# knife head breakage on a 1219 JD mower



## oliver (Aug 8, 2009)

I have had 3 knife heads break on my 1219 mower with each having less than 150 acres on them. I can't see where it would being hitting anywhere. I replaced all guards after the first two broke. I keep blades changed as needed and do not not try to run with a dull knife. Any ideas as to what could possibly be causing this?


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## iamloco4u (Apr 26, 2010)

I have a 1219 also that has broke two knife heads over the last three years.I was talking to a friend (he has a 1209)and he said the the jd dealer told him to keep the sickle bar gear box full of 90/140 gear lube. The dealer told him when the gear box gets worn it will chatter and cause vibration which causes the knife head to break. Also make sure your blade guides have some tension on the knife bar, this will keep the knife from having to much slop. I just spent most of this afternoon welding the knife head back on the knife bar. It moves back and forth by hand just fine. Will hook up to the PTO in the morning. Wish me luck..


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## oliver (Aug 8, 2009)

Couple of good ideas to look for. Thanks for the input.


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## hayeqdist (Dec 10, 2009)

Might look at replacing guards. The Deere ones are Import I would go with a SCH, Herschel or other.
They stand up better.


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## mlappin (Jun 25, 2009)

Did this just start or has it been a constant problem with that model?

Just wondering is all, we used to have a NH495. 12' haybine, sickle was driven from one end.

In tough cutting conditions you would need to keep at least 2 or 3 of the rubber bushing that went in the drive head, several of the grade 8 bolts that went thru it. I've snapped the head off that one as well. Other problem was it was driven by a single C belt. Had to keep that tighter than they suggested or it would slip enough and soon it would be glazed up and no matter how tight you set it after that, it'd slip.

We could go thru that mower, install all new guards, new sections and a brand new sickle back, and still have all the problems I listed when encountering some really tough mowing conditions.

The next model newer was the 499's and they solved the sickle problem by going to a triple B belt drive and having two over lapping 6' sickles. Course they were hydraulic drives which created another problem of it jamming the machine and blowing the pressure relief if you had tall hay leaning into the machine. If it was tall enough and leaned enough, the rollers would grab the plants and try to pull em thru before the sickle would cut it.


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## cynergy (Apr 30, 2010)

Your problem is with the installation of guard at the far left side of the machine and the installation of the pin in the knife head.

First the guard, this guard must have the trash bar cut off or it will make slight contact with the pitman head on the inward stroke. JD does not sell a guard with this removed it must be done by cutting a guard specified for the LS of cutterbar. Also note the first four guard on the LS do not have a wear bar as do the rest of the guards, this is to allow movement of the pitman arm back and forth without contact. Indicator for this is a hardly noticeable contact point on pitman head, look for a slight shiny spot this is enough to fatigue pitman and cause failure.

Second it the installation of the pin and knife head. The pin does not go to the bottom of the head. If pushed to the bottom it will cause knife to bow and break, to check if this is the problem look for metal scouring in bottom of broken knife head. The next one is very hard to identify, if pin is installed correctly be very careful not to over grease. Over greasing will push knife head away from pin and load up pressure on pitman arm. This will cause failure with with know way of knowing what caused it as there is no impact/abrasive marks on head. Grease guns generate around 7000 psi for the hand pump and 10000 psi for the battery operated so you can see how this kind of pressure can put the head in a bind during operation.


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## oliver (Aug 8, 2009)

When I replaced the guards last year, I replaced just as you noted which is the way the old ones were. The pin has a notch in the side of it for the bolt to keep it from being in too deep. If over greasing is the culprit, I would of thought that I would have had this problem in years past as I have the same greasing practice I've used since I've owned it since 95. One thing that I did notice though, is that the shoe (not sure if that what it's called) on bottom side of cutter bar below head is getting wore. I wonder if it is getting weak enough to flex somewhat and letting the head hit it some.


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## Vern (Aug 15, 2011)

I have discovered that my that my pitman arm is worn where the pin drops through it into the knife head. I am in the processing of changing my pitman arm. I can feel extra movement when I move the pin (with the bolt in place). I noticed that there is wear on both the top and the bottom of the opening where the pin drops through the pitman arm. Last season I replaced the pin as that was worn, but didn't think to check if there was any wear on the pitman arm itself. JD has a different style pin now as it has a grove all the way around the pin which enables it to rotate and not wear on the edges as the old style did which was slotted only on one side.


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