New Approach to 4500W Mid Drive

[cozy35]

The latest rendering so long.

 

[cozy35]

The latest parts and temporary assembly of the gearbox.

The assembled Box weighs 1178 grams and the APS 8055 motor adds another 1100 grams.

View attachment 4

View attachment 3

 

[Grantmac]

I wouldn't bother with the chain idler, it can be run really slack without issue which from my experience is also more efficient.

are you able to spin the gearbox to get a feeling for noise? Will you use a grease or are you doing an oil bath?

I have another idea I'll PM you about.

 

[nowholeself]

I'm watching this thread with great interest. I love what you've done so far. I'm particularly impressed by how lightweight your design is. I'm curious to know if that particular engine will be able to be run hard for very long, even with a light rider on a light bike (e.g. no more than 200lbs total). I'm suspicious. I'm rooting for you, though! It's a cool design.

 

[Andrewol]

How gearbox looks inside?

 

[SlowCo]

How gearbox looks inside?

See first post on page 1... :wink:

 

[cozy35]

I'm watching this thread with great interest. I love what you've done so far. I'm particularly impressed by how lightweight your design is. I'm curious to know if that particular engine will be able to be run hard for very long, even with a light rider on a light bike (e.g. no more than 200lbs total). I'm suspicious. I'm rooting for you, though! It's a cool design.

Since the motor will mount directly to the input side of the box which is also aluminum it should act as additional heat sinking material. I am planning a centrifugal fan to draw cooling air through the stators and this should also aid in cooling.

 

[SlowCo]

Maybe I'm overlooking something but what is the (3D printed?) blue "tube" for that you placed over the metal casing of the gear reduction part? Or are the metal and blue plastic tube just placeholders for the actual gearbox as a mock up?

 

[cozy35]

Maybe I'm overlooking something but what is the (3D printed?) blue "tube" for that you placed over the metal casing of the gear reduction part? Or are the metal and blue plastic tube just placeholders for the actual gearbox as a mock up?

Indeed a 3d printed temporary part.

It is a fitment test for a carbon fiber cover to enclose the bolts and ring-gear. Basically just to tidy up the box assembly.

 

[SlowCo]

I would think that the gearbox will get hot at the rpm and load it has to deal with. Leaving the cover off will let the ring gear lose it's heat better due to the airflow over it.

 

[cozy35]

I wouldn't bother with the chain idler, it can be run really slack without issue which from my experience is also more efficient.

are you able to spin the gearbox to get a feeling for noise? Will you use a grease or are you doing an oil bath?

I have another idea I'll PM you about.

The problem is that chain-wheels come in different tooth numbers and one chain link can really mess with chain slop. The BB brace is to adjustable to take up any excess slop.

 

[Ecyclist]

Yes, everything looks great on a computer screen, but once you apply forces all bets are off.
Cycloidal drive is very compact and it is perfect for an e-bike, but it has to be well made. You can't just slumdonk it and hope for the best. Making rotors out of aluminum, like in Tangent, is a joke. Proper materials and tolerance are absolutely necessary.

 

[Eryk]

Any construction progress? Is something going on in the topic?

 

[LeftieBiker]

I just saw this topic. I strongly suggest that you reconsider using straight-cut gears, as they will make a lot of noise. Just ask any Vectrix VX-1 rider! My VX-1 sounds like a family of banshees lives in the rear wheel, and that is considered totally normal for the bike. Please look into bevel cut gears and a really top notch lube for them.

 

[Tommm]

The project was doomed from the get go because of wanting to go high torque low rpm. You will be destroying reductions, freewheels, motor sprockets, chains, all in short order.

The correct way to size a motor is to have a huge rear sprocket on the rear wheel (50-70 teeth) and a small but not tiny one up front (12-16 teeth) this will give you the same wheel torque without destroying a bunch of components inbetween.

 

[Andrewol]

I strongly suggest that you reconsider using straight-cut gears,
.. and a really top notch lube for them.

The same or worse noise level comes from cycloidal gears.
What is the top notch lube for bevel gears?

 

[LeftieBiker]

I can't suggest a specific brand, but make it a full synthetic.

 

[Eryk]

Here someone's project started. From the description it looks like it works fine. The best part is that most of it is 3D printing
https://www.thingiverse.com/thing:3105152

 

[Hillhater]

Here someone's project started. From the description it looks like it works fine. The best part is that most of it is 3D printing
https://www.thingiverse.com/thing:3105152

Obviously a successful unit using simple jack shaft reductions and belt drives.
But, i suspect it is quite heavy due to the use of two reduction shafts, heavy belt drive pulleys and huge amounts of printed plastic.