Weak Spots On BB60?

[MikePA]

I did 2 hours of rotary cutting this morning with my Woods BB60, only knocked down 2 plastic step in posts /w3tcompact/icons/laugh.gif. Please don't tell my wife, I'm going to blame it on the horses. /w3tcompact/icons/wink.gif

Since I was spending plenty of time looking back at the mower, I noticed the 2 places the paint came off first {see attached}. Once I thought I saw this area flex /w3tcompact/icons/shocked.gif so I got off the tractor to look at them. They hadn't flexed but it gave me a start!

A potential problem?

 

[beenthere]

Mike
Remembering your thread on cutter setup back in April. The matter of whether the top arm (link) should swing through? I think you are seeing an example of when it does not. To me, some of the information you were given was not correct, but then to some, it was probably right. Did you change it so the top arm (link) would swing through, or leave the bolt restricting the swing through?

Those areas are signs that these brace arms have been bent under compression, due probably to the fact that the rear of the rotary cutter deck raised (went through a ditch, or backed the cutter up a bank), causing the top arm (link) to be in compression (too long) as well. The weakest link in the system are the braces. They look like the braces on my JD513. Sometimes I back the deck up a bank that is just too much for the slack I have at the top point. A chain in place of the top arm (link) would be better.

The trick is to get the top arm (link) adjusted so there is room for the rear of the cutter to raise and lower without picking it up when the rear tractor wheels go over a bump or rise, and without forcing the rear down when the rear tractor wheels go into a depression (or some combination of the same things happening when the front wheels go into a depression or over a rise).

 

[JimMc]

Most designs include these lft straps being made of thinner/weaker material so that when the limits of the flex link are exceeded the straps bend rather than bending or breaking the hitch itself or the top link. Most people would prefer straightening and repainting these straps to repairing or replacing hitch, deck or tractor parts.

 

[Gary_in_Indiana]

Jim, you are a rare one indeed... an engineer who can not only understand lay questions but also can explain things to us non-engineers in a manner that we not only understand but also seems logical and makes sense. Thanks for your input here on TBN.

 

[MikePA]

<font color=blue>Did you change it so the top arm (link) would swing through, or leave the bolt restricting the swing through?</font color=blue>
The bolt is still there. Should it be removed?

If I understand correctly, with the cutter and tractor on level ground, the swinging toplink on the cutter should be slightly less than horizontal when connected to the tractor toplink? This will allow the swinging toplink to rotate down as the deck rises, either from being raised by the 3ph or because of motion of the tractor.

 

[BKColeman]

Mike,

My first thought was going to be to ask if you still had that bolt in that prevented the toplink from swinging back through. But it looks like Beenthere has already beat me to it.

Personally, I don't think that bolt should be there, but I know some knowledgable people told you before to leave it. Mine doesn't have it and I do mow some ditches. I have found it works much better to back up to them and let the tailwheel ride up, but when I do this, the toplink does swing through a couple of inches. So far those support straps don't seem to have bent at all. I cut about 7 acres with it Saturday.

I have my toplink set as you suggest, just slightly less than horizontal, just enough tension the rotary cutter doesn't bounce much, but most of the weight sitting on the tailwheel.

--Brad

 

[MikePA]

Brad,

I noticed the paint had chipped off these 2 areas before I even used the cutter, which seemed odd. I have some ditches to cut and I will probably take the bolt out since it's working OK for you.

Do you keep the 3ph in the float section of the scale while cutting? Initially, depending upon the contour of the ground, the front skids made marks in the pasture. After a few passes I determined the height the 3ph had to be to not do this and set the stop.

I also discovered;
1. The rotary cutter is a good leveler of high spots. There was a small mound of dirt in the field and I went over it and the stump jumper flattened it right out.

2. I can stall the tractor if the cutter is set too low. Only did that once.

 

[BKColeman]

It does seem odd that the paint was already chipped off. I walked out and checked mine yesterday after reading your post and didn't see any paint missing. I've got about 25-30 hours on my cutter I would guess. I haven't kept real close track of it.

I keep my 3ph control in the very bottom of the float range, maybe just slightly below it. I do see marks from the skids on occassion, but I figure that will be a good indicator to the areas I need to work on with my box blade this fall.

As far as leveling ground, yep, I've flatten many a hump. In fact that is how I've broken all but one of my shear bolts, by scalping a hump. Luckily it is happening less often, I guess I've about gotten rid of all of them now. /w3tcompact/icons/laugh.gif I've only broken one bolt on a stump and I've blasted quite a few rocks into dust without breaking one. I guess the book isn't lying when it says hitting the ground is one of the hardest things you can do to a rotary cutter.

I haven't came close to stalling the tractor though. Did it stall because of high grass or due to hitting something?

--Brad

 

[MikePA]

<font color=blue>I haven't came close to stalling the tractor though. Did it stall because of high grass or due to hitting something?</font color=blue>
I've stalled my tractor twice, once with the rotary cutter and once with the mmm. The mmm was caused by grass that was too high, a deck that was too low and a ground speed that was too fast. I stalled the rotary cutter by taking it over some stall mats we have placed right outside the barn. We have 4 mats placed at an aisle way to prevent the horses from creating a muddy mess and dragging it into the barn. I thought all the mats were flush with the ground. Once wasn't /w3tcompact/icons/eyes.gif.

 

[Bird]

<font color=blue>The rotary cutter is a good leveler of high spots</font color=blue>

I flattened and leveled many a fire ant mound with mine./w3tcompact/icons/laugh.gif