Rotary Cutter 540 -vs- 1000 pto & rotary cutter

Richard · Sep 14, 2006

I've always been confused by this.

The blades on a "540" rated cutter will rotate at a certain RPM. Do the blades on a "1000" pto cutter rotate at the SAME RPM that they do on a 540 pto? Twice as fast?

I understand there is more power avaialable through the 1000 pto shaft. Is that similar to say, gearing on a car? Meaning, the tractor spins say two shafts, one at 540 and one at 1,000.

If the BLADE rpm is the same on BOTH (and I don't know if that's the case), then the 1000 shaft is turning the blade gearbox at roughly 1/2 speed that the 540 is turning IT'S blade gearbox. I'd equate that to being in a car in first gear under load, verses 3rd gear under load. Lower gear, easier to transfer power.

Do I finally get it?

Highbeam · Sep 14, 2006

There is no more power available to a shaft turning at 540 than there is a shaft turning at 1000 assuming the same engine is turning both with the same input power.

My PTO lever allows me to select 1000 or 540. My engine is still only 30 HP at full rated RPM. A lot of the ability of the brush hog to chop stuff up is the stored energy in the swinging mass of the blades. I think if you spin a 540 pto mower up to 1000 that things might break and be dangerous. If you use the 1000 rpm pto on a 540 rpm mower then I would recommend lowering RPMs of the tractor engine by half which would limit the power available to the mower.

schmism · Sep 14, 2006

i thought it was a diffrence in gear box....

my MMM on a 1000 rpm PTO would have a 1 to 1 gear box.... a RFM running at 540 rmp PTO would have a 1:2 gear box meaning finall pully speed = 1080 rpm or roughly the same speed as the MM PTO.

as for load on the spindle/PTO i see it as the same...

but it does lead me to a question....

can i run both the mid and rear PTO's at the same time?

Highbeam · Sep 14, 2006

Mid and front PTOs at the same time? Sure, why not? I thought that's how they ran snowblowers and sanders at the same time.

roxynoodle · Sep 14, 2006

I wouldn't run an implement rated for 540rpm at 1000, you will ruin it fast and it could be dangerous. I know there are some implements rated for 1000rpm but not any rear mount mowers that I'm aware of. Some tillers can be run at 1000 and I'm not for sure on other implements.

Richard · Sep 14, 2006

I'm not talking about running a 1000 cutter on a 540 pto, nor a 540 cutter on a 1000 pto... they have different splines and won't fit (as far as I know)

Aside from that, presume TWO diffeerent tractors.

All I'm trying to grasp is what I was told about how a 1000 pto can 'transfer more power'

I never got that (and that's not to say I was told accurately)

john_bud · Sep 14, 2006

I don't think that a 1000 pto can transfer any more power than a 540 pto. If anything, it would transfer less as it is geared higher, so there is less torque multiplication.

Now if you swap parts around and hook up a 540 pto cutter to a 1000 rpm PTO shaft, it will get spun nearly twice as fast and will sure whack things much harder. Up until it breaks, or tosses a rock or blade out.

I think that you were incorrectly informed.

jb

Soundguy · Sep 15, 2006

According to my owners manual, the power transfer issue on the pto shaft threshold is around 75 pto hp or so, and the issues is that the 1000 rpm shaft is 21 splines,, vs 6 splines on the 540 shaft.. and that the power transfer is less likely to damage the pto stub, ( when using the 21 spline shaft on loads requiring 75+ hp ).. must be more surface area of the splines on the 21 spline shafts.

This is from my FNH 7610s manual. ( mine has the option of swapping to a 21 spline shaft by change out.. vs keeping the same shaft and having a multi speed pto gearbox.. for instance.. like my yanmar 1700.

Soundguy

3RRL · Sep 15, 2006

I'm not so sure that the 1000rpm pto speed cutter rotates twice as fast as the 540? I think it may refer to the cutter being used on a 1000rpm pto rather than one used on a 540rpm pto? Maybe I'm wrong on this???
In other words, the gear box is different in the cutters, for they (the cutters) may spin at the same speed. One just takes more pto rpm to get it to that speed. Now, if that were the case, then the 1000 pto cutter would have more power because it's geared lower than the 540. What do you think?

roxynoodle · Sep 15, 2006

Sorry, didn't mean to assume you were going to use your cutter on 1000rpm. My tractor is a grey and has 3 PTO settings, 540, 1000 and whatever the engine speed is, so all 3 speeds use the same PTO shaft. Some people have used the 1000rpm on them to try to mow thinking it would get done faster or something. That's why I said don't run a 540 implement at 1000.