Rotary Cutter need advice on bush hog driveshaft

[mtmaning]

Hi, I just bought a used Bush Hog 2510 and am trying to match it up to my Ford 5900. My question is this, in the on line bush hog manual it appears the pull bar point must be 14 inches past the PTO shaft on the tractor. It also says you must have at least 6 inches of overlap in your driveshaft. The way my pull bar is right now, I only have about 2 or 3 inches of the one shaft inside the other. I know I can move my pull bar in some, but I would need to move it in at least 4 inches to have the adequate lap, but this may only leave me 12 inches or so of distance from the shaft to the pull bar center hole. Will this work, or do I HAVE to stick to the 14" recomendation?? Thanks for any help

 

[RoyJackson]

I suggest you buy one of these:
Pto Adapter 1-3/8 X6 Spline Male X 1-3/8X6 Spline Female Pto Adapter
This adapter will solve both of your concerns.
Got one for my chipper....works quite well.

BTW,
Welcome to TBN!!

 

[strum456]

If I understand what you are saying, when you move the drawbar in to the next hole, the shaft is overlapped more than recommended. If this is the case, how much stroke is remaining before it bottoms out (the whole way in)? If you have 4 inches or more, I wouldnt worry about it. Using it with only 3 inches of overlap is not a good idea, but Im sure you know that.

 

[Zebrafive]

My GUESS, and it's only a guess, is the reason for specing the drawbar pivot point distance from the end of the tractor pTO shaft is to position the U-Joint of the implement PTO shaft inthe proper relationship to the pivot point of the implement hitch. Changing this could cause binding or worse when making turns. I would stick with the 14"

If you can add an extention to your tractor PTO as Roy suggests and then can set your drawbar to the 14" spec that would work

 

[greg_g]

Since you bought it used, there's a chance the previous owner at one time replaced the PTO shaft with one that was too short. The Bush Hog recommended 6" overlap would make me uncomfortable. I mow undulating ground, and some of the crests and swales flex my mower shafts more than 6". I select PTO shafts with a minimum 1/3 overlap. And if an implement comes with a shaft that I feel is too short, I get a longer one.

Most shafts are sold on the basis of overall length, so you really need a tape measure to get specific. But just for example purposes I'm gonna guess your 10' pull type RC may use something in the neighborhood of a 51" (compressed) PTO shaft. With a RC of that size, you should be using a slip clutch. So that will take the actual compressed overlap down to maybe 42". Which means you can extend it to 56", and still have a 14" overlap.

Don't take these for exact numbers, you'll have to measure your own tractor/mower configuration. It's just that I personally wouldn't feel comfortable with only 6" of overlap. That said, if you mow billiard tables, maybe I'm making a big deal outa nothing.

//greg//

 

[grsthegreat]

on top of what Roy has suggested, they also make a slip on Over-running clutch that will add 6" to the length of the pto shaft.... and also allow for freewheeling of the mower when you shut down the pto unit while operating the machine. My over running clutch slips on and locks just like a regular pto device. Just make sure you dont get one that needs to be pinned on...as you cant remove it later on then.

 

[RoyJackson]

on top of what Roy has suggested, they also make a slip on Over-running clutch that will add 6" to the length of the pto shaft.... and also allow for freewheeling of the mower when you shut down the pto unit while operating the machine. My over running clutch slips on and locks just like a regular pto device. Just make sure you dont get one that needs to be pinned on...as you cant remove it later on then.

I'm thinking that overrunning clutch might be a better way to go, at least with some implements (those with high inertial loads such as a cutter or chipper)...especially after that thread that devolved into a "PTO Brake" pissing contest (original topc was PTO Chippers, if you recall).

One thing I have read, but no supporting links...use of a PTO extension can cause premature wear on the tractor's PTO mechanism. IIRC, it was due to the lengthening of the stub shaft (of the tractor) putting more loads on the bearings.
I use my extension ("adapter") with my chipper...that's the only implement. Since I probably don't put more then 10-12 hours (total) on the chipper in the course of a year, I don't see wear being a major issue.

 

[mtmaning]

Since you bought it used, there's a chance the previous owner at one time replaced the PTO shaft with one that was too short. The Bush Hog recommended 6" overlap would make me uncomfortable. I mow undulating ground, and some of the crests and swales flex my mower shafts more than 6". I select PTO shafts with a minimum 1/3 overlap. And if an implement comes with a shaft that I feel is too short, I get a longer one.

Most shafts are sold on the basis of overall length, so you really need a tape measure to get specific. But just for example purposes I'm gonna guess your 10' pull type RC may use something in the neighborhood of a 51" (compressed) PTO shaft. With a RC of that size, you should be using a slip clutch. So that will take the actual compressed overlap down to maybe 42". Which means you can extend it to 56", and still have a 14" overlap.

Don't take these for exact numbers, you'll have to measure your own tractor/mower configuration. It's just that I personally wouldn't feel comfortable with only 6" of overlap. That said, if you mow billiard tables, maybe I'm making a big deal outa nothing.

//greg//

The way mine is set up, the shaft I am talking about is pretty short, Im going to try to show a pic, kinda seems like there isnt a lot of room to play with. I also want to add I really appreciate your guys input, I dont know much about this, but with some help I will figure it out. I have bush hogged quite a bit before with a smaller tractor and a 5 foot bush hog, there just a lot more things to consider with a larger machine. I also noticed that with the draw bar in the position it is in now, that the hoses were a little snug when I hooked them up to unload it off the trailer, so that too suggests the draw bar needs to be shortened.

 

[greg_g]

In the order of cost to you I first hope your draw bar is adjustable like mine. I can pin it long or short. Hopefully yours is the same. If yes, push it in and pin it with the least amount possible sticking out. Downside may be the pull bar hitting a tire in turns. If not, the PTO adapter and ORC will give you a short extension - but don't expect more than about 4". On the negative side, there's the potential wear increase factor involved with this option. Third would be to modify the shaft segment that goes between the tractor and the pull bar. You can buy a splined coupler and female shaft alone, but get a shaft that's considerably longer than the one you're replacing. That will in effect get the tractor end of the shaft closer to your PTO spline. It does however, make the forward non-overlapped section vulnerable to twisting. Last but most expensive (yet safest), would be to replace the whole PTO shaft section between the tractor and the pull bar.

//greg//

 

[RickB]

The actual ASAE standard distance for a 540 RPM PTO is 14" from the end of the tractor's PTO shaft to the center of the drawbar pin hole. If the new to you cutter has a conventional PTO shaft (not a Constant Velocity joint at the front yoke) the driveline will chatter like mad in a moderate turn with the hitch attached as per ASAE standards due to the hitch pin not being centered between the front and rear PTO shaft U-joints. Shortening the tractor drawbar, or adding a shaft extender or slipclutch to the tractor's output shaft will cause more driveline chatter and EXPONENTIALLY increase the possibility of twisting/breaking your tractor's PTO shaft off.
The correct course of action is to replace the cutter's PTO shaft tubes (and shielding, if necessary) to provide the required minimum overlap when the tractor drawbar is set to the 14" ASAE standard. If longer hoses are required, add short hoses, or replace the existing hoses with longer ones. Ideally, the R/C would have a PTO shaft of the proper length and a CV joint at the front. Cost of this option would likely be prohibitive.

 

[EE_Bota]

I would ignore hydraulic line lengths...and concentrate on proper shaft overlap, and proper pivot points. If you hook the implement up, and go into a turn, the U-joints should be bent an equal amount for each U-joint, and the chatter will be related to the extent those angles are different. It is a bit nasty to have the pivot point wrong. It can be very nasty to have the shaft length wrong, or the shaft phase incorrect.

When I was a kid, square shafts seemed to be the norm..but most of my shafts now cannot have the wrong phasing, which is a nice plus for modern shafts.

 

[RoyJackson]

If not, the PTO adapter and ORC will give you a short extension - but don't expect more than about 4".

//greg//

The adapter does extend the tractor's stub about 4". That would increase the OP's overlap from 2-3 inches to 4-5 inches.
Don't know about the OR Clutch...but I don't think I'd want an adapter and an OR Clutch hanging off the tractor's stub shaft.

RickB has the best solution...buy a new, longer drive shaft. They're not cheap, but not all that expensive either. Definitely cheaper then a tractor repair.
I would definitely not want an implement climbing up a tire during operation!

 

[RickB]

The adapter does extend the tractor's stub about 4". That would increase the OP's overlap from 2-3 inches to 4-5 inches.
Don't know about the OR Clutch...but I don't think I'd want an adapter and an OR Clutch hanging off the tractor's stub shaft.

RickB has the best solution...buy a new, longer drive shaft. They're not cheap, but not all that expensive either. Definitely cheaper then a tractor repair.
I would definitely not want an implement climbing up a tire during operation!

Shaft extensions and the like are an acceptable crutch when asked to transmit 20 or 30 HP. There isn't one made that will stand up to a steady diet of 60-70 HP and added stresses caused by improper shaft joint angularity.

 

[RoyJackson]

Shaft extensions and the like are an acceptable crutch when asked to transmit 20 or 30 HP. There isn't one made that will stand up to a steady diet of 60-70 HP and added stresses caused by improper shaft joint angularity.

The adapter I bought is pretty robust. Nor was there any documentation or warning to use it with a range of PTO HP (to be honest, not documentation at all).
The bolded text...your opinion, or a factual statement for which you can provide justification?
I'd be more concerned about the side loads on the tractor's PTO stub shaft bearings then the PTO adapter failing.

 

[RickB]

The adapter I bought is pretty robust. Nor was there any documentation or warning to use it with a range of PTO HP (to be honest, not documentation at all).
The bolded text...your opinion, or a factual statement for which you can provide justification?
I'd be more concerned about the side loads on the tractor's PTO stub shaft bearings then the PTO adapter failing.

Are you going to start in again? I thought we were in agreement on this topic.
I have never seen a 540RPM PTO shaft extension successfully used on a 60-70 HP tractor; how's that?
I'd like to know why of the 116,000 plus TBN members you figure I'm the only one not entitled to post an informed opinion without a supporting list of footnotes.

It seems perfectly acceptable to you, however, to recommend the use of a shaft extension that will bring the OP's hitch and PTO shaft geometry further from the recognized and accepted ASAE standard (14 inches) for 540 RPM PTO shafts than it is to begin with.

 

[LittleBlueTractor]

One thing I have read, but no supporting links...use of a PTO extension can cause premature wear on the tractor's PTO mechanism. IIRC, it was due to the lengthening of the stub shaft (of the tractor) putting more loads on the bearings.

Sure wish you knew a little more about this Roy. I have an over-running clutch on my tractor's PTO shaft (EXACTLY like the one in grsthegreat's post) and I use my cutter pretty often. Makes sense the the added weight would have some effect on the bearings. Don't know how much it weighs, but it's not something you could forget about in your hand -- maybe 6-8 lbs. I only have 24 hp at the PTO, so I'm not too worried about breaking it. I got one because they seem to be cheap insurance.... Now I'm concerned about wearing out the PTO prematurely. Couldn't find anything on the intertubes about the subject though.

 

[grsthegreat]

Sure wish you knew a little more about this Roy. I have an over-running clutch on my tractor's PTO shaft (EXACTLY like the one in grsthegreat's post) and I use my cutter pretty often. Makes sense the the added weight would have some effect on the bearings. Don't know how much it weighs, but it's not something you could forget about in your hand -- maybe 6-8 lbs. I only have 24 hp at the PTO, so I'm not too worried about breaking it. I got one because they seem to be cheap insurance.... Now I'm concerned about wearing out the PTO prematurely. Couldn't find anything on the intertubes about the subject though.

well the Kubota dealer here sells them and said they doubted it would affect anything. He has installed these and shaft extensions for a long time and as far as he knew he did not have any issues with them....as far as he knows.

When im using my chipper the pto shaft is completely horizontal ....no bend at all, so i dont see how it can affect anything. Now if i was to continually raise and lower under power...than maybe i can see some future issues.

The only other implement i use the OR clutch on is the brushhog, which only gets 4-5 hrs a year worth of use. So I personally am not going to lose any sleep over. Now if i did alot more mowing...whatever... then i would seek out some more info on the matter.

 

[RoyJackson]

It seems perfectly acceptable to you, however, to recommend the use of a shaft extension that will bring the OP's hitch and PTO shaft geometry further from the recognized and accepted ASAE standard (16 inches) for 540 RPM PTO shafts than it is to begin with.

Yes...as long as the user realizes there is a pitfall to extending the PTO stub shaft. It's called making an informed decision.
BTW, after being on the "Friendly Politics" forum, with so much hearsay and BS being bandied about, I'm getting in the habit of asking for supporting data. Sorry about that...but, even on nonpolitical forums (such as this one), supporting data does provide for a more authorative post, doesn't it?

Sure wish you knew a little more about this Roy. I have an over-running clutch on my tractor's PTO shaft (EXACTLY like the one in grsthegreat's post) and I use my cutter pretty often. Makes sense the the added weight would have some effect on the bearings. Don't know how much it weighs, but it's not something you could forget about in your hand -- maybe 6-8 lbs. I only have 24 hp at the PTO, so I'm not too worried about breaking it. I got one because they seem to be cheap insurance.... Now I'm concerned about wearing out the PTO prematurely. Couldn't find anything on the intertubes about the subject though.

As I responded to RickB...just know any risk, and remove it from the tractor when you don't need that extra length. I use mine for my chipper...don't need the extra length for anything else (at this point in time). But it is something to consider if you add the Pat's Easy Change or a Quick Hitch (which is why I bought it in the first place...I had the Pat's Easy Change on my old 790).

Now, I cannot recall where I read this (about the extra wear) and I did Google using the query "can a pto adapter damage a a tractor?"...so, I have no supporting data I can lay my hands on at this time (shame on me!).
Did find an interesting .pdf file and link though: http://www.newtoncrouch.com/files/faq/pto_adjustment.pdf

 

[greg_g]

I have never seen a 540RPM PTO shaft extension successfully used on a 60-70 HP tractor; how's that?

Based upon my own experience, I'd say that's likely an accurate statement. I had the PEC system on both my 35hp and 45 hp tractors. To make up for the additional 4" extension of the lower lift arms, I installed the PTO adapter on both tractors. I wore them out faster on the 45hp than I did on the 35hp. Vibration wears the inside surface of the retainer pin until there's not enough material left to hold it in the PTO stub locking groove. So I'm pretty sure that adapter lifespan is inversely proportional to PTO horsepower. Can't speak to ORCs though, never owned one.

//greg//