Patented · Published at AGMA · DOE/NREL Tested

Convoloid® gear technology: The Shape
of the Future

Convoloid® is a patented, non-involute conjugate gear tooth form. Tested under a U.S. Department of Energy wind program, published at AGMA, and made on the gear machines you already own.

20–35% Higher Torque vs. Equivalent Involute · AGMA 11FTM19
240% Of Rated Load in DOE/NREL Gearbox Testing
≤20% Smaller & Lighter at Equal Power (Analysis)
License Convoloid→ Explore the Technology
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US Patent 10,527,149 · In Force to ~2036 ◆ European Patent EP 3 387 294 · Granted ◆ Published: AGMA 11FTM19 ◆ DOE/NREL Wind Gearbox Test · 200–240% of Rated Load ◆ Runs on Existing Gear Machines ◆ 20–35% Higher Torque Capability · AGMA 11FTM19 ◆ US Patent 10,527,149 · In Force to ~2036 ◆ European Patent EP 3 387 294 · Granted ◆ Published: AGMA 11FTM19 ◆ DOE/NREL Wind Gearbox Test · 200–240% of Rated Load ◆ Runs on Existing Gear Machines ◆ 20–35% Higher Torque Capability · AGMA 11FTM19 ◆
The Problem

200 Years of Diminishing Returns

The involute gear tooth form has dominated engineering for over two centuries. It's been studied, refined, and optimized to near perfection, and the remaining gains come mostly from materials and finishing, not from the tooth form.

New materials, coatings, and surface finishing help at the margins. But the fundamental geometry hasn't changed. Convex meets convex, with maximum Hertz contact stress built in.

Convoloid changes the equation. A computer-optimized tooth form where convex meets concave, lowering contact stress while remaining compatible with the gear-cutting and inspection machines on your floor.

Involute
Convex–Convex Contact
High Contact Stress
VS
Convoloid®
Convex–Concave Contact
Lower Contact Stress
Convoloid's S-curved flank creates a conformal mesh, naturally distributing load over more surface area.
Three Pillars

One Geometry. Three Breakthrough Outcomes.

The same physics that defines Convoloid's tooth form shows up in published rating analysis and in physical test. Every figure below is compared against an equivalent involute: same center distance, ratio, materials and heat treatment, face width, load and lubrication.

01

Higher Torque Capability

20–35 % Higher torque than equivalent involute designs

Rated per AGMA/ISO against an equivalent involute baseline, Convoloid shows 20–35% higher torque capability, published in AGMA 11FTM19 (Berlinger & Colbourne, 2011). The advantage is greatest in balanced designs with design freedom: face-width to center-distance ratios of about 0.2 and up, helix angles of 20–30° and higher ratios.

  • Published rating analysis, AGMA 11FTM19
  • Analysis shows power uprates approaching 20% in the same envelope, or the equivalent taken as longer life
  • Analysis shows higher single-stage ratios: smaller pinions with no undercut
02

Smaller & Lighter

Up to 20 % Smaller and lighter at equal power (analysis)

When a design is constrained to match an involute's power and stress levels, analysis shows the Convoloid gearbox can be up to about 20% smaller in enclosed volume and lighter. An analytical redesign of the Micon 108 wind gearbox came out 20.6% smaller in volume. (The unit DOE/NREL tested was a same-size retrofit, not this redesign.)

  • Up to ~20% smaller enclosed volume (AGMA 11FTM19)
  • Same materials, same power, same stress levels
  • Torque, size and ratio gains are alternative uses of the same stress margin; they don't add together
03

Durability

Tested Against Involute Two Test Programs

Convex-meets-concave contact lowers surface (Hertz) stress and root bending stress. In DOE/NREL gearbox testing at 200–240% of rated load, early micropitting on the Convoloid gears self-arrested and contact improved, while the involute's micropitting progressed to the end of the test.

  • Lower contact stress through the mesh (rating analysis)
  • Lower bending stress at the root (rating analysis)
  • DOE/NREL: Convoloid run-in stabilized; involute micropitting grew (see testing)
  • Penn State Gear Research Institute four-square testing confirmed Convoloid's surface-durability advantage and rating protocol
Hear It From the Inventor

Barney Berlinger Explains Convoloid®

Convoloid's inventor walks through what makes the tooth form different from the involute, and why that matters for power density, weight and life. It's the quickest way to understand the technology.

Convoloid® Gearing Technology Overview · Gear Innovations

The Technology

A Fundamentally Different Tooth

18T pinion × 33T wheel. Amber: path of contact · Glow: live contact · Orange: convex addendum · Steel: concave dedendum
01

The S-Curve Flank

Each Convoloid tooth has a characteristic S-curved profile. The dedendum (below pitch line) is concave; the addendum (above pitch line) is convex. This creates the conformal, lower-stress contact.

02

No Base Circle Limitation

Unlike involute gears, Convoloid has no base circle, eliminating undercut constraints on small pinions. More design freedom, optimized for each application via computer point-by-point calculation.

03

Conjugate Through the Full Flank

Convoloid is conjugate through most of the addendum and dedendum, with contact that accurately follows the Euler-Savary equation. Nearly constant relative radii of curvature maintain consistent Hertz stresses across the entire flank. No stress spikes.

04

Drop-In Manufacturing Compatibility

Convoloid is made on existing gear-cutting, grinding and inspection equipment at standard cycle times, and manufacturing sequences mirror involute processes. The transition is a design change, not a capital investment.

Gear Types Spur · Helical · Double Helical · Planetary · Epicyclic
Contact Ratio 1.1 – 1.3 (application optimized)
Helix Angle 20° – 30° optimal range
Rating Standards AGMA & ISO compatible methodology
Convoloid in Motion

Every Tooth, Generated True

These aren't illustrations. Every gear below is generated from the Convoloid® basic rack (convex addendum, concave dedendum, S-shaped transition through the pitch line) using the same rolling motion a hob uses on the shop floor. The amber dashed curve is the true path of contact; glowing points are live tooth contact.

Tooth Anatomy

From Involute to Convoloid®

Watch a standard 20° involute tooth become a Convoloid tooth. The flank turns into an S: a convex addendum above the pitch line, a concave dedendum below it, joined by a smooth transition where every junction is tangent.

The amber comb plots curvature along the flank. It flips sign at the pitch line, so a convex flank always meets a concave flank.

Spur

Small Pinion, No Undercut

A 13-tooth pinion driving 27 teeth. With no base circle there's no undercut limit, and the contact ratio stays above 1.0, so spur Convoloid gears run smoothly.

Helical · 3D

Helical Pair

The same transverse Convoloid profile swept along a 22° helix, in opposite hands. Contact lines stay unbroken across the full face width.

Double Helical · 3D

Herringbone

A 30° double helix cancels axial thrust. It's built for the heavy-duty drives (wind, mining, marine) where power density matters most.

Planetary

Epicyclic Set

A 21-tooth sun, three 15-tooth planets and a 51-tooth internal ring. The ring is generated to match the planet, so internal meshes get the same convex-to-concave contact.

Rack & Pinion

The Basic Rack

This is the rack that defines the whole Convoloid system. Every gear above is generated from it, which is why Convoloid can be cut on existing CNC hobbing and grinding machines.

Contact Close-Up

Convex Meets Concave

At the mesh, a convex addendum rolls against a concave dedendum. The two curves nest instead of touching at a single sharp point, so the load spreads over a wider band and contact stress drops.

Proof, Not Promises

Tested. Published. Patented.

Most licensors spend years and millions building test evidence. Convoloid has a federal test program, a published AGMA rating method, and the reports to back them. We call analysis analysis and test results test results, and every number names its baseline.

DOE/NREL Wind Gearbox Test

Tested under a U.S. DOE/NREL wind-energy research contract (2005–2008). A Convoloid retrofit of a 108 kW two-stage wind gearbox ran back-to-back against an optimized involute at up to 240% of rated load. Convoloid tooth surfaces stayed stable while the involute's micropitting progressed.

DOE/NREL Contract Program →

AGMA 11FTM19 Published

Published at the AGMA Fall Technical Meeting (Berlinger & Colbourne, 2011). "Convoloid Gearing Technology: The Shape of the Future" sets out design procedures, rating criteria, and apples-to-apples comparisons with equivalent involute designs.

AGMA Fall Technical Meeting

Rated by the Industry's Own Method

Rated per AGMA/ISO against an equivalent involute baseline, with the same dynamic, life and load-distribution factors applied to both forms. On that basis Convoloid shows 20–35% higher torque capability than equivalent involute designs.

20–35% Torque · AGMA 11FTM19 Analysis

Patent Position

US 10,527,149 in force to ~2036. European patent EP 3 387 294 granted, with Unitary Patent and UK validation, to 2036. Supported by the CONVOLOID® trademark and unpublished design software, protocols and know-how.

US & EP · to ~2036 →

Published Record

Published at AGMA (11FTM19), in Gear Solutions, and in a 247-page NREL final report, backed by an internal library of design, rating, manufacturing and application papers available under NDA.

See the Sources →

Apples-to-Apples Analysis

Convoloid design and rating work has been run in Gear Innovations software integrated with ANSOL Transmission3D. The same software computes the Convoloid and involute variants, so both are rated on identical terms. Point-by-point computation tailors the tooth to each application.

Same Software · Both Forms
Test Program

Two Test Programs

Convoloid gearing has been tested against involute baselines in a U.S. Department of Energy wind gearbox program and at Penn State's Gear Research Institute. In both, the involute baseline was built to the same constraints as the Convoloid gears.

Test 01 · DOE/NREL Contract Program

Wind Turbine Gearbox, 200–240% of Rated Load

Tested under a U.S. DOE/NREL wind-energy research contract (2005–2008). A Convoloid retrofit of a 108 kW two-stage wind gearbox ran back-to-back against an optimized involute at up to 240% of rated load. Convoloid tooth surfaces stayed stable while the involute's micro-pitting progressed. The test ended with an intermediate-shaft bearing failure unrelated to the gears.

12.8 dB
quieter (audio spectrum) and 19.2 dB lower vibration at the high-speed mesh fundamental than the involute, measured at 200–240% of rated load. Convoloid vibration fell about 10% over the test; the involute's rose about 6%.
Gearbox
Micon 108 kW, two-stage
Baseline
Optimized involute
Housing
Existing involute housing
Load
200%, then 240% of rated
Efficiency
98.9% per gearset, both (parity)
Contract
DOE/NREL ZAM-3-33200-12

Early Convoloid micro-pitting on the transition zone self-arrested and contact improved (“wear-in”); the involute's micro-pitting progressed to the end of the test with rising noise, vibration and metal in the oil. The bearings were stock-sized, with marginal rated life at 240% load; Convoloid gear wear was unchanged at test end. Early in the program the rig ran below its intended load for a period because of an instrumentation conversion error, which the report documents. Noise results apply to steady, high-load duty only; we make no noise claims for light- or variable-load duty. (Convoloid 13 teeth vs involute 16 on the high-speed pinion, so mesh frequencies differ.) Read the NREL final report →

Request the DOE/NREL Test Report
Back-to-back gearbox test rig with two blue gear housings connected by shafts
Back-to-back gearbox test rig
Test 02 · Penn State Gear Research Institute

Four-Square Surface-Durability Testing

Penn State Gear Research Institute four-square testing confirmed Convoloid's surface-durability advantage and rating protocol; tooth form was the only change.

Penn State testing used 28–32 HRC through-hardened AISI 4140, the material regime of large cast gears.

Rig
Four-square
Variable
Tooth form only
Material
AISI 4140, 28–32 HRC
Manufacturing & Inspection

Your Machines. Your Standards. A Better Tooth.

The differences between a Convoloid tooth and its involute equivalent are subtle, but they produce powerful results. Manufacturing sequences, tolerances and material allowances closely follow involute practice.

Convoloid tooth definition drawing: convex addendum, transition zone at the pitch diameter, concave dedendum, full-radius root, tip relief area, described in X-Y coordinates
The Convoloid tooth, defined point by point in X–Y coordinates

Same Processes

Hobbing, shaping, skiving, form grinding and threaded-wheel grinding all apply, at standard cycle times, and hob costs are comparable to special involute cutters. Shaving is not recommended. Pinion and gear need separate cutters. Because the tooth is described digitally, it is compatible with the CNC gear manufacturing and inspection equipment in use worldwide.

Same Inspection

Inspected on standard CNC gear checkers to AGMA, ISO, DIN and JIS quality grades. Accuracy classes use the same parameters, limits and identification. Lead modification, crowning, tip relief and root relief can all be designed in and measured. Center-distance tolerance practice is ±0.005 × transverse module.

Same Standards

Rating modifiers and tolerances from world-recognized standards apply directly:

AnalysisAGMAISO
Contact & bending2001/2101, 6011, 6013, 60156336, 13593
Tolerances2015-21328-1
Inspection91510064
Scuffing92513989, 14635-1
Sample Convoloid profile inspection chart from a 36-tooth gear, within DIN 3962 tolerance
Sample Convoloid profile inspection chart (36T, DIN 3962)
Sample Convoloid lead inspection chart
Sample Convoloid lead inspection chart
Applications

Where Capacity, Life and Downtime Matter

Convoloid's evidence is strongest in large, heavily loaded gearing: mills, kilns, wind and industrial drives. Other markets follow as the validation record grows.

Mining & Heavy Industry

Mill, kiln and heavy drives where a stop halts production and capacity is fixed by metallurgy. Backed by a DOE/NREL gearbox test at 200–240% of rated load, with lower measured noise and vibration at high load.

Capacity + life within fixed constraints
Explore the case →

Wind Energy

Tested under a U.S. DOE/NREL wind-energy contract: a Convoloid retrofit of a 108 kW two-stage gearbox ran at up to 240% of rated load, with stable tooth surfaces while the involute's micro-pitting grew.

DOE/NREL tested
Explore the case →

Industrial Gearboxes

Parallel-axis and planetary product lines. 20–35% higher torque capability than equivalent involute designs (AGMA 11FTM19), made on the machines you already own: a design change, not a new factory.

Higher rating per frame size
Explore the case →

Aerospace & Defense

Rotorcraft and ground-vehicle gearboxes (analysis only; not yet tested at defense duty cycles). UAV and actuator scale: validation partner sought.

Torque capability + envelope
Explore the case →

EV & Automotive

Analysis shows ~20% volume and weight reduction at equal power and stresses, and higher single-stage ratios that can replace a two-stage reduction with one Convoloid pair. Light-load noise behavior is still being characterized.

Stage elimination + package size
Explore the case →

Humanoid Robotics

Mass and torque density define humanoid joints. Convoloid has not yet been analyzed or tested at the fine pitches robot joints use, and we are seeking a robotics partner for a fine-pitch validation program.

Validation partner sought
Validate with us →
Intellectual Property

A Licensable IP Position

A licensee gets more than patent rights: the tooth-geometry protocols, design software, published rating method, application know-how and the CONVOLOID® trademark.

Primary
US 10,527,149
"Conjugate Gears with Continuous Tooth Flank Contact"
Issued: January 7, 2020 In force to ~2036 Assignee: Gear Innovations LLC
Patent Term Remaining
~10 years remaining
US Patent 10,527,149 In force to ~2036
European Patent EP 3 387 294 Granted, with Unitary Patent and UK validation, to 2036
Convoloid® Trademark Registered · Gear Innovations LLC
Software, Protocols & Know-How Unpublished design, rating, manufacturing & inspection methods
US 6,101,892 · 6,178,840 · 6,964,210 Foundational patents · expired
Convoloid applies across spur, helical, double helical and planetary configurations. See Resources for the full patent family.
License Convoloid

Your Gears. Our Geometry.

Gear Innovations licenses Convoloid directly and neutrally. There is no master licensee that competes with sub-licensees. A small, per-unit royalty on gears you already make, on machines you already own.

⚙

Direct Neutral Licensing

Per-unit royalty model. Arm-style. We license the design method and IP rights; you bake Convoloid geometry into gears you already manufacture.

🔧

Existing Equipment

No new machine tools required. Convoloid is made on existing gear-cutting and inspection equipment. Manufacturing sequences closely match involute processes.

📐

Application Support

A technical library of design, rating, manufacturing and inspection papers, plus application modeling and design support for your program.

How to Get Started

01
Book a Technical Intro

A 30-minute technical call to confirm gear-type fit for your application and answer your engineers' first questions.

→
02
Application Modeling & Design Support

Application modeling and design support at your gear ratios, loads and materials, so the advantage is quantified before any commercial conversation.

→
03
License & Integrate

Simple direct license agreement. We transfer the design files, protocols and design support to integrate Convoloid into your product line.

Book a Technical Introduction→

No commitment. We'll confirm the fit first.

Leadership

Built on a Lifetime of Innovation

Darryl Berlinger

Darryl Berlinger

President & CEO, Gear Innovations LLC

Son of Convoloid inventor Bernard Berlinger, Jr., Darryl has taken the helm of Gear Innovations to bring Convoloid to global markets. Carrying forward his father's vision, Darryl leads commercialization, licensing strategy, and industry partnerships for this breakthrough technology.

Allen J. Williston

Allen J. Williston, P.E.

Chief Engineer

Co-presenter of the AGMA Convoloid case studies webinar and co-author of technical papers on Convoloid implementation. Allen brings deep gear engineering expertise to application-specific design, licensing technical support, and heavy-industry engagement. His framing of Convoloid's longevity and lifetime-cost advantages resonates powerfully with mining, wind, and large industrial drivetrain operators.

A registered P.E. (University of Missouri, BSME), Allen spent 16 years at the Dorris Company, finishing as Senior Project Engineer. Since 2005 he has led the multi-year Gear Innovations test program under the U.S. DOE/NREL wind-energy research contract. An AGMA member since 1991, he has chaired the AGMA Computer Programming Committee since 1997 and serves on the Wind Turbine TAG.

Gregg Heimer

Gregg Heimer, CISSP

Chief Technology Officer

Gregg keeps Gear Innovations' technology aligned with its business: the digital presence that introduces Convoloid to engineers and partners, the secure handling of technical data shared under NDA, and the systems behind licensing and partner engagement. His strength is translating between the technical and the commercial, so every tool the company adopts serves a clear business purpose and every risk is managed before it becomes a problem.

Gregg brings more than two decades of technology leadership. He began his career as a broadcast engineer for local news affiliates and later worked in private aviation before moving into financial services, where he has led technology for investment firms and broker-dealers operating under SEC and FINRA oversight. Along the way he spent ten years building and running a managed IT services firm that supported small and mid-sized businesses across the Philadelphia and New York regions. A CISSP with multiple Cisco and industry certifications, he holds a bachelor’s degree from Millersville University and a master’s degree from Syracuse University, and is completing a Doctor of Business Administration in Information Systems.

In Memoriam
Bernard (Barney) Berlinger, Jr.

Bernard “Barney” Berlinger, Jr. 1938–2025

Founder · Inventor of Convoloid®

Barney founded Gear Innovations LLC in 1997 after founding ASI Technologies Inc. a decade earlier. He was the named inventor or co-inventor of the patents that define Convoloid technology, including the foundational US 6,101,892 and US 10,527,149, both with Dr. John Colbourne. He spent decades developing, testing and publishing the science behind Convoloid gearing. His work, tested under a U.S. DOE/NREL contract and published at AGMA, is the foundation of Convoloid technology.

An AGMA member from 1962, Barney chaired the Fine Pitch Gearing Committee, served on the Board of Directors and was AGMA President in 1986. He later chaired the Board of Trustees of the Gear Research Institute at Penn State (2000–2002). BSME, University of Pennsylvania, 1960.

Dr. John R. Colbourne d. 2016

Co-Inventor · Chief Technology Officer, 1997–2016

Dr. Colbourne joined Gear Innovations in 1997 and was the kinematic mind behind the Convoloid tooth form. He co-invented the foundational Convoloid patents with Barney Berlinger and was sole inventor of US 6,964,210 (gear tooth profile) and US 7,077,026 (gear tooth profile curvature).

He was Professor Emeritus of Mechanical Engineering at the University of Alberta. He earned his BS in Mechanical Sciences at Cambridge, including a year of study at the Technische Hochschule Darmstadt, and his PhD in Kinematic Theory at Stanford. He chaired the AGMA Nomenclature Committee and received the AGMA Technical Division Executive Committee Award for outstanding contributions to the art of gear design and utilization. He passed away in June 2016.

Resources

Check the Record Yourself

Every claim on this site traces back to a patent, a published paper, or a test report. Here are the primary sources, including independent reviews. The technical data room is available under NDA.

Patent Family

3 Published Papers & Reports

Gear Innovations' full technical library (design, rating, manufacturing and application papers) is available to licensees under NDA.

3 Testing & Manufacturing

3 Industry & Independent Coverage

Get in Touch

Start the Conversation

Whether you're a gear manufacturer evaluating Convoloid for a product line, an OEM exploring a performance advantage, or a researcher in the field, we want to hear from you.

⚙ Gear Innovations LLC
® Convoloid® Technology Licensing
☎ 215-680-0052
@ [email protected]
✉ Box 22, Carversville, PA 18913
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