001 5

Same configuration as SRO series but in stainless steel. Use in machines needing rust resistance.

Recommended mating pinion
SUS, SUSA

Click Here to Select Gear Rack
BSR_Racks1

BSR

Brass Racks

Module : 0.5 – 1
Length : 300mm
Material : C3604
Hardening : None
Tooth finish : Cut (non-ground)
Grade : KHK R001 4

Miniature rack available in modules 0.5 to 1. Use with BSS or DS pinions.

Recommended mating pinion
BSS

Click Here to Select Gear Rack
PR PRF_Racks

PR /PRF

Plastic Racks

Module : 1 – 3
Length : 500,1000mm
Material : MC901
Hardening : None
Tooth finish : Cut (non-ground)
Grade : KHK R001 5

Made of MC Nylon, it is lightweight and can be used without lubrication.

Recommended mating pinion
NSU, PU, PS, PSA

Click Here to Select Gear Rack
DRF DRFD DRFK_Racks

DRF / DRFD / DRFK

Plastic Racks

Module : 1 – 3
Length : 500,1000mm
Material : Polyacetal
Hardening : None
Tooth finish : Cut (non-ground)
Grade : KHK R001 5

This plastic rack has less water absorption than MC Nylon, leading to less dimensional change.

Recommended mating pinion
NSU, PU, PS, PSA

Click Here to Select Gear Rack
DR_Racks

DR

Molded Flexible Racks

Module : 0.8 – 2
Length : 2000mm
Material : Duracon
Hardening : None
Tooth finish : Injection molded
Grade : KHK R001 8

Flexibility unmatched by metal, suitable for special applications. Also available are attaching hardware and pinions.

Recommended mating pinion
SSDR

Click Here to Select Gear Rack
ssdr pinion

SSDR

Pinions for DR

Module : 0.8 – 2
Number of tooth : 15-35
Material : S45C
Hardening : None
Tooth finish : Cut (non-ground)
Grade : JIS N8

Recommended mating rack
DR

ARL_Racks

ARL

Rack Guide Rails

Recommended mating rack
DR

SRS_Racks

SRS

Rack Clamps

Recommended mating rack
DR

Gear Rack and Pinion – creation of linear motion

A rack and pinion are used when converting rotational movement to linear motion (or vice versa). A bar shaped gear with an infinite (flat surface) radius of a cylindrical gear is called a rack, and a meshed spur gear is called a pinion. A rack can be used by extending it combining as many racks with machining operation on the end faces when necessary.

A helical rack is a bar shaped gear with slanted linear tooth trace that is used when silence and high speed rotation are required, and it can be meshed with a helical gear.


Image : Plastic / Steel racks

Design and Application Examples of Rack and Pinion Mechanisms

Gears transmit power by rotating one gear to move the gear that is meshed with it. On the other hand, in rack and pinion, the combination of rack gear in the form of a gear stretched in a rod form and a small diameter gear (pinion gear) converts rotational motion into a linear motion to transmit power. For example, in a case where the pinion gear is stationary and the rack moves, the pinion is often connected to the output shaft of motors. The driven side of the rack is supported by a separate structure of machine elements. The pinion gear’s repetitive rotational motion produces a repeated forward-backward motion of the rack.

For the power transmission mechanism, the gear is attached to a shaft by means such as with a key, and its shaft is supported with ball or sleeve bearings. In case of a rack and pinion when the driven member is the rack, more creativity in design is needed since the rack is in the form of a rod (circular or rectangular).
When the rack is circular, sleeve bearings on the market can be used and the bearing support structure is relatively simple. On the other hand, to insure the constant meshing of the pinion and the rack, it is necessary to provide for means to stop the rack from rotating. The round racks have the gear teeth cut on the rod so that the cross section is different from the normal gears. They have the shape of a crescent moon with its shoulders shaved off. As a result, their strength is less than that of rectangular racks.
When the rack is rectangular, it becomes necessary to make suitable bearings. In this case, they can also act as the means to stop rack rotation, Also, the cross sections of rectangular racks are, unlike that of round racks, the same as those of gears with the same strength as the gears of the same specifications.

Rack and pinion has the characteristics of its function being drastically altered depending on whether the rack is stationary or movable.
When the rack is movable, its motion is in a straight line, and its use is mainly to take advantage of this behavior. For example, it is used as a jack or clamping system or, by modifying the tip of a rack, utilized as the pusher of a work piece.
When the rack is stationary, the pinion gear rolls on the rack and its application method varies widely. Positioning of machines, hand press, horizontal transport mechanism and elevating mechanism, etc. can be used as examples.

Also, if two racks are laid facing each other and a pinion is placed between them, the repeated forward-backward motion of the pinion will produce an alternating advance and retreat motion of the racks. For applications of this mechanism, work escapement mechanisms and air driven rotary actuators can be listed.

Racks can be placed midstream in conveyor transport mechanisms. By incorporating freely rotating pinions on transport pallets which engage the racks, the items on the pallet can be flipped or rotated. This is one special application example.

As shown, pinion and rack possesses a high degree of freedom in its applications depending only on the users’ ideas.

Rack and Pinion Used in Automotive Steering Mechanisms

The steering mechanism is used to change the direction of automobiles and are mainly classified into rack-and-pinion and ball nut types.

Of these two, the rack and pinion type steering mechanism has become the mainstream used in many small cars. Its construction is simple with other characteristics such as lightweight, high strength, low friction, superior responsiveness, etc.

The rack and pinion type steering mechanism consists of a pinion attached to the tip of the steering shaft on which the steering wheel is mounted. The pinion is meshed with a rack so that the movement of the handle rotates the pinion which in turn moves the rack sideways. The wheel is moved left and right through the system of tie rods connected to the ends of the rack.

(Caution : Currently, KHK does not supply rack and pinion for automotive steering mechanisms.)

Materials and heat treating racks and pinions

As for the materials of a racks and pinions, strength, abrasion resistance, and absorbency are considered.

With steel, S45C (1045 in AISI/SAE, C45 in ISO, equivalent to C 45K in DIN), SCM440 (4140 in AISI/SAE, equivalent to 42CrMo4V in ISO and DIN), 16MnCr5 (name in ISO, equivalent to 17Cr3 in DIN), with stainless steel, SUS303 (303/S30300 in AISI/SAE, 13 in ISO, equivalent to X10CrNiS18-9 in DIN), SUS304 (304/S30400 in AISI/SAE, 6 in ISO, equivalent to X5CrNi18-10 in DIN), with plastic material, reinforced nylon called engineering plastic, polyacetal (equivalent to Duracon and POM), polyamide, are used.

Regarding the heat treatment of a rack and pinion, thermal refining, carburizing and quenching, tooth face high frequency hardening, and tooth face laser hardening are used depending on the kinds of materials and purposes.


Image : Material of racks

Overall length and cross-sectional shape of a rack

The overall length of standard racks on the market is generally not more than 2000mm, and offered in 500mm units such as 500mm, 1000mm, 1500mm.

Furthermore, the cross-sectional shape is often a square or rectangle, and some are round called round rack type.


Image : Cross sectional shape of racks

Production of racks and pinions

Although the difficulty in production varies depending on the accuracy classes and specifications, the basic production of the rack and pinion is possible with a rack cutting machine and gear hobbing machine. They are produced by many gear manufacturers and rack specialized manufacturers in the world. They are especially produced on a large scale by famous rack manufacturers in Germany and Taiwan.

Using Racks and Pinions

The rack and pinion are used mainly for carrier devices, steering gear mechanisms for vehicles, machine tools, lifting apparatus, and printing machines.

When attaching a rack to a machine, mounting holes drilled though the bottom or through the side are frequently used, additional methods include counterbored bolt holes and tapped holes.


Image : Rack and pinion used for manual lifting device

The helix angle of helical rack

The helix angle of a helical rack is set at 19 degrees 31’42” by many rack manufacturers. When the helix angle is set like so, the movement when a pinion rotates (for instance one rotation) becomes an exact distance in mm, thus making it user-friendly.


Image : Helical rack

Lubricating Racks and Pinions

As for the lubrication of a rack and pinion, there are several methods used.

One such lubrication system consists of a lubricating device (main body), a tube to deliver the lubricant, a check valve and a special urethane pinion at the end of the tube.

The rack and pinion in this system are lubricated as the lubricant is dispered by the pinion.

Since the pinion injects the lubricant into the mesh as it rotates across the gear rack, the pitch of the rack must be the same as the module of the pinion, and in the case of helical rack and pinions, the rack and pinion must be of the same helix angle and opposite in direction.


Image : Pinion made of urethane

Comparison between racks and pinions and ball screws

As a mechanical element that produces linear motion, a rack and pinion system is often compared with to ball screw.

When compared with a rack and pinion, generally a ball screw has superiorities of accurate positioning, smooth motion with a little friction, and no backlash, on the other hand, ball screws have the disadvantages of higher cost, the difficulty of producing ball screws with long lengths due to deflexion, and unsuitability for heavy loads.


Image : Ball screw in machine tool

CP Racks & Pinions – Facilitates positioning in linear motion applications –

By adopting CP (circular pitch) racks and pinions, the travel distance with one rotation of pinion becomes an integer number. This improves the user’s convenience. For example, if the pitch of the pinion is CP5 (pitch is 5mm) and if the number of teeth is 20, then when the pinion rotates once, the distance traveled becomes exactly 100mm.

It has been listed elsewhere, but there are three international standards of gear pitches: module, inch standard of DP and above mentioned CP. The following link will lead to the comparison of these pitches :

Table of Comparative Gear Pitch

There is no interchangeability between pinion and rack if different pitch systems are used in the pair.

In addition, KHK offers tapered racks and pinions. These are produced by angling each tooth of the rack and pinion. Conventionally, in order to adjust the backlash, it was necessary to change the distance between the rack and the axis of the pinion. But with tapered rack and pinion, this difficult task can be easily accomplished by simply shifting the pinion in its axial direction. Because of the taper in the teeth, they are not interchangeable with regular rack and pinion.

KTSCP_CP_Racks

KTSCP

CP Tapered Pinions

CP : 5, 10
No. of tooth : 20-40
Material : SCM440
Hardening : Thermal refined
Tooth finish : Cut (non-ground)
Grade : JIS N8

Mates with STRCPF racks. Allows adjustment of amount of backlash.

STRCPF STRCPFD_CP_Racks

STRCPF / STRCPFD

CP Tapered Racks

CP : 5, 10
Length : 1000mm
Material : S45C
Hardening : None
Tooth finish : Cut (non-ground)
Grade : KHK R001 4

Mates with KTSCP pinions. Allows adjustment of amount of backlash.

MSCPG_CP_Racks

MSCPG

CP Hardened Ground Spur Gears

CP : 5, 10
No. of tooth : 20-40
Material : SCM415
Hardening : Overall carburizing
Tooth finish : Ground teeth
Grade : JIS N5

Increased strength from positive profile shift and designed to have integral number for the assembly center distance.

MRGCPF MRGCPFD_CP_Racks

MRGCPF / MRGCPFD

CP Hardened Ground Racks

CP : 5, 10
Length : 500mm
Material : SCM415
Hardening : Tooth carburized
Tooth finish : Ground teeth
Grade : KHK R001 1

Carburized and ground racks in Chromoly steel. Highest precision with cumulative pitch error of less than 10 μm.

KRGCP KRGCPF KRGCPD_CP_Racks

KRGCPF-H / KRGCPFD-H

CP Hardened Ground Racks

CP : 5, 10
Length : 500,1000mm
Material : SCM440
Hardening : Induction hardened
Tooth finish : Ground teeth
Grade : KHK R001 1

Heat treated ground racks with high strength and precision and excellent cost/performance ratio.

KRGCP KRGCPF KRGCPD_CP_Racks

KRGCP / KRGCPF / KRGCPD

CP Thermal Refined Ground Racks

CP : 5, 10
Length : 100,500,1000mm
Material : SCM440
Hardening : Thermal refined
Tooth finish : Ground teeth
Grade : KHK R001 1

High strength and abrasion resistant for accurate positioning applications.

SSCPGS_CP_Racks

SSCPGS

CP Ground Spur Pinion Shafts

CP : 5, 10
No. of tooth : 10-25
Material : S45C
Hardening : Induction hardened
Tooth finish : Ground teeth
Grade : JIS N7

Ground pinion shafts. Can be mounted into bearing by modifying the shaft.

SSCPG_CP_Racks

SSCPG

CP Ground Spur Gears

CP : 5, 10, 15, 20
No. of tooth : 20-40
Material : S45C
Hardening : Induction hardened
Tooth finish : Ground teeth
Grade : JIS N7

Ground CP gears. Perform secondary operations to suit your design.

SRGCP_CP_Racks1

SRGCP / SRGCPF / SRGCPFD

CP Hardened Ground Racks

CP : 5, 10, 15, 20
Length : 100,500,1000mm
Material : S45C
Hardening : Induction hardened
Tooth finish : Ground teeth
Grade : KHK R001 3

Abrasion resistant and reasonably priced ground racks.

KRCPF-H-KRCPFD-H_CP_Racks

KRCPF-H / KRCPFD-H

CP Hardened Racks

CP : 5, 10
Length : 1000mm
Material : SCM440
Hardening : Induction Hardened
Tooth finish : Cut (no-grinding)
Grade : KHK R001 5

High strength and durable heat treated racks suitable for compact design.

SRCPF H SRCPFD H_CP_Racks

SRCPF-H / SRCPFD-H

CP Hardened Racks

CP : 5, 10, 15, 20
Length : 1000mm
Material : S45C
Hardening : Induction Hardened
Tooth finish : Cut (no-grinding)
Grade : KHK R001 5

Stable heat treated and durable low cost racks.

KSCP_CP_Racks

KSCP

CP Hardened Spur Gears

CP : 5, 10
No. of tooth : 20-40
Material : SCM440
Hardening : Induction Hardened
Tooth finish : Cut (non-ground)
Grade : JIS N9

Thermal refined and tooth hardened chromoly racks. May be mated to KRCPF(-H) rack.

KRCPF KRCPFD_CP_Racks

KRCPF / KRCPFD

CP Thermal Refined Racks

CP : 5, 10
Length : 500,1000mm
Material : SCM440
Hardening : Thermal refined
Tooth finish : Cut (no-grinding)
Grade : KHK R001 4

Increased strength is obtained from thermal refined SCM440 material.

SSCP_CP_Racks

SSCP

CP Spur Gears

CP : 2.5, 5, 10, 15, 20
No. of tooth : 20-40
Material : S45C
Hardening : None
Tooth finish : Cut (no-grinding)
Grade : JIS N8

Widely applicable low cost pinions in many pitches and numbers of teeth.

SRCPF SRCPFD_CP_Racks

SRCP / SRCPF / SRCPFD / SRCPFK

CP Steel Racks

CP : 2.5, 5, 10, 15, 20
Length : 100,500,1000,1500,2000mm
Material : S45C
Hardening : None
Tooth finish : Cut (no-grinding)
Grade : KHK R001 4

Widely applicable low cost racks in many pitches and lengths.

SUSCP_CP_Racks

SUSCP

CP Stainless Steel Spur Gears

CP : 5, 10
No. of tooth : 20-30
Material : SUS303
Hardening : None
Tooth finish : Cut (no-grinding)
Grade : JIS N8

Uses SUS303 material. Its rust resistance is suitable for use in food machinery.

SURCPF SURCPFD_CP_Racks

SURCPF / SURCPFD

CP Stainless Steel Racks

CP : 5, 10
Length : 500,1000mm
Material : SUS304
Hardening : Solution treated
Tooth finish : Cut (no-grinding)
Grade : KHK R001 5

Uses SUS304 material. Its rust resistance is suitable for use in food machinery.

SROCP_CP_Racks

SROCP

CP Round Racks

CP : 2.5, 5, 10
Length : 500mm
Material : S45C
Hardening : None
Tooth finish : Cut (no-grinding)
Grade : KHK R001 4

Useful in applications where the rack has reciprocating motion.

FRCP_CP_Racks

FRCP

CP Metal Flexible Racks

CP : 5
Length : 2000,3000,4000mm
Material : SS400
Hardening : None
Tooth finish : Cut (no-grinding
Grade : KHK R001 8

Produced by continuously cutting teeth. Bendable and available in long lengths.

Technical Information of CP Racks & Pinions

Characteristics

KHK stock CP racks and pinions are suitable in applications where very accurate positioning in linear motion is required. For your convenience, we offer circular pitches of 2.5 to 20 mm and in lengths of 100 to 2000 mm. (FRCP is available to 4000 mm)

Movement of one cycle of the CP10-30 pinion on a CP rack vs.SS3-30 (m3) on a m3 rack.

About CP Racks & Pinions

The reference pitch of a metric module is computed by multiplying the number of module by π (3.14159). For example, the reference pitch of m 3 rack is 9.425 mm (3 * π). When using a rack and a pinion in a linear motion application, the fact that the pitch is not an integral number presents a difficulty in accurate positioning.

This problem is solved by CP racks and pinions where one rotation of a pinion moves it precisely 50, 100, 150, … or 600 mm. The following table lists the main features. The following table lists the main features.

Racks

Catalog No. Note1: STRCPF / STRCPFD
Pitch (mm) : 5, 10
Total Length (mm) : 1000
Material : S45C
Heat Treatment : –
Tooth Surface Finish : Cut
Precision KHK R 001 : 4
Features : By pairing with KTSCP pinion, the backlash may be adjusted.

Catalog No. Note1: MRGCPF / MRGCPFD
Pitch (mm) : 1.5-3
Total Length (mm) : 500
Material : SCM415
Heat Treatment : Tooth area Carburized
Tooth Surface Finish : Ground
Precision KHK R 001 : 1
Features : Has the highest strength and precision in the KHK standard rack series. Bolt holes can be remachined as carburizing is applied only within the tooth area. J Series products are also available.

Catalog No. Note1: KRGCPF – H / KRGCPFD – H
Pitch (mm) : 5, 10
Total Length (mm) : 500, 1000
Material : SCM440
Heat Treatment : Thermal refined, teeth induction hardened
Tooth Surface Finish : Ground
Precision KHK R 001 : 1
Features : Heat treated ground gears with high precision and strength has excellent cost-performance ratio. J Series products are also available.

Catalog No. Note1: KRGCP / KRGCPF / KRGCPD
Pitch (mm) : 5, 10
Total Length (mm) : 100, 500, 1000
Material : SCM440
Heat Treatment : Thermal Refined
Tooth Surface Finish : Ground
Precision KHK R 001 : 1
Features : High strength and abrasion-resistant for precision linear motion.

Catalog No. Note1: SRGCP / SRGCPF / SRGCPFD
Pitch (mm) : 5, 10, 15, 20
Total Length (mm) : 100, 500, 1000
Material : S45C
Heat Treatment : Gear teeth induction hardened
Tooth Surface Finish : Ground
Precision KHK R 001 : 3
Features : Reasonably priced ground racks with abrasion-resistant characteristics. J Series products are also available.

Catalog No. Note1: KRCPF-H / KRCPFD-H
Pitch (mm) : 5, 10
Total Length (mm) : 1000
Material : SCM440
Heat Treatment : Thermal refined, teeth induction hardened
Tooth Surface Finish : Cut
Precision KHK R 001 : 5
Features : This is a strong rack made of Chromoly steel, treated by carburizing. Has high-strength, high wear resistance, and enables downsizing of SR racks. J Series products are also available.

Catalog No. Note1: SRCPF-H / SRCPFD-H
Pitch (mm) : 5, 10, 15, 20
Total Length (mm) : 1000
Material : S45C
Heat Treatment : –
Tooth Surface Finish : Cut
Precision KHK R 001 : 5
Features : Stable Hardened racks with high strength, long life span are reasonably priced. J Series products are also available.

Catalog No. Note1: KRCPF / KRCPFD
Pitch (mm) : 5, 10
Total Length (mm) : 1000
Material : SCM440
Heat Treatment : Thermal Refined
Tooth Surface Finish : Cut
Precision KHK R 001 : 4
Features : Increased strength with SCM440 material which is thermal refined.

Catalog No. Note1: SRCP / SRCPF / SRCPFD / SRCPFK
Pitch (mm) : 2.5, 5, 10, 15, 20
Total Length (mm) : 100, 500, 1000, 1500, 2000
Material : S45C
Heat Treatment : –
Tooth Surface Finish : Cut
Precision KHK R 001 : 4
Features : Widely applicable due to low cost and large selection of pitches and lengths.

Catalog No. Note1: SURCPF / SURCPFD
Pitch (mm) : 5, 10
Total Length (mm) : 500, 1000
Material : SUS304
Heat Treatment : Solution treated
Tooth Surface Finish : Cut
Precision KHK R 001 : 5
Features : Suitable for food machinery due to SUS304 material’s rust-resistant quality.

Catalog No. Note1: SROCP
Pitch (mm) : 2.5, 5, 10
Total Length (mm) : 500
Material : S45C
Heat Treatment : –
Tooth Surface Finish : Cut
Precision KHK R 001 : 4
Features : Convenient in applications where the rack has reciprocal motion.

Catalog No. Note1: FRCP
Pitch (mm) : 5
Total Length (mm) : 2000, 3000, 4000
Material : SS400
Heat Treatment : –
Tooth Surface Finish : Cut
Precision KHK R 001 : 8
Features : Cut continuously. Long length and bendable to a contour.

Pinions

Catalog No. Note1: KTSCP
Pitch (mm) : 5, 10
Number of teeth : 20-40
Material : SCM440
Heat Treatment : Thermal refined
Tooth Surface Finish : Cut
Precision JIS B 1702-1 : N8
Features : By pairing with STRCPF rack, the backlash may be adjusted.

Catalog No. Note1: MSCPG
Pitch (mm) : 5, 10
Number of teeth : 20-40
Material : SCM415
Heat Treatment : Overall carburizing
Tooth Surface Finish : Ground
Precision JIS B 1702-1 : N5
Features : Designed with positive partial transposition and to have an integral value (mm) for the mounting distance, so both strength and usability are enhanced.

Catalog No. Note1: SSCPGS
Pitch (mm) : 5, 10
Number of teeth : 10-25
Material : S45C
Heat Treatment : Thermal refined, teeth induction hardened
Tooth Surface Finish : Ground
Precision JIS B 1702-1 : N7
Features : Ground Spur Gears with Pinions, can be directly assembled with the shaft bearing, by modifying the pinion.

Catalog No. Note1: SSCPG
Pitch (mm) : 5, 10, 15, 20
Number of teeth : 20-40
Material : S45C
Heat Treatment : Gear teeth induction hardened
Tooth Surface Finish : Ground
Precision JIS B 1702-1 : N7
Features : Perform secondary operations to suit your requirement on these ground CP spur gears.

Catalog No. Note1: KSCP
Pitch (mm) : 5, 10
Number of teeth : 20-40
Material : SCM440
Heat Treatment : Thermal refined, teeth induction hardened
Tooth Surface Finish : Cut
Precision JIS B 1702-1 : N9
Features : Thermal refined and tooth-hardened chromoly racks, excellent in abrasion resistance. Use as mating pinions for KRCPF(-H) Racks.

Catalog No. Note1: SSCP
Pitch (mm) : 2.5, 5, 10, 15, 20
Number of teeth : 20-40
Material : S45C
Heat Treatment : –
Tooth Surface Finish : Cut
Precision JIS B 1702-1 : N8
Features : Low cost and widely applicable, with a large selection of pitches and numbers of teeth.

Catalog No. Note1: SUSCP
Pitch (mm) : 5, 10
Number of teeth : 20-30
Material : SUS303
Heat Treatment : –
Tooth Surface Finish : Cut
Precision JIS B 1702-1 : N8
Features : Suitable for food machinery due to SUS303 material’s rust-resistant quality.

[NOTE 1] The catalog numbers in the above tables with a suffix of F have both ends machined so that they can be butted against each other to make any desired length. The items with (D) have mounting screw holes for easier assembly.

For safer handling and to prevent damage such as deformation, KHK stock CP racks have round chamfering on the corners of the top land of the gear tooth. This rounded chamfered shape is patented by KHK. Because it is effective for reducing noise, all of KHK CP racks have this chamfering treatment.

Black colored products are KHK stock gears that have an applied black oxide coating for rust resistance; this ‘blackness’ is a product characteristic of KHK stock gears.

Selection Hints

Please select the most suitable products by carefully considering the characteristics of items and contents of the product tables. It is also important to read all applicable notes before the final selection.

1. Caution in Selecting the Mating Gears

  1. KHK stock CP racks are mated with CP spur gears having the same pitch. Since CP2.5 (m0.796), CP5 (m1.592) and CP10 (m3.183) are very close in size to m0.8, m1.5 and m3 respectively, the selecting the proper mating gear should be verified to make sure that the items are correct. Otherwise, complications could arise.
  2. STRCPF and STRCPFD Tapered Racks are mated with KTSCP Spur Gears having the same pitch. They can also be mated with other spur gears, however, they can not be used as parallel axis gears due to the setting angles.

2. Caution in Selecting Gears Based on Gear Strength

  1. The gear strength values shown in the product pages were computed by assuming a certain application environment. Therefore, they should be used as reference only. We recommend that each user computes his own values by applying the actual usage conditions.
  2. The table below contains the assumptions established for these products in order to compute gear strengths.

Calculation assumptions for Bending Strength

Catalog No.: MRGCPF / MRGCPFD
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gear : 30
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2)NOTE 2 : 47
Safety factor SF : 1.2

Catalog No.: KRGCPF-H / KRGCPFD-H
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gear : 30
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2)NOTE 2 : 32
Safety factor SF : 1.2

Catalog No.: KRGCP / KRGCPF / KRGCPD / KRCPF
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gear : 30
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2) NOTE 2 : 32
Safety factor SF : 1.2

Catalog No.: SRGCP / SRGCPF / SRGCPFD
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gear : 30
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2)NOTE 2 : 20
Safety factor SF : 1.2

Catalog No.: SRCP / SRCPF / SRCPFD / SROCP / STRCPF / STRCPFD
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gear : 30
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2) NOTE 2 : 20
Safety factor SF : 1.2

Catalog No.: SURCPF / SURCPFD / FRCP
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gear : 30
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2)NOTE 2 : 10.5
Safety factor SF : 1.2

Catalog No.: MSCPG
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gear : Racks
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2)NOTE 2 : 47
Safety factor SF : 1.2

Catalog No.: SSCPGS
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gear : Racks
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2)NOTE 2 : 24.5
Safety factor SF : 1.2

Catalog No.: SSCPG
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gear : Racks
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2)NOTE 2 : 19
Safety factor SF : 1.2

Catalog No.: KTSCP
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gear : Racks
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2)NOTE 2 : 28.5
Safety factor SF : 1.2

Catalog No.: KSCP
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2)NOTE 2 : 30
Safety factor SF : 1.2

Catalog No.: SSCP
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gear : Racks
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2)NOTE 2 : 19
Safety factor SF : 1.2

Catalog No.: SUSCP
Formula NOTE 1: Formula of spur and helical gears on bending strength (JGMA401-01)
No. of teeth of mating gear : Racks
Rotation : 100rpm
Durability : Over 10^7cycles
Impact from motor : Uniform load
Impact from load : Uniform load
Direction of load : Bidirectional
Allowable bending stress at root σ Flim(kgf/mm^2)NOTE 2 : 10.5
Safety factor SF : 1.2

Calculation assumptions for Surface Durability (Except those in common with bending strength)

Catalog No.: MRGCPF / MRGCPFD
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 106
Safety factor SH : 1.15

Catalog No.: KRGCPF-H / KRGCPFD-H
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 112
Safety factor SH : 1.15

Catalog No.: KRGCP / KRGCPF / KRGCPD / KRCPF
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 79
Safety factor SH : 1.15

Catalog No.: SRGCP / SRGCPF / SRGCPFD
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 90
Safety factor SH : 1.15

Catalog No.: SRCP / SRCPF / SRCPFD / SROCP / STRCPF / STRCPFD
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 52.5
Safety factor SH : 1.15

Catalog No.: SURCPF / SURCPFD / FRCP
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 41.3
Safety factor SH : 1.15

Catalog No.: MSCPG
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 166
Safety factor SH : 1.15

Catalog No.: SSCPGS
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 99
Safety factor SH : 1.15

Catalog No.: SSCPG
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 90
Safety factor SH : 1.15

Catalog No.: KTSCP
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 74.5
Safety factor SH : 1.15

Catalog No.: KSCP
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 112
Safety factor SH : 1.15

Catalog No.: SSCP
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 49
Safety factor SH : 1.15

Catalog No.: SUSCP
Formula NOTE 1: Formula of spur and helical gears on surface durability (JGMA402-01)
Kinematic viscosity of lubricant : 100cSt (50 deg C)
Gear support : Support on one end
Allowable Hertz stress σ Hlim (kgf/mm^2) : 41.3
Safety factor SH : 1.15

[NOTE 1] The gear strength formula is based on JGMA (Japanese Gear Manufactures Association) specifications. The units for the number of rotations (rpm) and the stress (kgf/mm^2) are adjusted to the units needed in the formula.
[NOTE 2] The allowable bending stress at the root σ Flim is calculated from JGMA401-01, and set to 2/3 of the value in the consideration of the use of planetary-, idler-, or other gear systems, loaded in both directions.

Definition of bending strength by JGMA 401-01 (1974)

The allowable bending strength of a gear is defined as the allowable tangential force at the pitch circle based on the mutually allowable root stress of two meshing gears under load.


Example of the failure due to insufficient bending strength.

Definition of surface durability by JGMA 402-01 (1975)

The surface durability of a gear is defined as the allowable tangential force at the pitch circle, which permits the force to be transmitted safely without incurring surface failure.


Example of the defacement due to insufficient surface durability.

3. Selecting Racks By Precision

The precision standards of KHK stock racks are established by us. Please be sure to see the pages below when selecting.

  1. Pitch Error of Racks NOTE 2 (KHKR001) – Page 190
  2. Precision of Rack Blanks NOTE 2 – Page 191
  3. Backlash of Rack Tooth – Page 191

[NOTE 2] Convert CP to m (module) when reference is made to the data in the table. (m=CP/π)

Application Hints

In order to use KHK stock gears safely, carefully read the Application Hints before proceeding. If there are questions or if you require clarifications, please contact our technical department or your nearest distributor.

KHK CO., LTD.
PHONE: 81-48-254-1744 FAX: 81-48-254-1765
E-mail info@khkgears.net

1. Caution on Performing Secondary Operations

  1. CP racks except for the racks where the gear teeth are induction hardened. To avoid problems of gear precision, do not reduce the face width. The precision of ground racks and racks with mounting holes may drop if you do not exercise extreme caution during installation or while modifying.
  2. Pitch lines of racks are controlled by using the bottom surface as the reference datum and over-pin measurements on tooth thickness. If you machine the bottom surfaces, the precision of the racks may be affected.
  3. When connecting two racks, the machining of the mating ends requires careful consideration. The meshing will be poor if the pitch (CP) straddling the connection has a positive tolerance. We recommend a minus tolerance on pitch of at the connection. The below is an indication of pitch tolerance for each module.

  4. To use dowel pins to secure racks, attach the racks to the base and drill both simultaneously.
  5. KHK stock CP racks made of S45C and SCM440 (except for ground racks) can be induction hardened. However, the precision of pitch is decreased.
  6. To be able to handle parts safely, all burrs and sharp corners should be removed after the secondary operations are done.
  7. If you are going to modify the gear by gripping the teeth, please exercise caution not to crush the teeth by applying too much pressure. Any scarring will cause noise during operation.

2. Points of Caution in Assembling

  1. KHK stock CP racks are designed to give the proper backlash when assembled using the mounting distance given by the formula below (mounting distance tolerance of H7 to H8 required). The backlash values are given in the table on Page 191. Make sure that the mounting distance stays constant for the length of the rack.

  2. Mounting distance a = Height of pitch line of rack + Pitch radius of pinion

    [CAUTION] Pinions are assumed to be standard stock spur gears (x=0).

  3. KRGCP type of KHK stock ground racks have four surfaces ground parallel to within 10 – 15 μm. To maintain true angle, they should be mounted on high precision bases as shown below. It is even possible to correct for the angular errors of racks by compensating the mounting base. With recent increases in the requirement for zero backlash linear drives, such accurate assembly as shown is becoming more important.

  4. If the racks are not secured properly to the base, they could shift during operation and cause unexpected problems. It is very important to insure firm mounting by the use of dowel pins or similar devices.

  5. Machined end type racks such as SRCPF and SRCPFD series have the pitch tolerance of – 0.1/- 0.3 for modules less than Module 2.5, and – 0.1/- 0.4 for larger modules. If you try to connect the racks without any space, the pitch at the connection will be too small and will cause problems. Please follow the following diagrams for assembly.

An example of Rack Joining, we recommend the following method.



[CAUTION] Joining gauge racks for helical racks must have the opposite hand from the racks. Please use Module 1-10 100 racks as a joining gauge rack, or alternatively the rack of the same specifications on hand.

Related links :
Types of Gears - A detailed description of Types of Gears
Technical Information of Gear Racks
“Raw Material” and “Gear Precision Grade” Equivalent Tables
齿条 – 中文页

Go to Top