# Gilson impeller bearing- overengineered ?



## greatwhitebuffalo (Feb 11, 2014)

First I got the Cadet 268 running, with 8HP Briggs on it, made 1972, and the original impeller bearing in that was a little dry but still running true. It was also a real snap to change, too easy- just unbolt the flange halves, remove the bearing, insert the new sealed bearing, and re-assemble. The impeller shaft then simply passes through the bearing upon re-assembly. This machine had a rough life as the auger driven gear had broken teeth, and the engine had a blown head gasket.

On this Gilson 55012 gear drive, same 8HP Briggs engine, same 1972 model year, the impeller bearing and/or flanges are apparently shot. The entire auger gear box moves in a circular motion up/down/around as the machine is running. So it also needs an impeller bearing- ok. But to change it on the Gilson is more difficult with the eccentric locking halves. This machine also had a lot of use.

I'm just wondering WHY, Gilson didn't just put in a simple impeller bearing setup like the Cadet and Ariens used. Just put the bearing in and bolt the flanges back together, and slip the auger drive shaft through. 

Ariens and Cadet were not too worried about the bearings seizing on the shaft, and the bearing is therefore a lot easier to change. On the other hand, this offset eccentric bearing locking system on the Gilson, seems like going to **** to light a cigarette. It's overkill on an 8HP machine, not only that, it makes maintenance and r/r much more difficult.

any opinions on his welcome. Why not just slip in a new bearing of the proper size like the Ariens has and not use the locking offset eccentric setup ? There's really no big reason to use it. If the Cadet runs without it, so can the Gilson.


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## Spectrum (Jan 6, 2013)

That eccentric collar is the reason you only need a bearing right now. When a bearing fails a very common consequence is that the ID begins to slip and spin on the shaft. This will almost instantly spoil the fit of the shaft. With the inner race locked to the shaft you can run it into the ground as it sounds like yours was and the shaft is still safe.

Some designs use a similar bearing with a few set screws on an extended inner race. This is not as positive and those setscrews can seize up over time too.

To remove the eccentric collar is not usually much of a challenge if you pay attention to details. Having removed the impeller pulley be sure to dress the setscrew divot and any key way distortion with a file. Then loosen the collar setscrew and use a drift pin to rap the collar free. The common convention is to tighten CW and loosen CCW like a common nut. However, it will work the opposite way and it it has been previously serviced you may need to drive it CW to remove. Once it rotates 1/4 turn on the shaft it is released. Get a pickle fork or pry gently as needed to slide it up the shaft. Lacking rust it is a loose slip fit on the shaft. If a lot of corrosion got to it you may need to grind it to let it spring free.

With the collar removed dress the setscrew divot it left before trying to move the bearing. Again it may slide off with a pickle fork or if corroded to the shaft it may need to be shattered and the inner race split with a grinder.

Another reason to lock the mounted bearing to the shaft is that the pulley is not subjected to any deflection from he front of the bucket. it's all referenced to the back of the impeller chamber.

I don't know the designs of the brands you mention so I can't say if they adressed these points with other features or have design compromises.

In case anyone is not familiar with the eccentric locking collar I explain it here. It is a common power transmission feature, not a Gilson "invention".

Pete


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## greatwhitebuffalo (Feb 11, 2014)

yes I aware of the way it comes off and goes back on, and have reviewed the procedure on your site. 

but having just done one of these on the competing design of the time, the Cadet 268, another 8HP 26" machine, all Cadet did was put a bearing between 2 flange halves and bolt it together with 3 nuts/bolts. The bearing was still running but I changed it just because I was "in there" already looking at the clutch cog engagement issue. I even saved the old Cadet bearing and put it back in the box the new one came in.

the Gilson has a removeable chute/impeller chamber. That means there's some play up/down and side/side. That bearing is used to center things on the driveshaft first, before tightening up the 4 tractor to blower bolts.

it's just odd that the Gilson bearing looks more heavy duty but wore out sooner than the Cadet bearing did. Whenever I see something like that over my experience of the past 30 years, I ask why. Because many times it was a design defect. 

while the Gilson design may prevent the i.d. from seizing on the shaft, intuition tells me that bearing seizing on the shaft would not be an issue to begin with. What would happen is, the bearing would go dry and make a lot of noise and simply self-destruct and all the rollers would fall out of it, and develop a lot of sideplay.

what happened with this Gilson is there's a ton of sideplay and the auger box moves all around. It can be the previous owner hit something with it...but the more I look at it, the more it appears that the locking ring on the bearing, CAME LOOSE and the assembly is turning in there out of round on the eccentrics.

I have not had time to disassemble it but will do so shortly and report back my findings.

whoever owned this machine put belts on it that appear to be the wrong size, i.e. too short, because even when disengaged the augers still turn with force and are fully engaged, and the drive tires will still run if in gear. It appears they cut corners on a belt change using what was on hand and forced the belts on, this would create extreme side loading on the auger pulley- which could have led to the bearing situation I'm seeing here. I don't believe the design was made to take that much side loading from the belts as this has. The belts are definitely shorter than they should be.


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## Spectrum (Jan 6, 2013)

Yes the Gilson gear drive models do split but the auger/impeller, bearing, pulley ect are still all together in the forward weldment. 

It's impossible to select random machines that are decades old with no real history of maintenance, use or abuse and compare durability based on present day condition. I will say that EVERY machine of that age has stories to tell. A few weekends back I was parting down some machines. I cannot begin to tell how many unique jury rigged fixes I found. There were some clever and some not so clever things. In all liklihood you are looking at a machine that is not entirely as it was when it left the factory and sorting that out can be interesting.

For instance I think you have mentioned finding it a too tight belt. This defeated the clutching adding hours and probably stress to the bearing.


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## greatwhitebuffalo (Feb 11, 2014)

exactly...extreme side loading would cause premature bearing wear.

but in this case, the Cadet was the harder used machine. It had twisted impeller splines on the impeller drive shaft, broken teeth on the auger driven gear, no oil in the gear box, a blown head gasket on the engine. yet the impeller bearing was unphased and operational.

we'll see when I get the Gilson 55012 blower assembly apart, it's raining outside today so I won't be delving into it until the weather breaks

the point of my OP was, the difference between the 2 designs Ariens vs. Gilson in the impeller bearing, is dramatic. Yet it appears the Gilson is the one that has the history of worn impeller bearings. I don't see a lot of posts stating the Ariens i.e Cadet design had a problem in that respect. It is probably because the Gilson blower assembly, augers, shafts, auger gear box, are all heavier- so there would be more stress on that impeller bearing.

this puzzled me as the Gilson bearing design looks beefier and stronger with the locking ring. just something that made me go hmmmm....

if a simple replacement bearing would slide on without a locking ring, and give good service life, that may be something I'll look into. If it works on the Areins design with the same engine, it should by logic work in the Gilson.

the bearing with locking ring may be superfluous.

on the hard use issue, the New Holland i.e. Gilson 8HP Unitrol has augers that are bent in the OPPOSITE direction from hitting obstacles, they must have hit a boulder or rock with that machine...wait until you see the close up pics of that one....


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## greatwhitebuffalo (Feb 11, 2014)

after removing the impeller bearing from the 55012, and comparing the assembly to the Cadet, I can see what they did here. On the Cadet the front of the impeller shaft is C-clipped inside the auger gear box and that's what holds the impeller and impeller shaft all together with the auger gear box.

on the Gilson, the impeller bearing locking race is what holds it all together on the back of the assembly, behind the pulley. that sets the distance from the auger box to the impeller chamber backing plate and cinches it all together and holds it there. it's not only a bearing that takes up/down and sideloads of the auger assembly, it also is acting as a thrust bearing and absorbing front/back loads, and keeping the pulley in alignment with the pulley on the engine.

considering the much beefier size and weight of the Gilson chute and auger box, and heavy reinforcing bulkheads, the bigger bearing is there support all the weight on the back, along with the very hefty auger shaft side bushings.

talk about overbuilt, this thing is really a battleship

I took the time to MEASURE the belts the previous owner put on this machine. They are WAY too short. The tractor drive belt is 41.75" and the blower drive belt was 40.75"

so they shortened the belt length by 1.25" to 2.25" In the case of the blower drive, that put excessive upward loading on the impeller driveshaft, and most likely caused it to bend the shaft over time, or it bent the pulley, or both.


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## GMH (Dec 31, 2013)

Yeah those eccentric locking rings can be a real sob to remove. something has to lock the inner race to the shaft though, be it locking ring or set screws.


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## greatwhitebuffalo (Feb 11, 2014)

The Ariens and Cadet machines, just have a slip fit bearing between 2 bolt together flanges, floating in there. It slips right on/off. 

There's a snap ring in the nose of the auger gear box, holding the worm shaft from moving backwards out of the box. The rear bearing is pressed on and held in place and trapped by the race behind it in the housing. It can't move forward because the bolt on front cover is holding it back.











it's a better design because it's a helluva lot easier to change. It doesn't lock onto the impeller shaft.

I haven't had the Gilson design auger gear box apart yet, is there nothing holding the worm gear shaft inside the box, i.e. snap ring or C-clip on the front of shaft ?


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## RedOctobyr (Mar 2, 2014)

Phenomenal work, in your other thread, of getting this all apart! Wow. 

I just took this bearing off my Ariens. The inner race of the bearing did, in face, wear the outside diameter of the shaft somewhat. The rest of the shaft is about 0.746", the bearing area is about 0.732". 

I'm trying welding a few dots onto the worn area of the shaft, and grinding them back down, to reduce this clearance. Ideally, I'd weld up the area, and turn it back to size in a lathe. But there is no way I'd get the impeller off, based on how seized everything else has been on this machine, so I think getting the shaft in a lathe is not really practical. 

But the comment that the Gilson design can keep the inner race of the bearing snug with the shaft (preventing shaft wear) does seem like it could be a benefit. Granted, they sound like a real bear to take apart.


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## greatwhitebuffalo (Feb 11, 2014)

good points. The impeller on my Cadet 268 was seized on their solid. NO WAY that was coming off without a press and cherry red heat, period. You have to choose your battles and if it doesn't have to come off, leave it on there, because the shaft or impeller may be bent/damaged removing it. Gunsmiths run into this same problem removing receivers from barrels, with an action wrench, many times on an old gun, the entire receiver gets tweaked and bent from turning it off the barrel. I've put a few barrels on blackpowder antique replica pistols and the frames would begin to tweak and twist from putting them on/off. To resist this deflection the metal must be very precisely heat treated to the highest degree of perfection, otherwise everything bends easily.

good first hand info on the shaft being worn down. I'm thinking a grease fitting there with yearly lube would rectify that problem or at least slow it down. that little bit of play may not even deter it from running well. The auger drive is also supported by the end bushings in the chute, so they will begin to take up the load. You may also consider a split bushing placed over the shaft then machined to size, made of bronze. that would restore the size and give bearing material to ride on, and be self-lubricating to some degree.

let me relate this experience- on many old Chevrolet cars of the 1960's, both the 10 bolt and 12 bolt rear axles, had slip fit axles into the rear housings, held in by C-clips inside the differential. I rebuilt a ton of them when changing gear ratios. Usually they didn't need it but we put in bearings anyway being we have it apart. The outer axle/wheel bearings simply slipped into the housing flange, by hand, then the brake backing plate bolts over the flange to capture the bearing/race assembly. The axles slip in/out of the wheel bearings without being locked onto the axles.

this is a 3500 lb. to 4500 lb. car, and in the case of the SS396 and SS454 Chevelles had anywhere from 375 to 450 horsepower. You know what kind of abuse those axles get when someone is doing burnouts down the street back in those days.

those bearings almost never gave any problems. I'd change them and the old ones were just fine, almost all the time, just a little dry looking. The axles would be slightly burnished there but I never had to change an axle due to excessive wear.

it's all about MATERIAL HARDNESS and lube. The axles in the cars were very hard, so would stand up to the bearings and not wear, and the bearing grease would flow to the ends on hills and lube them. I'd always pack those bearings before putting new ones in anyway. There were seals at each end of the axle tubes.

With the Gilson blower design, the shaft is NOT highly hardened, I could file it easily with a common file. With the Areins machine, the shaft appears to be hardened somewhat. I could file the Cadet impeller shaft but it was harder than the Gilson.

they may have locked inner race to the shaft on the Gilson, to allow a softer heat treat on the impeller shaft, and cut costs. This way there's no metal to metal frictional contact there. Heat treating costs money, it's a very precise process and sort of an art in itself. Not having to highly heat treat those shafts saved a lot of money.

having said that, I think putting a slip fit bearing on the Gilson, or putting the bearing in and not installing the locking collar, would be a worthwhile experiment. Being these machines are only used a few times a year during winter it may last a very long time as a slip fit installed bearing. I may do it on this one, when I re-assemble it. First I have to take a good look at the auger drive to make sure the worm shaft is retained firmly enough in the gear box, so not to walk its way backwards in the machine from endplay and backward thrust.

if it works in the Cadet and Areins, it would work in the Gilson. I keep an open mind and have re-engineered many things for the better, which simple ideas like this. One doesn't know until it's tried. 

in the case of my Cadet blower, that shaft was not worn at all by the bearing race, and it was slip fit with no locking collar.

having the locking collar there, could also be why this 55012 had a bent impeller shaft. That shaft is obviously relatively soft material, and if it ingests a large object, there will be no give at that impeller bearing, so something has to give, so the shaft bends. If there were forward/rearward force on a slip bearing, the driveshaft would just move a bit through the bearing, rather than be stuck there and force the shaft to bend.

the area where these machines bend impeller shafts, is directly behind the impeller, between the impeller and the bearing.

this is great discussion because this is how improvements are mapped out, thanks for the posts


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## greatwhitebuffalo (Feb 11, 2014)

today I took some time and disassembled the auger drive gearbox on the Gilson 55012. The worm gear IS C-clipped onto the impeller/worm shaft just like the Cadet 268 was. This machine will run with a standard slip on impeller bearing, without the locking ring, without the impeller shaft walking rearward out of the auger gear box. But one thing about the blower section of this Gilson 55012, the impeller, shafts, tines are very SOFT steel material. While driving the impeller w/shaft rearward out of the bear box with a drift and hammer, I was amazed at how easily the inner boss of the impeller next to the shaft was deforming and mushrooming from the hammer blows- these parts are visibly very soft and obviously not heat treated at all, and are soft mild steel. One tang from the hammer and they mushroom, flatten, dimple. The impeller shaft and impeller being so soft, it why the design uses a locked center race impeller bearing, so eliminate wear on the shaft. Had it been heat treated to a harder spec like an Areins, it would be able to run a slip on bearing without locking collar.


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