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Post by racket on Dec 17, 2011 16:11:03 GMT -5
Hi Anders You could make the gearbox using straight cut spur gears ( bit noisy but you won't hear them over the engine noise ) with the driven gear splined onto your motorcycle angle drive , with the freepower mounted onto the other "outer cover" ....................duh , I can see this in my head but can't verbalise it :-( Its similar to the APU drive on my first bike www.ivcity.com/john/1257.jpg , simple to make :-) Cheers John
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Post by Johansson on Dec 17, 2011 16:21:23 GMT -5
Hi John, That sounds simple enough, so there is no need for any more advanced gear arrangements than just a small and a large gear? (with precise allignment and all that of course) Are straight cut gears better than angled ones for this? I don´t mind the noice. The "briggs" gearbox I bought earlier, what kind of HP rating did it have? Do you think it would be sturdy enough for 200hp with the oil mods or would it be better if I made my own gearbox like the one you showed in the picture? Cheers! /Anders
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Post by racket on Dec 17, 2011 20:19:44 GMT -5
Hi Anders
I think it might be easier to make your own gearbox considering the need to incorperate the ready made angle drive unit .
Most of the gas turbine starter units only use straight cut gears , no fancy/expensive helical gears , so yes a single set of gears is all you need , a pinion and driven gear with a ratio of ~6:1 or a tad less for your high speeds ,
The "briggs" gearbox is good for 17 hp at ~3,000 rpm , but the complication for you is grafting on the right angle drive , .......easier to make your own gearcase and mount the driven gear directly onto the input shaft of the angle drive
That setup for my turbine bike has never given trouble , the alloy casings on the IC motor have started to crack due to there not being any rubber mountings as on the brush cutter it was made for , the rigid mounting has meant the thin section castings aren't up to the job of containing the vibration from the 42cc engine :-(
We'll do some PM'ing on the subject ;-)
Cheers John
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Post by turbochris on Dec 18, 2011 8:54:59 GMT -5
I'm with John. Straight cut no end load and easy to set up. Adapting something to support the N2 bearings would be too much trouble, so you may as well make something yourself with a proper bearing arraignment and also use it to support your pinion. Then like John said use the 90 degree drive to hold the driven gear. Weld up a little case to hold it all together.
Try to make the N2 shaft tube and the area where the pinion is as small as possible with the driven gear underhung, that way you will have an easier time of turning the exhaust to go around the gearbox.
C'mon, guys, no PM's, I dont want to miss anything this is the part I've been waiting for! I'm 2 for 2 on hooking N2 to tires! Go free turbine or go home.......
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Post by racket on Dec 18, 2011 16:14:15 GMT -5
Hi Chris
LOL, too late , Anders and I have already had hundreds of PMs ;-)
Yeh , I agree , make something suitable rather than modify , it'll end up a more compact unit that way ...................after seeing Anders machining abilities it shouldn't be a problem .
I envisage a nice thick alloy plate , maybe 1"-25mm thick , that is securely fitted across the frame , a hole is bored into it that the right angle drive locates through at the back , the original mounting screws are fitted into the plate to hold it in place , the driven gear is a loose sliding fit on the input shaft splines .
The cast "cover" has a mounting pad for the freepower shaft assembly , the cover can be slid into position and fixed once the gear backlash is within specs , this is what I did with the bike APU and eliminates any need for precision boring of shaft centre distances , the straight cut gears will easily cope with any increase in backlash caused by the alloy expansion during running .
When I made the bike's APU "cover" , I made up a wooden pattern and got it cast , then it was a simple matter to machine the IC engine mount pad ( freepower shaft pad) and "pinion" hole thru the casting , ..............then turn up a mandril and mount the gearcase to it so that I could machine the case jointing face parallel to the IC engine mount , ...........................Anders case will be a bit bigger than my APU case , but not that big that it will be a problem , maybe only ~8 or 9 inches at its widest/highest.
Cheers John
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Post by Johansson on Dec 20, 2011 2:27:55 GMT -5
I could make one of the freepower cover bolt holes round and the rest milled in both directions so the cover can move and adjust the gear tooth gap.
Some sort of lockable adjusting screw would probably be needed to assure that the cover cannot move when the gears under load and try to push each other apart, wouldn´t want them to disengage with the gas producer at top revs... EDIT: Didn´t think that thought to the end before I wrote it down, if I move the cover I won´t have the shaft centered in the power turbine housing any more... With the new digital scales on my mill I can drill the gear shaft holes with a 5/1000mm precision so I think I can get it done without any adjustability at all. This sounds like a fun build, it was a while since I did some serious work on the mill.
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Post by ernie wrenn on Dec 20, 2011 8:22:45 GMT -5
How about a shortened rear differential out of a small car or truck. Cap one end and shorted other shaft to any length?
Ernie
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Post by turbochris on Dec 20, 2011 11:26:41 GMT -5
If you need any waterjet or laser work I'll donate. It's for selfish reasons. I want to see what happens when someone like Anders gets all the stuff in his head into projects. It's as much fun as giving little kids some guns and explosives to play with! Just get the video!
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Post by Johansson on Dec 20, 2011 15:41:45 GMT -5
How about a shortened rear differential out of a small car or truck. Cap one end and shorted other shaft to any length? Ernie I think it would be too bulky, but I might be wrong. I haven´t been too involved in automobile overhauling so I have little knowledge of rear differentials from cars.
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Post by Johansson on Dec 20, 2011 15:43:54 GMT -5
If you need any waterjet or laser work I'll donate. It's for selfish reasons. I want to see what happens when someone like Anders gets all the stuff in his head into projects. It's as much fun as giving little kids some guns and explosives to play with! Just get the video! Careful there Chris, I might hold you to that.
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Post by racket on Dec 20, 2011 16:46:50 GMT -5
Hi Ernie
When I was hunting around for a suitable redux to fit in my first turbine bike I looked at differentials , but most only have ratios in the 3-4 :1 range , though I did find a ~5:1 unit from a light commercial vehicle but it was still too big and bulky for a bike .
I then pulled apart a transmission from a small front wheel drive car , it had a large ratio diff helical gear set but the amount of work required to "remanufacture" the bits made it a no go :-(
Bikes are buggers of things to fit engines into , theres never enough room.
Cheers John
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Post by Johansson on Dec 30, 2011 11:59:03 GMT -5
After some well deserved rest at my parents place I found some time today to make a new and better way to mount the preheat fan than before when I had a plastic bottle as the nose cone. I used a 3" tube bend to make the new air nozzle. Here is the fan securely mounted with duct tape. Cheers!
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Post by racket on Dec 30, 2011 17:13:10 GMT -5
Hi Anders
That'll get a blast of cooling air going into her :-)
Cheers John
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Post by Johansson on Jan 10, 2012 17:19:28 GMT -5
Since I am still waiting for the damn Autometer fuel pressure gauge to arrive from the US I made a temporary solution with an industrial gauge and a homemade coupling. I will do some fuel pressure tests later this week and if everything goes as planned I will run her again this weekend. This time I will: * Measure the absolute pressure in the jet pipe * Measure RPM at different P2 settings * Monitor the fuel pressure and try to figure out why the revs fluctuate above 2.6PR Sounds like a fun evening to me! Cheers!
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Post by racket on Jan 10, 2012 19:53:02 GMT -5
Hi Anders
Sure does :-)
Cheers John
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