Bush Hog BH25 yokes breaking

[Boatman62]

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.

 

[Gee Ray]

There seams to be a to be two fold problem. First I would weld some reinforcement on the arms, then paint them up and run them. Second I would remove the top link. I would guess the field is very rough or the mower is being forced against a solid object. Perhaps the field has a ditch and as the rear tractor tires drop into the ditch the bar becomes overloaded because the movement allowed by the top link is not enough.

Use a piece of chain to replace the top link so the mower can still be lifted.

 

[ptsg]

Ditch the flat bars, replace those with chains and be done with it. And doing this way, the top link can stay connected as it will still be able to float just fine.

Something like this:

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[LD1]

I hope they are being replaced under warranty.

Is the flexible A-frame and toplink working as it should and have plenty of travel? Or is it bottoming out on uneven terrain and causing extra stress on those links.

If being covered under warranty I guess I'd keep trying the OEM ones until the issue goes away. If you are having to buy the parts....Go to a steel supply place and have them make you some out of hot rolled bar. Those look like they are cold rolled and by nature is a little more brittle and breaks alot easier if it gets bent.

 

[Boatman62]

I hope they are being replaced under warranty.

Is the flexible A-frame and toplink working as it should and have plenty of travel? Or is it bottoming out on uneven terrain and causing extra stress on those links.

If being covered under warranty I guess I'd keep trying the OEM ones until the issue goes away. If you are having to buy the parts....Go to a steel supply place and have them make you some out of hot rolled bar. Those look like they are cold rolled and by nature is a little more brittle and breaks alot easier if it gets bent.

No warranty..... both the dealer and BH have said its user error. That top pic is the latest failure. You can see it's partially broken before even being used.

 

[Boatman62]

It's quite possible that there isn't enough free play. He has about 200 acres he cuts twice a year. Part of it was an old apple orchard that the pulled the trees.

My question was more geared to if anyone else has the yokes break and noticed they seem to be compromised right from the start.

I think the best solution is to go with chains. I can reinforce and weld the bars but if hes breaking the bars from bottoming then something else will have give at some point.

 

[LD1]

Was that pic of the one partly broke happen on the same day it was installed.

Or was this a second mowing with it on...and it was partially compromised already?

If that stress crack happened....and he waited only a few days or a week them went back at it and it broke.....good chance it wasn't shipped like that, rather it was compromised by something he did the first time he mowed

 

[Boatman62]

Was that pic of the one partly broke happen on the same day it was installed.

Or was this a second mowing with it on...and it was partially compromised already?

If that stress crack happened....and he waited only a few days or a week them went back at it and it broke.....good chance it wasn't shipped like that, rather it was compromised by something he did the first time he mowed

Same day.

 

[Boatman62]

Also point out hes not new to mowing. Been doing for 20+ years. Breaking the yokes is new. First one was replaced maybe 2 years ago. Since then it's been an ongoing issue.

 

[wirlybird]

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.

 

[Smokeydog]

My similar BH brand, 286 uses round bars. Storing over the winter has my usual grapples on the FEL resting on them bending them down. Still haven’t broke in 25 years of abuse on rough ground and woods. The flex top hitch allows for articulation in dips and backing over trees. I use a solid top link.

Your break looks like a crack then break. Faulty flat bar stock? Surprised by a major manufacturer. Counterfeit and sub standard materials in our supply chain is a real problem. From the other broken bars you have enough materials to make substantial repairs. Letting your dealer and BH know might be remedy too.

 

[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

I can get more pics next time I go over in a day or so.

Where your arrow is pointed is where they are breaking and there is about a 15-20° in the bar.

All that have broken are OEM Bush Hog.

 

[Boatman62]

My similar BH brand, 286 uses round bars. Storing over the winter has my usual grapples on the FEL resting on them bending them down. Still haven’t broke in 25 years of abuse on rough ground and woods. The flex top hitch allows for articulation in dips and backing over trees. I use a solid top link.

Your break looks like a crack then break. Faulty flat bar stock? Surprised by a major manufacturer. Counterfeit and sub standard materials in our supply chain is a real problem. From the other broken bars you have enough materials to make substantial repairs. Letting your dealer and BH know might be remedy too.

As I said above. He has talked to both the dealer and directly to BH. No love from either one.

Looks to me the stick the bars are made from is hardened to some extent and when the bend is stamped its ctacking/shearing the steel.

 

[wirlybird]

I can get more pics next time I go over in a day or so.

Where your arrow is pointed is where they are breaking and there is about a 15-20° in the bar.

All that have broken are OEM Bush Hog.

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.

 

[Boatman62]

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.

I don't believe they would be hardened either,,, maybe a mistake in the manufacturing process.

They are breaking exactly at the point of the bend.

I never got a look at the first one that came original with the machine to see what the broken ends look like. But the two replacements look like they were compromised before installation.

 

[wirlybird]

I don't believe they would be hardened either,,, maybe a mistake in the manufacturing process.

They are breaking exactly at the point of the bend.

I never got a look at the first on that came original with the machine to see what the broken ends look like. But the two replacements look like they were compromised before installation.

Since they are breaking at the bend that is why I suspect that an excessive lifting at the rear of the hog is bending those bars outward until they break. Which is also unusual since I think they would just bend. I've bent them on one of mien but never broken one.
Really odd.

 

[LD1]

They aren't hardened. Looks like it's just cold rolled steel. Which is a very poor choice if it needs to be bent unless it's heated.

Question is....how old is the cutter. And is it still under warranty even though they are denying this claiming operator error?

I'd be inclined to seriously push back.

Not sure I'd cite manufacturing defect.....rather engineering defect of they spec'd cold roll and to bend it cold in a break

 

[Boatman62]

They aren't hardened. Looks like it's just cold rolled steel. Which is a very poor choice if it needs to be bent unless it's heated.

Question is....how old is the cutter. And is it still under warranty even though they are denying this claiming operator error?

I'd be inclined to seriously push back.

Not sure I'd cite manufacturing defect.....rather engineering defect of they spec'd cold roll and to bend it cold in a break

Don't know exactly but probably around 10 years old..... well out of the 1 year warranty.

I agree with the metallurgy.

 

[LD1]

Don't know exactly but probably around 10 years old..... well out of the 1 year warranty.

I agree with the metallurgy.

Either just go to a local shop and have them made out of hot rolled, or use some chain as another poster suggested

 

[hosspuller]

The ends of the break show a progressive cracking typical of a stress fracture. This happens under a cyclic loading. It usually starts at a material defect or stress riser. A bend qualifies for this definition. Either replace with chains or adjust the top link to allow the tail wheel to roll and follow the ground without loading these links..