Convoloid® Test Results & Evidence

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 Supported by the CONVOLOID® trademark and unpublished design software, protocols and know-how.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