PTO Chippers on over hp tractors

[Charlieh]

Hi,

 

I have a technical question really, what would be the downside of running a pto chipper on a tractor that exceeded the max pto hp as specified by the manufacture. Say the chipper was 40-60hp and I wanted to stick it on a 85hp tractor, is it just the wear on parts like bearings will be accelerated, or will it be putting to much stress on parts like flywheel shafts??

 

I am suprised at how low the HP requirements of some PTO chippers seem to be, compared to their size really, I have a couple of tractors available to me and would be interested in putting a pto chipper on one, I would have liked to use an older massey I drive, but at 130+hp its going to destroy all but the biggest hand fed chipper by the looks of it. Shame as the smaller tractors arent really suited to using in rough terrain and woodlands.

Edited September 7, 2011 by Charlieh

[PhilBeech]

Surely the stress control would manage that issue? usually the HP requirement on a chipper is just that, a minimum requirement rather than a maximum.

 

I could be being thick mind!

[18 stoner]

I think Phil is right Charlieh but if you were worried about anything jamming and the tractor twisting the machine up, could you not fit a pto shaft with a shear bolt in it?

[Charlieh]

I have been looking at several manufacturers and they have min and max hp recommendations, Shear pin may be the way to go I suspect, I just wondered how the guys running chippers on big mogs went on etc?

 

Surely the antistress wouldnt kick in soon enought to protect the machine as your not likely to cause a 150hp tractor to slow enough to activate it by feeding into a mchine that is recommended to only be run on half the hp? my understanding was stress control was on chipper flywheel rpm, so this wouldnt help in this case?

[Bald Ed]

Something you need to watch is that the higher the hp of the tractor driving the chipper the less the stress management will cut in, if the tractor is so overpowered the flywheel speed will never drop enough to allow the no stress to kick in so where the no stress would protect the shafts etc from being twisted with a correctly matched chipper and tractor there will be no protection with too much hp, some chippers may have a slip clutch on the shaft which will offer some protection and some may also be belt driven which also gives a weaker point to slip but the right chipper with the right tractor is the best bet all round. IMO:thumbup1:

[PhilBeech]

Probably then that issue could best be managed by the operator. If its you operating it and you don't do something stupid then you should be ok. Infeed operation is hydraulic after all, you can only over stress the chipper if you try and over feed the chipper?

[Bald Ed]

Probably then that issue could best be managed by the operator. If its you operating it and you don't do something stupid then you should be ok. Infeed operation is hydraulic after all, you can only over stress the chipper if you try and over feed the chipper?

 

This would be ok but there would be no warning for the operator that the chipper was upto capacity especially if the tractor is very overpowered as the chipper would not pull the tractor down suffisciently for the operator to notice the change in engine note. The welfare of the chipper would be solely in the hands of the operator, which is not too much of a problem if the operator is sensible and does not get distracted. I would still say get the chipper to suit the tractor or visa versa and take the pressure off the operator and the chipper:thumbup:

[renewablejohn]

Our heizohack is protected by a shear bolt in addition to the stress control and can confirm that it works due to stupid operator error.

[RobRainford]

if you want a chipper to run on a 130hp tractor, have you looked at the TW pto 300h? its a 12" and i have run it on a 200hp tractor, double its minimum requirement, and never had a problem. The antistress kicks in on bigger logs, but surely putting big logs in and working the chipper at capacty is what causes the anti stress to kick in because its chipping a lot, and the tractor powering it isnt much of an issue?

[dent]

what about a tp 230 that is only 10hp under the massey and should fare fine

if you have and economy setting on the pto why not run it in that as it should drop the revs of the engine and in theory allow the stress control to work