noshell
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Post by noshell on Feb 2, 2024 11:44:32 GMT -5
Hi Monty
Thanks for the info there. I had been thinking if i end up making my own gearset to have a spur gear either side of the pinion so there is no transverse load on the turbine shaft.
What do you think about this?
I suspect this is the reason planetary gears are common in high rpm applications.... Thinking about it, it would half the load on the gear teeth. So long as they mesh just right
Edit:
I do have a reluctance to manufacture something myself. For example, angle grinder gearboxes.
Cumulatively there has been tons and tons of r&d gone into that little box. I cant really match that.
Think of how many cars/bike have common bearing/gear issues. Think of their resources, knowledge, r&d. And they still fuck it up.
Im not very confident i could make something good, so the preference is for something ready made.
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monty
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Post by monty on Feb 2, 2024 21:22:44 GMT -5
The critical load in a highly loaded gear train is counterintuitively the compression load on the back side of the pinion tooth. Not the bending load in the shaft. The second spur does nothing to fix the tooth compressive load. The second spur mostly idles and the first spur takes the majority of the load and the pinion is still the critical element. This bending/compression issue isn't fixed unless there are three planet gears. Most supercharger drives are just a single spur. No need to complicate things. If you want off the shelf, just buy a vortec supercharger gearbox. They are universal and have a lot of mounting points. Gear ratios should be approximately correct. presearch.com/images?q=vortec%20supercharger%20gearbox#viewThe problem with the angle grinder is power. They aren't designed for the power you will be making. 90 degree drives have a lot of loss. Do the reduction first, and then use a 90 degree gearbox at low speed if you need that. |
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noshell
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Post by noshell on Feb 3, 2024 3:39:36 GMT -5
Out of interest, what do you do for a living Monty?
Im a test engineer, most of my work is in engine emissions so gearsets arent my specific area of expertise.
What you've said makes sense, 50k rpm at 10kw is less than 2nm of torque lol. So yeah the bending moment is negligable.
Do gears actually touch eachother in normal operation, or are they separated by an ehd film?
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richardm
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Post by richardm on Feb 3, 2024 6:59:22 GMT -5
Just another idea ( out of nowhere) that might be worth considering given you put your hands on a high quality unit They have a gear ratio of about 30:1 and can handle a lot of torque ..
An earth auger gear box similar to those...https://ykhuachen.en.made-in-china.com/product/IShQKwLTnzce/China-First-Generation-Planet-Gearcase-Old-Vortex-Gearcase-Gearbox-for-Earth-Auger-Hole-Borer.html
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Post by wannabebuilderuk on Feb 3, 2024 7:19:33 GMT -5
Just another idea ( out of nowhere) that might be worth considering given you put your hands on a high quality unit They have a gear ratio of about 30:1 and can handle a lot of torque .. An earth auger gear box similar to those...https://ykhuachen.en.made-in-china.com/product/IShQKwLTnzce/China-First-Generation-Planet-Gearcase-Old-Vortex-Gearcase-Gearbox-for-Earth-Auger-Hole-Borer.html That's actually a good idea, they're pretty high torque with high rpm input and you could couple two together for a higher reduction and surprising cheap www.ebay.co.uk/itm/225763846643 |
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richardm
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Post by richardm on Feb 3, 2024 7:57:59 GMT -5
Yes It is worth a tough Might need an input bearing upgrade for higher rpm and may be an oil lube system Nothing out of reach for an average builder
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monty
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Post by monty on Feb 3, 2024 10:42:46 GMT -5
Out of interest, what do you do for a living Monty? Im a test engineer, most of my work is in engine emissions so gearsets arent my specific area of expertise. What you've said makes sense, 50k rpm at 10kw is less than 2nm of torque lol. So yeah the bending moment is negligable. Do gears actually touch eachother in normal operation, or are they separated by an ehd film? I'm a mechanical engineer. I was once a test operations weenie for Lockheed. Eventually wound up doing product/mechanical design work. I'm a decent machinist, and like to cast things...In short: I dabble.. I dove deep on the gear design stuff when I was working on the gear reduction for my turbofan project. I wouldn't say I'm an expert. But I know enough to be dangerous. 
I'm not sure if the gears actually touch. I know the contact stress is a big issue. At the pitch line velocities we are talking about, no imperfection in the profile is acceptable. The problem is surface fatigue usually.
Monty
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noshell
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Post by noshell on Feb 3, 2024 23:12:09 GMT -5
Bloody brilliant idea. Reduction is actually too high. Its certainly doable though. I was thinking petrol disc cutter but theyre chain drive  |
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noshell
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Post by noshell on Mar 17, 2024 8:33:56 GMT -5
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richardm
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Post by richardm on Mar 17, 2024 9:42:07 GMT -5
That might be good idea if you feel confident enough to machine the back cover.
Also you talked about 50K rpm before Don't think this gear set will take it happily.
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noshell
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Post by noshell on Mar 17, 2024 10:03:47 GMT -5
I think i could make the rear cover.
As i said my understanding of gears isnt brilliant. The gears themselves look good quality, im thinking the limiting factor would be the bearings?
Feel free to correct me.
Id imagine these gears probably see 20k rpm in normal operation, assuming the engine revs to 10k and the cvt maybe doubles that.
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richardm
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Post by richardm on Mar 17, 2024 10:57:11 GMT -5
I dont think a scooter motor does 20 K rpm Maybe 10mK at the most..
Hard to telle about the bearings from the picture. I dont see any on the pinion input shaft. Could have been removed but the housing looks too small for a decent ball or roller bearing.It might be using Bronze sleeve?..
And the gears are possibly bathing in thick gear oil too..
may be a search for a part list schematic on this thing could shed some light about it
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richardm
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Post by richardm on Mar 17, 2024 11:19:43 GMT -5
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Post by wannabebuilderuk on Mar 17, 2024 17:02:48 GMT -5
Pretty good reduction going on and an alright price, worth having a play with I'd say. |
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richardm
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Post by richardm on Mar 17, 2024 17:56:41 GMT -5
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