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Thread: Transmissions. yeah.

              
   
   
  1. #21
    Senior Member Brutus's Avatar
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    Quote Originally Posted by Richard230 View Post
    Could the substantial torque of an electric motor, compared with an IC engine, make life tough on a transmission and clutch setup?
    More so on the clutch than the trans, truth is you do not need the clutch in electric because letting off the throttle "unloads" the trans making it shift like butter.

  2. #22
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    I was wondering about how the clutch would work in the Brammo system. When I spoke to the Brammo staff earlier this year, I was told that the transmission system would employ a clutch and one of their design issues was getting the clutch to work like one on an IC motorcycle when shifting between gears. Up until that point, I didn't think a clutch would be necessary.

  3. #23
    Senior Member Brutus's Avatar
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    That is interesting because I had the same "feel" issues on Brutus. An electric motor doesn't want to continue spinning when the throttle is off and it wreaks havoc with the clutch and shifting feel. I decided to eliminate the clutch all together and it hasn't had a single issue yet. The hardest part to get used to is remembering that it is a brake lever now and not the clutch

    There are a few ways to correct the clutch issue I just felt it wasn't worth the cost or time to continue with the clutch just to have it.
    Last edited by Brutus; 01 January 2012 at 1923.

  4. #24
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    Quote Originally Posted by Brutus View Post
    truth is you do not need the clutch in electric because letting off the throttle "unloads" the trans making it shift like butter.
    Not exactly- upshifting yes (reduction in ratio) only requires an "unload" however downshifting requires an "unload" via raised or lowered RPM's depending on the current torque command (i.e. rider is off throttle because they are braking for a corner requires an RPM increase to "unload" as the gears are loaded by the rear wheel and not the motor) followed immediately (.040 sec's max.) by a raise in the motors RPM (blip) to match the increased ratio change and current wheel speed then followed by an RPM reduction to employe desired engine braking effect, easy in theory, very hard (and risky) in practice.

    There are other, very advanced theories but too difficult (and unnecessary) to explain here, at this time. The clutch (unless executed perfectly) is a VERY costly addition...

  5. #25
    Not to be taken seriously DaveAK's Avatar
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    101 ways to skin this cat, but if I'm going to be putting in two motors then I'd be looking at serial/parallel switching. If I were going with a transmission I'd go with two or three gears depending on what I needed. As it so happens the bike that I have works for my needs with just a single motor and a single gear. I've considered all three options and will continue to consider them for any future projects, as they all have their merits. All the torque curves in the world won't get you anywhere unless you can apply them to any given design situation. As someone mentioned above it all depends on your design needs, and whatever you end up with will always be a compromise based on any number of factors. That's just the nature of the beast.

    Quote Originally Posted by mechanic
    As far as helping. Most of my posts have information in them, even may last one; my ass spoke and said "look to the curves", if you choose to use it or not is your decision.
    That's not helping though. Giving someone a set of torque curves is meaningless without some explanation. It's the explanation that's the helping part. Noah could give me any number of textbooks and tell me go read them, but that wouldn't teach me physics. Likewise Ted could give me a camera and a bag full of lenses and filters and I wouldn't be able to just go out and take a picture of a beautiful landscape. If you really want to help then you need to expand a little on the point you're trying to make.

  6. #26
    Senior Member Brutus's Avatar
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    The whole downshift "theory" is a little flawed because of the whole compression thingy going on with an ICE motor. I can shift from 5th to 2nd and not experience anything you are describing.

  7. #27
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    You are not running any significant regen and an induction motor?

  8. #28
    Senior Member Brutus's Avatar
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    Quote Originally Posted by mechanic View Post
    You are not running any significant regen and an induction motor?
    No regen and I am quite fond of the series dc that I started with.

  9. #29
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    Quote Originally Posted by Brutus View Post
    No regen and I am quite fond of the series dc that I started with.
    I suspect this is not a sport bike? With regen, downshifting will become more challenging.

  10. #30
    Senior Member Brutus's Avatar
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    Quote Originally Posted by mechanic View Post
    I suspect this is not a sport bike? With regen, downshifting will become more challenging.
    I am not interested in regen and don't think it would work well in the system I built. I did stumble onto something that eliminates all the issues with shifting you talk about. Since you are a transmission guy you will smack your head when you see what it is.

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