Bagger Shear Pin on Kubota OEM bagger

[KeithInSpace]

I have the same bagger as BlackMajicWoman and can attest to its hunger for shear pins.

I found that the spring pin would "mush" during use and rattle out to one side, so only half the pin was being engaged (it no longer went the whole way through), placing it in a much weaker single-shear. I have taken to putting an extremely cheap, thin machine screw through the center of the pin, putting a nut on the end, and bending the remainder of the screw so the nut can't back off. This keeps the shear pin "centered" in true double-shear. I'll only break 2 or 3 pins a year now. And if I'm really careful about not loading the impeller (pick up sticks and not let the system choke on wet grass), it will last a very long time. Still a weak link, but it can be mitigated.

Mr. MJPalmer, I think the new bagger is a different design...for some reason I think the power transfer between the PTO shaft and the impeller is through a BELT instead of a SHAFT. This would greatly increase the system's resistance to shock damage. As the previous generation is all shaft driven, all shock load to the impeller is transferred directly to the PTO shear pin. I could be wrong, though. I'm sure someone will confirm or correct.

 

[David_Kb7uns]

Have only gone through three bolts on mine but was careful to get ones that had a shank all the way through instead of threads on one side. Also engage just above idle and then rev up to full throttle. Also making sure that grass is dry before bagging helps as if clumps form and a large one breaks loose it will take out the shear bolt. If enough space was in there wonder if a slip clutch would work better?

David Kb7uns

 

[Stradbash]

Mr. MJPalmer, I think the new bagger is a different design...for some reason I think the power transfer between the PTO shaft and the impeller is through a BELT instead of a SHAFT. This would greatly increase the system's resistance to shock damage.

Quite true! I've just been looking through the manual of my yet to be used bagger (Model GCK60-23BX) and there are in fact two belts and I see no mention of a shear pin or bolt and do not see one on the PTO shaft.

 

[blackmajicwoman]

So far, so good. Installed the new shaft, with new shear pins, new lock nuts and new lock washers, along with some loctite. Mowed twice so far with no issues (YET!). For the record, I always enage the PTO at the lowest RPM, then ramp up to highest RPM in a reasonable manner.

After close inspection of the old shaft tube, it is clear of the worn holes where the pin extends through right at the shear point. To save a little time, I already drilled 5/16" holes 90 degrees from previous shear pin holes and have a pair of 5/16" rolled pins ready to be installed if my new shaft tube decides to start shearing pins!!!

 

[blackmajicwoman]

Well, that didn't work...during my thrird mowing, broke the same shear pin. Shaft looked good. The ONLY thing I can thing of now is that the actual gear box is snapping the pin. I attempted one more try using a nylon thread lock nut. Guess what, this didn't work either. I left the guard off the back of the bagger, and starting my last mowing session, the pin snapped immediately. Note, this was at the lowest RPM with the mower deck at the raised setting on a concrete slab!!! Frustrated as all heck, I finally took the advice of another TBN'er, I installed a 5/16 roll pin in place of the shear pin (roll pin was modified at one end to accomodate a shoulder to fill the large hole in one side of the shaft). So far, so good. The pin doesn't look worn in the least. I was/am a little nerveous that I don't have any protection on one of my gear boxes, but I have no other solution at this point in time. My local dealer thought I would be OK, pending I don't bag anything too wet and heavy...and of course to use common sense. I'll keep you all posted after numerous mowing sessions.

 

[KeithInSpace]

installed a 5/16 roll pin in place of the shear pin (roll pin was modified at one end to accomodate a shoulder to fill the large hole in one side of the shaft)...I was/am a little nerveous that I don't have any protection on one of my gear boxes...

? No protection? I promise you, it'll break the roll pin, too.

Since I started putting a cheap screw though the pin to hold it engaged in double-shear, my shear-pin-demolition-fest has reduced greatly, but they still break. I'm on mow #4 for the season and (knocking on head), I'm still OK. Hasn't broken yet. Getting a little loose, though. It'll probably go the next mow or two if I hit a big stick or a beaver or something.

 

[BimmerRacer]

Where are these pins? Apparently, there are two? Anyone got a picture?

 

[jfralph]

The pins are located on either end of the PTO driveline, under the safety shield. Pull the safety shield (using a 7/16" wrench, loosen the two screws holding the covers,) and you will see them going through the spline of the yoke. Just curious, was not familiar with Kubota grass catcher, and the pitfalls of their ownership, and purchased an older model unit to use on my new tractor. For the record, I only use it in the sprint to pick up the dry thatched grass from first mow. Mine does not allow me to fill bags twice before breaking. FYI, mine uses 1/4" grade 8 bolts with a shoulder full length. I will begin tonight, to peen the threads of the bolt to guarantee the locknut does not loosen. Can you guess I also am having this very same problem, 9 years later!

 

[BimmerRacer]

Ha, I solved my "problem" by selling the bagger. Way too many leaves to use it efficient. I got the cyclone rake and even that was a pain. Now I just use a backpack blower a few times and get them past the fence. Of course, some tree losses helped things along as well

 

[jfralph]

OH, that's the one I got the great deal on! ha ha