Karl Townsend wrote:
here's a pic of a similar unit:
http://www.jacto.com/sprayers/agricu...arbus_400.html


"spaco" wrote in message
.. .
I don't know what an air blast sprayer is, but I have used a lot of 540 rpm
pto equipment and I have never had that sort of an issue with the PTO shaft
itself.
My guess is that the problem is deeper inside the machine and not really
related to the PTO shaft at all.
If you are repairing it "for about the fifth time", It sounds as though
you haven't ever gotten to the real problem.
Could you contact the mfr about it or a dealer? It may be a common
problem.

I guess you have a lot more modern tractor than any of mine. My 60 Hp
Case 800 diesel only goes 1450 rpm's at 540 PTO speed.
Have you really checked PTO speed? Could it be that you are over revving
the sprayer?

Pete Stanaitis
--------------

Karl Townsend wrote:
I'm repairing the same issue on my airblast sprayer for about the fifth
time. Own something long enough and the same problems keep repeating. the
sprayer has a vibration in it at 2500 tractor RPM, 540 PTO RPM. The
vibration is not like a tire out of balance but its a bucking forward to
reverse. When it gets a little lose, in a few more hours of run it will
damn near shake the tractor off the ground. Its also a natural harmonic
at this RPM, slow down and the vibration goes away. Unfortunately, this
REALLY reduces sprayer performance.

I'm replacing the entire PTO shaft and tightening up the clearance in the
gear box again. if everything is tight, the problem is less severe. The
is working on the symptom, not the cause.

This is a long shot, anybody know about balancing this sort of vibration
or changing the natural harmonic frequency?

Karl


If your PTO shafts are not the same height as in this picture it WILL
give you vibration! When the rear U joint is not the same height, the
speed change from the front U joint is not cancelled by the rear U joint.
This is why all good designed machinery has a way to adjust the PTO
shaft or drawbar up or down to align the PTO shaft.