Bolens tubeframe hub cracked

[mcanders]

I have a Bolens 1000 that is down for repairs. Last season while plowing, I noticed a clunking sound coming from the right rear tire. I stopped plowing and I could not figure what was happening. Over the winter I was doing some prev. maintenance and I was going to check the grease in the hub. I was suprised to find that the inner hub was cracked above the keyway. After some brake parts cleaner, I realized that the hub is basically shot, looks like a big piece has broken completely off.

I found a used hub and noticed that it was cracked also. I wanted to know if anyone has run into this before, and does anyone know why this happens, or is it a weak point in the design?
Here's a picture of the used replacement hub to show the crack, can this be successfully welded and used?

I will take a shot of the existing hub and the piece that broke off.

[chipmaker]

I am not at all familiar with Gravely except for a short time fooling with my friends old Gravely L convertible 2 wheel tractor, however I do like to mess with metals.

Is this hub what goes on the axle to which you mount a wheel/ tire or what? From the image it appears to be made out of cast iron. I also am assuming there is a hole with a keyway machined in it that paralells the visible crack, so any of what I say is related to what I am assuming.

If there is insufficient material above the keyway in cast iron it is prone to cracking. There can be other factors that put undue stress on it in that area as well. Rust or corrosion is one of them. As metal corrodes it expands and it is pretty darn forcefull. Since the keyway is machined with a sharp 90 deg inside corner at both sides of the keyway slot, this is going to be an area stress is imparted to. To elimiante this I would use a key with the edges of it radiused slightly so it does not extend up into the corners of the key slot, so it has some room. A better way would have ben to machine this keyslot with a radiused inside corner, as a radius or fillet is usually sufficient to redirect stresses in different directions instead of in one line, thereby eliminating a concentration of stresses. This is why ends of shafts with raised portions like along a crankshaft journal are radiused, and not machined at a 90. That small radius of metal left makes for a world of difference in strenghts. If Gravely left a bit more material on ithe hub it maya have helped as well, as it looks like its made just as it came out of the sand mold if it was cast to begin with.

Well there is not much you can do to remachine it now, but if its cast iron, it can be rewelded with cast iron filler rod, if you can find a welder that truly knows how to weld cast iron properly. It has to be preheated evenly, and allowed to cool very slow in a draft free envirionment. Braze on it is at most a bandaide and not something I would trust for this application, besides it would be hard to V groove it properly and deep enough without sacrificing more of what strength the item has left.

What I would do if it was mine would be machine the outside of the hub down so its round and concentric, and turn a steel collar for it. I would make it a very snug temperature fit. By this I would make it so the cast iron hub is placed in a deep freeze so it contracts and becomes slightly smaller, and heat the steel collar up so it expands. Bring them both out together and slip or press steel collar over cast iron hub, and when they both reach ambient temps, they will be locked together quite firmly, which would not come apart in use. I don't know how much material is inside or surrounding the bore and keyway so an end view would have been good to see, as this is just a stab in the dark if its like I envision it, because like I stated I am not at all familiar with gravelys or their components, but metals are metals and all metals follow a certain regimine when it comes to properties. Of course the repiar that I suggested would be only good for the hub without the broken off pieces if it happened to be in the keyway area.

There is a type of keyway known as a double dutchman. Its used in high stress areas in small sectioned castings, and it virtualy eliminates this kind of crack from occuring. However its not normally encountered in a lot of equipment due to its complexity to machine, but it does work and works extremely well. Its a series of round holes machined with 35% of one round holes section in the outer material (hub), and 35% of the second holes section in the inner material (shaft) with the result of the overlaping of the inner and outer sections making the key between the two. These holes have round keys inserted, and view on end it looks sort of like a squashed in number 8. Thgis particular profile gives a keyway with a rounded inside corner and eliminates imparted stresses that cause cracks.......just like a radius or fileted corner would.

[sixchows]

mcanders

Look in the 1050 parts list posted in the manual thread. Your tranny is the same. This is the drive collar, part # 1716506, ref # 8. Is a little hard to tell with only half of it pictured but I think that is the end that goes into the hub.
These drive collars are pretty easy to find. They fit all the gear drive tubeframes. Usually the only thing wrong with them is the busted tab for the lock pin. Even if you find one with a busted tab there should still be enough meat on it to hold the pin in place. If not you can use a radiator clamp to hold it.
I think a repair is out of the question on this part unless you can turn the collar on a lathe when you are finished to get the correct dimensions back. You should be able to find a perfect used one for under $75 if it needs to be removed from a good tranny. A good price would be $40-$50. Hardly worth screwing around with it.
You could try bolensboneyard, joes outdoor power, ray's mower. Try Rick Show first he may have one. His email is rlshow4@wardcom.net

[chipmaker]

I am still lost here. Just where does this hub go, and what is its purpose?
Approximately how large in diameter is the round portion of this hub, and approx how large a bore is in it? Curiosity has me?

[sixchows]

Chip

Look on page 2 in this link, the exploded view of the rear end/tranny. See ref #8, that's this drive collar. It goes inside ref #6 the right wheel hub.
http://www.mytractorforum.com/images/reference/1050parts.pdf

[sixchows]

Chip
the OD is about 1.75" the inside is about 1.1"

[chipmaker]

Ok, so then its not as big as it appears to look in the images. In the images it looks considerably larger without actually knowing what it is or a reference to us that are clueless.

Now what is the purpose of this "hub" connect tranny to axle, driveshaft or????

[sixchows]

Chip

Yes it connects the tranny to the right rear wheel. There are two parts. This is the drive collar. The cracked area goes inside the R/R hub which holds the wheel and they are locked together by a heavy pin and spring clip. The pin and clip need to be removed in order to freewheel the tractor.

[mcanders]

Sorry I have been busy, I haven't had time to post the pictures of where the hub goes on the tractor. I have a shot of the current "breakaway" piece that will allow others to see where the keyway is and how it all goes together. the pictures above were taken on the trunk of my car close up to show the detail.

[Rodster]

HI
I had two tractors and both had the hub cracked. Try this link for parts. It is Yahoo site.
Rodster
http://groups.yahoo.com/group/BolensGTractorClassifieds/

[sixchows]

Rod
That's strange. I have 4 tubeframes and none are cracked. I even have 2 extra drive collars, both are perfect. Two of my 1050's have the tab broken and will eventually be replaced with these two collars.

[mcanders]

I have already contacted someone about a hub replacement.
Just to be curious has anyone experienced the clunk while pulling or plowing. Its like the wheel gets ahead of the tractor and then the tractor speeds up to the wheel. An audible clunk can be heard, sounds like the low thump of cast iron.
The two implements used with this tractor are, a 12inch sleeve hitch moldboard plow and a agrifab disc cultivator.
I have never "hooked" any roots or had the plow more than about 4-6 inches deep. I also use agri-fab disc with a little weight. I never noticed any bogging or hesitation from the bolens just the usual drivetrain whine and the engine noise.
It maybe cracked from the previous owner, we found signs of abuse, nasty welds, hammer marks, engineered/rigged to the gills, and the blue silicone sealant in the tranny.

[Rodster]

I sure miss my old Bolens but it was just too wore out and parts were high. I ran two hydro pumps for my blade. One to lift and one to angle.
Rodster

[sixchows]

mcanders
I seriously doubt you pulling a plow or a disc harrow had anything to do with it. Most likely the previous owner pulled everything and anything with it.

[mcanders]

Here are the pictures of the existing hub. Its a pretty worn out Id say. I am holding the piece that broke off with the needlenose pliers.

[mcanders]

Safe to say the axle keyway is not worn at all, but the key itself looks like an hourglass from the end. It has probably been wearing for a while.

[mcanders]

Got the welded hub back from the welder today. Nice clean welds, now I just have it machined down to the correct size. I really dont use the "freewheel" with the pin out that much, unless I have to move it. If the motor is having trouble or off the tractor i usually jack the rear of the tractor up with a floor jack and swing it around where I need it. Much easier than busting knuckles trying to get that spring clip out. I will post a picture tonight of the weld before the machinist goes at it. Hopefully it will get me by until I locate a good hub.

[pmilano1]

In rebuilding a 1050, I had to replace the collar because the freewheel pin collar was sliced off. I would imagine not locking the pin may cause a problem, but is it just a general stress point? Is that pin the centerpoint on the tractors load?

[mcanders]

I think most of the damage to the pin area of the hub comes from hammers and other striking objects when people try to hammer the pin in or out. I dont know what the actual stress point would be on the hub but im sure its near or around the keyway after finding all the cracked hubs.

[mcanders]

Just a little late on the pics, sorry. I will take more when the hub is ready to use again.

[sixchows]

So what's the plan? Are you going to turn it on a lathe? I would just search out another one and keep that for a spare.

[mcanders]

I was going to have it turned on a lathe and I decided this afternoon to grind it back round with a sanding disk. I have a guy that is looking for one for me. This is just a temporary fix until the other hub comes through. Go it all back together and it seems fine, I wont be doing any heavy pulling or plowing but more or less cultivating some small plants.

[sixchows]

Yeah, I would think it would hold up OK, but I'd rather get a hold of a good while they are still plentiful. Sounds like you have the right idea!

[mcanders]

The temporary hub is still holding on. I pulled my disc harrow this afternoon in the garden and everything still feels good. Here's a pic of the Bolens after the "hard" work.