Need help constructing motorized wheel, help please

[exia00]

Hi everyone,

I am very new to the mechanical engineering field, all I currently have is knowledge of basic physics.

I am trying to construct motorized roller blades (not for practical use, just a demonstration).

I need help either building a small/power motor, or after purchasing one, how to connect it to the wheels to be able to make them rotate, and how to make a mechanism to be able to turn the motor on/off.

Preferably it would be best to add the motor to already existing roller blades, but new ones can be created as well.

Can someone please help me out with this? Thank you very much.

 

[Danger]

Welcome to PF, Exia.
I think that powered axles would be impractical in this application. A friction transfer to the tops or sides of the wheels via rollers or a belt would be easier to handle.

 

[exia00]

@Danger:

Thank you very much for the suggestion. Unfortunately I am a complete rookie and have no idea how to construct such a feat. Do you have an instant messenger like AIM or skype to discuss this further? If not, could you please take a bit of time to try and explain it in more detail please?

Idea 1) I was thinking that the motor would hook onto the back of the roller blade, and be attached to an extra wheel that I would add to the back of the blades as well (The motor would be a bit higher than the extra wheel).

OR

Idea 2) Is there a way to power all 4 of the already existing wheels on the blade?

 

[Danger]

I don't have any kind of instant message stuff that I know of (I'm still a 'net newbie'). In any event, I prefer to put forth my suggestions in the threads so they can be critiqued by those more knowledgeable than me.
Your idea of an extra driven wheel makes a lot of sense, as long as it doesn't mess with the dynamics of the skates themselves (ie: not restricting bank angle and the like). I hadn't thought of that, since it will stretch your wheelbase quite a bit, but it could very well be the simplest solution.
What I was thinking of is basically the same thing, except that the extra wheel would be running in reverse, in contact with the top of one of the regular wheels. To power all of the wheels, I was thinking of something like a snowmobile track rather than a single roller.
This is all just coming off the the top of my head, so I really need to think on it a bit. That will be done during commercials, since a new episode of 'Smallville' is just starting.

 

[exia00]

smallville is an excellent show, however House is a little better =]

I drew some schematics and added another factor. They can be found here: http://img145.imageshack.us/my.php?image=rollerdu3.jpg

Similar to a race car's "NOS" (as seen in the fast & furious movies), these roller blades will have a turbo factor as well.

The crosshatched area in the middle of the blade will be stuffed with home-made rocket fuel. Allow me to explain the parts labled with numbers.

1) a hatch at the front end of the metal tank for refueling.

2) Cylinder expanding outward from the end of the tank and goes out past the motor. This prevents burns and damage to the blade/motor from the flames.

3) The motor powers an axel (or a wheel... hmm?) to rotate. The axel is surrounded by a gear. The axels from all the other wheels also have extensions surrounded by gears. The gears are all surrounded by a rubber belt, which is powered by the rotating axel (or wheel?) from the moter. This causes the wheels to move forward. I figured that this wouldn't be a satisfactory speed, hence why I added the turbo factor.

4) a fuse extending from the end of the fuel (The fuel is chunky and clay-like). by lighting the fuse, the rider is given time to get ready and into position before ignition.

5) The rubber belt (already explained).

The problem is I am not sure exactly how to make the axel or the wheel rotate from the engine. This is where I desperately need your help, as I have no degree in engineering.

Ideas?

 

[Danger]

I think it's about time that I ask how old you are, and what your level of education is. The idea of the motorized skates is kind of cool, but the rockets are bordering upon insanity. Especially as shown in your sketch, all that they would do is set your feet on fire. If, by some chance, you actually get some useable thrust out of them, they'd send you ***-over-teakettle. Don't mess with them!

 

[exia00]

19, freshman in college, chemical engineer major.

The rockets were just an idea, we can just toss it out and stick to the motor. Any ideas on the motor?

Would more power/speed by achieved with:

1) The rubber belt idea? or
2) enlarging the gears, and placing a gear between each wheel, so gears solely power the rotation?

Also, how would I make the motor rotate an axel (or powering a wheel) in the first place?

 

[Danger]

I guess that I can lay off the lecturing; your education exceeds mine.

Your torque and speed won't be dependent upon the type of power transfer. The gear/pulley/whatever ratio will determine that.
As for a motor type, I really don't know. Perhaps a high-powered cordless drill would suffice.

 

[exia00]

My education may exceed yours, but your idea of the most basic of basics is my idea of complicated physics and terminology

I looked up cordless drill motors, it seems like a cylinder with an axle sticking out from the middle. Are there any drill motors that have axles coming out from both sides? Or would I be able to mod the motor to have another rotating axle on the other side? If not, how would I get gears turning on both sides of the blades?

I am also thinking about replacing the rubber belt with a series of gears. This is because the motor will be above the rest of the gears. When i picture it in my head, it doesn't seem like the belt will work optimally unless all the gears are on the same level.

Will I just be able to weld the gears onto the axles of the motor?I also just noticed from looking at http://www.productwiki.com/upload/images/rollerblade_aero_6.jpg that the axle of the wheels doesn't spin along with the wheel...

Well this pretty much destroys my entire theory. Any ideas on how a series of gears can cause the wheels to turn?

shows how someone made an electric skateboard from home, pretty much the same idea. He explains everything like it is simple and i thought it may be simple to you as I have no idea how the motor works. It seems as though he attached a motor to cause the back wheel to rotate...

Any ideas on how we could edit our design of the rollerblade using this info?

 

[montoyas7940]

I think Danger has a good idea with the friction drive. You really only need to drive one wheel. Maybe a dc electric motor and controller from a battery powered drill. Do you need to power two skates? If so you still might keep it under a hundred bucks if you find a couple of cheapie drills.

A "friction drive" commonly drives the rolling surface of the wheel. And would probably be the easiest and lightest to build.

 

[exia00]

@montoyas:

Thank you very much for your input. Could you please throw in some specifics as to how this could be built?

EDIT:
I just researched friction drives a bit. Looks like a great idea, I think I'm beginning to understand it now. However, would a friction drive be able to power an entire person? Are there any ways to increase power output?

If not, does the idea of all regular wheels being removed and replaced with friction drives sound feasible?

 

[Danger]

I don't think that you're quite grasping what a friction drive is. It doesn't replace the existing wheels; it imparts a rotational force to their circumference through frictional contact with a drive capstan. There are no gears involved, other than whatever comes between the motor and the capstan. Think of it as if you were to touch a belt sander to the tread of a bicycle tire.
How much power can be transmitted depends upon the motor and the integrity of the contact area. Most friction drives are heavily spring-loaded to maintain that contact.

 

[Topher925]

I think before you go an figure out something trivial as to how you will connect a motor, you first need to figure out how you will be powering and controlling this motor.

 

[montoyas7940]

Here is a good example. It is a much larger application but it might give you
an idea what Danger is proposing.

http://cyclehappy.com/library/FDRSub3311.jpg

 

[Danger]

Thanks, Montoyas.
I've been kicking myself for not having mastered Inkscape well enough to make a decent sketch, and it never crossed my mind to look for an existing photo.
That is indeed a great example of the concept.