snowblower build

[ohiojeff]

OK PILOON, point well taken . the intermediate shaft idea was simply what I saw on the SnoVac site. simple is better for sure so if I don't need a third shaft then so much the better. I appreciate your comments . thanks!

Sure you could use an intermediate shaft but then you'd have 2 chains and 4 sprockets plus bearings and shafts and some structure.
Also add 2 adjusters.
You are blowing snow which is frozen water and when wet belts will want to slip.(and no matter how you build, snow will fly)
When I rigged my setup I mounted the motor on top of my blower with shaft sprocket lined up with the blower input shaft.
When the PTO shaft removed my blower had a short keyed shaft sticking out ready to accept the large driven sprocket.
I venture to say that all blowers will have a similar short keyed shaft setup as that is how the PTO shaft has to couple.
Brief shopping and you will find that any diam shaft combined with diam sprocket is available in different chain sizes.
Your driven sprocket can in fact be almost as large as the blower impeller and still clear.

As a tensioner you need a 3rd idler small sprocket on a pivot that you add pressure or tension to the slack side of the chain.
I think the chain generally used is # 40 but could be wrong..
Naturally the idler needs to run on bearings and a method devised to adjust.(hinged with longish screw)

I am sure belts could do the job but you'd probably need double or triple belts to handle the HP.

 

[jimgerken]

Stick with chains. Yes its a pain when they stretch, but belts will slip when they get snow on them. They are warm, the snow turns to water, and they won't transmit as much power when wet. To minimize the chain stretch, use a good grade of motorcycle "O" ring chain, in 520 or 530 size. I believe it runs fine on #50 sprocket. "O" ring chain is a wise investment, compared to #50.

 

[ohiojeff]

I once used a 13 hp to drive a 4 ft blower. Used a 3" drive sprocket to turn an 8" blower sprocket.
The setup worked just fine, in fact overpowered, so 6' with 30hp would probably be fine.
At worst possibly 9 or 10 inch driven would do the trick.
You will absolutely need a tension set up as chains do stretch.
By my math, wanting 500 rpm at blower using the 13 hp is how I arrived at 10 and 3 ins and in fact I was probably turning the blower at 700 rpm or so. My biggest challenge was to keep the engine from digesting cold snow so some creative baffling was in order.

PILOON, I did some calculations . The engine I am considering is rated at 3600RPM. In order to get to the 540 RPM neighborhood I would need a 2.5" drive sprocket and a 16" driven sprocket. does this sound plausible to you?

 

[PILOON]

Quick guess that you have the sizes correct. The 16 sounds a tad big as I'd doubt that you have the clearance for it. Simple, it would need to be smaller than the blower 'fan' otherwise you will be scraping pavement.
I'd simply go about 2" dia less than the blower fan and live with that.
As I recall my old setup blew the snow 'clean across the yard', like 2-3X what it did compared to the PTO @500rpm ( so obviously I was faster than with PTO.)
Now to compare, my tractor is rated at about 20hp which is why I guessed that I needed at least 13 hp.
Since I now always blow using my PTO on my 750 speed (like 5 yrs) I can suggest that over speeding a blower won't harm it, only perform better.
Mind you a lot depends on the blower I guess.
Mine has a 3 blade 16" fan which in itself not great so by adding RPMs I compensate.
If your blower is 4 bladed and 24" fan then you'd better stay at 500rpm.
Have fun!

 

[ohiojeff]

Quick guess that you have the sizes correct. The 16 sounds a tad big as I'd doubt that you have the clearance for it. Simple, it would need to be smaller than the blower 'fan' otherwise you will be scraping pavement.
I'd simply go about 2" dia less than the blower fan and live with that.
As I recall my old setup blew the snow 'clean across the yard', like 2-3X what it did compared to the PTO @500rpm ( so obviously I was faster than with PTO.)
Now to compare, my tractor is rated at about 20hp which is why I guessed that I needed at least 13 hp.
Since I now always blow using my PTO on my 750 speed (like 5 yrs) I can suggest that over speeding a blower won't harm it, only perform better.
Mind you a lot depends on the blower I guess.
Mine has a 3 blade 16" fan which in itself not great so by adding RPMs I compensate.
If your blower is 4 bladed and 24" fan then you'd better stay at 500rpm.
Have fun!

Ok, got it . thanks for the help!

 

[2458n]

I was at TU now UT, For the blizzard in the late 70's. Plowed malls for days. May you have such a winter in your life.

 

[ohiojeff]

Ha! I remember the Blizzard of '78 well. Toledo had similar weather last winter. set record for snowfall and temps. it was a real old fashion winter. I am currently about 550 miles northwest of Toledo on the south shore of Lake Superior. Just yesterday we were up in the Keweenaw where they had 348 inches of snow this past winter. now that's some snow!

 

[ohiojeff]

Hey PILOON, another question. What about a clutch? do you think I should have an electric clutch included in design or even a manual clutch of some type?
BTW, my blower does have the four bladed fan so I guess I should try to get into the 540 RPM range.

 

[PILOON]

On the setup I made there was no clutch and I really wanted one.
Starting while spinning the blower was a hassle as all that weight would not allow RPMs to build up, granted the engine was a one cylinder so the compression was high on that one cylinder.
YES a clutch would be ideal but pricy from my checking around and might even need to be custom made.
A plain sprocket can be simply attached to the shaft while a clutch would want some outside support mechanism.
For the cost of the sprocket why not just try and see how it goes? A lot would depend on the starter's power.