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“Fluid gears” invention offers promise for improving mechanical devices

phys.org

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Re: “Fluid gears” invention offers promise for improving mechanical devices

#21

Post by HPsquared »

bluGill wrote: post #17
mcherm wrote: post #7

Ever driven a vehicle with an automatic transmission rather than a manual gearshift with a clutch? Then you almost certainly used a fluid coupling: basically two fans in a can with oil so turning one turns the other. The article is so full of hype it doesn't bother to explain how this is different from the "fluid gears" invented in 1905.

Many automatics these days are manual transmissions with a computer controlling the clutch. They have nothing in common with the slushboxes of old, the oil is just for lubrication.

Even slushboxes tend to aggressively lock up the torque converter. It's usually only in a "fluid dynamics" mode for brief moments. (Except maybe on a gentle hill start)

Re: “Fluid gears” invention offers promise for improving mechanical devices

#23

Post by operation_moose »

zahlman wrote: post #4

Do we understand fluid mechanics well enough now to just design things like this from scratch, or is it still mostly trial and error? TFA seems to imply the latter, but....

This could have been designed in CFD in an afternoon. Building it in real life is always somewhat cool but the amount of hype they're putting on this is crazy.

Re: “Fluid gears” invention offers promise for improving mechanical devices

#24

Post by dcanelhas »

ErroneousBosh wrote: post #11
dvh wrote: post #3

Virtually zero torque right?

I don't see how it could even have any measurable torque. You could improve it by making the cylinders have sticky-out bits that would scoosh the fluid around better, like little paddle wheels, and if you wanted to get some serious torque transfer you'd push the two paddle wheels so close together that the paddles actually kind of intersect.

Indeed, then this design will truly have come full circle.

Re: “Fluid gears” invention offers promise for improving mechanical devices

#25

Post by like_any_other »

ErroneousBosh wrote: post #11
dvh wrote: post #3

Virtually zero torque right?

I don't see how it could even have any measurable torque. You could improve it by making the cylinders have sticky-out bits that would scoosh the fluid around better, like little paddle wheels, and if you wanted to get some serious torque transfer you'd push the two paddle wheels so close together that the paddles actually kind of intersect.

That's a slippery slope that leads right back to traditional gears.

Re: “Fluid gears” invention offers promise for improving mechanical devices

#26

Post by donw »

jgrahamc wrote: post #9
mcherm wrote: post #7

Ever driven a vehicle with an automatic transmission rather than a manual gearshift with a clutch? Then you almost certainly used a fluid coupling: basically two fans in a can with oil so turning one turns the other. The article is so full of hype it doesn't bother to explain how this is different from the "fluid gears" invented in 1905.

As immortalised in the 1978 song "Greased Ligthnin'" from the film Grease: Well, this car is automatic It's systematic It's hydromatic Why it's greased lightnin' (greased lightnin') I am pretty sure that "hydromatic" there is actually "Hydramatic" ( https://en.wikipedia.org/wiki/Hydramatic ).

If it’s a hydramatic, be careful to only lubricate it with snake oil.

Re: “Fluid gears” invention offers promise for improving mechanical devices

#27

Post by snow_flake »

The phys.org article and headlines are misleading, the authors did not investigate systems to actually transmit torque. From what I gather, the interesting findings are the parameters for co-rotation and counterrotation of the driving and driven cylinder, depending on the Reynolds number, distance and so on. To illustrate one of the images of their publication: https://i.imgur.com/m8P2iVw.png

Re: “Fluid gears” invention offers promise for improving mechanical devices

#28

Post by ROOFLES »

bluGill wrote: post #17
mcherm wrote: post #7

Ever driven a vehicle with an automatic transmission rather than a manual gearshift with a clutch? Then you almost certainly used a fluid coupling: basically two fans in a can with oil so turning one turns the other. The article is so full of hype it doesn't bother to explain how this is different from the "fluid gears" invented in 1905.

Many automatics these days are manual transmissions with a computer controlling the clutch. They have nothing in common with the slushboxes of old, the oil is just for lubrication.

ZF 8HP is still a traditional torque converter transmission. Most high performance or high torque applications use that design. Dual clutch automatics or automated manuals can't take it.

Re: “Fluid gears” invention offers promise for improving mechanical devices

#29

Post by simonjgreen »

I’m super confused how this any more useful than an oil based hydrodynamic torque converter like you’d find in a “slush box” automatic transmission. The video in the article shows such a low rate of transmission it’s crazy, I can’t think of a purpose!
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