Tractor Repair: New Holland 275 Square Baler, flywheel bolt, inch gap

Question
We have a New Holland 275 Twine Square Baler- We need to replace the needles. How do we reset the timing or what exactly do we need to do to make sure we do not break the new needles off too?
Thank you

Answer
Hello,

  It's very important that you find out why the needles broke, or it will happen again.  If you only replace the needles, you're just fixing the symptom and not the problem.  There is a safety stop on the left side of the baler that should protect the needles by shearing the flywheel bolt if something goes wrong, rather than breaking the needles.  It's pretty common for this safety stop to not work if the spring is broken, the linkage or pivot is rusted tight, or the clevis pin has been replaced with a bolt that has been tightened on the clevis.  The safety stop is operated by the needle yoke so that whenever the needles move forward during the tying cycle, the safety stop should move so that it will hit the arm on the main gearbox if the needles don't move back in time before the next plunger stroke.  If the knotter shear bolt or drive chain breaks, the needles will be broken if the safety stop does not shear the flywheel bolt. The needles should be timed so that as the plunger moves rearward, the tips of the needles just start to enter the slots in the bale chamber as the tips of the plunger start to go past them.  Adjust by loosening the knotter drive chain and moving the knotter clutch sprocket on the chain.  The plunger can't actually hit the needles, as there are slots in the face of the plunger.  It's the hay in between them that breaks the needles.  Don't forget, the needles have to be adjusted after they are installed on the yoke.  They should be adjusted so that as they go up into the knotters, they barely rub the knotter frame and have 1/8 inch gap between the needle and the twine disc of the knotter.  The twine fingers under the knotters should just clear the needles without hitting them.  This is important because if not adjusted correctly, it won't tie and could also damage the knotters, twine fingers, or needles.