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JohnDahl


Joined: Jan 22, 2008
Points: 7

How much increased speed will the Ariens cast iron gearbox safely handle.
Original Message   Jan 22, 2008 6:38 pm
First off I am new to the site, and I have enjoyed reading the different posts. This site looked like I could get the most help for my aging snowblower. I have an  Ariens 924016 with the 8hp snowking, and 32 inch cut. My impeller pulley was destroyed while changing the impeller gearbox seals. I originally had a 9 in dia. impeller pulley and a 2.75 in diameter engine pulley. I have a 8in on the shelf. I am concerned if the cast iron gearbox will be able to handle to increased speed. With the 9 in pulley I have a ratio of 3.27/1 and with the new setup the ratio is 2.90/1. Has anyone done this, and if so has the gearbox held up? Any suggestions would be welcomed.
This message was modified Jan 23, 2008 by JohnDahl
Replies: 1 - 8 of 8View as Outline
JohnDahl


Joined: Jan 22, 2008
Points: 7

Re: How much increased speed will the Ariens cast iron gearbox safely handle.
Reply #1   Jan 23, 2008 3:23 pm
I could really use some help on this one, install with smaller pulley, or wait a week for the stock  pulley. I would not mind increased throwing power, but I do not want to damage additional components.
Professorpi


Joined: Jul 26, 2007
Points: 16

Re: How much increased speed will the Ariens cast iron gearbox safely handle.
Reply #2   Jan 23, 2008 4:20 pm

I would say no, b/c it looks like Ariens already bumped up the impeller speed by 10% for your model. For example my 1971 Ariens has a 2.5in/9in pulley setup =1000rpm impeller speed, yours has a 2.75in/9in setup=1100rpm i.e. a 10% increase. If you go with the 8in pulley then 2.75in/8in will equal an impeller speed of 1237.5rpm ~24% increase from Ariens original design spec. FYI impeller speed = (engine pulley dia./impeller pulley dia.)*(max. engine rpm).  BTW. There is usually a 10:1 ratio between impeller speed and auger speed i.e. 1000rpm(impeller) to 100rpm(auger). Hope this was useful.

This message was modified Jan 23, 2008 by Professorpi
borat


Joined: Nov 10, 2007
Points: 2692

Re: How much increased speed will the Ariens cast iron gearbox safely handle.
Reply #3   Jan 23, 2008 4:35 pm
Changing the gear ratio will give you approximately an addition 109 rpm at the auger shaft.  That's equivalent to a 9% increase.   What you will gain in auger/impeller speed will be lost in torque.  I doubt that you will realize a real difference in throwing distance.  As the load on the engine increases, torque demand will also increase.  An eight horse power Tecumseh engine on a machine with a 32" intake will be stressed with stock gearing let alone a taller ratio.  I had a machine with a 10 h.p. on a 32" machine and it was a terrible combination.  Way too much intake capacity for the available power.  That machine was the worst I ever owned.  It finally rattled itself to oblivion.   That was my experience with a 32" intake and what I would consider insufficient power.  Your machine may be much better.  I don't know.   How does the 8/32 combination work with the Ariens?   Does it bog down in heavy/deep snow?

If you're in a pinch, I doubt  that the 2.75" pulley will cause any immediate problems with your gear case.  However, if I had a machine with those dimensions, I'd be looking at something with deeper gearing in the 2.5" range or better yet, look at re-powering with an eleven or twelve h.p. motor in the future.    

This message was modified Jan 23, 2008 by borat
JohnDahl


Joined: Jan 22, 2008
Points: 7

Re: How much increased speed will the Ariens cast iron gearbox safely handle.
Reply #4   Jan 23, 2008 5:00 pm
Thanks for the reply, for clarification, Its the impeller pulley that I have to change. My 9in is destroyed, and I have a 8 in on the shelf. I understand that the 8 in would work the engine harder. But like I said I don't want to damage anything else. I inherited the blower from my brother, who lived in the sierras. He said when it ran, it did a decent job. I have not had enough snow to really get a good idea.
borat


Joined: Nov 10, 2007
Points: 2692

Re: How much increased speed will the Ariens cast iron gearbox safely handle.
Reply #5   Jan 23, 2008 6:37 pm
Going from a 9" to an 8" will give you approx. an 11% increase in impeller shaft speed.   I can't say for sure that you're gear box will fail or not but I'd be willing to give it a shot.  The cast iron gear case on the older Ariens machines were pretty stout and I'd bet that they're stronger than many units today.   As previously mentioned, you will lose torque.  You may have to slow down your drive into deeper snow in order to keep the engine in it's power band to keep it from bogging.  You can also take smaller cuts to reduce overall engine load.  If the 8" is all you have, go for it.       
JohnDahl


Joined: Jan 22, 2008
Points: 7

Re: How much increased speed will the Ariens cast iron gearbox safely handle.
Reply #6   Jan 23, 2008 8:24 pm
Thank you for the info. I havent put the gearbox together yet, But when I do, I will base that decision on the condition of the brass gear shaft etc. I will also take into account that the 8hp motor does have some age to it. I also have the  clarence kit for my impeller. Would adding this kit have a better or worse effect with the smaller pulley. More leverage less torque kinda thing?

John

borat


Joined: Nov 10, 2007
Points: 2692

Re: How much increased speed will the Ariens cast iron gearbox safely handle.
Reply #7   Jan 23, 2008 8:32 pm
The impeller kit will add load to the engine.  By eliminating clearance between the impeller and housing, it will not allow for much slippage therefore the engine will taxed a bit more.  However, it will also move snow better provided it can make enough power to keep it from bogging down.
Snowmann


Joined: Dec 3, 2003
Points: 494

Re: How much increased speed will the Ariens cast iron gearbox safely handle.
Reply #8   Jan 23, 2008 10:30 pm
JohnDahl wrote:
First off I am new to the site, and I have enjoyed reading the different posts. This site looked like I could get the most help for my aging snowblower. I have an  Ariens 924016 with the 8hp snowking, and 32 inch cut. My impeller pulley was destroyed while changing the impeller gearbox seals. I originally had a 9 in dia. impeller pulley and a 2.75 in diameter engine pulley. I have a 8in on the shelf. I am concerned if the cast iron gearbox will be able to handle to increased speed. With the 9 in pulley I have a ratio of 3.27/1 and with the new setup the ratio is 2.90/1. Has anyone done this, and if so has the gearbox held up? Any suggestions would be welcomed.

JD,

Don't worry about the gearbox, it'll be fine. However, your auger brake will not function with a 8" pulley as-is, which will make the unit dangerous (your auger won't stop when you de-clutch). You could try to modify it, but I wouldn't recommend it. And as other have indicated, you'll be loading up the engine more and possibly recirculating more snow (faster isn't always better).

PK
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