Converting a hubmotor to a middrivemotor

fechter said:
That's one of the best parts of the conversion. There would be room for cooling lines as well, though forced air would be much simpler.
Click to expand...
Air cooling will definitely be a fast and easy way to go big power with this motor. I could envision this set up being faster and more powerful than the big crystalyte bikes like stealth. Certainly it will have a better power to weight ratio.
 
BlackArrow said:
Hi,

Mr Electric, I'm impatient to see you MAC running because I have the same motor in my hand. I'm not sure if I understood correctly but if the motor shaft turns this way the planetary the new ratio is now 6:1??? Or did I miss something ?

Nice work guys, good day!
Black Arrow
Click to expand...
I not sure of the final ratio. I guess I could draw some paint lines with the cover off and check the ratio pretty easily.
 
With force air cooling I think we will test the mechanical limitations of the gear set before burning the windings. Fechter and I both had little scooters with forced air cooling running 150 amps to the currie motors that would out run 60cc gas scooters. You can double the motor output as compared to sealed can operation with the right fan set up. The key is that the cooling keeps running while you are stopped unlike a shaft mounted impeller type cooling.
 
hi y BlackArrow!

problem is, we know the gears wont stand more than 2000W input. They only take 2000W if geared very fast, that's why we try spinning them as fast as still efficient.
BUT these MAC hubs can't take more than about 800Watts (even perfectly geared) continous cause they overheat. SO we cool them better and they will take 2000W continuous i hope. But not more since the gears wont make it.

If you force air (and dirt) into the hub it will only last a few weeks. dirt destroys gears quickly
 
you mean impeller forced air and aircleaner? aren't these systems always load? would be an option, but the MAC has a closed bell, it's hard to pass air through . WIth and RC outrunner this concept makes sence, since it has holes at the end of the rotor bell, to let the air pass.
 
I might add something here :idea:

The new MACs have many holes in the rotor but I don't think it will help a lot for cooling. Most of the holes are restricted by the clutch, gears and the stator. If you cooled it with air it would have to be forced by a separate higher pressure blower. The MAC turns too slow to drive a fan.

The new clutches have a one piece housing, very beefy, and gray gears. Unfortunately mine did not come with the new clutch, but I had ordered a new clutch and gear assembly when I ordered the motor. I installed the new one during the mod.

bØb
 
Spun it with hall sensors. What a nice quiet gear reduction system this motor uses. I'm happy with the motor , now to stick it in a bike. I'm trying to ride ASAP.
 
I'll take a video on Monday when I get back to the motor. I forgot to capture the moment yesterday. It does make a sweet sound. Not too winy no scraping noises. Sounds like lab equipment whirring and the shaft turns supper slow with gobs of torque.
 
How have you secured your cogs/freewheels to the axles Mr.Electric?

I've been working on the problem here. Crossbreak's brass inserts seem to soft for the types of power we're going to try and use with these motors so I have been trying to come up with a more "off the shelf" solution.

I may have found something that would work.

I don't know what the thread count is on the motor axles, but I think a coupling nut with the flats rounded off to fit into a FW adapter could work well. They are relatively cheap, available at just about any hardware store, and even come in stainless!

coupling nuts.jpg
 
. Crossbreak's brass inserts seem to soft for the types of power we're going to try and use with these motors
Click to expand...

the threads do not take any torque. They are just for axial alignment. The threads are 12x1mm, not sure if it's the same threads on the MACs.

For radial alignment, I use at least 6mm steel. At the ouput sprocket I use 2x6mm steel, may take a pic later...These pieces are very similar to common torque arms used with hubmotors. They see the same torque and hold up well, so this will last forever.
 
I am hoping to get something machined that has flats on the id and threads on the od. The problem with this plan is I don't have any machine tools.
Extreme Green is having one adapter made at a machine shop. I think a single adapter with enough threads for two free wheels would be what is needed. The motor will be mounted "mid" behind the cranks. The motor slides and is mounted on a plate that is welded to the frame. This will allow tensioning of the pedals chain. The bike has nice long horizontal drop outs so tensioning the motor to wheel chain will be easy too. I'm not sure if this bike will be running some type of internal gear hub or derailleur. I will have to ride it to get an idea of what size crank and motor sprockets will be best.
 
The flats are not going to do well at high torques. I've seen some freewheel adapters that have a keyway:
http://www.staton-inc.com/store/pro..._Sprockets_1_10_wide_2_set_screws-874-27.html

2499.jpg


Making a slot in the axle shaft and using a key of some sort would probably be much stronger.

A ghetto way to make the key is to drill into the axle and insert a piece of drill rod that sticks out enough to engage the keyway on the adapter. Maybe two rods. Otherwise using a dremel tool it may be possible to grind a keyway into the shaft.

The bolts sticking out in the picture could be replaced with set screws to keep it flush.
 
fechter said:
The flats are not going to do well at high torques. I've seen some freewheel adapters that have a keyway:
http://www.staton-inc.com/store/pro..._Sprockets_1_10_wide_2_set_screws-874-27.html

2499.jpg


Making a slot in the axle shaft and using a key of some sort would probably be much stronger.

A ghetto way to make the key is to drill into the axle and insert a piece of drill rod that sticks out enough to engage the keyway on the adapter. Maybe two rods. Otherwise using a dremel tool it may be possible to grind a keyway into the shaft.

The bolts sticking out in the picture could be replaced with set screws to keep it flush.
Click to expand...
You may be right about the torque on this motor breaking weak parts. I am not completely sure which side of the motor will be used to drive the bike. I did not take notice which way the shaft is turning. The two axles are quite different. One side ( brake side) has flats almost all the way down to the hub shell. The other has a nice thick unmolested shaft that normally lives under the freewheel that would be well suited for some dremel key way work.
 
I think it's the same as on the Ezee motor I'm working with.

003.JPG002.JPG

Another idea is to use a welder and build the axles up with beads and then turning the shaft down smooth to 15mm to use with the Stanton FW adapter. Pretty easy if you have a welder or access to one, but otherwise you'll need to farm the work out. Might be the best long term solution if these drives work the way we're hoping they do. :D

I have also made a nice narrow freewheel adapter by welding a 1/2" collar lock inside a bottom bracket cup. The whole thing is only slightly wider than a freewheel by doing that when you are done and since the bottom bracket cup I used was made out of hardened steel it is very tough.
 
The motor I am using is a rear motor so the axle is much longer on the non disc side. Pictures to follow Monday. When I am back to the motor.
 
I guess I'm not clear on the drive direction either. I think if you're looking at the hefty side of the axle (opposite the wire side) it would turn counter-clockwise. It may be necessary to mount the freewheel on the other side to make it go the right direction. The freewheel would need left hand threads too.

It's going to be a bit harder to get a good solid connection on the wire side of the axle.

Edit:
Now I'm even more confused. I took a look at a Puma motor I had in the garage, which is supposed to be just like a BMC. I swear the freewheel inside that thing is backwards. If mounted on a frame with right side drive, it freewheels backwards but it has a right hand thread for the external freewheel. I figure the internal freewheel on the ring gear must have been installed backwards. This brings up a good point, however, that it should be possible to remove and flip over the internal freewheel to make the motor run in the reverse direction.

If you want to reverse the motor direction, it may be necessary to change the hall sensor positions to maintain timing advance.
 
I believe the hub shell must be flipped over, so the disc brake side is next to the chainring for a single-reduction chain to a BB-drive.

As I understand it: Normally the rotor spins the opposite direction than the shell+wheel (rotor normally spins backwards). The planet-gear holding plate and stator are pinned to the stationary axle. The planet gears (whose 3 axles are also stationary) not only reduce the RPM @ 5:1, they also reverse the direction of spin.

If we un-pin the stator from the axle, and pin it to the shell...The normal backwards-spinning of the rotor will cause a backwards-spinning of the planet-holding plate+axle (but at a reduced speed, 6:1?). Flip the entire assembly around and the the axle will now drive the rear wheel in the proper direction.

In the earlier pic, (http://endless-sphere.com/forums/viewtopic.php?f=28&t=45245&start=90#p669628) the motor axle is cleverly being used as a jackshaft. Since the longer axle of the rear hub has its extra length on the FW side, if it is flipped over, the extra length would now be on the left side of the bike.

Could there be some benefit to using a longer rear-hub axle? Using the axle as a jackshaft with the chainring on the left has some interesting benefits. There would be no difficulty getting the 80-RPM pedal-cadence matched to a 30-MPH drive (as it is when raising the voltage on a GNG).

edit: crossbreaks configuration of using the hub axle as a jackshaft not only has the benefit of easily allowing the pedal cadence to be a low and usable 80-RPM's (using readily available chainrings), but it also allows for greater obstacle clearance because the appropriate chainrings are smaller than average.
 
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