Power in Flux
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Thread: Transmissions. yeah.

              
   
   
  1. #191
    Senior Member Ted Dillard's Avatar
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    Yeah, like I said, it's about finding stuff later. Go on ES and look at threads that are 43 pages long, and cover 6 topics. I'm only saying this because I've spent a lot of time doing just that. My opinion, you want to talk about dual motors and thrash around ideas about that? Have a blast, on a Dual Motors vs Transmission Random Speculation thread. Then, old bastids like me can find them, if per chance someone actually comes to some conclusions that make sense.

    Please do me a favor and stop trying to troll me out into this "discussion". Old Ted, new Ted, I left this forum for several very good reasons, and I'm starting to reconsider recently re-joining it.

    ...back to the peanut gallery. Done with this foolishness.
    Last edited by Ted Dillard; 03 April 2018 at 1211.
    Power in Flux: The History of Electric Motorcycles
    www.powerinflux.com

  2. #192
    Senior Member T Rush's Avatar
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    oh then, I tried

  3. #193
    Senior Member Ted Dillard's Avatar
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    27,000 views on this thread. wow.

    I was waxing sentimental, and went back and started reading it again. This thread, mind you, was after months, if not years, of discussion, research, illustration, and actual attempts at proof of concept and use. Not to mention some very heated debate. Not at all an easy thing to manage, considering the nature of a forum and the internet.

    In spite of all that, it was a great, respectful (for the most part) discussion, if not final conclusion, amongst people who were committed to building bikes. Funny story, that one guy, mechanic, was the one standout, typically pretty snarky and abrasive, and pretty opinionated. At one point the moderators tracked his IP, and it turned out it was coming from the office of one of the most talented and brilliant engineers/builders on the planet. Even with his snark, after that, the people who knew tended to at least try to understand his points.

    Now we're in a much different time... and the transmission discussion has some real, actual testing and demonstration out there, as I've said before. Kinda cool.

    What can I say? I'm a history nerd.
    Power in Flux: The History of Electric Motorcycles
    www.powerinflux.com

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  5. #194
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    Quote Originally Posted by Richard230 View Post
    I still like the concept of using a compact two-speed transmission on an electric motorcycle, but finding an off-the-shelf transmission like that that is of the correct size and has sufficient torque capacity, is likely to be a real challenge.
    Since I didn't see a mention of it keep in mind that the ICE transmission/clutch needs to be designed for the torque spikes, and not just for the average/nominal peak torque.

    I talked with an engineer at Tilton (race car clutches) about clutches many years ago when I had a small-block Guzzi hopup project. He said they'd built a clutch for the 1000cc Wittner Guzzi endurance racer based on the torque shown on dyno runs. It didn't do the job. They had not done a clutch for a big twin like that and hadn't taken into account the torque spikes, and they ended up with a lot higher capacity clutch on the redesign.

    So a transmission for a 100 hp 4-8 cylinder ICE is likely to be much less beefy than a 100 hp twin, because the multi is having a lot of small torque spikes from the multiple small cylinders (bangbangbangbang) vs the large and less frequent events (BANG . . . BANG . . . BANG) hammering of the twin.

    So I'll speculate that a 50 hp e-motor with a smooth/constant flow of power might get away with a lighter transmission than a 50 hp 4T single would need. A 50 hp 2T single will use a lighter gearbox than the 4T because the power events are twice as frequent and the BMEP is significantly less.

    Of course, all that is of only academic interest if you aren't going to put a transmission on your electric vehicle.

    cheers,
    Michael

  6. #195
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    Quote Originally Posted by Michael Moore View Post
    Since I didn't see a mention of it keep in mind that the ICE transmission/clutch needs to be designed for the torque spikes, and not just for the average/nominal peak torque.

    I talked with an engineer at Tilton (race car clutches) about clutches many years ago when I had a small-block Guzzi hopup project. He said they'd built a clutch for the 1000cc Wittner Guzzi endurance racer based on the torque shown on dyno runs. It didn't do the job. They had not done a clutch for a big twin like that and hadn't taken into account the torque spikes, and they ended up with a lot higher capacity clutch on the redesign.

    So a transmission for a 100 hp 4-8 cylinder ICE is likely to be much less beefy than a 100 hp twin, because the multi is having a lot of small torque spikes from the multiple small cylinders (bangbangbangbang) vs the large and less frequent events (BANG . . . BANG . . . BANG) hammering of the twin.

    So I'll speculate that a 50 hp e-motor with a smooth/constant flow of power might get away with a lighter transmission than a 50 hp 4T single would need. A 50 hp 2T single will use a lighter gearbox than the 4T because the power events are twice as frequent and the BMEP is significantly less.

    Of course, all that is of only academic interest if you aren't going to put a transmission on your electric vehicle.

    cheers,
    Michael
    Like Brammo.
    Richard - Current bikes: 2018 16.6 kWh Zero S, 2016 BMW R1200RS, 2011 Royal Enfield 500, 2009 BMW F650GS, 2005 Triumph T-100 Bonneville, 2002 Yamaha FZ1 (FZS1000N) and a 1978 Honda Kick 'N Go Senior.

  7. #196
    Senior Member Ted Dillard's Avatar
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    Power in Flux: The History of Electric Motorcycles
    www.powerinflux.com

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  9. #197
    Senior Member Stevo's Avatar
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    LOL... now that's funny shit, I don't care who you are!! (But Ted, look at your view count NOW!!)

    I agree with Michael though, I was toying with the idea of using a tranny out of a YZ125 (2T) when I first started this adventure years ago... though with only 3 gears instead of 5.... I just settled on the idea that it was way more complexity than was needed.
    Last edited by Stevo; 1 Week Ago at 0957.
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4
    Current builds: http://elmoto.net/showthread.php?t=4354

  10. #198
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    A friend told me of some simulations he did for a clients e-scooter project some years ago.

    This was a 45 mph top speed, 770 pound total weight with rider, lead acid battery, 10.2 kW continuous power simulation. He compared the direct drive version against a CVT with a 4:1 speed range. He pointed out that if the final drive is optimized for high steady-state cruising speed then it is a wash on either version when they are operating at that cruising speed. But the CVT version had much better acceleration to speed as well as enhanced range if operating in the "less than maximum" speed range (as with in-city use). At that time and for that project he felt trading L-A battery mass/space for the CVT would have been a good choice.

    Direct drive time to top speed was 40 seconds and the CVT reached it in about 15 seconds. For a 40 second run the direct drive would have covered about 590 meters and the CVT version about 720 meters. Energy efficiency against distance traveled for 600 meters saw the direct drive at about 35% driving efficiency at 100 meters and 70% at 600 meters, while the CVT was about 78% at 100 meters and 91-92% at 600 meters. The CVT curve on that last rose steeply to 100 meters and then was pretty flat from 400 meters on while the direct drive curve was rising the entire distance and presumably would have needed more distance to reach top speed and equal efficiency with both running on an final equal gearing..

    But that was then. He told me he saw the situation now as being like with personal computers -- if you want better performance you don't optimize the code, you just add more CPUs and RAM to the PC. With modern motors and controllers and batteries performing better for less money it is easy to add more battery and higher power motor/controllers and have direct drive work fine and there's not as much need for a transmission for efficiency. He did say that doesn't invalidate the benefits of some sort of transmission in variable speed use, but the payoff in the riding experience is smaller.

    I'd guess that if you are handed a low power system to use for stop/start traffic and then told that's all you are going to get then you may want to give serious thought to some sort of variable speed transmission.

    YMMV,
    Michael
    Last edited by Michael Moore; 1 Week Ago at 1426.

  11. #199
    Senior Member Stevo's Avatar
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    I still think a 2 or 3 speed tranny for use in a true dual sport would have advantages on an emc. A nicer, usable low end to power through technical single track and up/down slippery hills, then throw Hwy speeds and city commuting into the mix. But, is it necessary? Especially after next gen batteries lose some weight. Tranny=Added complexity, added weight, & power lost thru mechanical losses

    Well, The Guys at Alta think so!
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4
    Current builds: http://elmoto.net/showthread.php?t=4354

  12. #200
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    An acquaintance who is a very fast MXer had a test ride on an Alta and he gave it a very positive review and liked it a lot.

    Yes, next-gen batteries+next-gen motors/controllers will probably put the transmission question off the table for very many applications. But I suspect it is a good idea to be open to using them IF it appears that will give the best results for a particular project. It is easy to let preconceptions blind one to potential solutions.

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