Rack Teeth: Pressure Angle 20° or 14.5°, Module 1.5 to 3.0 mm

Component Specifications

Definition

Rack teeth are the linear gear teeth machined onto a steering rack component in rack-and-pinion steering systems. These teeth engage with the helical teeth of a pinion gear connected to the steering column. When the driver turns the steering wheel, the pinion rotates, causing the rack to move laterally along its axis. This linear motion is transmitted through tie rods to the steering knuckles, ultimately turning the vehicle's wheels. The geometry, pitch, pressure angle, and surface finish of rack teeth are critical for smooth operation, minimal backlash, precise steering response, and durability under varying loads.

Working Principle

The rack teeth operate on the principle of a rack-and-pinion mechanism, converting the rotational motion of the pinion gear (driven by the steering wheel) into linear motion of the rack. This linear displacement directly controls the angle of the front wheels via the tie rods and steering knuckles, enabling directional control of the vehicle.

Materials

Typically made from case-hardened alloy steels such as 20MnCr5, SAE 8620, or similar grades to achieve a hard, wear-resistant surface (58-62 HRC) with a tough, ductile core. Alternative materials may include powder metallurgy steels or, for some applications, engineered plastics for reduced weight and noise.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Pitch	Linear pitch corresponding to module
Length	Varies by vehicle (typically 300-600 mm)
Module	1.5 to 3.0 mm
Backlash	0.05-0.15 mm
Core Hardness	30-40 HRC
Tooth Profile	Involute or modified involute
Pressure Angle	20° or 14.5°
Surface Finish	Ra ≤ 0.8 μm
Surface Hardness	58-62 HRC
Straightness Tolerance	≤ 0.1 mm over full length

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 4156, DIN 3960, DIN 3961, ISO 1328, SAE J1124

Parent Products

This component is used in the following industrial products

Pitman Arm (for recirculating-ball type) or Rack (for rack-and-pinion integration)

A critical steering linkage component that converts rotational motion from the steering gearbox into lateral motion to turn the wheels.

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Engineering Analysis

Risks & Mitigation

Tooth wear leading to steering play
Tooth chipping or fracture under impact loads
Corrosion in harsh environments
Misalignment causing uneven wear and noise
Inadequate lubrication accelerating wear

FMEA Triads

Trigger: Insufficient or degraded lubrication
Failure: Accelerated abrasive wear on tooth surfaces
Mitigation: Use sealed systems with lifetime lubricants; specify regular inspection intervals; apply wear-resistant coatings.

Trigger: Misalignment between rack and pinion
Failure: Uneven tooth contact, leading to localized wear and noise
Mitigation: Ensure precise machining and assembly tolerances; use alignment fixtures during installation.

Trigger: Overload or impact from road shocks
Failure: Tooth bending, chipping, or fracture
Mitigation: Design with adequate safety factors; use materials with high core toughness; implement overload protection in steering design.

Industrial Ecosystem

Compatible With

Rack-and-pinion steering systems in passenger vehicles, light trucks, and some heavy vehicles

Typical Suppliers & Equivalents

ZF Friedrichshafen, Bosch, JTEKT, NSK, Nexteer Automotive, ThyssenKrupp

Compliance & Inspection

Tolerance

Tooth profile tolerance per ISO 1328 Grade 6-7; linear pitch tolerance ±0.02 mm; cumulative pitch error ≤ 0.05 mm over 100 mm

Test Method

Coordinate measuring machine (CMM) for geometry; hardness testing (Rockwell C) for surface and core; profilometry for surface finish; functional testing in steering gear assembly for backlash and smoothness.

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Rack Teeth

Manufacturer profiles associated with Rack Teeth.

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

What is the function of rack teeth in a steering system?

Rack teeth convert the rotational motion from the pinion gear (connected to the steering wheel) into linear motion, allowing the rack to move side-to-side and turn the vehicle's wheels.

Why are rack teeth case-hardened?

Case hardening provides a hard, wear-resistant surface to withstand constant meshing with the pinion gear, while maintaining a tough core to absorb shock loads and prevent brittle fracture.

What causes wear on rack teeth?

Wear can result from inadequate lubrication, contamination (dirt, debris), misalignment, excessive loads, or material fatigue over time, leading to increased backlash and reduced steering precision.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Rack Teeth