Adding an "idler" gear for reverse rotation?

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sbcnyc
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Adding an "idler" gear for reverse rotation?

Post by sbcnyc »

I was wondering if adding an idler to my spur gear, than driving the idler off the pinion changes the overall ratio of the transmission.. I've heard of this being done, but nobody ever got in to the dynamics of the ratio, like does the idler now act like a pinion gear?

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Re: Adding an "idler" gear for reverse rotation?

Post by GoMachV »

As long as the idler is not a compound gear (like you see on an Ultima or the early Traxxas cars) then it won't effect ratio. For example, the idler gear inside the trans is not figured into the ratio between the top shaft and diff gears.

I did this bitd with an Eagle that I converted to nitro well before the Nitro Hawk came out.
It's time to stand up to the bully. Support the companies that support the industry, not the ones that tear it down. Say no to Traxxas
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sbcnyc
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Re: Adding an "idler" gear for reverse rotation?

Post by sbcnyc »

Cool, so do I have to match the tooth count on the internal idler gear?

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Re: Adding an "idler" gear for reverse rotation?

Post by jwscab »

Nope. Just find a gear that fills the gap and you are good.

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Re: Adding an "idler" gear for reverse rotation?

Post by klavy69 »

GoMachV wrote: Sun Jan 29, 2017 3:29 pm
I did this bitd with an Eagle that I converted to nitro well before the Nitro Hawk came out.
:shock:

Closet Traxxas guy... You and scr8p being the closet Kyosho guy should start your own club. :mrgreen:
Peace and professionlism.....Kabunga signing off!!!

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Re: Adding an "idler" gear for reverse rotation?

Post by GoMachV »

I'm ok with traxxas, as long as it came with white plastics 8)
It's time to stand up to the bully. Support the companies that support the industry, not the ones that tear it down. Say no to Traxxas
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sbcnyc
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Re: Adding an "idler" gear for reverse rotation?

Post by sbcnyc »

So my big question is how do you now calculate your final drive with the additional idler, does it affect the pinion/spur/final drive ratio?

i worked out mounting a gear in between, but clueless how it affects pinion spur selection or where to read up on basic gear calculation...now that i got my sensored stuff running in the correct direction, id just go out, run, and temp the motor but id like to know the actual calculation or theory required. if there's an effect on final drive

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Re: Adding an "idler" gear for reverse rotation?

Post by jwscab »

It doesn't. just use the pinion/spur math times the internal ratio. the idler is 1:1 between the pinion and spur, it doesn't work into the calculation.

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Re: Adding an "idler" gear for reverse rotation?

Post by sbcnyc »

Done and done. Thanks all!

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