New Holland 451 Sickle problems

[pinus]

I've had my cutter probably 5 years now and short of some general expected stuff it has worked without a hitch, not used a lot but I have cut 5 acres of hay on occaision. Now this year when I went to using it the machine seemed to be making a chattering like noise and broke the sickle knife head along with the bolt through the head. The machine came with 3 sickles so I changed to another sickle and replaced the bolt with the wedge type bushing and lug type nut that is supposed to be on the machine. Prior to this I think it was a regular bolt, nut, and washer. I put this all together and yeah dummy me knew it was noisier than I thought it should be but I continued using it until this time it broke the bolt and basically wrecked the busing in the knife head and damaged the drive plates. So I get another bolt, wedge bushing, and lug type nut and reassemble it. This time I realize the bearing nuts are somewhat loose around the drive plates. I snug all this up, really tighten the knife head bolt like it should be, and head out to the field this evening. Keep in mind the drive plates are sort of bent or a little twisted by now but I'm hoping for the best.

The mower started out fairly quiet with occasional chattering but after 3 rounds around my hay field this evening the mower picked up some chattering noise and all the sudden quit cutting. The lower ends of the drive plates basically tore off where it attaches to the knife head.

So I guess my question is what am I missing that could be causing me so much trouble? Have the drive plates been wrecked enough by using the wrong bolts that its finally swarmed on me? Is there something in timing of these machines I'm not aware of? The sickle points seem to go from one point guard back to the next.

These plates are not cheap and I just don't want to replace things to have it come apart again.

 

[pmsmechanic]

When you were using it with worn bolts the stroke on the knife would have been shorter due to the slop in the drive system. If you tighten everything up then there is no slop and the stroke is back to factory specs. My guess is that something is worn and a full stroke is causing the knife or the drive to bind. That's my guess just by looking at your picture and seeing how the part is broken.

 

[pinus]

The plates were slightly bent or twisted from the first grenading of the knife head and bushing. It may be a matter of my learning from someones cobbled up assembly with the wrong knife head bolt being used which wore into the plates, etc. Do you think the plates being damaged as mentioned binded things up to give me all these problems?

I guess my hopes at this point are to replace the plates, bolt in the knifehead, and possibly any bearings while there and be confident I'm not missing something else that will destroy pricey parts.

 

[pmsmechanic]

Do you think the plates being damaged as mentioned binded things up to give me all these problems?

The simple answer to your question would be yes. My thoughts lie along the line of something in the cutter bar being worn and when the bolt was replaced the "slack" was out of the knife and it's binding against something. I could be wrong about this i just don't know for sure. If I could spend about five minutes looking it over I would know.

The knife should slide relatively freely in the cutter bar. Something is causing severe forces on the parts that are broken and it's hard to diagnose without seeing the mower.

 

[DogT]

I'm looking at your picture and I can't imagine what it takes to shear that plate like that, are both of those plates sheared off? I'd say maybe it's time to rebuild the whole head assembly. I've had my 451 for maybe 10 years, bought it used and rough and cut about 20 acres with it at least 3x a year. It's always a bit noisy and the guards and hold down clips are a bear to adjust, plus taking off the knife section means loosening up all the guard and clip nuts to get it off, mine is that tight. But I can mow in first gear high range which is somewhere around 4-7mph, I need to measure it. I only have a grade 8 bolt, lock washer and nut on those plates through the knife bushing, I don't think that nut/bolt wants to bind on those plates. I keep my guards up against the front of the knife sections and the hold down clips pretty close except on outer end plate where I've got a double section blade and sometimes I knock off the ledger plate on the end runner. I don't think you problem is in the knife section, I think it's in the head. Let us know how you approach it.

 

[pmsmechanic]

I don't think you problem is in the knife section, I think it's in the head. Let us know how you approach it.

Just another thought. Are there loose bearings somewhere?

 

[powerscol]

Check your end plate clearance to make sure the knife bar is not hanging up at the tip. Also while you have the head out, get it serviced internally. That kind of external damage may have played heck with the internal bearings. From the picture it went through a huge shearing bending action to bend and break the plate the way it is. The pin is also hammered, so there was a lot of slop in the mounting hole.

 

[soccermania421]

I am also having to swap out my drive plates for new ones. Is there a way to easily remove them without having to disassemble the whole box?

 

[majorwager]

I have a 451, replaced the reciprocating bar years ago, never any issues since. I still have the factory bar, great condition, just hate dealing w/ rivets.