Bush Hog BH25 yokes breaking

[redman135]

Could you show a pic of BOTH bars ( the broken 1 AND the intact 1) on the machine on the BH please? The photo cuts of the intact bar.

 

[Boatman62]

Could you show a pic of BOTH bars ( the broken 1 AND the intact 1) on the machine on the BH please? The photo cuts of the intact bar.

I'll get back over there in the next couple days and take a couple more pics.

 

[Grandad4]

Ok, good to know they at least look correct.
I'm not sure why they would be "hardened" I would think it might make them more brittle.
Looking at where the break is and trying to compare to the picture it looks like the "bend" is further back or closer the mounting point in the picture I found.
May not be, hard to tell!

The only real force on those bars would be -
1: when lifting the brush hog but that is a "pull" type force. It might stress the bars if he drives fast on bumpy ground and the hog bounces a lot but I don't think that would break them.
2: The other would be a "push" type force such as if he backs into an incline or backs into brush/trees forcing the rear of the hog to lift up. This could cause the two bars to try to bow outward and enough force like this could conceivably snap them. This is the most likely scenario I can see.
Nothing else makes much sense.

When making sharp turns (particularly if the tail wheel isn't pivoting freely), or hitting a rock or stump from the side while turning could put a lateral force on those bars also. I could see fatigue cracks developing from doing that repeatedly.

 

[ericm979]

Maybe you and the owner have already tried this but make sure the bolt on the pivot link is not too tight. My mower has a similar link. It's easy to over tighten that bolt and make the link solid, especially when it's fully extended as in the pic. I give the pivot a shot of spray grease every so often as well.

 

[Rebeldad1]

best if he does 400 acres a year is to get a heavy duty brush cutter for commercial use. chain the top link.
problem solved.

 

[RickB]

best if he does 400 acres a year is to get a heavy duty brush cutter for commercial use. chain the top link.
problem solved.

I don't see where he's cutting 400 acres a year, but if it is all grass he doesn't need a heavier cutter, just a solution to his immediate concern.

 

[Boatman62]

best if he does 400 acres a year is to get a heavy duty brush cutter for commercial use. chain the top link.
problem solved.

This is his "edger". The main mower is a batwing.

 

[Boatman62]

I don't see where he's cutting 400 acres a year, but if it is all grass he doesn't need a heavier cutter, just a solution to his immediate concern.

I mentioned in an earlier post that he cuts about 200 acres twice a year,,, so about 400 all
together.

As I said in the last post.... he has a heavier cutter. This small cutter is for just getting where the batwing can't easily go.

Occasionally he'll go and knock down some actual brush but yup.... mostly tall grasses.

 

[Boatman62]

Maybe you and the owner have already tried this but make sure the bolt on the pivot link is not too tight. My mower has a similar link. It's easy to over tighten that bolt and make the link solid, especially when it's fully extended as in the pic. I give the pivot a shot of spray grease every so often as well.

Yes I have to check that top connection. It was raining while we were talking the other day and I got distracted.

 

[Gord Baker]

Those bars should have NEVER broken in that way. Wrong metallurgy, chineeeeesium parts. Replace them with locally obtained flat bar.

 

[Howard57]

simple fix really, add 3 or 4 links of chain to the bar at the mower end which will allow flexibility and you will have better sway control then just chain an old rule here in Canada ''anything can be broken'' the tough part is why is it breaking
good luck

 

[Tx Jim]

IMHO the 3 pt center linkage on mower isn't pivoting as designed. My 1st guess is bolt with nut in photo too tight & preventing any designed pivoting of hitch components. Please post a complete view of mower top link attachment to confirm

 

[JWR]

My primary Bush Hog is a model 297 (photo below.) I had the lift straps break on it too. The circumstances when the strap broke was excessive bending backing up into brush and small trees. In my case the break was at the weakest place in the strap -- namely where a hole has been drilled and where the max bending also occurs. The hole seems to have been for mounting the instruction booklet container/plastic tube that they are delivered with these days.

In my opinion the steel straps from the factory do not make sense for rough and tumble widely varied use of a bush hog. Maybe in cases where it is high volume use (cutting corn stalks, crop debris, etc.) but not the hilly farms and pasture fields.

I switched to chain, not for the top link but rather replacing the factory lift straps. Never a problem since. I use rubber straps and one bungy for tension to avoid the chain slapping around. I think you will find most old hill farmers use chain. Another reason I replaced the straps rather than the top link with chain is I want to keep my hydraulic top link in place for essentially all tractor work.

 

[tractorcrazy]

I take care of some equipment for my neighbor, fixing broken things and maintenance. He has a BH25 that has broken the yoke bars a number of times and I was trying to figure out why and it seems a manufacturing defect. Where they stamp the bend at the factory it seems its somewhat shearing the steel. 3 of them have broken this summer. This last one only made a couple laps around the field. So I investigated the break a little closer and can see there isn't much metal left to break.

Anyone else had/have this issue?

The pics of the broken ends are two different yoke arms.

View attachment 720512
View attachment 720513

View attachment 720514

I had a six foot international brushhog that did the same thing but not as often I took them off and use one half inch chain down the center to the rear of the brushhog been problem free for fifteen years

 

[Bentrim]

Those straps must have pivot or some way to "give" when the tailwheel tries to raise the mower. In you pictures I just can't see how the top of those straps are fastened to the A frame If they are bolted solid and have no give they will break, It should be a single bolt through the top and loosened so it can pivot, allowing the A frame to move. Others have replaced the straps with chains even some have cut the straps and welded some chain for the A frame to pivot

 

[DieselBound]

I've got a BH286 that I picked up severely used: had been used commercially. I've run the snot out of it and if something is breakable I'm able to break it. Tail wheel was compromised and I finished it off: had re-welded with extra gusseting and it's held up to all my abuse. The bars that are on it have a slight bow to them; and perhaps it's this bow that allows enough flexing rather than pushing a straight-on compressive force? Almost certainly the metal on this older unit is the good stuff. Has a floating top link.

I don't mow a lot, but the stuff I mow and the ground I mow on is pretty harsh.

Here's what mine looks like:

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[Boatman62]

Can we get more pictures of the setup? How the top link attaches?
In my opinion I'd say 1 breaks it is a manufacturing issue.
3 break in one season and it is more likely to be a set up or use issue. Unless the 3 came from the same batch, manufacturer, etc.

I's take them to an experienced welding/machine shop and see what they say the cause of the break is.
To snap a bar like that is highly unusual.

Also, were those bars replaced and where did they come from? Was the first break an original one?
Looking at a picture of the BH25 the bar looks to be angled where it bolts at the rear and not straight like his appear to be.

View attachment 720636

Got over there this morning to look it over again. I don't see anything wrong with the set up. The top link has the right amount of play and moves freely. The bolts holding the bars are loose enough to provide free travel. The main yoke that attaches to the top link swivels freely. Nothing wrong. Here's a few pics.

The one pic is of the other bar that's not broke and a close up looks like a crack in the paint right at the bend line.

Hes picking up new bars today and taking the broken ones in with him. They already said in the past they won't do anything but they asked him to bring them in for "inspection".

Personally I would just go with chains. It was my thought before even asking here. But he's not real keen on the idea. If he brings the broken bars back I'm going to gusset and weld them.

 

[RickB]

I see torch marks on the back end of that toggle/flex link and there shouldn't be any. Has it been shortened enough so it aligns with the failing bars? If they are aligned and parallel in tension the link won't work as designed in compression.
The fore/aft centerline of that flex link needs to be at a lesser angle from horizontal than the center line of the black bars.

 

[JWR]

I notice that the BH25 was manufactured with sudden/sharp bends or kinks at single places on each strap. My 297 straps (as well as those on a smaller 5ft hog) do not have pre-determined bend spots but rather are continuous with no 'kinks.' While mine broke at the weakest point (where a hole had been predrilled) yours broke at a predetermined kink point.

In my mechanical intuition mode, I say that design change means that ALL the breaks in that model hog straps will be at that bend/kink. I think it is a designed-in breaking point for no good reason (well, a poor decision.) The older non-kink designs flapped around a good bit when not under tension and PROBABLY the idea in the design change was to reduce that flapping around and thus minimize fatigue. The kinked ones are no doubt stiffer and tend to flap a lot less. I think they created a fresh problem while trying to fix another. Shame we have no way to directly ask the Bush Hog design engineers (and let them know really.)

My conspiracy tendency & suspicious mind wonders if there was some lawyer-perceived liability issue with Bush Hog being advised to not deliver these things with chains in the first place. At least as an option.

All the more reason to go to chain ourselves and have it over with.

 

[ericm979]

The pivot link allows only so much travel. Is he backing up to steep banks or something similar that would bottom out the link? Or operating with the link already well into its travel?

Even with the link bottomed out the 3pt should allow the deck to get pushed up. So there shouldn't be that much force through the bars, just some fraction of the weight of the mower. Clearly that's too much for that bend but it should be ok with some reinforcement.