Planetary + Clutch Dual Speed

[etard]

Everyone seems to want stump pulling torque AND 40 mph top speed ( I do ). So, I was wondering if it would be possible to have both worlds with dual geared drive. Here is what I propose, please correct any physical limitations as you see them.

Start with Matt's E-box. On the second stage shaft add a planetary geardown and a clutch. Your orbiting gears are cone shaped, the sun gear is fixed to the shaft and your planets and housing are attached to a cluth somehow. The clutch disengages the drive while you slide the planetary over the sun gear, let out the clutch and now you are ready to pull stumps. I don't think I have the logistics worked out correctly yet, but I think you guys get the general idea. The clutch might not even be necessary, just a way to inhibit any motion while the gears line up and engage.

Anybody good with CAD and want to sketch thier interpretation of this?

 

[PaulM]

Set up properly, you would not need to slide any gears, all you need is a couple clutches to hold or release certain parts of the planetary setup.

For instance, place the sun gear on the output of the E-box, the sprocket to your rear wheel goes on the planet carrier. Now, if you fix the ring gear, you will get the stump pulling torque you are looking for. If you release the ring gear and somehow lock it to the carrier, the entire planetary assembly will rotate as one effectively making it direct drive, giving you 40 mph.

A couple issues: gear lubrication and noise, and weight

 

[natem]

What your talking about is just recreating a automobile's auto gear box. It's kinda complicated even though conceptually it's a good idea... planetary gears are a super-strong transmission design..

If you want a nice transmission then a Nuvinci CVT transmission is the way to go. This replaces your rear hub in your bike. Cyclone-tw has them on sale for 230 dollars or so.

They are designed for bicycles and lightweight electric things. They are a little heavy (newer versions are lighter then the older ones, but I don't know when this happened or by how much), but they are strong and have a wide range of 'gears'. The best thing about them is that unlike Derailleurs you can shift them at any speed or any power load... from full blast on the throttle to stopped on a hill. Very simple to use.

Right now they are manually controllable, but if you want something very fancy then it would be quite possible to design a automatic shifter for them so that they will always let your motor run in it's best efficiency zone. It would require a designing/programming a 'smart controller' that would monitor amperage and wheel speed and use a couple servos to ramp up and down the range offered by the Nuvinci hub. That way you could always operate the motor at the perfect speed for maximum torque and efficiency. Right now you have to manually do it.

 

[Miles]

Right now they are manually controllable, but if you want something very fancy then it would be quite possible to design a automatic shifter for them so that they will always let your motor run in it's best efficiency zone. It would require a designing/programming a 'smart controller' that would monitor amperage and wheel speed and use a couple servos to ramp up and down the range offered by the Nuvinci hub. That way you could always operate the motor at the perfect speed for maximum torque and efficiency. Right now you have to manually do it.

http://www.fallbrooktech.com/09_LEV_Kit.asp :wink:

 

[recumpence]

Geeze Miles, you have an answer for everything.

You are my hero.......... :wink:

Matt

 

[lepton]

The NuVinici is certainly neat, and that dev kit is quite cool, but a lot of the user reports have been mixed or even negative for its use on e-bike applications. The efficiency of it when it's far from it's native ratio gets to be pretty bad, and slipping seems to be a problem.

There are some decent threads on here talking about it in greater depth.

 

[j3tch1u]

i wonder if that elec shifter pulls down the throttle for shifting. either that or they're using some super strong servo motors. mine is impossible to shift even under the slightest load.

 

[John in CR]

I guess I need to crack open that 2 speed self propelled lawnmower transmission that I picked up cheap, and post some pics. It has a clutch and 2 speeds. We don't need the probably inefficient 90° input it has, but otherwise it may be something we could copy with slightly beefed up gears and have a real 2 speed transmission for ebikes. Another one still untried on the forum is a multi-speed transmission from a power drill. Might be perfect for a high speed RC motor application, and those things can handle significant torque at the output.

John

 

[natem]

I have had two mopeds. My old one I got in highschool was a Honda thing.. it actually featured a CVT. It was the common belt-type were one pulley was split in half and got squeezed together, thus changing the diameter of the pully and thus the gearing.

The one I currently have is a Puch with a two speed transmission. I am not sure how it switches gears, but both know the speed based on springs and spinning weights. Same as a governer. The engine speeds up, the weights swing out, and push on levers or whatever that move the clutches around or pushes the pulleys together.

There are a absolutely huge number of cheap scooters out there that feature this sort of thing... I don't think that you could easily adopt them to bicycle parts, but I expect it would be quite possible to mount a electric motor onto a small scooter's transmission and get something that would work very well. If you look at the 'Gy6'-style scooter, which seems to stem from a reliable honda design that the chinese manufacturers copied (actually purchased, beleive it or not.. I think) the entire engine and transmission and rear wheel mount integrate into a single long unit that get used as the entire swing arm. A 50cc model could probably be adapted to a ebike, maybe something with a 20 inch wheel. I haven't looked at it closely, yet.

I am actually thinking about using a 50cc 4-stroke motor of this type for a combination pusher engine and cart for long distance trips. (if I end up liking the idea of commuting in a bike)

Would probably work out well for a recumbent bicycle or Velomobile. It would probably provide all the gearing reduction you'd need for those larger RC-style motors.

 

[etard]

Natem,
I understand that the CVT V style belt loses alot of energy, that is why nobody is incorporating one onto thier builds. I am looking for something relatively simple, inexpensive, and lightweight, and efficient. I was just wondering if anybody here had an idea of how to incorporate my design, or complications that might come up. I don't want the planetary gears to be spinning all the time, just when I need them. Hopefully, I can come up with some sort of drawing this weekend.

 

[gwhy!]

Natem,
I understand that the CVT V style belt loses alot of energy, that is why nobody is incorporating one onto thier builds. I am looking for something relatively simple, inexpensive, and lightweight, and efficient. I was just wondering if anybody here had an idea of how to incorporate my design, or complications that might come up. I don't want the planetary gears to be spinning all the time, just when I need them. Hopefully, I can come up with some sort of drawing this weekend.

Im not totally convinced about a v-belt cvt would be that un-efficient and think the pro's of such a system would out weigh any efficiency losses , I plan of looking into this when I get the chance I also don't think it would be that difficult to make using off the shelf parts with a few slight mods.

 

[natem]

Compared to a derailer then ya the V-belt thing is VERY inefficient. In larger vehicles it's better and with CVT cars that use that type of drive train tend to get in between the efficiencies of manual transmission and automatic transmission. The advantage is that you can design the motor to operate at a peak efficiency/power and keep the motor at that speed through out the entire time the car is in operation.

Normally motors in vehicles have to be designed to operate over a wide range of speeds and thus are full of compromises.

----------

I was thinking though more along the lines of the types of transmissions that use gears, but use clutches and governers to do the shifting for you.

 

[natem]

I found a detailed example of a automatic 2-speed transmission for a scooter.
http://scooter.wikia.com/wiki/Evo_two_speed_transmission

It uses centrifugal clutch mechanism to switch between two belted gears. Pretty snazzy.

 

[gwhy!]

Compared to a derailer then ya the V-belt thing is VERY inefficient. In larger vehicles it's better and with CVT cars that use that type of drive train tend to get in between the efficiencies of manual transmission and automatic transmission. The advantage is that you can design the motor to operate at a peak efficiency/power and keep the motor at that speed through out the entire time the car is in operation.

Normally motors in vehicles have to be designed to operate over a wide range of speeds and thus are full of compromises.

----------

I was thinking though more along the lines of the types of transmissions that use gears, but use clutches and governers to do the shifting for you.

Compared to a derailer it will be very inefficient of course it would. But for simplicity and far less moving parts it could be a winner with carefully selected roller weights and spring it can be set to use as you say the peak efficiency/power of what ever motor you decide to run . You would not need the clutch part of the system just 2 v-belt pulleys. All the parts are available off the shelf ( pulleys, weights , belts and springs ) would have to make some form of housing for it. As long as its setup right for acceleration and torque and you will be set to get more speed you just increase the speed of the motor so the jobs a good'un http://www.teamcalamari.com/zuma/variator.html
http://www.youtube.com/watch?v=9TnkUIecRE4

Off the shelf parts would be initially to large for a cycle even with the smallest available scooter parts but is was thinking of along the lines of a self contain system with a sprocket on the input and a sprocket on the output to drive the rear wheel

 

[etard]

I found this on Ebay:

http://cgi.ebay.com/SEW-EURODRIVE-P...ewItemQQ_trksidZp1638Q2em124#ebayphotohosting

It looks very heavy duty, but I don't see any specs as to the reduction or weight on the manufacturer website. Probably way too heavy for these purposes is my guess.

 

[etard]

Actually upon further review, I see that it is 9:1 reduction, will handle 6000rpm at 110nm, and weighs only 3.3kg. Not bad for our purposes.

 

[John in CR]

I thought you wanted 2 speed. Also, what does "low backlash" mean? That sounds like it doesn't turn freely to me and low efficiency.

John

 

[etard]

John,
I am looking for a base mechanism with which to develop a 2 speed tranny, this unit came up in my planetary ebay search, but comes in a lil heavy at over 6.5 lbs. If I drill the body out, might be able to get it down to sub 4 pounds. But you are probably right about the possible inefficiency designed into this system.
SOMEBODY needs to open up a drill and see what can be made with one.

 

[John in CR]

John,
I am looking for a base mechanism with which to develop a 2 speed tranny, this unit came up in my planetary ebay search, but comes in a lil heavy at over 6.5 lbs. If I drill the body out, might be able to get it down to sub 4 pounds. But you are probably right about the possible inefficiency designed into this system.
SOMEBODY needs to open up a drill and see what can be made with one.

I'll try to crack open the 2speed tranny I have and take some pics tomorrow. It's probably simpler and has a clutch of some kind, which I don't think a drill would have. Plus it might prove useful for us after dumping the the probably inefficient 90° at the input. I need to take a look in there anyway before making any final design decisions for my long range build to be sure I've considered all my possibilities.

John

 

[etard]

Sounds good John, I have been waiting for somebody to do the obvious and use everything from the drill to power their ride, maybe even use a 36 volt drill, but no brave soul has come forward. Anyway, I have come across this website:http://www.rinomechanical.com/gearbox_planetary.htm
For $325 you can get a 15:1 reduction unit that weighs 1.4 kg (3 lbs.) and handles about 120 NM. It's not as elegant as Matt's system, probably not as efficient, but certainly more tidy and better protected from the elements.

They also have these units which could be added to any motor if start up torque begins to be a problem. It's a slipper clutch that can be adjusted, mounted to a pulley or 2 shafts. Very neat stuff from this company! Oh by the way John, I just got my Bosch 36 volt batteries (damn those chargers are HUGE ) and I am trying to design a mounting system for them to clip into in their present state, if you have any ideas let me know. Thanks

http://www.rinomechanical.com/pdf/Slip-Clutch/HowSlipClutchesOperate.pdf

 

[John in CR]

For that kind of price you can get a gearbox that you simply plug your Dewalt drill directly into to drive your bike. When you get there, just pull the drill out and use it.

As promised, I cracked that $20 self propelled lawnmower 3 speed tranny open and post a pic here: http://endless-sphere.com/forums/viewtopic.php?f=28&t=7695&p=131239#p131239

For our bikes we need something simpler and smaller. In fact it would be so simple, I can't believe someone with the proper tools hasn't already fabricated one. Too bad a grinder doesn't have multiple speeds in it's gearbox. I've been on the lookout for a used wheelchair for cheap to get some stub mount hubs, so I can use one of the angle grinder 90° gearbox with it's reduction for a hearty DIY shaft drive. Just add a multi-speed gearbox from a big drill, and you're in business.

John

 

[natem]

Well if your going to go with the dewalt hammerdrill route then the already come with a very nice all-metal gear reduction in them. On the low gear the output shaft runs 0-400 RPM which is about perfect for a bike. If you take the drill apart you can shove in spacers to force it always to be in low gear.

Then you can add on two sprockets from a machine supply house and maybe manage some sort of derailer setup to shift between two or more speeds, or better yet tie it into your normal drive chain (with the standard crank freewheel setup) and use a rear derailer or geared rear hub (like the Alfine) to have multiple gears..

 

[MitchJi]

Hi,

If you want a nice transmission then a Nuvinci CVT transmission is the way to go. This replaces your rear hub in your bike. Cyclone-tw has them on sale for 230 dollars or so.

Cyclone-tw price with shipping to the U.S.

Amount: $298.00 USD
Shipping & Handling: $89.40 USD

The best thing about them is that unlike Derailleurs you can shift them at any speed or any power load... from full blast on the throttle to stopped on a hill.

Not with the current models. The LEV will provide that.

Anyway, I have come across this website:http://www.rinomechanical.com/gearbox_planetary.htm
For $325 you can get a 15:1 reduction unit that weighs 1.4 kg (3 lbs.) and handles about 120 NM. It's not as elegant as Matt's system, probably not as efficient, but certainly more tidy and better protected from the elements.

I think when you add a motor it will be too wide for most bikes. Gears for the first stage will probably be noisier than Matt's drive. You could use a belt for the first stage. That will solve the noise issue and if you face it the other direction that will solve width problem but unless you need 45:1 reduction its going to be cheaper and probably easier to just use Matt's dual stage.