Diffrunner concept

[lincpimp]

Ok, place the magnets on the outside of the diff case, and use a oversized can with the windings on the inside as an inrunner does. The can would be solidly mounted and the "diff/stator" would ride on bearings that are suppored by the ends of the can. In reality the endbells of the can could be made as bulkheads, and the center of the can would be removeable with the windings attached. 1/4 turn design would make removing one endbell easy, just pull the 4 chassis mount screws (2 in each bulk) turn 1 bulk 90deg and remove the stator/diff. Have one end of this stator/diff unbolt and you can service the diff as easily as a regular diff. Solidly mount the other bulkhead to the can, maybe with screws. This would allow kv chages easily, as only the center section of the can would need to be removed, or make it completely modular like a novak motor.

Multipole woould be required, and the diff height would be taller, as would the center drives. Worm drive ft and rear diffs with top output and bevel gears (think dump truck axles) would allow for more reduction and higher center driveline angles without raising weight too much. Place the rx/servos below them to offset this. Chassis could be narrow due to center motor mount and saddle syle trays with lipos split into series packs. Center motor/diff could also be placed front or rear for desired weight bias.

Aside from the added complexity of the center section and multi gear diff assemblies it would offer alot of benefits. Solidly made al or fiber reinfored plastic (carbon fiber?) front and rear diff bulks would be required to keep the worm drives meshing well. Off power coating would not be doable, unless you use one way bearings between the diffs and the wheels. Or you could use a gear reduction with std gears in the diffs, with a bevel output to direct the flow back to the center assembly. Seeing as these could be made smaller, and sealed it would be better than a center diff with exposed gears, even though it is more complex.

Of course a reduction could be applied to each end of the center assembly's outputs, and sealed. This would aloow std front and rear diffs and still not wear like an exposed setup. Gears could be spiral cut to improve effecintcy and strength and thus be made smaller. Still more complex that what we currently run.

[What's_nitro?]

For the inrunner concept... I think you'd basically need a cu$$$tom motor. I think the picture is pretty self-explanatory.

[zeropointbug]

Yeah man! Great idea, maybe not doable any time soon with our R&D access, but doable. Although, I am not too keen on using warm gears for anything R/C however, I just don't like them. This idea though having the diff being physically built into the motor housing is awesome, and on each end of the chassis you are saying? I don't think you would even need warm gears, as you can really do anything with motors, increase torque, lower speed, yada, yada.

Sike, ya, I think a sufficiently thick alum. plate screwed to diff housing then if the motor shaft was keyed, or squared, or splined..... then it would just slide in and be supported by the motor shaft, which because of the fact that it would be over sized from the increased size hollow shaft then it would be fine maybe.

[zeropointbug]

Originally Posted by What's_nitro?

For the inrunner concept... I think you'd basically need a cu$$$tom motor. I think the picture is pretty self-explanatory.

Wicked man, I was like perfect solution. But then I am wondering how we screw the large motor shaft plate to the diff housing. This is one PITA of a problem.

[What's_nitro?]

The yellow area is the center diff. The little black rectangles are "screws". There are a few things missing. I left out the "wall" of the diff that houses the bearing, which would be between the red rotor and the blue pinion.

[zeropointbug]

Ya, okay but how do we thread the screws in?

[PBO]

Funny, after seeing B4maz X2 vehicle I had a glimmer of an idea like yours zpb. You've taken it a fair bit further



Sure you may need to create some space for the screw heads but why don't you think What's_nitro? idea would work?

[pinkpanda3310]

PBO is that you street basher for idle wednesday arvo's

Looks like some serious power in there! Strictly speed runs or something else? Do you have a diff in it. If so we need the full monty.

[zeropointbug]

No, it will work, and it's exactly what I have in mind, it's just the troublesome coup,ing of the motor to the diff housing. Observe the DIFFiculty (really no pun intended ;) ) in getting the screws into the diff from the motor side.

[lutach]

I think CEN (I might be wrong) has a metal diff cup and it opens from both sides. It would make things easier then the conventional plastic diff cases.

[PBO]

@ zpb, I was thinking you'd go the other way, from the diff toward the motor. Probably need a customer diff cup but at least assembling would be as normal as possible?

@ pinkpanda3310, it's not mine but when I saw it I thought of a diff each side

[sikeston34m]

Originally Posted by zeropointbug

No, it will work, and it's exactly what I have in mind, it's just the troublesome coup,ing of the motor to the diff housing. Observe the DIFFiculty (really no pun intended ;) ) in getting the screws into the diff from the motor side.

The screws need to go into the coupler from inside the diff cup.

[zeropointbug]

Alright, I guess I am not too familiar with 1/8 differentials as I have not yet owned one, this project is for one however.

So, could you guys post some links or pictures to diffs? I am only familiar with Traxxas garbage... I recall a diff that can be opened from either end like Luc mentions, but I also can't find anything on CEN diffs.

Maybe a diff housing could be modified even to thread in from the diff side, if not already?

[lutach]

Originally Posted by zeropointbug

Alright, I guess I am not too familiar with 1/8 differentials as I have not yet owned one, this project is for one however.

So, could you guys post some links or pictures to diffs? I am only familiar with Traxxas garbage... I recall a diff that can be opened from either end like Luc mentions, but I also can't find anything on CEN diffs.

Maybe a diff housing could be modified even to thread in from the diff side, if not already?

http://www.rcplanet.com/ProductDetai...GS001&CartID=1
http://www.rcbasher.com/savcendiffs.html

Hope that helps.

[lutach]

How stupid of me. Here's a nicer example:

http://www.rc-monster.com/proddetail...diffcup&cat=40
http://www.rc-monster.com/proddetail...aplarge&cat=40
http://www.rc-monster.com/proddetail...iffcapt&cat=40
http://www.rc-monster.com/proddetail...Msldiffrebuild