PTO speed for a chipper shredder

[CalG]

I've been really pleased with the service I've received from the MacKisscs TPH185 chipper shredder that I purchased second hand years ago.

Just recently, I flipped the shredder hammers, they are on the fourth and last sharp corner, small stones are hard on them.

At any rate, I run the chipper on three of my smaller tractors, with two of them offering a hi speed pto rpm.
Those would be the Hurlimann, and the Kubota B7200. The Kubota B2601 does not have a high speed pto, and the E27n is a Cat 2 tractor so get little "attachment" service.

Again, at any rate, the rated input for the shredder is 540, BUT......

I find every function of the tool, both chipping (up to four inch, more than that I burn) and shredding all sorts of tree branches, fallen leaves, pruning, berry canes , and garden waste etc. are processed more readily, with less clogging at HIGHER pto input speed.

Say 800 RPM rather than full rated 1000 or the 540 alternative.

I've been running this way for over 7 years, and the bearings on the implement have not failed or even squeaked ;-) I do give each a pump of grease each season, but that's all.

The pivot shafts for the hammers showed no adverse wear when I did the hammer flip (48 hammers are a half days work!)

I can;t say much about the chipper knives, I try to keep them sharp, mostly, the high input spped keeps the chipper housing from clogging on stringy stuff.

What could go wrong?

Comments?

 

[doneill127]

That’s ironic, I also have a second hand MacKissics, not sure of the model, but it’s rated for 1000 rpm but the manual says it will also work on 540 rpm pto.

 

[Runner]

Since it feels weird to me to have my tractor sitting there running "wide open" for chipping, I tend to do the opposite. 540 on my 2520 is supposed to be 2600rpm, but I usually run about 2400rpm for chipping because it reduces my cringe factor. If I'm chipping things likely to clog (cedar branches, trees/bushes with green leaves), I will run it at full rated speed.

Same goes for the stump grinder. I couldn't imagine running that thing at 2600rpm.

 

[steve tym]

My TYM has a three speed PTO. I try to run the pto at 540 rpm. I'll choose the pto speed based on the hp needed to do the job. So, I may choose 1000 rpm rated speed, then adjust engine speed down to get 540 at the shaft. Prevents running at WOT. If I'm not developing enough hp at the lower engine speed, shift to 750 pto and throttle up. For my tractor, to maintain 540 pto rpm- 1000 pto shaft is 1200 rpm engine, 750 pto is about 1800 engine rpm and 540 pto is 2200 rpm. Did I word that well?

 

[steve tym]

Oh, and back to the OP's question. I would think higher speed might be a bearing issue, as long as you don't run so fast stuff starts flying off. Don't forget, the chipper is running much faster than 540 rpm. Depending on gear reduction (pulley sizes) that chipper probably runs 3000 rpm or so. If you increase shaft speed by 10%, that gets you to 594 rpm shaft speed, but chipper speed goes to 3300 rpm.

 

[Runner]

Did I word that well?

Yes, but I still don't understand. I would think the rated engine speed would always be the same (theoretically where it generates the highest HP), just the gearing of the PTO would be different.

My 2520 has a 540 and a 1000, but the rated engine speed is the same for both.

 

[steve tym]

The two ends are tied together with gears, your pto has a transmission, as engine speed changes, so does the pto. The pto shaft will spin at 1000 when the engine spins at rated speed, slow down the engine to half that and the shaft will spin at 500 rpm.

 

[Runner]

The two ends are tied together with gears, your pto has a transmission, as engine speed changes, so does the pto. The pto shaft will spin at 1000 when the engine spins at rated speed, slow down the engine to half that and the shaft will spin at 500 rpm.

Mine isn't like that. It has a selector lever for front/mid which is 1000 and rear, which is 540. Each is geared to run at the same engine speed of 2600.

 

[CH4Ohio]

Mine isn't like that. It has a selector lever for front/mid which is 1000 and rear, which is 540. Each is geared to run at the same engine speed of 2600.

I don't think that's what most people would consider having "both 540 and 1000 RPM". Seems to me that the mid-PTO is much more specialized and designed to drive snowblowers and mowers. For either your mid or rear PTO, you're running at near Wide-Open-Throttle. Most people would say that your tractor has a 540 RPM PTO. It also happens to have a mid-PTO.

At least that's the way I would expect it to be described.

 

[oldnslo]

My little Branson has option to run rear PTO @ either 540 or 960 RPM. This is done via mechanically changing gear ranges suspect 960 is European or Asian based.

My WoodMaxx 8500 is rated for 540 or 1000 and I find it works much better at 960 RPM option.

No concern on bearings but what is flywheel RPM capability on the chipper?

 

[Runner]

My little Branson has option to run rear PTO @ either 540 or 960 RPM. This is done via mechanically changing gear ranges suspect 960 is European or Asian based.

My WoodMaxx 8500 is rated for 540 or 1000 and I find it works much better at 960 RPM option.

No concern on bearings but what is flywheel RPM capability on the chipper?

OK, but is there any need to change the engine RPM when you change the PTO speed selector? Is your "rated PTO engine speed" the same RPM, regardless of which PTO speed you have selected?

 

[oldnslo]

OK, but is there any need to change the engine RPM when you change the PTO speed selector? Is your "rated PTO engine speed" the same RPM, regardless of which PTO speed you have selected?

On my tractor engine speed is the same for both 540 & 960 PTO since it is mechanically different drive gears in the transmission housing.

I think confusion is if you have a tractor with 1000 RPM PTO at 2500 engine RPM lowering engine RPM to 1250 will result in approx 500 RPM PTO speed