lawn mower transmission...?

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joshpit2003

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I've read an article that suggested it was a bad idea, but i was just wondering if anyone here has actually built a kart using a lawn-mower tranny?

Thanks.
-josh
 

freakboy

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i got a racing mower with a mower transaxle in it and its gona go faster then half the karts on here.
 

joshpit2003

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i dont think the transaxle was what I had in mind... but maybe (if so it's a small one that I'm picturing).
Brigs... do you happen to have a link to the one you are planning on using?

I'd love to find one w/ a huge gap in ratio:
example: 1:1 5:1 10:1... but i understand that is unlikely.
I'd also love it to have an input (i'd convert to chain drive)
that is 90* out of two output shafts (that I plan on attaching a front and rear driveshaft to).

basically turning a mower tranny into a transfer-case.
I may just be dreaming, but i thought i've seen a few that match that description. If you guys know of any please feel free to post some links.

Thanks a lot.

-Josh
 

Doc Sprocket

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A mower transaxle could work as a transfer case, sure- Mount it logitudinally along the frame. Than the two axle shafts become your driveshafts. Then you'd have to have a RAGB at each end to drive your axles. Lotsa fab work involved.
I don't think you're gonna get your wide-ratio wish, though!
 

joshpit2003

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so I have a few questions:
1. whats RAGB?
2. is there no such thing as a shift on the fly lawn-mower tranny? (if not thats a bummer)
3. Do the trannys typically have a live axle or diff in the gearbox??

if they have a diff then I think I need to start looking for other options.

Thanks for the help guys.
-Josh
 

BriggsTwins

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RAGB is known as a right angle gear box, housing two gears and changes the power output from parallel to perpendicular making it easier to run a chain to your axles

a shift on the fly trans isnt that common anymore, hydrostatic has taken the lead on transmissions. normally a trans like mine isnt on the fly, but can be coerced into shifting while in motion as long as you dont SLAM gears.
all tractor transmissions have a differential, "all" being the ones that wheels are connected to them directly, not by chain or other means

your idea will work, but finding RAGBs and welding the diff are your BIGGEST setbacks
 

Kaptain Krunch

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If its shifting you want, get a motorcycle or ATV engine, if your after a low budget go kart, which uses a vertical shaft engine, than a lawnmower transmission is alright.
 

joshpit2003

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thanks for the responces.
I'll be building an off-road pedal powered kart.
I may add an electric assist depending on how hard it's gonna be to get the thing moving. I dont expect it to go very fast.
I'm thinking a top speed of 18-20 mph (cranking your *** off) and a cruising speed of 12-15 mph.
 

joshpit2003

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so what are my options for trannys?
So far I have only seen 2 types for tractors:
1. the transaxle.
2. the in-line looking type.

is there anything I'm missing?
I'll have to find a picture of the one I was looking at... it didnt look like it was a big enough housing to fit a diff.
 

joshpit2003

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http://www.petessmallengine.com/images/6686208-HO.jpg
this one looks like the belt driven Pully is the Input and the two shafts are the output.
now that i look at it again, you are probably right that there is a diff in there... which will need to be welded in my case.

The best thing about this tranny is I could simply swap out the pulley for a sprocket and turn it into a sprocket input. the shaft outputs will both be coupled to driveshafts w/ u-joints.... so I really only need an inch or two of material (shaft) comming out of the tranny.
I'm guessing this type of tranny is one of those transaxles right??
 

Kaptain Krunch

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15mph pedaling is A LOT, especially for a kart. I would expect a top speed of 10mph pedaling your *** off. If its pedal anyways, i would just use the same shifting system a mountain bike would use.
 

joshpit2003

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so, do you think these things should be able to shift if there isn't any force applied to the driveline??
My diffs may actually freewheel, allowing the driveline to pretty much not spin when coasting.
 

joshpit2003

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also please note that my application will not allow for a clutch.
I was just assuming that these lawn mower trannys did not use one... is that correct?
I would assume also that an ATV tranny Does use a clutch... in which case I couldn't use that.
 

Kaptain Krunch

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Those trannies are both overpriced, and weak. There meant for self propelled push mowers.

Lawnmowers use belt tensioner clutches.

Your going to have to pedal your *** off to go 10mph, this is going to an exercise machine and a half.

A lawnmower transaxle will add quite a bit of resistance to a pedal powered vehicle, why not just do a del-railer setup like on a mountain bike?
 

joshpit2003

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a de-railer is not an option for this build.
i understand this isn't going to be the most efficient of vehicles.
I'll be happy w a cruising speed of 10 mph and a top speed of 15... just trying to be optimistic.

I think the 15 mph top speed is a good guess... if you think about it you are able to get those huge 4 person (rental) bikes going 20 mph w/ just 2 people pedaling.

Like you mentioned... it may feel more like an excersize machine and if that is the case i will be needing the electric assist.
a belt-drive is not an option either... so if thats what the internals of all the lawnmower trannys are then I'm hosed.
 
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