Brush Hog Trans. HP?

[HeavyToy]

Can anyone explain the impact of a Brush Hog's transmission HP on the engine load relative to cutting power?

Does high HP mean slower tip speed but more power or does it mean higher tip speed. Which is most likely to load the engine in tall heavy brush?

I have a 25 hp tractor with 21.5 to the pto. I do not want to bog the tractor down with too big of a cutter, but I would prefer a 60" over a 48" as I have R4's and the width of a 48" would be inside the tires. If I can realize an advantage with a higher hp 60" over a 40 hp 60" I would entertain the added expense.

 

[Soundguy]

A rotart cutter that has a gearbox HP rating, is the max input hp that your tractor should be so to ensure that you do not damage the cutter. For instance.. a generic KK 5' comes with a 40hp gear box. That means.. you can use a tractor up to 40pto hp on that mower fairly safely. While you could use a higher pto hp tractor.. and the mower would work.. you could get into a situation wher ethe mower may be damaged due to the excess hp available at the input shaft.

A 60hp box is just heavier duty.. shouldn't effect quality of cut, or blade tip speed of the mower.

21.5 pto hp is right on the edge for a 5' mower. If I were mowing light grass.. or simple brush.. I'd go for it. If you are mowing thick / tall grass.. or tall woody brush like multi flora rose.. I think you will be less than satisfied with a 5' machine.. if you are worried about bogging down.

The variable here that may be a pass/go issue is speed. In that thick grass, if you used..say.. a creeper gear.. you probably would be fine int he heavy stuff.. mind you.. mowing at .75 mph will probably drive you insane.. most people prefer to drop back on size of mower , in favor of speed of cut.

Kinda like.. " I could mow in 1st gear with a 15' mower... or 5th gear with a 10' mower".. add that all up and you will probably cut more grass in a day with the faster smaller mower.. etc.

Soundguy

 

[RonMar]

The brush hog's gearbox HP figure is just a rating of what the gearbox is designed to handle in terms of loading. IE: a 40 HP gearbox and a 60HP gearbox are not going to place that different a load on a tractor by themselvs. The larger rated gearbox would be typically used on a larger mower. If you have two 60" mowers, one with a 40HP box and the other with a 60HP box, the load on the tractor will be about the same for both mowers under the same mowing conditions. The gear ratio should be about the same and the blade tip speeds for that size mower should be roughly the same. The difference is that the 60HP gearbox should be tougher.

Of bigger concern in making this decision is the terrain and conditions you will be trying to use it on. Is it really wet or do you get enough dry time to mow? How much area are you trying to cut? Is there enough room to maneuver a 60" deck? What type material are you mowing?

I have a tractor similar in HP ratings to yours and it runs a 60" hog very well under my conditions. I have mainly been using it for brush and sapling clearing(growths taller than the tractor) so I can have more grass and the only times it bogs down is when I roll over a clump of sapplings that are too big/too many(3-5 or more trunks ranging from 1 1/2"-3" dia or more) or it settles down onto a mound of dirt while passing over uneven terrain(scalping). This just requires that I raise the deck while I pass over these obstacles. In the case of the saplings, I re-lower the deck slowly once it is back up to speed to finish shredding the sapplings as low as possible. What grass I have cut was waste high and a little wet and it didn't even slow the mower down. I was mowing slowly as I was moving over an area that I had not mowed before. You should be able to handle a 60" deck but your conditions will determine what speed you will mow at.