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Old 01-04-2006, 01:44 AM   #16
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Originally Posted by PitCrew
I agree that for the RC 1/10 application, using a shifting gearbox is probably not going to be any benefit to the overall performace of the car.

If one could be produced, that was extremely effecient and lightweight, I would suggest a constantly variable transmission.

All electric motors have a power curve similar to I.C. The transmissions could be tuned to stay within the motors power curve for increased acceleration and run time. Mainly, you would want to stay within the most effecient part of the motors curve.

But we just race toy cars...
CVT would be good idea for RC.. but I haven't see any design which make it small and lightweight enough to put it on RC... anyone have a good link with lightweight, small size CVT?
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Old 01-04-2006, 02:45 AM   #17
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The reason Nitro cars have 2 or 3 speed transmissions in because a nitro engine has very little torque in the lower range. The lack of torque means that a nitro engine would find it very hard to pull a tall gear ratio off of the line. An electric motor however has a linear torque curve meaning that it can pull a higher gear ratio off of the starting line.

If you were to take an electric motor that maxed out on the dyno at 40,000 revs and compare it too a Nitro .12 that maxs out around the same mark. Put the same Final drive ratio in each car and drag race them the electric car would blow the nitro car away because it would reach full speed much much earlier.
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Old 01-04-2006, 03:17 AM   #18
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2-speeds don't have much of an effect on an electric motor. Nitros benefit from a 2-speed because engines create maximum power at high rpm. The 2-speed is there to provide an easier first gear, so the car can accelerate more quickly. The transmission doesn't really increase top speed, it just decreases the time required to reach top speed. Electric motors develop maximum power at low rpm and don't need an easy first gear to accelerate well. At high rpm, an electric motor doesn't have the power to exploit an upshift to a lower gear ratio. Two-speed trannies aren't often seen in electric vehicles simply because the minor potential for performance gain is usually outweighed by the cost and complexity of a 2-speed system.
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Old 01-04-2006, 04:18 AM   #19
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PB had a 4wd buggy back in the mid 80's called the Mini Mustang (and it's followup the Maxima then the Ace). These had 2 speed transmissions fitted which were quickly outlawed based on the performance advantage they offered - and that's in offroad where the difficulty of unwanted gear changes over bumps and jumps plays a part. I have no doubt that given the freedom to do so, ep tourers would be much quicker with 2 speed boxes and motors tuned/designed to make the most of them.
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Old 01-04-2006, 04:30 AM   #20
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I doubt it would ever be a mainstream reality.
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Old 01-04-2006, 05:13 AM   #21
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Also Yokomo tried a 2 speed in their first touringcars but was meant for backyard bashers.
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Old 03-14-2006, 01:35 PM   #22
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how does this work?

it says : Features:
-Nova Two Speed Transmission is an one-piece design, it is easy to assemble and compatiable with many RC cars. and blah blah blah

but I think it's too long or wide for many cars, and how can it fit?
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Old 03-14-2006, 02:15 PM   #23
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I think the HPI Pro2 had a 2-speed once.
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Old 03-14-2006, 02:56 PM   #24
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should work, i think T-MAXXs shift via button on transmitter.
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Old 03-14-2006, 03:49 PM   #25
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the reason nitro cars need a 2 speed is because of the need to produce torque.if you use just one speed or two it would produce the same top speed.
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Old 03-14-2006, 04:49 PM   #26
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How can you have a linear toqrue curve
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Old 03-14-2006, 06:08 PM   #27
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Originally Posted by John_Stones
How can you have a linear toqrue curve
Yeah, I was thinking the same thing. Wouldn't it be a linear torque line?
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Old 03-14-2006, 06:27 PM   #28
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I had a 2 speed for my hpi rs4 before, it's pretty neat. But it doesnt shift at the right time, that I have adjust it, sometimes it won't even shift. When it does shift, you can see it move and hear it too, especially out of a turn to straight.
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Old 03-14-2006, 06:31 PM   #29
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I don't think that will fit...
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Old 03-14-2006, 06:40 PM   #30
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Originally Posted by nekmiyevo2
just wondering...
is it possible to make the electric on-road cars switch gears like the nitro ones?
how do they work anyway? (I am quite new in RC)
Seems everybody explained why they aren't used in electric but not how they work. It's basically a clutch. Springs retain a set of shoes, that as the RPMs increase, let the shoes touch the clutch bell(centrifugal force), and engage the second gear. 1st gear is on a one way bearing, so as the clutch engages, 1st just free-wheels so to speak. The taller second gear does all the work, until you slow down. When the RPMs decrease, 1st gear takes back over. Very simple, and effective system. But as I'm sure it's clear by now, it's not really effective with electric cars.
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