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Discussion Starter #1
It seems that it may be best to have a 5 speed transmission, as Tesla's big problem was dropping the high RPM's (13,000) down to the speed required for 2nd gear (6,000 - 7,000). It would be the same if you were driving 100 mph and tried to drop into first gear. If GM had a 5 speed, then the gear ratios could be close enough so that the transition wouldn't be so severe - 13,000 down to 11,500, worst case.
 

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I think go with Constantly-variable (CVT).

Anyway, I'm sure they've investigated all kinds of transmissions.
 

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Discussion Starter #3
Tesla Motors Chairman Elon Musk stated that their engineers have developed a motor that does 20,000 rpm, so a single reduction gear would be all a vehicle needs, no shifting of any kind. The transmission has now been obsoleted, as reverse is simply achieved by running the motor backwards.
 

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Tesla Motors Chairman Elon Musk stated that their engineers have developed a motor that does 20,000 rpm, so a single reduction gear would be all a vehicle needs, no shifting of any kind. The transmission has now been obsoleted, as reverse is simply achieved by running the motor backwards.
That's true; although, citing the maximum RPM is kind of meaningless without a torque curve. Electric motors are usually the polar opposite of gas engines terms of torque. They produce the higest torque at the lowest RPMs instead of vice-verse. So, a traditional transmission is kind of usleless in that case.
 

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Discussion Starter #5
That's true; although, citing the maximum RPM is kind of meaningless without a torque curve. Electric motors are usually the polar opposite of gas engines terms of torque. They produce the higest torque at the lowest RPMs instead of vice-verse. So, a traditional transmission is kind of usleless in that case.
Fortunately, you only need torque to accelerate, which you tend to do at low speeds. I suppose the only concern is how well you can hold 125 mph on a 6 percent grade.
 

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Forgive me if I'm wrong, but I thought there would be no transmission on the Volt. Part of the concept, with which I'm not too familiar, I thought is to reduce the number of parts and thus weight: No drivetrain or transmission and all power by wire?
 

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I also want to join the "no transmission" club. I'm expecting the motors to eventually make it to the hubs so that there are four individually controlled motors with minimum part count and added weight. I'm confident the engineers of the world will come up with great wheel-hub motor designs in the future. Just think how nice it would be to be able to switch out a bad motor in 15 minutes. These motors should last well over 100,000 miles and may not even need brake pads. When we talk about the electrification of the automobile I guess we should also talk about the simplification of the automobile.

Start with a full carbon nanofiber body and frame in a fully automated production facility, add wheel-hub motors, a four-way motor controller, nanowire battery, solar panel, battery charger for plug-in and you are good for around 500,000 miles! Switch out the battery every (insert new spec. here), change the wheel-hub motors every 250,000 miles, Solar panel should be good for at least 25 years, same for the carbon fiber body. Well, you get the point. At the end of the life cycle the car is fully recycled.
 

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Discussion Starter #8
Start with a full carbon nanofiber body and frame in a fully automated production facility, add wheel-hub motors, a four-way motor controller, nanowire battery, solar panel, battery charger for plug-in and you are good for around 500,000 miles! Switch out the battery every (insert new spec. here), change the wheel-hub motors every 250,000 miles, Solar panel should be good for at least 25 years, same for the carbon fiber body. Well, you get the point. At the end of the life cycle the car is fully recycled.
I believe the convergent configuration in the future will be:

1) all 4 wheels will be driven directly by motor(s) (4, 2 or 1 motor) for most efficient regenerative braking performance
2) energy storage will be battery or supercapacitor
3) range extender (gas/diesel/alcohol/natural gas/hydrogen ICE, hydrogen/alcohol fuel cell, compressed air) will be standard, unless rapid recharge batteries with accompanying charging stations become available

I don't think exotic building materials (carbon fiber, etc.) will be necessary in the long term, as performance / efficiencies reach satisfactory levels to allow cheaper / heavier materials to be used.
 

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5 speeds is a bit much

Lion EV is a company that converts Ford Ranges to all electric power. They use the existing transmission and drive train.

Interesting thing from the site is that they dont recommend selecting any gear lower than 3rd (i believe the range has a 5 speed) because of the amount of torque that the DC motor has. They state that unless you are towing up a hill 1st and second gear are completely unnecessary. Also 4th and 5th could be selected for better mileage but where also not needed.

While i like the idea of being able to change gears for better economy. I wonder if the benifits of slightly higher gearing really out way the cost of having (and eventually repairing) a transmission.
 

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What sells

Transmissions aside,The Volt does need to be simple. The owner of Tesla was quoted in an NBC interview that the Tesla had only 17 moving parts. That type of simplicity would translate into a car lasting nearly a lifetime. I currently drive an Aveo, a very simple car, yet it has hundreds of moving parts. I hope the Volt will have sexy styling and affordability and simplicity. I like my Aveo, but the styling is VERY basic. It's like driving a refrigerator carton.
 

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just desserts

Fortunately, you only need torque to accelerate, which you tend to do at low speeds. I suppose the only concern is how well you can hold 125 mph on a 6 percent grade.
Anyone who is trying to do 125 on a 6% grade is going to get what they deserve.

If the Volt can only do 80, that's fine by me. I'd rather have a low (though not too low) top end, and have a less complex car. I don't want a 5 speed transmission, just a 5 gauge.
 

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About the number of moving parts on a modern automobile I found this answer on the web (see below) and it seems about right. The number given was over 10,000 moving parts. I just think about a modern ICE, transmission, differential, U-joints, suspension, etc. and the number of moving parts just grows and grows. I wrote before that I understand how concerned automobile companies are about how the reduction of moving parts, when a full EV design is considered, will affect their business but these numbers only shows just how extreme that reduction is! The auto parts market is where the big auto companies make a lot (if not most) of their profits. However, that is where the industry is going and business plans will have to change accordingly. Just think, if you can get an inexpensive 4 wheel wheel-hub motor drive system from PML Flightlink (for example) connect that to an inexpensive nanowire lithium-ion supercell and we are talking about a potential platform with almost no maintenance required. I can't wait to see what the 2020 EV models look like!


Here are two general estimates of the number of moving parts:

"When you consider that a car has more than 10,000 moving parts and
more computing power than the Apollo moon launch, it is easy to
understand why the sale of such a complex machine requires
regulation."

National Automobile Dealers Association
http://www.nada.org/Content/NavigationMenu/MediaCenter/Press_Releases1/20032/reg_5_27_03.htm

"Traditional combustion cars, on the other hand are extremely complex
machines that have around 10,000 moving parts."

Better World Club
http://www.betterworldclub.com/newsletters/v5/memberletter.htm

This is the most specific figure I have found, but it does not apply
to any particular model of Chrysler:

"Gold Plan provides repair cost protection to the mechanical and
electrical components on your CHRYSLER car or light truck, from the
engine and transmission to the sophisticated electronic computers and
modules common in today's vehicles. There are over 14,000 moving parts
in your vehicle. Except for specified parts and services, they are all
covered by Gold Plan."

Carter Chrysler
 

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Discussion Starter #13 (Edited)
Texas,

There aren't 10,000 parts in a vehicle, unless you start counting capacitors on circuit boards and stitches in upholstery.

I suppose, given that the whole car moves forward and backward, that you can claim all these parts are "moving", but the number of parts actually moving relative to the chassis is at least one order of magnitude fewer than that. Moreover, if you want to eliminate parts like lug nuts, etc., that are moving relative to the chassis, but aren't really moving relative to their adjoining parts, the count drops even further.
 

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Jason, I'm only quoting what came from the listed sources. Probably includes Every moving part including screws but I'm not going to count them. Since you are so sure, how many parts are there? I'm sure it's quite a lot if you include things like knobs and switches, relays, engines, transmissions, pulleys, suspensions, U-joints, seats, doors, hinges, slides, etc. You are so quick to discount the quotes but not so fast to tell us how many parts there are. Please enlighten.
 

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Discussion Starter #15
I got my information from following the Tesla Motors website and news articles, where Martin Eberhard estimates 200 moving parts for the typical engine. Double that to include the drive train, and you have 400 - not very accurate, but certainly puts a good upper bound on reality, especially if you ignore lug nuts, etc. That is far, far below a count of 10,000.

Now there may be many, many parts in the engine and drivetrain, but not that many, and far fewer that create power and transmit it to the tires.
 

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Ok, since we both don't know the actual number then maybe we can agree that the number of moving parts is reduced greatly by using only wheel-hub motors and a battery. Add to that a simple touch screen display for all control, fly-by-wire controls, electric braking, etc. and you begin to see how the auto companies are worried about spare parts revenues. Hey, is there anyone out there that has accurate data for the number of parts in a modern ICE vehicle? If any of you GM engineers are reading this... ;)
 

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I can understand not needing a transmission. But if a simple one was created with maybe 3 speeds, wouldn't that be enough to cut down on battery depletion based on say 15K RPMs to 3K RPMs during Highway usage? Transmissions are the most complex systems in cars today- and they are heavy. Maybe the pros and cons should be weighed.
 

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Discussion Starter #18
I can understand not needing a transmission. But if a simple one was created with maybe 3 speeds, wouldn't that be enough to cut down on battery depletion based on say 15K RPMs to 3K RPMs during Highway usage? Transmissions are the most complex systems in cars today- and they are heavy. Maybe the pros and cons should be weighed.
That's all I'm saying ...
 

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No Need for Transmission

I don't pretend to be an authority on electric drive, but it is used in locomotives and on some fairly large ships.

I believe the drive for the Volt will use a synchronous permanent magnet motor with a variable speed drive. See this link for more info:

http://www.freescale.com/webapp/sps/site/overview.jsp?nodeId=02nQXGrrlPZL8l

Note the speed range for the motor can be 0 to 20,000 rpm. With this design, the speed of the motor is controlled by the input frequency of the power. And I believe the specifications for the Volt call for a 3 phase AC motor. I also remember that this type of drive was used for the EV-1, because synchronous motors are very efficient.

With this speed range, I don't believe there is a need for a transmission.
 

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Discussion Starter #20
I don't pretend to be an authority on electric drive, but it is used in locomotives and on some fairly large ships.

I believe the drive for the Volt will use a synchronous permanent magnet motor with a variable speed drive. See this link for more info:

http://www.freescale.com/webapp/sps/site/overview.jsp?nodeId=02nQXGrrlPZL8l

Note the speed range for the motor can be 0 to 20,000 rpm. With this design, the speed of the motor is controlled by the input frequency of the power. And I believe the specifications for the Volt call for a 3 phase AC motor. I also remember that this type of drive was used for the EV-1, because synchronous motors are very efficient.

With this speed range, I don't believe there is a need for a transmission.
I agree there may not be a real "need", but when everybody is building E-REV's, competition may force some automakers to eek out just a little more range / performance, which could be easily had from a transmission.
 
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