Too much HP on pto?

[jenkinsph]

If it were mine I would use shear bolt protection as recommended by the attachment manufacturer. If it has a slip clutch on it now I would take it off and store it. Install the shear bolt set up and use the proper rated shear pins. It can be difficult to set the clutch up, so too tight and you damage the implement and drive line, too loose and you burn up the clutch.

 

[Gary Fowler]

I take exception to the statement that a machine will last X hours with lower hp than the same machine with a higher HP motor. All things being equal, there is no more load on the machine with 100 Hp driving than it is with a 10 HP. The limiting factor is the shear bolt or slip clutch so no additional load is put on the machine regardless of HP. There might be additional fuel used to drive it that is not needed, but otherwise one would expect the same lifespan regardless of the driver used. One exception would be if the lowest HP was not capable of delivering the required torque to shear the bolt or slip the clutch when necessary, then the machine MIGHT last longer but I doubt it. Wear on rotating equipment is usually limited to the ground engaging or a part that is contacting some type of wear agent (soil, weeds grass, rocks etc) and bearings. Therefore the wear is going to be about the same based on revolutions and not the driving HP.

That is my two cents.

 

[k0ua]

I take exception to the statement that a machine will last X hours with lower hp than the same machine with a higher HP motor. All things being equal, there is no more load on the machine with 100 Hp driving than it is with a 10 HP. The limiting factor is the shear bolt or slip clutch so no additional load is put on the machine regardless of HP. There might be additional fuel used to drive it that is not needed, but otherwise one would expect the same lifespan regardless of the driver used. One exception would be if the lowest HP was not capable of delivering the required torque to shear the bolt or slip the clutch when necessary, then the machine MIGHT last longer but I doubt it. Wear on rotating equipment is usually limited to the ground engaging or a part that is contacting some type of wear agent (soil, weeds grass, rocks etc) and bearings. Therefore the wear is going to be about the same based on revolutions and not the driving HP.

That is my two cents.

I agree.

 

[TerryR]

Is it possible to run that implement and say reduce the engine rpm/pto rpm so that I could avoid damage...

... but I'm wondering if running the attachment at reduced rpm therefore HP) is safe seeing how rpm does not affect the performance of the implement as much as it would on say a pto generator.

What everyone else said about shear bolts and slip clutches. But nobody seems to have addressed these points.

Running at a lower RPM will have little effect on the torque delivered by your more powerful tractor - it will still have plenty of torque at any usable RPM to break your implement if the shear bolt or slip clutch fails to do it's job. So that's not a solution.

I'm not familiar with your harley rake, but many PTO-driven implements do not work well if you drop the RPMs significantly below the rated speed. Among them are tillers, various types of mowers, and chippers. So not only does that not help with the stated issue, but for many implements it hurts performance.

 

[newbury]

If his current shaft works with the implement overtorque safety system it will work likewise on the higher power tractor.

However the OP indicated he had to "slow down abit".

Are you saying running the rake at 32 HP will operate fine and not keep busting 3/8" shear pins (implement overtorque safety system) if he has a series 1 PTO designed for 16 HP ?
PTO Shaft, Series 1, 1-3/8 6-Spline, 1-1/4 Round, 51 In. | Agri Supply #61194
I was just recommending he look at upgrading.

Also is his PTO shaft long enough? When I went from my B7610 to my M4700 my shafts were all to short and I had to use an extender, but most of them were series 2 or better.

Alright so I have a question concerning pto's.

Being somewhat new to tractors and only owning one PTO attachment, a 5 foot Harley Rake, it has a recommended PTO hp range of 18-32.

My current tractor has 16pto hp, and having used the rake this summer it did a fair job. I had to slow down abit over roots or rocks, and the weight on the 3PH is about at the maximum lift capacity of my tractor (2012 yanmar SC2450).

Fast forward to today I am looking at a tractor with ~49-50HP PTO. <snip>

/edit - for those that don't know the B7610 is rated at 18 pto HP and the M4700 is 42 pto HP, not quite the jump the OP is writing about.

 

[SPYDERLK]

However the OP indicated he had to "slow down abit".

Are you saying running the rake at 32 HP will operate fine and not keep busting 3/8" shear pins (implement overtorque safety system) if he has a series 1 PTO designed for 16 HP ?
PTO Shaft, Series 1, 1-3/8 6-Spline, 1-1/4 Round, 51 In. | Agri Supply #61194
I was just recommending he look at upgrading.

Also is his PTO shaft long enough? When I went from my B7610 to my M4700 my shafts were all to short and I had to use an extender, but most of them were series 2 or better.

OP says nothing about breaking shear bolts. Hes probably having to slow down due underpower. I assume the PTO shaft is paired to the Harley Rake - Probably furnished with it. It would be adequate for the implements intended use load and the safety devices that are a part of it. ... Yes, length could definitely be an issue on the new tractor.