Rotary Cutter shopping for a 4' rotary cutter

djradz · Sep 16, 2002

Re: shopping for a 4\' rotary cutter

I've never heard of failing a clutch by having too big a load on the PTO. How is this possible?

manganos · Sep 16, 2002

Re: shopping for a 4\' rotary cutter

How about this. If you have a cutter designed for say 35 to 40 hp the shear pin will break at the point so you won't hurt a 35 to 40 hp tractor. Putting the same size cutter on a 20 hp tractor the shear pin will NOT break and put the load on the internal clutch therefore putting premature wear on it. I believe a slip clutch will do the same thing because it would be set up for a bigger tractor.

JimMc · Sep 16, 2002

Re: shopping for a 4\' rotary cutter

Most 4, 5, and 6' cutters use the same shear bolt and the same PTO slip clutch. The shear bolt obviously doesn't know what size cutter it is on and therefore shears at the same load regardless of cutter size. The slip clutch, however, can be tailored to the level the user desires within the parameters of disc diameter, number of plates, and tension on adjustment. This, of course, ignores any friction disc glazing, impurities such as oil contamination etc. But the bottom line is that a slip clutch is the system which would allow one to tailor the maximum load for both tractor and cutter, as long as you're willing to replace clutch elements frequently if you set it too low and constantly slip it.

JimMc · Sep 16, 2002

Re: shopping for a 4\' rotary cutter

Now there is another tack to this cutter size thing. Most manufacturers use the same design within a given series of cutters. So the smaller cutter in a given series is heavier built than its next size up brother. For instance if a manufacturer builds its "40 HP Super-Whack Cutter" in a 4', 5' and a 6' version it probably has the same gearbox, blade width and thickness, PTO Series, deck thickness, side height and thickness, gearbox mount, and though the deck reinforcements are longer, they are typically the same material. In short, this means the 4' is overbuilt for it's duty cycle so that the 6' is heavy enough to last.

professor · Sep 16, 2002

Re: shopping for a 4\' rotary cutter

Manganas
Thanks for answering the clutch question. I have seen several burned clutches on small tractors trying to do big tractor work. Last year I loaned a relative my AC5020 approx 21hp and a JD 403 4ft cutter. The tractor had 480 hours on it. He mowed thick material in too high a gear range. I spent $800 replacing a crystalized clutch. Neither a borrower or loaner be!

djradz · Sep 17, 2002

Re: shopping for a 4\' rotary cutter

That clutch shouldn't be slipping no matter what the load is. That's why tractors occasionally stall under heavy load. Too big an implement should be evidenced by the engine really bogging down and unable to maintain RPM. If the clutch was damaged, it likely was already slipping beyond normal in the first place.