Help me understand PTO speed

rademamj1 · Dec 13, 2019

Same number I came up with. 1807rpm in low gear should do the job at a 400PTO speed which comes out to .88mph actual ground speed. Your tractor should have no problems doing the job. It's a very slow methodical process. Find a testing area to get your procedures right, before doing it on the greens and fairways. I am always fascinated watching the SR60 at work.

Sean2202 · Dec 16, 2019

@CobyRupert I have used many different types of aerators and yes it can be a "rotor-tiller" in certain conditions. We have Toro 648 walk aerator and it can take quad tines. If the speed is set too low, tines too large, root zone very shallow this can all lead to tearing of the turf and rotor tilling. The SR60 had 14" tines that go deep into the ground. The speed that it is currently run it tears when first going into the ground which tells me the ground speed is too fast. This machine is only used on golf greens which are a mix of sand and native soil from 1917 when the course was constructed.

@ChevyBlazerBoy good thought on the photo tach! I have one and use it often for checking RPM on machines. Never thought about using it on a PTO shaft! Thanks for the tip.

The SR60 is quite a overbuilt machine. I think it weighs just under 1 ton.

CobyRupert · Dec 16, 2019

Sean2202 said:
.. Reading in the manual it states "The rear PTO rotates at 540rpm when the engine speed is approx. 2,444 ( eng. rpm).......in first gear lowest range with turf tires and the speed in the tractor owners manual states 1.16mph

Here is the new recommendations that I just received from the SR60 aeration machine which I never had a book for until today.

[*]

The machine should be operated at 1mph, 1.16 seems pretty close to me.

The SR60 aeration machine should be operated at 450PTO with short tines or 400PTO speed with long tines. We use the long tines.

We operate the tractor at about 2100RPM when using the machine.

@Sean2202:

...but you can see that with a gear tractor (vs. a hydro), that when you adjust engine speed for correct pto rpm you're also adjusting ground speed (and vise-versa)....so it may be impossible to get 1 mph at 400 and/or 450 pto rpm. Now whether it still works at a slower ground speed in 1st gear (or faster in 2nd?); or turns into a "roto-tiller" is the experiment.