Only Cub Cadets - QA42A Speed

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I feel for ya. A lot going on there. Sounds like the belt was a result of the strain of the other failures. Hate to say it, but I think it needs to come apart.

For next year I will be changing out my chain drive gearing I think. This one will blow snow once I am done!

I am a bit confused (which doesn't take much at times) what are you calling the "rotor"? is it all turning up to the small sprocket your saying?
Tony

Quote:

Originally Posted by aldiesel (Post 233787)

I am a bit confused (which doesn't take much at times) what are you calling the "rotor"? is it all turning up to the small sprocket your saying?
Tony

Part number 3 ( Rotor assembly)
Part number 7 is the number one suspect of the problem, if I'm lucky I just need to replace the 1/4 X 1-1/4 Hv Coiled Spring pin (19-689-R1) but I got enough for the moment, I stay as far I can from it ...:angry:

http://img541.imageshack.us/img541/2366/yg4g.gif

That dogbone I think they call it (5) is what I fear is damaged. It is the part I concern most with overspeeding the unit. Those are bushings not bearings(11) so lot of wear with heat and poor lube system.

So does the auger(rotor) move at all? Something should be able to wiggle within chain slack. Sorry for the questions, just trying to understand all the failure points. Something locked up for sure, but have sheered a pin?? Once you figure out and fix what locked the rest might not be so bad.

My qa42's have needle bearings with grease zerks for (11), not bushings. Overspending the machine has not hurt anything yet but I grease frequently and let a little slack in the chain to put less stress on everything.

Good to know. I made a bad assumption from the drawing. Thankfully my two are in good shape so not apart yet. Let the whir commence. Lol

Quote:

Originally Posted by 782CC (Post 233800)

The rotor hand move with chain and both sprockets together, but no power is transfer from the drive shaft or (number 6) small shaft, I think the small sprocket slip on the small shaft.

I take 2 weeks off work so I fix the problem ASAP and try again :-)

Thanks to Macman81's info I took mine apart today to give it a good cleaning. There is a shear pin in the sprocket and shaft. That part should be an easy fix for ya. Ensuring there is not something else may take a bit more checking.

Did a little measuring and math today on our snowthrowers to try and put values to our varied results. Assuming a 4 5/8 pto pulley and 4.5 thrower pulley.

QA42A (H42) - belt=1:1.02, Gearbox=2:1, Chain drive=1.7:1 Total reduction is .2997
So stock 1072 RPM rotor for a 38.5 mph release (leaving the rotor impeller) speed. Now there are losses for the chute and impeller efficiency. The bend of the chute could be as much as half. And the rotor could only be 80%. Assuming both and not digging up better math. 30mph release for 15mph at the end of the chute.
Mine throws 4-6ft with heavy snow. Barely gets over the side of the blower. Only used once but not expecting much better with light snow.
PTO (worn so belt sit lower) 4 inch & 4 inch thrower pulley.
Total reduction is .2916. Rotor=1050RPM, Release 37.4MPH, 80%=29.9MPH, Chute=14.9MPH.

Now my old HiCast38 that throws anything. Heavy snow better than light. 20ft easy and could do 40. Pretty much the same blower housing as my H42.
Guessing on my PTO as I can't measure it. Between 5.375 and 5.875 inch from searches. So will give both.
5.375 - Rotor=1612RPM. Release=57.5mph, 80%=46mph, Chute=23MPH
5.875 - Rotor=1762RPM. Release=62.9mph, 80%=50.3mph, Chute=25MPH.
Video of the Haban
http://www.youtube.com/watch?v=Exs0eg4l4Ds
http://www.youtube.com/watch?v=45j1q6hCp90

Sorry for the long post

Took apart the dogbone today. Very easy to change out the drive sprocket so I will be doing that to get my speed up where I want it. Should also note my blower needs worked to clean it up.

Quote:

Originally Posted by macman81 (Post 231578)

Best I can tell the pitch diameter is where the belt rides. Our belt is equivalent to an A belt so effective diameter would be 3.4". I tried a 2/1/2 pulley first, way way too fast and belt slipped all the time. Then tried a 3.25" pulley which was good but a too fast for fluffy snow so I went to this 3.4" now and 90% throttle with light snow is perfect! And if it's wet heavy stuff then I'll give her wide open throttle. I found if you run it too fast with light fluffy stuff you end up wearing it all! So I just adjust the throttle according to how wet the snow is. Your results may vary but two years worth of tinkering has led me to this setup.

So I reread and realized Macman covered it very well.
Probably a dead horse thread by now. But I will post this final info just cuz.
Here are the rotor speeds of his changes very much like my MTD experience. I did this because I also have an h48 with a larger rotor and needed some math to change it with.

Thrower Pulley=2.5, Rotor=2498RPM, MPH=89.2
Thrower Pulley=3.25, Rotor=1494RPM, MPH=53.3
Thrower Pulley=3.4, Rotor=1428RPM, MPH=51
Thrower Pulley=4, Rotor=1214RPM, MPH=43.3
Thrower Pulley=4.5, Rotor=1079RPM, MPH=38.5

I will be changing the drive sprocket. To avoid a smallish pulley. Plus I already have the 4 inch lower. (18 tooth drive sprocket.)
Thrower Pulley=4, Rotor=1434RPM, MPH=51.2