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Question regarding differentials

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Old 03-11-2019, 01:09 PM
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Tanque
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Default Question regarding differentials

Hello all. I don't post here much as I over on the RC tank/ military RC forum most of the time so if this out of place point me in the right direction.

I've a project, 1/10 scale truck project, for which I need to build the two rear axles for. I already have machined castings for the axle bodies and what I'm
looking for are adaptable differential gear units that will hold up to this very heavy model. I do my own fairly precise machining so if I must I will build
carriers an all but I was hoping to find something I might adapt. The 'ring' gear will be about 44-46mm in diameter and I want it to be a spiral cut gear.
The remaining gears are to be steel.

I believe 1/8 scale diff units seem more appropriate but I have concerns. I have several example of off the shelf diff units I purchased some years back
and the output shafts to the wheels do not run on bearings of any kind but rely on a lubricated aluminum - steel interface. I feel uncomfortable with that.

My question boils down to this then: are there differential made that use either bronze or ball/ roller bearings on the gear carrier for the output shafts
to ride on?

Thanks for taking the time..

Jerry
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Old 03-26-2019, 03:39 PM
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My experience with 1/8 and 1/10 scale racing buggies and trucks is that they typically do have bearings on the output shafts, leading to ballcups and dogbones which then lead to bearing raced ballcups and axles shafts at the wheels. These are sufficient for running 50+ mph and should be sufficient for your use. There are no axle bodies per se because they serve no purpose, but if you're designing for much slower speeds a lubed alum/steel interface will probably be fine for upwards of a 10 pound model.
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Old 03-26-2019, 08:49 PM
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JREEVES thanks for your reply and input. I probably should have been more specific in what I'm trying to do. The truck in question is a 1/10 scale
version of a German Kaelble Z6W2A 130 heavy towing tractor and finished weight is about 50 pounds. It's powered by tandem 540 class brushed motors
housed in a diesel motor casting and geared down approximately 3:1 In it's original form it has a multi speed transmission.It's designed to tow a 24 wheel
lowboy trailer(Schwerlast Anhänger Typ R 80 II 'Gotha') the Germans used to tow some of their largest armored vehicles. Altogether truck, trailer and
a 1/10 scale tank can weigh well over 200 pounds so the drive train needs strength. I have three of these trucks, one is capable of running, one needs
a transmission and the third needs everything.

The manufacturer sells display or 'basic' kits without all the running components which is what one of my 3 trucks is and my first goal is to make the
axles functional. The originals are complex but I wish to duplicate their function as much as possible. I've already built the motor. I was hoping to use
as much off the shelf stuff as I could but I suspect much machining is in my future.. I'll make the axle guts myself if need be. I don't like plain metal to metal
running interfaces. I learned my lesson when I built my first tank transmission.

You can find my work on one of these and my other armor projects here:
http://tanks.linite.com/Kaelble.html
http://tanks.linite.com

Jerry
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Old 03-27-2019, 02:18 AM
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Wow Jerry, your work is incredible! I hope you're sharing this story on other forums as you go!

https://www.rctankwarfare.co.uk/foru...da90f477d8126e
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Old 03-28-2019, 12:35 PM
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Thanks for the kind words, I tend to update my website more frequently but I also post bits out here. I hope I can post a photo of the number 1 truck I've been working on
with trailer loaded with a tank either under this thread or over in the tank sub forum. When I get around to the work on the axles I'll probably post some of it here.

Here is the simulated engine I wrote of previously that I built for the number 2 truck. The full sized Kaelble used a inline 6 cylinder diesel ( GN 125 s -~ 128hp) but
I'm not certain how closely these castings simulate that engine. Again this motor was made up of aluminum castings made by Stehr modellbau of Germany with my own internals
and other parts. The twin 540( 80 turn) electrics draw about 2 amps with no load and I was unable to stall them at 6 amps under load. Apologies for the blurry photos:





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