DaveOmak
Platinum Member
Knife cutter speed versus PTO RPM.
In the operators manual they discuss knife blade speed and have different toothed sprockets to adjust the knife speed. These sprockets accomodate 540 - 1000 rpm pto shafts. Also they mention different types of grasses cut differently at different knife speeds.
The 9w mower I purchased last fall. I about have it ready to put into service. A couple of days ago I had it all oiled and was running it to "wear in" new parts etc. I was increasing the engine rpm and listening to the "hum" of the sickle etc and enjoying the success I had with the restoration.
Now the BAD NEWS. At about 480-500 rpm the pitman arm EXPLODED! Pieces all over.
As I contemplated the situation, I had noticed the sickle was REALLY MOVIN'. I marked the pitman arm flywheel with chalk and turned the PTO shaft 1 revolution. The pitman flywheel rotated 1.45 revolutions. I rechecked etc.
This means the sickle was moving about 725 cycles per minute at 500 pto rpm.
Is the gearcase on my 9w stepped up?
Have any of you determined pto-in rpm vs. pitman cycle speed?
I would be curious as to other machine gear ratios to the cutter bar.
Lastly, please recomend a knife speed to get me started and maybe save a pitman arm.
New guy still trying to learn how to farm. Dave
In the operators manual they discuss knife blade speed and have different toothed sprockets to adjust the knife speed. These sprockets accomodate 540 - 1000 rpm pto shafts. Also they mention different types of grasses cut differently at different knife speeds.
The 9w mower I purchased last fall. I about have it ready to put into service. A couple of days ago I had it all oiled and was running it to "wear in" new parts etc. I was increasing the engine rpm and listening to the "hum" of the sickle etc and enjoying the success I had with the restoration.
Now the BAD NEWS. At about 480-500 rpm the pitman arm EXPLODED! Pieces all over.
As I contemplated the situation, I had noticed the sickle was REALLY MOVIN'. I marked the pitman arm flywheel with chalk and turned the PTO shaft 1 revolution. The pitman flywheel rotated 1.45 revolutions. I rechecked etc.
This means the sickle was moving about 725 cycles per minute at 500 pto rpm.
Is the gearcase on my 9w stepped up?
Have any of you determined pto-in rpm vs. pitman cycle speed?
I would be curious as to other machine gear ratios to the cutter bar.
Lastly, please recomend a knife speed to get me started and maybe save a pitman arm.
New guy still trying to learn how to farm. Dave
