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We have 5 x739 tractors with 60" rotary brooms. Since Winter of 2014 we have broken the shaft that runs between the gearbox and the chain about 5 times on different brooms. Some multiple times. The shaft will break right at the drive sprocket. It looks like it just twists right off. I called my dealer and they have not heard of any such thing. The other dealer near me said that the local school has the same broom and went through 3 shafts over the same 2014 winter.

These shafts are a PITA to repair. I cannot for the life of me press the shaft out of the gearbox which means I have to also replace the gearbox as well as the shaft and misc. parts. This is getting to be a regular thing and it isn't fun to have to do in a time crunch. It has gotten to the point that the local dealer stocks the parts to repair these, which is why I am surprised there isn't a TAC case.

I thought maybe it was because they were engaging the PTO with the engine at full speed but my dealer said that shouldn't matter. Also when the other shafts broke I noticed the chains were super dry and some links were seized so I figured they were binding but this recent break the chain was nice and free.

Any ideas?

Also, Hi, I'm Travis, the grounds mechanic for the State of Michigan.
 

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I thought maybe it was because they were engaging the PTO with the engine at full speed but my dealer said that shouldn't matter.
This is normally not best practice when using shaft-driven implements.
 

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I have had my 60 broom for over 7 years and have never broken the shaft and this is the first time I have heard of your problem. The only thing I have done besides routine maintenance is pull the gearbox and put new seals in it. I don't understand your need to press the shaft out of the box unless they are highly corroded. My shaft came out quite easily, but when I re-assembled it I never seized it and the key. Something isn't adding up here. :think: How badly corroded are your brooms? Does the brush spin freely with the PTO disengaged? Are your bearings good? Is something miss-aligned? Any funny noises when they are running? Lot of questions to answer. And yeah, tell the operators to stop engaging the drive at full RPM.
 
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Another thought, are you keeping the chains tensioned properly? What are you using the brooms for? Are they set properly for height and contact area?
 

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I have had my 60 broom for over 7 years and have never broken the shaft and this is the first time I have heard of your problem. The only thing I have done besides routine maintenance is pull the gearbox and put new seals in it. I don't understand your need to press the shaft out of the box unless they are highly corroded. My shaft came out quite easily, but when I re-assembled it I never seized it and the key. Something isn't adding up here. :think: How badly corroded are your brooms? Does the brush spin freely with the PTO disengaged? Are your bearings good? Is something miss-aligned? Any funny noises when they are running? Lot of questions to answer. And yeah, tell the operators to stop engaging the drive at full RPM.
I would have to assume they are corroded enough to not press out. They sit inside a garage with high moisture, and two salters which are usually full of salt. I don't like it but I have no say in anything anybody does and even if I did, they would still do whatever they wanted. As far as the condition of the broom, the bearings are fine, I can turn the broom by hand and the pto shaft will turn when not connected to the tractor but I have never supported the pto shaft and tried to spin the broom. I replaced this shaft and gearbox last March for the same reason so all the parts are a year old. Everything was aligned correctly. As far as noises, I don't run these machines and the people who do don't pay attention enough to noises or the such. They don't usually even report when something is broken until we need to use the machine.

Another thought, are you keeping the chains tensioned properly? What are you using the brooms for? Are they set properly for height and contact area?
I had modified the tensioner when I installed new chains because I found that only the tip of the tensioner was touching the chain when adjusted properly, even with a new chain. I ended up drilling a new hole up a bit and now the chain rides on the tensioner much better. The brooms are used mainly for snow removal and sometimes surface cleaning. I adjust the contact patch whenever I service the machines and if anything, the bristles when worn, would have less drag on the surface.

The people running these machines, and all our other machines, are not the brightest. They are just laborers with no responsibility or accountability for anything they do. Their thought is if they break something, oh well, not their problem.

Then to top today off I find out somebody put diesel fuel in the tranny filler of our brand new 544K wheel loader. FML.
 

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You are correct the, the tensioner is a poor design and I too modified mine to work better. It really sounds like you are doing all the right things you can. My next thought is your operators are running the brush up against something and jamming it. I know this doesn't help but, if we have covered all of the logical mechanical issues there aren't many left.

Oh, and by the way, welcome to the forum.

Next thought would be to modify the new shaft immediately with a welded on sleeve and bore the sprocket to match. Problem is, if the operators are jamming the brush and the shaft doesn't break something else will. Also, Never Seize the shaft and gearbox so you don't have to replace both if there is a next time.
 
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No shear pins on these brooms?


Sent from my iPhone using Tapatalk
 

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No shear pins on these brooms?


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Yes, there is one that attaches the drive shaft to the gearbox. But, if his units are as corroded as I am led to believe, the drive shaft and gearbox are froze together. :unknown:
 
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No shear pins on these brooms?


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I was thinking the same thing. I just got a 52" broom. According to the parts breakdown, the 52" and 60" use the same driveshaft. My driveshaft simply slides on the broom gearbox (no splines or key). You align a hole in the driveshaft yoke and the gearbox input shaft and insert the shear bolt.
Of course the shear bolt will only do it's job if the shaft is not corroded fast to the shaft. A little never-seize does wanders.
That said, if the drive shaft is free on the input shaft, the shear bolt should be the first thing to break. For sure not the driveshaft. I am amazed the chain or gearbox didn't break before the drive shaft.
The shear bolt is item 5 in the breakdown.
 

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