Rhino Shedder (TR120) - had a breakdown and want some advice. (PICS)

[pharmvet]

I have a Rhino TR120 (10' heavy duty pull behind shredder). I have had it for about 3 seasons. Probably have about 30 - 40 hours on it. This weekend I was shredding along just fine (diddn't hit anything except occasionally some dirt on a dip or rise).

All of a sudden I heard "CLANK, CLANK, CLANK". I immediately throttled down the tractor and shut off the PTO. I assumed I had hit a T-post or something and it was hung under the shredder making noise with every rotation. I raised the mower all the way up and killed the tractor. I got out and looked under the mower. Everything looked fine, except that there was a fresh "quarter sized" chunk knocked out of the very end of a a couple of the blades. I then determined that it was the blades hitting each other (one from each side) Knowing that the blades were intentionally offset so that they could not hit I immediately assumed I had stripped something in the drive line and the blades had been allowed to get out of time. I first checked that main drive line (from tractor to middle gear box) Everything looked fine. I then checked the left and then the right connections from middle to outer gear boxes. I found my problem where the input shaft on the left gear box and the shaft collar meet.

The splined shaft and the collar would freely rotate and there were metal shavings everywhere.

I went to the parts house today, and the mechanic suggested that the shaft could very well be OK, as it was made of very hard metal, but the collar shat slips on the shaft was most likely the part that gave way. I ordered a collar and will now dis-assemble things to see what really happened.

1) Do you also feel that the shaft could be OK?
2) What likely caused this failure and why were no other shaft/collar units damaged?
3) From looking at the rubber shock absorbers, would you replace them?
Thanks in advance for any and all advice.

 

[DT86]

Yes the shaft should be fine, as the guy mentioned it is very hard.

As for the cause, it'd say....???


I would not bother replacing the rubber absorbers unless they fall apart.

 

[treman]

^^^
I agree T
Think back to the last time you used the shredder. Its possible that you hit a high spot or post and stressed it and it just gave way with the most recent mowing. similar thing happened at work. a guy hit a rock, completely trashed the blades and replaced them but it was a bout a week later when we went to mow again that everything gave way and we needed to put a new collar end on our drive shaft. just the stress of use put it over the edge.

 

[pharmvet]

I got the collar taken off the input shaft this afternoon after work. Splines on Shaft have just a little wear. Collar definitely was the weak link. This is a prime example of why it is a good Idea to really look your equipment over periodically for potential wear and tear. If I had caught this earlier, I could have possibly prevented the small amount of wear that the shaft received.

I noticed that each collar has 4 threaded holes spaced equally around the circumference. Im assuming they are for set screws. My shredder came from the dealer with 1 set screw in each of the collars on the output shafts from the center gear box. NO set screws in the collars attaching to input shafts on the outer gear boxes. Also, it looks as though the set screws that "were there" were not particularly set into the groove in the shaft. In fact, if you look at the collar, you can clearly see that there is about a 1/4" portion where the splines are still intact. Apparently, this area was in the groove on the shaft. I think this setup was designed for there to be 4 set screws in each collar, and for them to seat in the groove. What do you think?

 

[RickB]

I got the collar taken off the input shaft this afternoon after work. Splines on Shaft have just a little wear. Collar definitely was the weak link. This is a prime example of why it is a good Idea to really look your equipment over periodically for potential wear and tear. If I had caught this earlier, I could have possibly prevented the small amount of wear that the shaft received.
I noticed that each collar has 4 threaded holes spaced equally around the circumference. Im assuming they are for set screws. My shredder came from the dealer with 1 set screw in each of the collars on the output shafts from the center gear box. NO set screws in the collars attaching to input shafts on the outer gear boxes. Also, it looks as though the set screws that "were there" were not particularly set into the groove in the shaft. In fact, if you look at the collar, you can clearly see that there is about a 1/4" portion where the splines are still intact. Apparently, this area was in the groove on the shaft. I think this setup was designed for there to be 4 set screws in each collar, and for them to seat in the groove. What do you think?

The setscrews are used on one drive collar for each shaft; the other is left to float so as to self-adjust and not unduly (axially) load the bearings supporting the respective gearbox shafts. Do not install setscrews in both collars on a single shaft. The holes are all drilled and tapped so one part number accomplishes both tasks. Use a high quality grease on the joints without setscrews and Never-Seize on the splines with setscrews. Consider checking/replacing/lubing the other shaft connections.

 

[pharmvet]

Rick. That's exactly the information I needed. Regarding the set screw, Should I try to make it line up with the groove on the shaft, or just tighten it down wherever it finds itself? Further, would you use more than one set screw in the same collar (there are 4 holes) or just the one like it came from my dealer? Also, is it abnormal that I had this failure with such low hours on the shredder?

 

[RickB]

If you can get the setscrews into the shaft groove without putting the opposte drive collar in a bind with the inner end of the shaft splines, set the screws in the groove. I would probably use two setscrews 90 degrees to each other. This does seem like an early failure but I know little about the quality of Rhino's metallurgy.

 

[AKfish]

I'd have to wonder if the opposite drive collar has moved or the set screw(or screws) have worked loose, too. Something caused that drive collar to jump/shift position - excessively. Beyond just normal "adaptive motion" i.e. impact movements and side-to-side movement with the rubber dampening coupler.

Do both of the gear box input shafts turn relatively Ok? No grinding or bearing rumbles? No excessive "in and out" movement of either gear box input shaft?

I'm also assuming that you're replacing the drive collar?

AKfish

 

[pharmvet]

Well here she is. $102 and 1 hour later. Yes I replaced the drive collar. I checked the other collars, shafts, rubber couplers. I suspect I will be replacing those rubber couplers eventually. This time I made sure the set screw fell into the shaft groove. I don't think that was done when it was originally assembled. Thanks to everyone for all the advice and help. This is without a doubt the best technical source for things such as this as I have ever found.

 

[RickB]

Don't be afraid to make use of that zerk once in a while!