rotory cutter gear box differences ???

the6shooter · Nov 6, 2007

I have a question that I can't find and answer to? looking at cutters and some have 40 hp, gear boxes and others 50, and 65 hp these are on 60" brush cutters. would someone please explain the diffences? I have 24.5 hp to the pto and wouldn't a 65hp gear box hurt my tractor ?
thanks david

Crash101 · Nov 6, 2007

There are many who know more about this subject than I do, but the rating of those gearboxes seems to be a measurement of ruggedness. One will stand up to 65 hp , another will stand up to 45 hp. It wouldn't hurt at all to have much more than you need but the mower assembly of a higher rated gearbox itself may be too heavy than the 3 point capability or weight of the tractor should withstand.

jbrumberg · Nov 6, 2007

Crash101 sums it up pretty well. The problems occur when there is too much HP at the PTO stub than at the gearbox or as Crash points out the weight of the heavier RC exceeds the lift capacities of the 3PH or balance of the rig.

Jay

Farmwithjunk · Nov 6, 2007

As was already mentioned, the ratings are suggested MAXIMUM hp. A rating higher than your tractor's output should in no way harm anything.

rbargeron · Nov 6, 2007

The rating of a gearbox is determined by several design factors - the type and quality of the gears (material, hardness, precision, finish), the quality and precision of the roller or ball bearings (size, fit tolerance), the strength of the gearbox housing and the accuracy of the setup of the internals. Sometimes a box rated at 65 hp but with high-end design and components can actually weigh about the same as a box rated at 40 hp with lower-grade parts.

Gearbox horsepower ratings are based on "mean-time-to-failure" analysis that accounts for the load and speed that a given machine will stand on average before it statisticallyy becomes likely to fail. On the same tractor in the same use, an agricultural gearbox rated at 65 hp can be expected to hold up longer than one rated for 40 hp.

heymack · Nov 6, 2007

In theory a 65 HP gearbox would be overkill for your 25 HP tractor, but shouldn't hurt anything provided your smaller tractor could handle the size/weight of the implement in question. Conversely, a higher HP tractor running a lighter/lesser HP rated shredder gearbox could damage said gearbox because the tractor could overpower it while working in heavier and thicker mowing applications.