Convoloid was tested at 200–240% of rated load under a U.S. DOE/NREL contract. In mills, kilns, crushers and conveyors, where a gearbox stop halts production, it spreads load over a conformal contact to lower stress where heavy gears fail first.
When a mill or conveyor drive stops, the whole circuit behind it stops too. Gear life is a production number, not a maintenance number.
Large cast girth gears cannot simply be case-hardened, and center distance and face width are fixed by the installation. More capacity has to come from somewhere else.
Large gears and gearboxes can take months to replace. Every year of added life defers a major spend.
Published analysis (AGMA 11FTM19) shows 20–35% higher torque capability than an equivalent involute with the same center distance, ratio, materials and face width, or the same load at lower stress for longer life. The advantage is greatest at face-width to center-distance ratios of about 0.2 and up.
| Involute | Convoloid® | |
|---|---|---|
| DOE/NREL test load | Same load, back-to-back | 200–240% of rated load |
| Noise at 200–240% load (audio) | Baseline | 12.8 dB quieter |
| Vibration, high-speed mesh fundamental | Baseline | 19.2 dB lower |
| Tooth surfaces in test | Micro-pitting progressed | Early micro-pitting self-arrested |
| Efficiency (measured) | 98.9% per gearset | 98.9% per gearset (parity) |
| Torque capability (AGMA 11FTM19) | Equivalent involute | 20–35% higher |
A convex addendum nests into a concave dedendum. The load spreads over a wider band than two convex involute flanks can offer, lowering contact stress.
Mill and crusher drives favor double helical gearing to cancel thrust. The Convoloid profile carries over unchanged. Penn State testing used 28–32 HRC through-hardened 4140, the material regime of large cast gears.
Heavy industry buys on reliability. Here is the evidence. Noise and vibration results apply to steady, high-load duty.
Under a U.S. DOE/NREL wind-energy research contract (2005–2008), a Convoloid retrofit of a 108 kW two-stage gearbox ran back-to-back against an optimized involute at up to 240% of rated load. Convoloid surfaces stayed stable; the involute’s micro-pitting progressed.
See the source →Published: 20–35% higher torque capability than equivalent involute designs, rated per AGMA/ISO with the same derating factors applied to both (Berlinger & Colbourne, 2011).
See the source →US 10,527,149 in force to ~2036. European patent EP 3 387 294 granted, with Unitary Patent and UK validation, to 2036.
See the source →Noise and vibration were measured at 200–240% of rated load in the DOE/NREL test and apply to steady, high-load duty only (Convoloid 13 teeth vs involute 16 on the high-speed pinion, so mesh frequencies differ).
Barney Berlinger, Convoloid's inventor, explains what makes the tooth form different and why it matters for mining & heavy industry.
A short briefing for engineering and leadership: the problem, the technology, the comparison and the test record, in nine slides.