Rear Inverted Snowblowers 2019

[Hilbilly]

Well the new replacement blower finally arrived! I think the guy that delivered it must have driven over every dusty side road he could find before getting here. The whole thing was covered in dust and the auger drive chain was packed with dust that clung to the chain grease. Not a great idea. The dealer said he ran the blower at his place and said it was working properly. After cleaning it up and greasing the gears I ran the blower to see if there were any issues and it appears there is. Here is a video of the blower at idle speed. It appears the collar on the end of the fan shaft was not welded to the fan properly, causing the driveshaft to wobble.

What do you guys think?
Farm King PT842 Inverted Snowblower - YouTube

 

[airbiscuit]

I can't exactly tell from the video. Could be movement as a function of the coupler?

 

[leonz]

That blower is defective!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The impeller is not running true and that is causing the entire driveline to wobble out of round.
You can see in the video that the orbit of the impeller is defective.
That means the impeller shaft is orbiting out of round by a few degrees from center.
There is no way you can fix this yourself unless you have access to a machine shop as the impeller
shaft is not running true since it appears to be binding at one point.

 

[Dave M7040]

You are not buying a Swiss watch but rather a low cost blower.

The shaft is connected to the fan by a flex coupler looking like a double wide chain. See attached photo

At the back of the blower, the fan shaft is supported by two bearings bolted to a welded structure making up the open gear box.

This is not a real gearbox which has line bored bearing races to ensure true rotation of the shafts.

The flex coupling is not intended to support the fan but turn it which is is doing.

If the fan does not vibrate at full pto speed, I do not think there is anything to worry about.

Dave M7040

 

[leonz]

Hello and good evening Dave 7040,

A magnetic base dial indicator will show the dealer what is wrong and where simply spinning it by hand.

This was the same trouble he had with the original unit from what I remember of the gentleman's initial snow blower trouble during last years snow season.

If worse comes to worse he should ask them to take it back and ask them to send it to a machine shop to fix the out of round condition that is the cause of the wobble and noise.

I candidly think the entire driven shaft is not straight as you can see the shaft bind slightly all the way to the rear bearings.

 

[airbiscuit]

Checking it with a magnetic base dial indicator is excellent advice.

 

[Hilbilly]

Wow, 2 opposing opinions; one says it's horrible and the other says no big deal. I tend to side with the opinion that this is not acceptable. With this not being concentric it will be out of balance and surely will affect the longevity of all the bearings. By the way, I wouldn't call a $7,000 snowblower a low cost one. Maybe not the most expensive but it is new and should be properly constructed.

The first blower kind of self destructed within the first 100 feet or so of use. The fan assembly slid forward and caused the fan blades to hit the housing, which caused 2 blades to get badly bent and the other 2 to rub against the housing. Plus the gears weren't properly shimmed.

Looking at it closer it looks to be a poorly installed sprocket hub on the end of the fan shaft. Tomorrow I will take off the protective top plate and use a dial indicator to see where the problem lies. Sure not impressed with the quality of these blowers.

 

[leonz]

Wow, 2 opposing opinions; one says it's horrible and the other says no big deal. I tend to side with the opinion that this is not acceptable. With this not being concentric it will be out of balance and surely will affect the longevity of all the bearings. By the way, I wouldn't call a $7,000 snowblower a low cost one. Maybe not the most expensive but it is new and should be properly constructed.

The first blower kind of self destructed within the first 100 feet or so of use. The fan assembly slid forward and caused the fan blades to hit the housing, which caused 2 blades to get badly bent and the other 2 to rub against the housing. Plus the gears weren't properly shimmed.

Looking at it closer it looks to be a poorly installed sprocket hub on the end of the fan shaft. Tomorrow I will take off the protective top plate and use a dial indicator to see where the problem lies. Sure not impressed with the quality of these blowers.

=======================================================================================


Hello Hillbilly;

I am glad to hear that you have a magnetic base dial indicator in your tool box, is it a Starrett??
You should not need much tension at all when you set the ball on the shaft and spin it by hand.

I look forward to seeing the video of the dial indicator at work showing the wobble.

I would start at the rear with the first open section of shaft between the rear bearing and the one in front of it.


The propeller shaft from the underslung carrier bearing is fine right up to the chain coupler where the trouble starts.

It would be advisable to disconnect the chain coupler to spin the impeller by hand to find the complete wobble.

 

[Dave M7040]

When evaluating the movement of the shafts, think of the basic design. The fan is supported by two pillow blocks bolted to a weldment. The precision of this design is limited!

The shaft on the pto side of the fan is supported on only one pillow block and then uses the chain coupling to the fan to hold it up.

The fan shaft is not bent it is just not perfectly in line axially or radially with the shaft on the pto side. It. is the job of the coupling to deal with this condition

If it was part of an electric motor and pump setup running 1,750 or 3,600 rpm then the design would have to be different and the alignment of pump and motor would require skill to accomplish.

This unit runs at most 600 rpm. Take 10 brand new blowers from the assembly line and it would be amazing if even one did not act like the two this forum member has now or previously.

Avoiding this condition means buying a more expensive unit with an enclosed cast iron gear box.

The open gear design has served owners for decades but is not found in commercial grade equipment for a reason.

Dave M7040

 

[Reb954]

I have to agree with Dave.

Bearings using an eccentric locking collar have runout built into them which is why they aren't used on things that require precision, no vibration or that run high speed. You can use an indicator to check how much runout there is but it wouldn't surprise me the manufacturer will say that runout is within their design limits.

Also, the input shaft may run truer when a load is put on it. I can't see the input shaft bearing in the video but I would imagine they used a self aligning bearing, probably a pillow block with an eccentric locking collar, that will self align once a load is put on it. Keep in mind that self aligning doesn't mean it will run perfectly true, it just means it will run true enough for the intended use.