Rotary Cutter Bush Hog 297 Problem

[Farmwithjunk]

Ground speed isn't HELPING, but that mower should be able to take a bit of abuse.

Something else jumps out at me. Is the "toggle" free to move? That's the flexable link just behind where the A-frame attaches to the quick hitch, and where the struts divide and continue to the rear of the mower. There should be EASY movement there. (see picture #3) Something looks peculiar in that picture. My 297 is still sitting at the dealer, waiting for delivery when they bring a new tractor that's on order. If I'm near there any time soon, I'll try to get a picture. Make certain that toggle is allowed to move freely to let the mower and tractor flex with irregular terrain.

Also, I don't see a problem with possibly using grade 8 bolts where you're snapping the grade 5's, OTHER than the fact that may make a more expensive component the weak link in the chain of events.

Raise the hitch, back the mower up where the tail wheels are over something a foot or so tall, then lower the hitch. Does that toggle flex and allow the front of the mower to continue down with ZERO resistance? If NOT, there's your problem.

On a Woods BB840 I owned, that toggle wouldn't allow ENOUGH flex. It moved freely, but ran out of travel in some situations. I cut a 12" section out of each of the top struts and replaced it with chain. That allowed substancially more freedom of movement. Proir to that, I was bending those struts every time I ran over a sizable irregularity.

 

[chh]

Will the top pivot move? Check like Farm said, your lower bolt holes show a lot of wear but I don't see any signs of it moving up by the pivot. How much acreage are you cutting? You have enough hp to be pulling a much larger mower if you wanted. If you have a large area and rough terrain a tow type mower might be better for you situation. You could easily use a 10' pull type up to a 15' batwing. The JX 95 is 90 engine hp and 80 pto hp if I looked at the chart correctly.

 

[Robert_in_NY]

Is it just my eyes this moring or does the supports from the rear to the top of the A-frame have a different size hole then the tailwheel support and they are using one mounting point for both supports? If so the aparent lack of flex on the top link would make a shock point where the tailwheel support and toplink support come together. The slack from a small bolt going thru a larger hole will eventually shear the bolt.

I wonder if Bush Hog had a special bolt for that hole (either it came with a bushing or was two sized and when it broke the first time the mechanic just tossed a bolt that fit the small hole in it with a large washer to keep the head from going thru the larger hole.

Then again the medication I am on right now can just be making me a little crazy.

Best of luck to you.

 

[Alanray]

It's going back to the dealership for a Wood's Loader after the first of the year - I'll have them fix it again and check to see if it is flexing like it should.

Would the pull type shredders take the rough ground better? A 10' would be better for someone like myself with ADD who likes to see a difference everytime I make a turn.

 

[Robert_in_NY]

A pull type cutter follows the ground a lot better then a 3pt setup and gives you a much more even cut.

 

[firemanpat2910]

I agree it looks like the quick hitch is eliminating the front pivot point. either try it without the quick hitch or make a flexable top link out of chain or cable.

 

[chh]

Look at a 10' the next time you go by a dealer, heavy duty, not a grass shredder. They will take a lot going over rough ground. I use a 15' Rhino batwing on several hundred acres every year. This was year #5 for the current one and have had 0 problems with it so far. The wider path you cut the better it is for ADD, just ask my wife.

 

[Farmerford]

Alanray:

I may be overlooking it, but I don't see a toggle in the top link, either in front of or behind the quick hitch.

It also appears that the holes in the tabs on the mower deck are elongated to the front, which indicates that the primary stress comes from the mower dropping against the TPH. If the wheels were overstressed, wouldn't the height adjusting bolt be the first to break. It is a fulcrum in the wheel arms and the vertical force on it will be the sum of the forces on the wheel and the front pivot bolt. Furthermore, a vertical force would tend to elongate the tab holes downward.

I believe the rough ground is bouncing the mower up and down more than you think, and the downward movement is frequently caught by the TPH. The single shear strength of a 5/8" Grade 5 bolt may be only 10-15 thousand #. That mower probably weighs 2000# and the shallow angles of the arms from the a-frame to the tabs means the force on the bolts is at least doubled. I don't have my mechanics book handy, but 2000# moving several feet per second has considerable momentum, and if the movement is stopped in just a few inches the initial forces could easily approach the shear strength of the bolts.

As Robert said, the slack in the bolt holes adds to the sudden impact, as does the other slack in the top link system.

 

[Alanray]

From the 290 Series Manual:

"E. Position tailwheel frame arms inside of attaching
lugs on cutter deck (behind gearbox) as shown in
Figure 5-1. Position free ends of yokes outside of
attaching lugs and place a yoke bushing inside of
holes on yokes and a 5/8 SAE washer on the outside
of the yokes. Align holes in tailwheel frame,
lugs, yokes/bushings, and washer and connect them
using a 5/8 x 2-1/2 capscrew. Secure using a 5/8
locknut and tighten until nut is almost bottomed on
tailwheel frame, but not so tight as to prevent rotation
of tailwheel frame."

BUT, I never saw any type of "yoke bushings" on my cutter - it didn't come with any on the tail wheel assembly when I got it and the mechanic only installed bolts when they broke.

Am I reading that right - it does require bushings at those connections right?

 

[Alanray]

And attached is the parts diagram from the Bush Hog website - it also shows a bushing at that location. So now I'm assuming that the lack of bushings could cause the bolts to shear since one of the holes is bigger than the bolt causing a hammering action against the bolt...I assume thats the reason a bushing is used here.