Rotary Cutter Rotary cutter specifications

[samstride]

I visited a tractor dealership that sold Woods rotary cutters and the salesman said something that peaked my interest in rotary cutter specifications.
The Hp rating on the rotary cutter gearbox is usually the maximum rated PTO output of the tractor.
75 Hp gearbox means no more than 75 Hp output from tractor PTO, Got it.
The spec for output PTO Hp from tractor is a min-to-max for a specific rotary cutter: A Woods BB72X is 30-65 hp.
I have Mahindra 6530 with a rated PTO output of 57Hp. I was looking at the Woods BB720X (30-120Hp)

The dealer told me it might better to stick with the BB72X the reason would be that the BB720X has the larger gearbox in terms of Hp and that if I came across a tree 3 in diameter that the tractor would stall before the clutch slipped on the rotary cutter.
So my question: is the gearbox hp of a rotary cutter related to the slip clutch 'breaking' of the rotary cutter?
I would expect that the slip clutch is rated in foot-pounds and things like rotating speed and rotating mass would determine the clutch slipping?

T. Smith
Guilford county, NC

 

[jeff9366]

So my question: is the gearbox hp of a rotary cutter related to the slip clutch 'breaking' of the rotary cutter?

The point at which the slip clutch gives should be related to the gear box, which should be related to the PTO horsepower generated by the tractor. The R/C gearbox should be considered sacrificial relative to the tractor PTO. If the slip clutch is properly adjusted, this should not be a "choice".


I would expect that the slip clutch is rated in foot-pounds and things like rotating speed and rotating mass would determine the clutch slipping?

The pressure holding the slip clutch plates is adjustable.

Also, how rusty the slip clutch plates are effects at what point the slip clutch will begin to slip.

As there is a wide variation in tractors used for every Bush Hog, and the implements vary in age, slip clutches require adjustment to each tractor's power output, then periodic/annual adjustment thereafter.

Too loose and you cannot apply full power of tractor to implement. Too tight and the slip clutch effectively is not there and you may bend a blade or do other damage.

VIDEO: pto slip clutch adjustment - YouTube



PTO shaft length also needs to be suitable to each individual tractor. PTO shafts are supplied a little long, so they can be shortened if necessary. Too short and the PTO shaft can separate, leaving a deadly flair attached to the PTO splines. Too long and it can bind severely as you pull through a low spot.

Questions like this can be more accurately answered if your SATOH tractor model is part of your TBN profile.

 

[Soundguy]

Simply exercise your slip clutch at normal maintenance intervals, and adjust it to slip to protect all the attached equipment, mower and tractor.

 

[sawtooth]

As soundguy stated. Also the larger the gearbox the less energy that's transmitted to your tractor upon blade impact with trees, rocks etc. reason being is they are less efficient at transferring the energy through the larger gearbox back to your pto. On the downside they also take a little more power to run vs a smaller gearbox.