"This Gear Solved A Problem Most Engineers Couldn't Handle" At first, engineers thought gears only needed one thing. Teeth that mesh. But when factories started running bigger machines at higher torque and speed, something strange happened. The gears sounded like metal hammers smashing together. Vibration exploded. Bearings wore out... faster. Entire systems became unstable. Then came the herringbone gear. Instead of straight teeth slamming together all at once, its angled double-helical design transfers force gradually across the surface. Smoother contact. Less shock. Almost silent operation. But here's the genius part most people miss. Normal helical gears create massive sideways axial thrust that pushes shafts apart under load. Herringbone gears cancel that force completely by using mirrored tooth geometry. No extra thrust bearings. Less wear. Higher load capacity. That's why you'll find them inside marine propulsion systems, heavy industrial gearboxes, and oil-field machinery where failure is not an option. The crazy part? Engineers still avoid them because manufacturing these gears is brutally expensive. Which brings us back to the question... if regular gears already work, why build the impossible one?show more

Installed in a rolling mill coupled with 15 ton flywheel and 1200 hp motor

Most Navy ship reduction gears utilize double helical instead of herringbone due to the stress induced at the "V" of the herringbone tooth intersection.

Here’s some anchor winch gears i was working on the Transocean Rather, all 4 winches got upgraded..

Race car gear boxes use straight gears for strength and quick shifting they are also super loud. A manual straight cut gearbox will shift without the clutch. F1 gearboxes are briefly in two gears at the same time. When one gets a pushed in the other gets pushed out shifting gears in milliseconds. They are actually in two gears at once for a brief moment.

And the mirrored tooth geometry is still the emblem of Citroën, a french car company. André Citroën did not invent the manufacturing process of double chevron, but buyed the licence and used it to create the logo.

A big difference is the amount of teeth in contact, which impacts both load capacity and smoothness (smoothness translates to wear). The number of teeth in contact varies as the gear rotates. A herringbone (double helix) gear, with teeth cut at an angle (helix angle) rather than straight across, multiple teeth share the load simultaneously. (~3.5 teeth in contact on average), where cog/spur gears have ~1.2-1.7 teeth in contact over time (1.4 is typical). More teeth in contact = more power can be transmitted. But more teeth is also smoother: a cog/spur gear cycles abruptly between 1 and 2 pairs of teeth in contact, briefly having just a single tooth transmitting the load. A herringbone gear (Ratio 3.5): cycles smoothly between 3 and 4 pairs of teeth in contact. Herringbone gears are great for high-power speed reduction applications, such as a main engine reduction gear on a ship (fast steam turbine to slow propeller shaft), where the gears are fixed in place and that is your gear ratio for life - the gears don't clutch in and out. (As noted, the axial forces are cancelled out) Expensive to build, reserved for specific use cases.

Couldn't you just use two helical gears side by side?

Citroën, Andre.

How about make two in mirror and bolt them together?

Unless I am very much mistaken, I would state that my Singer sewing machine from 1963 has these gears. It's a beast of a machine and sews incredibly well. The stitches it produces are a work of art.

Double Herringbone gears transmission i harder to asemble and disassemble. It's impossible to slide gear from side.

The Citroen Logo Sir

Try making the contact surface resemble a wave and i bet it would work even better. No sense in using straight lines when your motion is circular and periodic. Look up the bike wheel that uses sinusodial shape and its efficiency. Also use a prime number of teeth.

How can you talk about herringbone gears and not mention Andre Citroen? Its even in the company logo on their cars.

Beautiful, but a Sumitomo (cycloidal reducers) is better than gears anyway.

...hellical!

At some point, 3D printing technology will get to where heavy-duty high-stress metal parts can be made. Don't think we're there yet, but I haven't looked lately.

What does engineer mean in this post? What do you mean engineers avoid them? These were invented by multiple engineers by definition

Was it not Citroen that invented the double herringbone gear? That's why their logo is 2 chevrons, or so I thought.

Grazie al sig Citroen. Ed è ancora il marchio Ruota dentata elicoidale a spinta eliminata

Citroen - double chevron //\\ // \\

I find herringbone gear design absolutely fascinating for high load applications

Smooth is fast

Just make two…mirror images…instead of machining it that way

Life cycle cost analysis. Use only when needed.

Quand vous mettez la première lettre de chaque mot en majuscule (première ligne), cela fausse la traduction.

Engineer: A straight-tooth gear will do. Reality: The gear is screeching. Helical gear: I’m here to save the day—and solve the axial force problem while I’m at it.😂

A) spur gearing is still used and does not "explode" B) you don't need thrust bearings just because you are using single helical gear sets 😂

@xdownloaderbot download this video for me

Very smooth

They also sacrifice torque. So its not all good news. Traditional gears do not.

Genius stuff! Thanks for the explanation. I had seen such gears before but I never stopped to think "why?".