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.

I think go with Constantly-variable (CVT).

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

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.

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.

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.

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?

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.

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.

Lion EV (http://www.lionev.com) 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.

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.

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.

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

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.

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.

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.

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... ;)

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.

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 ...

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 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.

If it can already get 40 miles range EOL (30 IMO), any additions or changes in design better add needed reliability, safety, or be very inexpensive.

My 2 cents -- keep it simple on the Gen 1 Vehicle. Why add complexity, and it

First off, when I was at Volt Nation I directly asked one of the engineers about a transmission in the Volt. He looked at me like I was a complete idiot and asked; "Why would you want one?" He then stated emphatically that the Volt will not have a transmission. Of coarse Tesla instantly came up and his response was, "Oh, well they just were doing that to get faster performance." When it was pointed out that even electric motors have a sweet spot in RPM range where they are most efficient, he did concede that the problem was building a transmission that could hold together reliably at over 10,000 RPM, and that this was the problem that caused Tesla to give up.

Unfortunately you don't get unlimited time to discuss things with these guys at an event like this. On reflection afterward I remember him telling me just after asking "Why would you want one?" that the irony was he started his career in the transmission division of GM. Well, what's the only kind of transmission GM has ever spent any time developing? Automatics. So I suspect that in their mind, any transmission for the Volt would have to be an automatic thus it becomes problematic.

All this got me to thinking later. Lots of people will tell you, "You don't need a transmission." and that's true, but back in the '60s Chevrolet would sell you a Malibu that had a transmission with only 2 speeds and you could drive that car anywhere at any speed. So clearly you don't need the 6, 7 and 8 speed automatics you see today delivering mpg near manual tranmissions. I still believe a two speed manual could be beneficial to an electric car. Clearly if they are planning on turning the motor at 10,000 RPM and above, there needs to be a gear reduction somewhere to slow that down at the wheels. It seems that if a transmission can't handle over 10,000 RPM, then put the gear reduction just before the tranny.

Gear reductions and transmissions add complexity, expense and energy losses associated with them, so some math has to be done to see if there is any real benefit in range or if it does improve 0-60 times how much do we have to sacrifice in range? It might be worth it. Clearly in the interest in getting the Volt out as fast as possible and as cheap as possible things like a performance transmission are right out. However, I don't believe that the subject of transmissions in EVs is going away.

It seems that if a transmission can't handle over 10,000 RPM, then put the gear reduction just before the tranny.

That is so simple / obvious as to be brilliant. You are right that it may cause a small amount of running losses, but you could determine whether or not there might be a small overall gain by running in the right gear.

Another aspect of the argument is this - if all the energy you are using is clean, cheap and plentiful - who cares if you sacrifice some efficiency for performance. If you can afford, then there is no harm to the rest of society.


However, I don't believe that the subject of transmissions in EVs is going away.

I agree. Now that Tesla and Aptera have announced serial hybrid versions of their vehicles, competition is going to force similar platforms look for performance advantages to grab more market.

I agree. Now that Tesla and Aptera have announced serial hybrid versions of their vehicles, competition is going to force similar platforms look for performance advantages to grab more market.

I doubt that Tesla or Aptera really blimp much on GM's radar as anything besides a marketing flash. With even the first year production numbers for the volt (10,000?) being met GM will produce more volts in a week than Tesla AND aptera will make all year (there respective cars, not volts).

So, i dont really think that GM is worried about what Tesla or Aptera are doing besides seeing what technologies are working for them.

Back on the topic of transmissions. The main reason for a transmission on a ICE engine is that the motor is really only efficent in a narrow power band and that range is well above 0 rpms.

Electric motors are capable of full power at 0 rpms, so you dont need a neutral position. The motor can be run backwards for reverse. So as long as you dont put in additional forward (and reverse) speed you dont need a clutch(or automatic clutch, a stall converter makes no sense attached to an electric motor).

So why add the complexity, weight, and cost?

So why add the complexity, weight, and cost?

In the first few years of EV's being produced, I would be surprised if they do have transmissions, but after several years, automakers will start introducing transmissions as a performance differentiators, to beat EV's within their own market space, and to draw customers away from ICE high performance vehicles.

I disagree about the future of EV's. I think that the motor is where most of the performance increases will come from.

I believe that the move will be towards lighter more powerful DC motors that will probably be moved to the hubs (maybe with short axles to avoid unsprung weight).

I think the big advantage that the electrics will have over the ICE's will be the flexibility in delivering the power to the wheels without a heavy, oil needing drive train.

A Little off topic but i think that the EREV's future and product differentiator(sp?) will be in the Range Extender. Who will be the first to offer a diesel, microturbine, fuel cell. you name it. When you disconnect the generator from the wheels you gain a lot of flexibility.

I disagree about the future of EV's. I think that the motor is where most of the performance increases will come from.

I believe that the move will be towards lighter more powerful DC motors that will probably be moved to the hubs (maybe with short axles to avoid unsprung weight).

I think the big advantage that the electrics will have over the ICE's will be the flexibility in delivering the power to the wheels without a heavy, oil needing drive train.

A Little off topic but i think that the EREV's future and product differentiator(sp?) will be in the Range Extender. Who will be the first to offer a diesel, microturbine, fuel cell. you name it. When you disconnect the generator from the wheels you gain a lot of flexibility.

I agree with all that, but I still believe some manufacturers will offer transmissions - we are going to see an explosion of configurations in the next few years, including all that you listed above.

So why add the complexity, weight, and cost?

For performance and effiecency. Every motive system has a range in which it is most effiecent. Electric motors are no different. Sure you dump more power into the motor and it'll go faster, to a point, but at what point in that range of operation does the motor start to perform less effectively? Gearing allows the use of smaller motors.

You've got to wonder, if the electric motor makes all it's power at 0 rpm and flat all the way up, why then is GM planning to put a gear reduction in at the rear axle? The GM engineer I spoke to at Volt Nation assured me that this was the case. I believe they do this so they can use a smaller motor that draws less power. Now imagine a transmission that might allow you to use an even smaller motor. Smaller motor means maybe less power consumption and If nothing else, faster eccelleration and better hill climbing.

At some point the numbers have to be crunched to see if it really is of benefit or not. I seriously doubt that more than two speeds would be of help. I have heard that in the case of folks with gas to electric car conversions that they have found that one gear ratio works better in city driving and another better on the highway for range. My feeling is that this would be the case with the Volt too, but to keep the project cheaper and faster, the engineers skiped it.

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.

The characteristics of electric motors make multi-ratio transmissions LESS necessary than in vehicles with internal combustion engines.