# NH 472 Haybine Problems



## jefbow (Jun 30, 2011)

I keep shearing the shear bolt at the sickle bar. I know I need to replace the bushing after the last failure. I can cut about an 1 acre of hay before it shears. I mades sure all my guards on the cutter bar and clips are good. I have recently noticed the sickle bar does not immediately engage when the PTO is engaged. Any suggestions? I am using NH bolts


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## bigdoug43 (Jun 23, 2011)

I don't have any great words of wisdom but it sounds like the sickle bar is binding on something. On my 479 I can move the bar by hand fairly easily. If your sickle bar doesn't immediately start moving when you engage the pto, you're stressing the belt and the wobble box before the belt heats up enough to create enough friction to get things moving. Have you unbolted the sickle bar and tried to slide it back and forth?


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## Toyes Hill Angus (Dec 21, 2010)

I agree with Bigdoug, check the knife and the belt out before you get too carried away. Those belts tend to get neglected because they are a bit%^ to change, and the knife is the usual culprit


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## Mike120 (May 4, 2009)

I replaced the sections on my sickle this winter and replaced some hold down clips. The new clips bound the bar and I had to put shims under them. My experience, like the other guys, is if it doesn't move freely, by hand, you're gonna have trouble.


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## jefbow (Jun 30, 2011)

Thanks for the advice. I think I will check the sickle bar again. One thing I learned on this problem is the value of genuine NH parts on this machine.


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## NEHerdsman (Sep 23, 2009)

Also, if the bolt holding the knife bushing to the wobble box arm isn't tight enough that can cause the bolt to shear. There must be absolutely *no* play in that connection or the back and forth action will "hammer" that bolt and cause it to fail.


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## Hogleg (Dec 20, 2009)

Check your up and down motion on the wobble box. Breaking sickles can be caused by improper shimming and lack of proper load on the main wobble bushing.


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## VA Farmer (Jul 5, 2011)

there is a skid plate that is attached to the side of the machine mine was bent after replacing that plate no more sheared knife bolts - you could see it was bent after taking it off the machine - can't recall the name but will look for the exact part tonight.


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