JD 40 Brush Hog

Meanwhile I am using it on the 50 which has live PTO. Are there strength concerns with this trans/PTO also?

The 40's have a weak link in the trans, and that is a cluster gear through which (if I remember correctly) 1st and 3rd grear are driven, as well as the PTO. If you are brush hogging along and hit something, the weakest spot between the engine and the PTO/drivetrain is generally the teeth on this gear. The gear is the last thing that comes out of the trans if you have to dismantle it, and can run a few hundred dollars. (I've been there.) I believe this info also applies to the 320's, 330's and the 420's with 4-speeds and no live power.

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I'm curious. Is the 5-speed transmission on a 420 or 430 a stronger transmission and better suited for bushhogging?

Thanks,

Steve

The problem with this cluster gear is that the engine force is always being pushed through it to the PTO if the PTO is engaged, and is also used for 1st and 2nd gear (correction to my earlier post). This means that while brush-hogging in 1st or 2nd gear, the engine, drive train, and PTO are all in sync with each other, all because of this cluster gear. If any one of these suddenly tries to stop (engine sieze, tractor hits tree, brush-hog hits rock) there is all sorts of torque put on this gear, and it's very likely that some teeth are going to let go.

I was recently reviewing some 420 info in JR Hobb's book "The Little Giants" and there was a mention that the live PTO option on the 420's was a popular option as it greatly reduced the amount of breakdown in the PTO.

Now, thinking about this and looking at the 420 parts manual, this makes sense. With the live PTO, the PTO was no longer driven by coupling to the cluster gear, but by coupling to a new gear introduced for this purpose. This now leaves the cluster gear to serve the drivetrain only, not both the drivetrain and PTO. The load was now spread over more parts in the trans.

The five-speed trans w/o live PTO is very similar in design to the four-speed.

So I think the answer to your question is that the five-speed trans with live PTO is not necessarily stronger than those four- and five-speeds w/o live PTO, but that it is indeed better suited for brush-hogging.

One added note on the non-live-PTO tractors - An overrunning clutch on the PTO will certainly help in the situations where the tractor stops and the brush-hog doesn't. But it won't do any good in the case where the brush-hog stops but the tractor doesn't. You may want to consider adding some sort of shear pin to your PTO drive train. It would be a whole lot cheaper and easier to replace than this cluster gear!

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It is rated at about 29 h.p. and handles a 5' brush hog with a slip clutch on the pto drive.

Works very good in up to 3" brush. You will have problems tearing up gears without the slip clutch (not overriding clutch) if you get into heavy brush. Been there. The gear costs $350 plus installation awhile back.

Works very well with the slip clutch. You just punch holes in the tires.

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I purchased my brushhog (model 305 bush hog 5') used with it already installed. I guess it's an option. It sure saves on gears.

I have a model 306 6' without this clutch and I do not use it in heavier stuff, even though I have it on a 46 hp tractor.