2 Speed Gearbox

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iwyze
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Post by iwyze »

Hey Paul, have you checked out the 2 speed gearbox discussion on endless-sphere.com ? Jaron

http://endless-sphere.com/forums/viewto ... =7&t=17794

procrastination inc
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Post by procrastination inc »

how about something like a torque converter with a centrifugal lock-up clutch driven of the output shaft?

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Post by Electrocycle »

I think that was mentioned earlier in this thread :)

I think it'd work pretty well in the right setup. Plenty of take off torque, and direct drive efficiency when cruising.
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Post by EV2Go »

iwyze wrote: Hey Paul, have you checked out the 2 speed gearbox discussion on endless-sphere.com ? Jaron

http://endless-sphere.com/forums/viewto ... =7&t=17794


That's just a rip off (lets call it a copy) of my design from last August http://aeva.asn.au/forums/forum_posts.asp?TID=1028&PN=8

I contacted PPG a while ago to see if they could provide me we some custom made gears, but they never bothered to get back to me. Their website claims they can make them, but clearly they are not interested in making money.

I am going direct drive as I don't have a lot of space to play with but I would have liked a really basic two speed (say no more than 4 or 5" long) that is inline between motor and tailshaft, and preferably bolt up to the Kostov motor.
Last edited by EV2Go on Fri, 07 May 2010, 05:56, edited 1 time in total.

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Post by NSVD »

Sorry, can't be bothered reading through 11 pages. Planetary gear sets have been an of the shelf item for years, they're small, and most(if not all) come 1:1 to any ratio you want. Pretty sure electric shift is on the market now don't know who makes them though.

Example of installation: http://www.jimerico.net/index.php?main_ ... ge&pID=183
Example of manufacturer: http://www.lencoracing.com/CS3MasterPage.html

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Last edited by NSVD on Thu, 27 May 2010, 18:44, edited 1 time in total.

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EV2Go
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Post by EV2Go »

Thanks Joel and welcome to the forums. A Lenco was suggested previously in jest, but I don't know why it didn't dawn on me sooner that a Lenco was a planetary gearbox (being modular and all).

I just "assumed" to my detriment that because they handled such high horsepower that they would be some heavy gear driven box.

Hmmm wonder if it is too late for a redisgn... Really like the look of that first one you posted, looks ideal for EVs.

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Post by EV2Go »

Well after 11 pages of discussion I may have finally found the answer... I stumbled across two potential candidates.

The first I flicked an email to Jim Husted about a picture that is posted on his website. Picture here of dual motor and trans

he said a customer brought it in and it was a "Gear Vendors", their website listed here, Gear Vendors

OK so not for those on a budget, but great for people who have limited space or want a box that is low drag and powerful.

The second lead I got was when I emailed Lenco to see what they had, they forwarded my email to a company called
ie-drives they also make a two speed that seems to look the part.

From what I can gather it would seem to be a joint partnership with Lenco to create a Lenco like box for EVs.

Again not for the budget conscious, but seems to be tailored to suit EVs nicely, things like a female input to accept the motor output shaft to reduce space and weight.

They have an interesting read on why you should use a gearbox over direct drive here... Performance

Obviously they are trying to sell transmissions sure, but it seems to make sound reasoning.

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Post by Johny »

Their argument of increased range is largely based on delivery vehicle and buses though...

"A typical city bus only averages 13 to 15 mph as it follows its route. Delivery trucks operating in the same downtown city centers and surrounding metro areas would have similar speeds. All of these vehicles experience frequent stops for traffic lights and slow moving traffic. For these types of electric vehicles, the majority of their operation is very much concentrated in the zero to 10 mph speed range. This speed range coincides with one of the low to very low efficiency regions of all traction motors. "


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Post by Johny »

Sorry that tended to sound negative. Image I'll be very curious to see pricing on the 2 speed box.

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Post by EV2Go »

Raises a very interesting point though.. we tend to think of electric motors as this perfect 80-95% efficient device, when in reality every set of lights where you stop it drops to 0%.

In Toowoomba I seem to be constantly stopped at lights, and since I like to play traffic light grand prix (even if only by myself, and only to the speed limit, mumble mumble speed cameras everywhere here mumble)

I am only really looking to get off the lights that bit quicker more so than any efficiency gain. I certainly will take any power reduction and gains on offer though.

The other thing is with a 1.73:1 first gear times the 3.1:1 diff ratio, it gives me an effective 5.36:1 ratio. When on the odd occasion I do take off slow and the motor is making far less torque (pulling less amps) the 5.36:1 ratio would make life much easier on things.

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Post by 7circle »

EV2GO
Do you have a performance graph for the motor you are looking at.
Is it the Kostov mentioned in the Series or Parallel Post.

I'm having trouble finding a graph of Max Torque Vs RPM.
The graphs on the iedrives performance are for Induction Motors.

I'm trying to evaluate gearbox with DC motor.

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Post by EV2Go »

Yes it is one and the same. Waiting on its arrival in Australia, hopefully in the not too distant future.

it's the third one from the bottom Kostov 11" 250v

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Post by Who42 »

The photo below is only a mockup but I thought using an old Holden 3 speed gear box would be a cheap way to go , they are small and light you could shorten the imput shaft and have a keyway cut into it to match the electric motor and a short adaptor plate made to suit Image

Image

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Post by EV2Go »

Cheap and unfortunately about 10" too long. The two speed I was looking at has a female input so the male output of the motor can slide inside it to save space.

I only have about 10" to play with from motor end plate to the uni at the other end. BTW that looks like an old 3 speed crash box from the 60's, that would be a pig to change gears with.

Gearboxes without a clutch are a no go, drove one without a clutch and didn't like it at all. I want quick and hard changes so it doesn't loose momentum getting it into the next gear.

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Post by EV2Go »

Well the IEDrives unit is definately out of the running, at US$6150 plus extras it is too dear for this little black duck.

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Post by Who42 »

Quoate::that would be a pig to change gears with.!!! Actuly you only use 2nd and top gear there is no problem changing gears quickly if you real want to you could use a all syncro 3 speed if you wanted to but you don't need it. I have helped convert a 64 VW Beetle to EV with out a clutch and it works fine using its 4 speed gear box and you realy only use 3rd and 4th gear and it changes gear fine np

Image
Last edited by Who42 on Tue, 08 Jun 2010, 13:13, edited 1 time in total.

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Post by EV2Go »

I'm still not convinced that using a gearbox that was designed for a clutch without one is a great idea. I have driven an EV with a clutchless manual, and to be honest while it is drivable, it really is a huge compromise.

You can't change anywhere near as fast as you can with a clutch, and that leads to loss of momentum while you fumble for the next gear.

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Post by Who42 »

"QUOATE V2Go You can't change anywhere near as fast as you can with a clutch, and that leads to loss of momentum while you fumble for the next gear?????   Tell that to a V8 supper car driver or a Heavy Truck driver once you get used to not using a clutch its Quicker Besides you rearly need to change gears in the city use 2nd Highway use Top gear. and its not like you fumble you only use 2nd to Top leaver on the gear box so its a staight shift 2nd - N - Top you can't go wrong

Image Image
Last edited by Who42 on Tue, 08 Jun 2010, 20:55, edited 1 time in total.

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EV2Go
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Post by EV2Go »

EV2Go wrote: Been a thinking.... As the EV scene gains maturity, we are likely to see “necessity” the mother of all invention, deliver a whole heap of products that are probably not available today.

Which got me to thinking... How to solve the conundrum of going direct drive or having a gearbox.

If you go direct drive you might wind up with a more expense or bigger motor than you might optimally want (weight, size, cost etc).

If you use a gearbox, you are faced with additional weight, mechanical losses, decreased available space, clutch issue if you want an acceptable gear change.

What would be ideal would be something in-between...

A non complicated 2 speed gearbox. I did a bit of a search to see what I could come up with and found this http://www.dimontegroup.com/Our_Work/Ou ... earbox.htm\
not quite what I was looking for but is along the right lines.

What I see as a EV must of the future is a simple no fuss 2 speed gearbox that eliminates current limitations.

Something that doesn’t require a clutch for quick gear changes (yes you can change gears without a clutch but it isn’t what you would call “fast”)
Something that doesn’t require a complicated gear shifter and associated rods etc (preferably something cable or electrically shifted to allow multiple installation positions)
Something compact and not too bulky with a big bell housing
Something that is suited to being bolted up directly to a range of popular motors bolt patterns and shaft sizes (obvious not all at once) or maybe as a stand alone unit
Something light(ish) weight as weight is an EVs biggest enemy
Something strong enough to put behind even the torquiest of motors

Well there we go, who thinks they have what it takes to go into production? Geoff? Anyone?
As you can see from my first post... I was deliberately staying away from existing gearboxes because they don't fit many of the criteria I listed.

Yes you can semi successfully run a gearbox without a clutch, but they are slow to change, I am building a vehicle I want to take to the drags, 3 second gear changes may be just acceptable on the street but definately not on the strip.

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Post by EClubman »

My car has a clutchless 5 speed gearbox.
On the drag strip, I have no probs changing from 3rd to 4th.
(back off, change, power on - all in less than a second)
Mind you, the car is quicker down the track just staying in 4th the whole way.

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Post by EV2Go »

EClubman wrote: My car has a clutchless 5 speed gearbox.
On the drag strip, I have no probs changing from 3rd to 4th.
(back off, change, power on - all in less than a second)
Mind you, the car is quicker down the track just staying in 4th the whole way.


I caught the tail end of one of your runs that night. I was also running my bike and Speedily said you were about to run.

Your experiences believe or not proves my point exactly. The purpose of a gearbox is to accelerate the mass quicker. When the change takes more time then the benefit of the gear change it results in a negative benefit (i.e better off leaving it in the same gear).

That's why automatics are almost without exception quicker than a manual to change gears (not necessarilly saying a better coice), maybe a flat changed manual might be close, but damn you have to be quick with that left foot.

Same goes for the street, while I found that with a little finesse it helped change the EVs gear reasonably quickly and smoothly (extremely minimal crunch), I still felt that the loss of momentum outweighed the weight saving quite dramatically.

Obviously this is going to be a case by case basis as every gearbox will engage differently based on design and age, but consider for a momement we are talking about converting cars that may have in some cases considerable millage on the gearbox before we start.

Then we are asking it to change without a part it was designed to use, the whole purpose of this thread was to spur on new thinking on ways to optomise the gearbox.

Don't get me wrong repurposed gearboxes still has it place, try launch a space shuttle wthout first trying a few practice goes with smaller test rockets...

I was just trying to get people to think the step beyond "converted cars" into purpose built EVs. You can bet your bottom dollar once the big manufactures get serious about straight powered EVs gearbox development will come.

Edit: Disclaimer:
I'm not advocating the use of a typical gearbox clutch either, as engines are equiped with crankshaft end bearings that are designed for thrust loads, motors are typically not, they generally use a single race bearing designed for radial loads not axial.
Last edited by EV2Go on Wed, 09 Jun 2010, 09:50, edited 1 time in total.

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Post by Squiggles »

EV2Go wrote:
Well there we go, who thinks they have what it takes to go into production? Geoff? Anyone?
I have a relative that is a very experienced gearbox design engineer. I have discussed the concept of a two speed clutchless synchroless transmission with him and we believe it is achievable. In the end though there is one word that he keeps using, "liability". In his opinion, to produce a transmission, any type, is a job for the big boys as they can afford the cost of liability. We small folk no matter how clever cannot afford to take the risk.

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Post by EV2Go »

Squiggles wrote:
EV2Go wrote:
Well there we go, who thinks they have what it takes to go into production? Geoff? Anyone?
I have a relative that is a very experienced gearbox design engineer. I have discussed the concept of a two speed clutchless synchroless transmission with him and we believe it is achievable. In the end though there is one word that he keeps using, "liability". In his opinion, to produce a transmission, any type, is a job for the big boys as they can afford the cost of liability. We small folk no matter how clever cannot afford to take the risk.
hmmmm if it was a a wheel or a wheel bearing I could probably understand his concern about liabilty, but a broken gearbox has seldom taken a life. If the product is up to scratch it should be fine, and if not that's where a warranty comes into it.

Seems most of the more suitable two speeds use automatic internals or similar with a wet clutch. That way the axial load of the clutch engagement is placed up against the housing of the transmission rather than the motor.

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Post by Squiggles »

I am not sure that having a gearbox fail and lockup at 110kph on a freeway would be a safe event. I agree that it is extremely unlikely with a properly engineered and manufactured item, but it would only take one occurrence and you would likely lose everything you have. Ask Toyota how much a simple failure can cost!

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Post by EV2Go »

If everyone thought like that the world would stop turning. You cant let what-ifs, stop you from taking calculated risks.

A gearbox lockup isn't the end of the world. Off the top of my head I can think of three different lock ups I have had that resulted in zero damage to me.

1) HQ 2 Door Monaro - 350 Chev / Turbo 400 transmission with dodgey B&M Mega Shifter, instead of hitting neutral I hit reverse by mistake when the reverse gate lockout failed. The Turbo 400 is such a strong box it just locked up the wheels and tried to turn them backwards.

2) Honda H100S the seperate oil pump failed resulting in a total engine locked up while doing 100KPH, left one hell of black mark but otherwise no damage.

3) Holden UC Torana, kicked a rod or two out the side of the block while doing a little more than 100KPH, again two long black marks but no harm done.

There may be more but those are off the top of my head. While inconvient none were even close to life threatening.

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