pitman length

Hi Mitch:

I have been there many times with my own mowers and helping a friend rebuild his. Getting the lead and register correct can be very frustrating. The interplay between the two adjustment mechanisms can be confounding. I never have shortened the pitman though opting to assemble re-assemble until I got things correct. I am interested to hear how it turns out for you.

Happy mowing.

George

There are a lot of different theories on how to get the proper lead and timing. The method I subscribe to does not include pulling the head end of the mower forward. I learned from an Amish shop (Rudy Beiler – Fort Plain, NY) that the lead is lost through the push bar (big diagonal bar from under the seat) looses the correct angle where it is bent on the big end. A combination of a jig (to ensure proper realignment) and a heavy press are used to rebend this bar slightly. The reason this becomes important is it allows the head to stay where it belongs. The pitman stick should be square to the pitman shaft and this is easily checked by placing a framing square against the face of the flywheel. Now as I turn the threads to adjust timing I use the framing square each time I put the head back in to maintain the same placement. I move the push bar threads and timing bar (bar in front of pitman) together (both in or both out) to adjust the timing. Anyway that is how I do it. If your pitman stick is far from square it is generating torgue that will be relieved with bad barings or broken plates on the pitman stick. Donn

Hi Mitch, The knife and the pitman don’t line up exactly. The far end of the knife or cutter bar is slightly in front of the inside end and the reason for this, is the pressure of the grass while mowing will push it back to a straight line. This is what we call the “lead”. If you measure the lead with a string running straight down the pitman the outer end of the knife should be 1/4″ per foot advanced. That means a five foot bar would have 1 1/4 of lead and a six foot bar would have 1 1/2″ of lead. You can usually eyeball lead by getting down on the ground and looking up the knife at the pitman. There is some flexibility with how perfect the lead needs to be. I have seen many mower with the lead less than perfect that ran good. when the bar appears neutral or actually behind the line of the pitman is when I have started to see problems with broken pitman bolts or plates, or other mowing issues. So, use a square to check the pitman and a string to check the cutter bar.