planetary gear transmission

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Apr 15, 2005
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Would it be feasible to convert an automatic transmission to a manual.
I don’t mean replacing the transmission, converting it.

replace the TC with a clutch, Replace all the automatic clutch packs
and drums with synchros to engage and lock various parts of the planetary gear assembly.

Is there a manual transmission like this that uses planetary gears

What would be the downside? is it weaker then standard gears?








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Mace

rock scientist..
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there are true lock ups for autos.. But they still use the TC

Why would you want something that is bigger and more complen than a manual converted to a manual?
 
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I guess I didn’t explain my question properly. It’s just an idea I had while reading how AT’s work http://auto.howstuffworks.com/automatic-transmission.htm

But I suggest reading this first.
http://www.howstuffworks.com/gear7.htm

You can see how almost all the Automatic transmission’s size is used for controlling
the Planetary gears, which are small.
Smaller then a manual trans.

I didn’t mean hack a A440f case in particular, just use “a” planetary gear set instead of standard gears. With a stick shifter to switch gears instead of hydraulic pressure and clutch packs.

For instance look at the Klune-V
http://www.klunev.com/page_toyota_landcruiser.htm

I’m sure it can be done, just wondering why manufactures don’t ? Cost? weakness?
 
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Ive seen a turbo 350 that has a clutch instead of a torque converter, it was wierd. I think it was a turbo 350, it may have been a glide. I dont see the point though, it was a weird old tech thing.
 
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Don't know of anyone who has reused planetary sets out of an OEM auto trans, but manual planetary transmissions have been around a while. Drag cars and boat have used them, they're super strong, but very expensive. The planetary boxes are "modular", so the number of speeds you have is based on how many boxes you stack.

Check out http://www.lencoracing.com

I think the reason manufacturers don't use planetaries for manual trans is as you can see on the lenco, to get 5 speeds you get a loooong trans. The hydraulic clutches in an automatic take up less room than synchros would, plus they can be mounted internal to the planetary to save extra space.
 
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Thanks for the link.
It appears that Lenco isn’t using the full capabilities of a PG set for simplicity.
They only use one gear ratio from the set.

The reason I’m interest in planetary gears is I’m looking to make a under / over drive.

You actually have 4 gear ratios with a PG set depending which gear you use as a input/ output, one of which is reversed.

For instance if I use a 23T sun gear and a 91T ring gear and the input is the (sun) output is (planetary) I get 4.9:1 underdrive

If my input was the (planetary) an out was the ring I have 0.8:1 overdrive.

Also if I lock all gears I get 1:1

That’s 3 speeds in a small package and bad autos are free.
 

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