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Reduction Unit fab for Brigs motor

papee

papee

Well-known member
Or maybe even if someone could help me with my aging memory. It would make it much easier to search if there were a mini forum also. Oh and I am heading right from this post to donate! ANy way, I am looking for info on reduction for my mini, specifisly the top shaft portion. I'm interested in mounting and adjustment ideas. Also places to buy pullys.
thanks in advance Dave
 
I never thought of that papee, let's give it a try. I'll get one setup sometime today.

Thanks,
Rick
 
Edited to remove my mis-interpretation of this thread. My previous post seemed out of place now that the title has been changed.

Thanks to whoever cleared that up.

:)

Interesting stuff here as usually the case on Southern Airboat!!!

Southern engineering at it's finest! Gotta love it!!!

matt.
 
rick":3q45injn said:
I think papee was talking about a "Mini-Airboat" forum.
Click to expand...

Yes Rick I was, I know I have brought up a few subjects on them and I was trying to find info on dealers to get more info and searching was rather fruitless. I know some are going to these rigs for hunting and just had the idea that if there enough need for the forum it would be nice. Thanks for the consideration.
 
Anybody that supplies bearings normally supplies pulleys also. I still think a wheel hub or trailer hub would be perfect for a mini. Mount the hub stationary and mount the pulley and propeller flange on what would normally be the axle shaft. You can get multiple groove taperlock pulleys and they are pretty inexpensive if you can get jobber price. if YOU WANTED TOOTHED BELTS like polychain, Goodyear manufactures them and you should be able to get them from the same bearing supply place or a machine shop could make them out of aluminum for you. here is a picture of a Franklin bearing assembly. Does it kind of look like a wheel hub to you? You wouldn't even need to do a through shaft and just have the pulley and prop shaft on the same side as the hub as I have seen the mini stuff built like that as well. Someone previously suggested a wheel bearing wouldn't handle 3000 RPM but all I can say to that is think of that 8" tent trailer tire and wheel doing 70 MPH down the Hi way, Sure it would need frequent inspection and a shot of fresh grease before you run but. We have pumps at work that use a triple V belt set-up and the pump requires about 80 HP and we can usually get about 1000 hours out of them if kept adjusted.

849done.jpg


If you wanted to do the through shaft you would just have to machine the grease cap end for a seal.
 
Cold I like the way you think - You are a regular "Fred Sanford" :) I'll bet you can't say have not been "dumpster diving" recently. LOL I know I have!

But the wheel hub and bearing has one thing that I'd want more info on - that's thrust.
The force PUSHING on it by a prop is not there on a trailer wheel. Are those bearings designed to take that kind of force from that direction????

Just curious.
 
If you look at how a wheel hub is made, you will see that the
lug plate ( where the load is sitting ) is over the inner bearing
usually the larger of the two. The outer bearing carries less
load but keeps the assembly in line . on some smaller hub
assemblies the lug plate is centered and the bearings are the same
this would load the top of one bearing and the bottom of the other
and would likely wear out your races in no time.
As for the RPM's , the circumference of a 4.80x8 trailer tire
is about 52'' one mile is, 63,360'' which would work out
to 1218.5 rev's per mile, at 1 mile per min. ( 60 mph. )
that would be: 1218.5 RPM's, that would be: 2437 RPM's
120 MPH. and : 3655 RPM's at a whopping 180MPH.
I guess what this means is, you'd have to be pulling your
little boat trailer pretty darn fast to turn your hubs 3000 RPM's
Or something like that .
 
Papee, a high quality gokart wheel hub works pretty well. Get a good one, with tapered roller bearings in it. They're designed to be spun pretty fast, take a fair amount of thrust load, and they're servicible.
 
Olf Art":5iu80de8 said:
Papee, a high quality gokart wheel hub works pretty well. Get a good one, with tapered roller bearings in it. They're designed to be spun pretty fast, take a fair amount of thrust load, and they're servicible.
Click to expand...

This is what I was thinking, The shaft on my engine is 1 in and I have a gocart axle that is 1 inch with keyway here. I also have two 4 bolt hubs to fit. The existing one that is on the engine and a spare. these hubs will allow me to slide the hub on a piece of shaft with a bearing on each end of the top pully. I am not sure about end travel, a way to mount the shaft and make it adjustable to tighten the belt. I was thinking of dual serpintine belts. If one would break I could possibly make it back on one depending how hard it is to rplace a belt on the water.

edit: BTW thanks Rick for the forum, it should make searching easier.
 
You're only running around 25 hp, right ? I have a new redrive for a 24 hp Zenoah ultralight motor around here somewhere.
If you want, I'll find it and mail it to you and you can use it for a model.
When you get done with it, just mail it back. :?:

I also have a brand new 54 X 24 Tennessee Props propeller that was made to run on it if you need that too. :)
 
Thanks for the offer Olf, I'll keep you in mind. I know if I can get the general idea down my buddy that has a machine shop can take it from there.
 
You could build a "Southern Mini Airboat Drive" We got engineers on here who could do the math and draw it up and CNC guys that could build it and perhaps it could be profitable for many! Target the applications that seem popular and maby a generic universal kind of thing that has to be fit? People involved benefit, SA benefit and airboating public as well! 8)
 
Got any pictures of the go-cart hub and pullys?
How about a source?
There's a ton of stuff out there, but most anything I would want would need to be ordered, trick is knowing what's needed as well as where to get it.
We're still looking to build a mini using the 4A032 military engine with a reduction unit.
 
Fp, quality hubs like Papee and I are talking about can be found on eBay, and often at good prices.
 
OK, I got some of my "honey do" list done, poured a new concrete front porch and got the flower beds all weeded so I'm back to the project. Still have to build a roof over the porch. I was looking over the motor and saw that it has four taped mounting holes. Would these hold if I made something to fit? I was thinking I could add a brace somwhere on the top kicked at an angle to the top of the motor. This way the top pully would be easy to make adjustable and I could use a spindle setup for the top pully.
 
Papee, those four tapped holes are what you can use. The redrive on my Zenoah motor bolts on there.

Just keep in mind that all of the thrust load will then be transferred to the four engine mounting bolts, and since you'll be turning a bigger prop with the new drive you'll probably want to beef up that mounting pad a little.
 
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