hp rating on axles

[wheels]

Hey guys... i'm getting ready to start another build. I am researching axles at the moment and need a little help.

background:

i have two motors to choose from with this project: 75hp(60-65 to the wheel) or 25hp(15-120 to the wheel). I'm really wanting to use the high hp motor. The project is going to have a swingarm setup with live axle and is going to be for offroading.

my questions are:

1. what size axles seem to be the strongest? aluminum, steel, hollow, solid, 1 inch, 1 1/4 inch, etc???

2. what is the hp rating of a keyway? i ask this b/c i've seen some live trophy karts with bike engines(>50hp) and they seem to work fine.

any opinions or information would be appreciated.

thanks.

 

[r97]

I know on minibuggy.net they strongly suggest going for a splined shaft rather than a keyed one. I think if you went splined and kept the axle at at least 1-1/4" you would be fine. A solid axle is what you want.

I will add that the edge sidewinder uses a section of 4140 steel rod, 1 1/4" in DIA with 10mm keys. Those things usually run between 400 and 600cc enduro bike engines.

 

[Badot]

The larger the diameter, the stronger.

Chromoly steel is typically going to be the strongest axle material you can find.

Hollow axles give better strength to weight as well as strength to material cost. Hollow axles are much more prone to buckling on an impact though, and have a lower strength to size ratio.

Keyway strength is linearly proportional to length. Double keying, geometric shafting, and splines are stronger, generally in that order.

 

[wheels]

I know on minibuggy.net they strongly suggest going for a splined shaft rather than a keyed one. I think if you went splined and kept the axle at at least 1-1/4" you would be fine. A solid axle is what you want.

I will add that the edge sidewinder uses a section of 4140 steel rod, 1 1/4" in DIA with 10mm keys. Those things usually run between 400 and 600cc enduro bike engines.

when you say splined, I'm assuming you mean a keyed axle with splined ends. right? fogive my ignorance... still learning.

The larger the diameter, the stronger.

Chromoly steel is typically going to be the strongest axle material you can find.

Hollow axles give better strength to weight as well as strength to material cost. Hollow axles are much more prone to buckling on an impact though, and have a lower strength to size ratio.

Keyway strength is linearly proportional to length. Double keying, geometric shafting, and splines are stronger, generally in that order.

sounds like i need to go with a 1 1/4 axle. quick question for ya about 'double keying'... i've searched google and don't see any double keyed axles. is that a custom setup that you've seen? or can you buy the setup some where?


thanks for the responses guys... i appreciate it.

 

[r97]

You could just put splines on the ends and then weld sprocket and brake hubs in the center of the axle (or have them on splines too). I guess I was thinking of a fully splined axle but I like your idea better .

A lot of people in the mini buggy crowd (including yours truly) use tractor PTO shafting. It is readily available (agricultural supply stores & some at surpluscenter.com), 1-3/8" DIA with 6 or 21 splines, and has properly fitting hubs available. Reasonably priced too (not cheep as far as I'm concerned, but not crazy expensive either)

You could also either salvage some splined shaft and fitting hubs from a car, or have some splines custom cut ($$$).

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I was considering double keying before I decided on splines. If I am thinking as Badot is then double keying is simply having two keyways on a shaft 180* from each other. I think it has potential as a good candidate, although I don't think it has been documented so you would have to find out how well it works yourself.

 

[Badot]

I was considering double keying before I decided on splines. If I am thinking as Badot is then double keying is simply having two keyways on a shaft 180* from each other. I think it has potential as a good candidate, although I don't think it has been documented so you would have to find out how well it works yourself.

Yep. I doubt you'll find any commercially available because most of the power transfer methods we use originate from industrial machinery design where initial cost is of little issue, but they're very simple and can be made easily with basic machine shop equipment, as opposed to splined shafts which are typically the next step up but are very difficult to make, and somewhat cost prohibitive for smaller scale gokart projects.

 

[anderkart]

If I was building your kart, I'd try to find a deal an older/used Japanese quad with a blown up engine. You'd get a strong axle with rims that fit, plus all kinds of other parts you'll need for your build.

 

[wheels]

You could just put splines on the ends and then weld sprocket and brake hubs in the center of the axle (or have them on splines too). I guess I was thinking of a fully splined axle but I like your idea better .

A lot of people in the mini buggy crowd (including yours truly) use tractor PTO shafting. It is readily available (agricultural supply stores & some at surpluscenter.com), 1-3/8" DIA with 6 or 21 splines, and has properly fitting hubs available. Reasonably priced too (not cheep as far as I'm concerned, but not crazy expensive either)

You could also either salvage some splined shaft and fitting hubs from a car, or have some splines custom cut ($$$).

-----------------------------------------

I was considering double keying before I decided on splines. If I am thinking as Badot is then double keying is simply having two keyways on a shaft 180* from each other. I think it has potential as a good candidate, although I don't think it has been documented so you would have to find out how well it works yourself.

Thanks for the info r97. Hey, are you the same r97 that is over on minibuggy.net??

Yep. I doubt you'll find any commercially available because most of the power transfer methods we use originate from industrial machinery design where initial cost is of little issue, but they're very simple and can be made easily with basic machine shop equipment, as opposed to splined shafts which are typically the next step up but are very difficult to make, and somewhat cost prohibitive for smaller scale gokart projects.

good to know, thanks Badot.

If I was building your kart, I'd try to find a deal an older/used Japanese quad with a blown up engine. You'd get a strong axle with rims that fit, plus all kinds of other parts you'll need for your build.

funny you say that... i found a smokin' deal on two 300ex's. no plastics on either of them and only one runs. i'm using most of the parts, except the rear axle. and i should have extra's should something break.

thanks for the replies guys.

 

[r97]

Thanks for the info r97. Hey, are you the same r97 that is over on minibuggy.net??

That's me! , Still trying to get my avatar to work over there so people might recognize it. oh well