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Discussion Starter · #1 ·
Guys I've lurked around this forum and gotten some pretty good info over the past few years. Thought I would sign up and see if you could guide me in the right direction. I have a New Holland 275 square baler and i'm shearing alot of flywheel pins. The baler bales good tight bales. Last season I was having issues with the shear pins so I pulled the flywheel and replaced the front seal in the gearbox (bearing was good still so we didn't replace it). I had a buddy work with me to check the timing (he has alot of experience rebuilding one of these) and he said it was good.

Now this season out of the gate I'm shearing pins. I can bale 4-10 bales (or more at times) and then I shear a pin. I've noted that I can run through a row and shut it down and the shear pin nut is loose so I tighten it up (they continue to work loose then snap). It seems to me the issue is the nut working loose (or the pin stretching?). I ran out of shear pins and used Grade 5 bolts after (i will get more shear pins this was on a Saturday...). I've tried every type of lock nut/washer I can think of (I've bought a few more to try when I get to bale again).

I have my book out now looking at other options. Just wondering if you guys have seen this before. Is the issue the nut loosening or is the nut loosening because of some other issue?

Thanks

West KY Boy
 

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You could have a driveline vibration thats shaking them loose but I figure you would feel that. How tight does the bolt fit into the hole? It might be egged out from year of abuse and a loose bolt or two.
 

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Discussion Starter · #4 ·
I had been using New Hollands Shear bolts (until I ran out). I didn't note the loose nut issue until I was using the grade 5 bolts. I'm picking up more shear bolts from NH this afternoon.

Will the back of the flywheel is slightly egged. I've thought about trying a washer there (on the backside).

My plan tonight is to loosen the bales up and start tightening it back down as we go.
 

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If everything else appears to be in order, look at the shearbolt sleeve in the flywheel. The machined sleeve where the shearbolt goes through may be getting worn. This allows the shearbolt to slant in the hole while driving which can work the nut loose and cause premature failure of a shearbolt. The sleeve is a replacement item in the flywheel. Also check the shearhub in front of the flywheel to see if the bolt hole is getting elongated in it. The squareness of the shearbolt hole is very important.
 

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Hay Master
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I had been using New Hollands Shear bolts (until I ran out). I didn't note the loose nut issue until I was using the grade 5 bolts. I'm picking up more shear bolts from NH this afternoon.

Will the back of the flywheel is slightly egged. I've thought about trying a washer there (on the backside).

My plan tonight is to loosen the bales up and start tightening it back down as we go.

If you can grab the flywheel rock it more than 1/8" the part highlighted in red is your problem, as long as the pinion shaft is not chewed up you can have a knowledgable machine shop bore it out and make up a bronze sleeve that will bring everything back to normal.
 
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Discussion Starter · #8 ·
"If you can grab the flywheel rock it more than 1/8" the part highlighted in red is your problem,"

it doesn't have movement to it. I've ordered the sleeve mentioned above and will try that. I'm still going to try a few adjustments tonight too.
 

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We have not experienced the problem you are talking about, but in regards to the "NH Shearbolt" My dad and I just drilled out the hole to hold a 3/8" diameter bolt or 9/16". This has worked quite well for us and then you do not need to use the specific shear bolts from NH.

Good luck on getting your bolts to stop shearing, they are always a pain in the a$$ to change and if you have to change them that often...I can't imagine that.
 

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This is an interesting read. I would appreciate knowing what the final solution is when you find it. I am learning.

On our 278, if we sheared many bolts then the cutting knives were dull. I do not believe that is your problem. We have never had an issue with shear bolts working lose.
 

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On our 278, if we sheared many bolts then the cutting knives were dull.
That was my first thought. Any ideal when the last time they were sharpened? Are they sharp now? The sharper they are the easier the baler runs.

An egg shaped or worn out shear bolt hole will definitely cause the problem you are describing. I can't recommend just drilling it out, a lot of engineering went into the baler and if they have a certain size shear bolt it's there for a reason.
 

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Discussion Starter · #13 ·
Results from tonight, I took the cover off the baler so I could watch the cycle closer and know when it was breaking exactly. We lightened the bails up alot to try to get through the afternoon.

Every time we sheared a pin hte knives were in the back position (plunger in the back position). So we are going to pull them and sharpen (went ahead and cleaned out the chute tonight).

to some of the replies i did run the regular shear pin and locknut with another lock nut (with attached star washer) on top of that. I didn't have the backing out issue.

I also noted that there is a good bit of play in the plunger pin bearing (the one with a remote grease fitting). I'm not sure if its a deal breaker or not. I plan to start with the knives.
 

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Hay Master
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Folks have given some good information regarding the mechanical side of things, so let's take a look at some of the operational stuff.

You said it makes a nice tight bale. How tight? Could you provide some info about the size bale, how many flakes are in the bale, and how thick are the flakes. The reason I ask is to see if you're trying to put too much hay through the machine and/or if the tension is too tight.

Also, what rpm are you running the baler? You want to keep the flywheel spinning to provide the inertia to power the plunger through the stroke. Does your engine speed seem to be fluctuating with each stroke?

What type of hay are you baling and what are the conditions? Hay baled early in the morning or late afternoon (dusk) tends to have greater moisture than hay baled during the heat of the day. It makes a huge difference.

In the past, when I have sheared bolts, it was due to some combination of high humidity, high tension, low rpm's, or too much hay being fed into the baler.
 

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One last thing I just remembered having happen on our old 276. There is a safety build into the baler that if your twine needles are not retracted all the way a finger will catch the plunger arm immediately shearing the bolt. One of two things can cause this to happen, some play in the linkage for the twine needles or the cable is loose running up to the trip by the gear box. I'm also thinking this may not be your problem as I think it catches the arm when it is straight down, not pointing straight back.
 

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Discussion Starter · #16 ·
Folks have given some good information regarding the mechanical side of things, so let's take a look at some of the operational stuff.

You said it makes a nice tight bale. How tight? Could you provide some info about the size bale, how many flakes are in the bale, and how thick are the flakes. The reason I ask is to see if you're trying to put too much hay through the machine and/or if the tension is too tight.

Also, what rpm are you running the baler? You want to keep the flywheel spinning to provide the inertia to power the plunger through the stroke. Does your engine speed seem to be fluctuating with each stroke?

What type of hay are you baling and what are the conditions? Hay baled early in the morning or late afternoon (dusk) tends to have greater moisture than hay baled during the heat of the day. It makes a huge difference.

In the past, when I have sheared bolts, it was due to some combination of high humidity, high tension, low rpm's, or too much hay being fed into the baler.
I'll try to answer all these. I try to bale about 65 lb bales... not sure a flake count off hand.

I run the baler about 2100 rpm.

IT is mixed grass hay (fescue, orchard grass, timothy).

I try not to bale until its ready and not after the dew has fallen.

I know there are alot of factors but I'm sure there is an issue.
 

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What tractor exactly?

2100 engine RPM would be over speeding the baler if my 1600 Oliver was on it as PTO speed is 1700 RPM.
2100 engine RPM on one of my older Olivers (66,77, 770, 88, 880) would eventually leave engine parts and pieces of block all over the hayfield and would be overspeeding the baler.
2100 engine RPM with one of my 354.4 Perkins would be slightly under 540 PTO speed as they are rated at 2200 RPM.
2100 engine RPM with either the 1755 or 1855 would be even more under 540 PTO speed as they are rated at 2400 RPM.
2100 engine RPM with one of 3208 Cats would be way under 540 PTO speed as they are rated at 2800 RPM.

One of the older tractors would run the baler, but all kinds of random problems could pop up in heavy rows pulling a big wagon with any kind of hills.

Least problems we had baling hay was pulling the baler with enough tractor that the tractor didn't even notice it had a baler or wagon behind it no matter the size of the hill. 100 hp always worked well, 72 not so bad, 60 or less was the pits.
 

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One last thing I just remembered having happen on our old 276. There is a safety build into the baler that if your twine needles are not retracted all the way a finger will catch the plunger arm immediately shearing the bolt. One of two things can cause this to happen, some play in the linkage for the twine needles or the cable is loose running up to the trip by the gear box. I'm also thinking this may not be your problem as I think it catches the arm when it is straight down, not pointing straight back.
You just turned the light bulb on in my head. I remember the safety device you are talking about. It is a block of metal that slides into a "stop" if the needles are not timed right. I believe it is spring loaded?

I only sheared a bolt one time on that. It broke pronto, absolutely no way the plunger was going any where.

I wonder if that safety mechanism is partially engaging some times?

The plunger is in the back of the chamber when his bolt shears, so it probably will not be that but it is worth having a look.
 

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Discussion Starter · #19 ·
It's a Kubota M5700 ~60horse . 2100 is within the pto range (and has baled fine for the past several years. I typically run in Low range 2nd gear when baling unless it's a really large windrow I would then be in 1st.
 

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Discussion Starter · #20 ·
One last thing I just remembered having happen on our old 276. There is a safety build into the baler that if your twine needles are not retracted all the way a finger will catch the plunger arm immediately shearing the bolt. One of two things can cause this to happen, some play in the linkage for the twine needles or the cable is loose running up to the trip by the gear box. I'm also thinking this may not be your problem as I think it catches the arm when it is straight down, not pointing straight back.
i was wondering the same thing but didnt see it engage last night. The arm was straight back each time. I will pull the knives out tomorrow night and we'll see when I can get weather to lay some more hay down to test.
 
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