Pitch Line: Tooth Height 2.25 × Module, Module 1-10 mm

Component Specifications

Definition

The pitch line is a theoretical line along the length of a rack's teeth where the tooth thickness equals the space width, defining the reference for pitch measurement. It represents the ideal contact path for mating with a pinion gear, ensuring smooth linear motion conversion from rotational input. In rack-and-pinion systems, this line determines the effective radius for calculating linear displacement per pinion revolution.

Working Principle

The pitch line serves as the reference datum for tooth geometry, ensuring consistent spacing (pitch) between teeth. When a pinion gear engages with the rack, its pitch circle rolls along the rack's pitch line without slipping, converting rotational motion into precise linear motion. This line defines the neutral axis where no sliding occurs during proper meshing, minimizing wear and maintaining accuracy in positioning systems.

Materials

Typically matches the rack material: carbon steel (AISI 1045, 4140), alloy steel, stainless steel (304, 316), or engineered plastics (nylon, acetal) for specific applications. Surface treatments include carburizing, induction hardening (50-60 HRC), nitriding, or zinc plating for corrosion resistance.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Pitch	π × Module
Module	1-10 mm
Tooth Height	2.25 × Module
Accuracy Grade	DIN 5-9, AGMA 10-14
Pressure Angle	20° or 14.5°
Surface Finish	Ra 0.8-3.2 μm

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 53, ISO 54, DIN 867, AGMA 2015

Parent Products

This component is used in the following industrial products

Rack

A linear gear component with teeth cut along its length that meshes with a pinion gear to convert rotational motion into linear motion.

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Engineering Analysis

Risks & Mitigation

Inaccurate pitch line causing gear misalignment
Wear altering pitch line geometry
Thermal expansion affecting pitch consistency
Improper lubrication leading to pitch line degradation

FMEA Triads

Trigger: Manufacturing tolerances exceeding standards
Failure: Increased backlash and positioning errors
Mitigation: Implement statistical process control (SPC) during machining, use coordinate measuring machines (CMM) for verification

Trigger: Abrasive wear from contaminated environment
Failure: Pitch line geometry distortion causing erratic motion
Mitigation: Install protective covers, use filtration systems for lubricants, apply wear-resistant coatings

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±0.02 mm per 300 mm length for precision grades

Test Method

Laser interferometry for pitch accuracy, profile projection for tooth geometry, hardness testing per ISO 6508

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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Manufacturers of Pitch Line

Manufacturer profiles associated with Pitch Line.

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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

Why is pitch line accuracy critical in rack systems?

Pitch line accuracy ensures proper gear meshing, minimizes backlash, reduces vibration/noise, and maintains positioning precision in linear motion applications.

How does pitch line relate to module in metric systems?

Pitch = π × Module. The module defines tooth size, while the pitch line provides the reference for spacing these teeth consistently along the rack.

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.

Pitch Line