Planetary reduction tranny

[rc4wd]

Another amazing design work from Fracture. Gear ratio is 9.87:1 (a transfer case will be made to match these) Any 540 motor is direct bolt up, and the whole unit has its own mounting bracket, this would be used in conjunction with a supplementary bracket supporting the motor.

[jimecm]

wow that is a great design

[roktoy]

Wow .......looked all over for something like that for my scaler and couldn't find one close to the ~10:1 I wanted.
Jay

[Thundermaxx]

Might be able to pull off the motor under the hood easier for a scaler. Be great if the T-case small too so not to protrude. That's a good gearing for the reduction too.

[Fracture]

Oh c'mon... cant people keep things a secret around here

Yep, thats the new reduction, it is designed to work in conjunction with a r2 spaced, metal geared delrin transfer case.

The parts are designed so that if made properly it should have no strength issues with any brushed motor (dunno about the cobalts).

It is very similar in weight to the reduction used on your average cordless drill, they of course can take quite a beating

The outer ring gear/housing will probably be made from delrin, I think that will be strong enough as a gear, and it will quiten operation significantly.

The internal gears will be hardened steel, in 48p

The gear sizes are - 45 ring, 12 planets, 21 sun.


If you saw the last updates before my Fj thread died, you will see the sort of drivetrain layout this is designed for.

as a primary reduction, it is only the diameter of a motor, and slightly shorter.

Single output, for a traxxas yoke or similar.

Im glad rc4wd has taken up the challenge

with 2.66:1 axles, 2.17:1 transfer and 9.87:1 transfer your final will be 57:1, thats the lowest I could get it without the gears becoming weak.


If you have seen stefans jeeps body off, you will know what I mean by auxillary motor support bracket.


6 m2 cap screws keep it together, and it has twin lips to prevent leakage.

[Fracture]

And this is designed primarily for realisticly drivelined scalers, not random comp rigs, so dont complain about the single output.

But if people like it, Im sure they could get it to work

Basically, it means no more spur gears:-P

[Thundermaxx]

How far are you on the T-case design?

[Fracture]

I finished it - a while ago. rc4wd either isnt working on it, is keeping it secret, or is changing things

[lunchbox]

It could work on a comp rig to though. Mount the motor on the front axle, run the driveline to the transfer case in the chassis, then down to the axles. Wouldnt that eliminate torque twist and wheel lift? It also gets the weight of the motor out of the chassis.

[Fracture]

Originally Posted by lunchbox

It could work on a comp rig to though. Mount the motor on the front axle, run the driveline to the transfer case in the chassis, then down to the axles. Wouldnt that eliminate torque twist and wheel lift? It also gets the weight of the motor out of the chassis.

Yep, its probably small enough for that, its the sort of thing you could mount almost anywhere with a bit of imagination.

[chino63]

Nice job, Fracture! Any way something around 8:1 could be made?

[Fracture]

I was aiming for 9:1, but due to the design (ring stationary, sun input, planets output) it is difficult to get that ratio. the optimum ratio is aprox 5:1 per set, meaning 8:1 would be to low for a double set, yet a bit high for a single set.

It would be far better to do get 8:1 using a single set combined with a spur gear, like the new tamiya planetary.

My reduction can be made 16:1 using the same ring gear/housing, it would infact be stronger like that but it is to much reduction imo.

thats the original design; same size planets and sun, 16:1 reduction:

[Stormin2u]

Fracture, you have truly amazing CAD skills. Looks very interesting.

[roktoy]

Another nice thing about the planetary setup for a scaler is it's sealed against the elements.
One thing you have to deal with on a spur setup most times is the exposure to dirt.
Jay

[exesivefire]

[Fracture]

Thanks guys, I am pretty pleased with it to

Someone needs to show me a gear generation tool for autocad, I had to draw the gear teeth using a a jpeg template from an online gear generator
They did come out with close tolerances though...

[r/cSith]

Fracture, how hard would it be to mount a planetery like this to the out side of the axle where the wheel would mount to it, would this help take stress away from the ring and pinion and also take away torque trwist?

[lunchbox]

Do you mean set it up like a Clod, with the trans going right into the transfercase and then down to the wheels running one for the front and one for the back?

[chino63]

He means like a gear reduction out at the hub. Like a Monster Truck.

[Fracture]

It would almost be possible, especially with improvements in motor technology, but It really isnt on my priority list, its something for someone with a mill and lots of free time to think about