Chains instead of a top link for bush hog?

[Soundguy]

If you look at the PTO-shaft-to-gearbox angle & the PTO-to-PTO-shaft angle, neither seem all that extreme to me ... ?

15-30' max before you are significantly reducing the joint and driveline lifespan. at max angles vibration will also damage the telescoping portion of the driveline.

I've no doubt that joint would be happier with less angle, or if it had been born a CV joint instead.... since it's probably an off the shelf driveline oem'd with that mower and not a special replacement like a wide angle joint especially.

soundguy

 

[beppington]

In that pic the PTO-shaft-to-gearbox angle is 18.5 degrees & the PTO-to-PTO-shaft angle is 17.7 degrees.

 

[Soundguy]

yep.. 15' is the usual number I see quoted for a joint. they do make some wide angle joints.. but those are special application.

as for lasting a few seasons.. yikes! If I had a mower that was eating uj's every few seasons I'd just put a cv shaft in it.. or figure out something different on the mowing.. like a v-wing, or offset mower.. Not that a UJ is that expensive.. but who wants to mandatorilly have to break the driveline down every few seasons to fix something.. perhaps when you really need it or are pressed for time.

I don't mind routinely replacing 'routine' wear items.

It's replacing the items that would otherwise last decades when used within normal paramaters that I don't like changing every few seasons..

looks like a great place for a cv shaft.. I have them on my JD batwing and mid mount mowers. no knocking and rocking at angles..

soundguy

I agree that constant use at those angles would result in increased wear and a shortened lifespan of the U-Joints, but I doubt these U-Joints see more then a few minutes of operation at that angle during mowing. The U-Joint life might be reduced, but I'd guess they'd still last for several mowing seasons before replacement becomes necessary.
Just my opinion...

BTW, the recommended maximum angle for U-Joints is about 15 degrees and the articles I read that in were discussing pick up trucks with lift kits.

 

[Soundguy]

In that pic the PTO-shaft-to-gearbox angle is 18.5 degrees & the PTO-to-PTO-shaft angle is 17.7 degrees.

thus exceeding the 15' max angle that most drivelines quote.

i know it's not by much.. but the manufacturers chose to draw the line somewhere, and apparrently higher angles than 15' per joint equates to that extreme driveline wear..

thus my comment of that joint not feeling the love....

soundguy

 

[LD1]

15 degrees is also what I have heard.

But that is also for constant and highspeed use.

I wouldnt consider that constant or highspeed.

And I certainly wouldnt consider it EXTREME wear to do what that picture is illustrating.

Care to take a guess what kind of angles PHD run???

 

[BigBoyinMS]

Well, after reading this entire thread... I need to make some updates on my cutter I've used for the last 6 years. It didn't come with the "U" bracket or lower chains so it was solid mounted. It's done a pretty good job of knocking the high spots down in the field!

 

[Soundguy]

But that is also for constant and highspeed use.

see below

I wouldnt consider that constant or highspeed..

The pto driveline is designed around 540 rpm.. and if mowing.. I'd assume it's well.. right around 540 rpm.. it's rated speed. Looking in the manuals, they tell you not to run over 'x speed' on those drivelines. Looking at my mower manuals, some allow 600, some say do not exceede 540.. so.. at least to the makers of those producs.. that's high speed.

And I certainly wouldnt consider it EXTREME wear to do what that picture is illustrating.

The manufacturer does, as a few of the pto shaft sites i hit to find the info online earlier listed that the angles about 15' 'caused extreme wear'.

Now the issue of constant. that's the one thing going for him. it's not constant. and that's why it was stated earlier that he could very likely get away with it for some seasons down the road, with it wearing a bit faster when at the high angles..e tc.

I don't recall saying it would explode and engulf the planet as soon as he exceeded 540 rpm, or 15'.. I said it would wear out faster. no more.. no less.

if it's worth it to the op to wear it out faster.. then it's worth it... not a 'right vs wrong' issue here.. just a decision.

i have tools i use in such a fashion that I know limits their life, and I plan for it.

every time I buy an antique tractor I also buy a 9$ special 4.5" angle grinder from the chinese store. The usual sequence of events with me working on an antique involves lots of grinding or wire wheeling for long periods.. or with abrasive pads. It's way easier to remove paint with an abrasive pad on an angle grinder than by hand or with an orbital sander or pad chucked into a drill. When it comes to removing paint or surface rust on cast iron i like a wire wheel or cup on the angle grinder.

I have a nice makita, but i keep a few other beaters around, all setup different.. one with a wheel, one with a cup, one setup for abrasive pads or flaps.. invariably, the one that is for the cast gets about 30 run hours broken into good 3-6 hour sessions to remove paint and rust from the metals.. that grinder.. usually wears out in 1-2 tractors... thus I use a cheapy.. then toss it into a bucket when it dies. every couple years I build 3 out of 5 or 1 from 3.. etc.. right now i have a couple frankie's doing my dirt work.

same deal with an old electric chain saw that used to be a pole saw.. bar is worn, chain has been sharpened alot.. handle is cracket and wrapped and patched. it's not worth fixing.. however it's great for cutting roots out of trees and shrubs when I've dug around them.. and on that one.. i don't mind it if the bar goes goes into the dirt some.. or more than some when cutting something out.

so.. i'm not against using a machine past it's 'normal' use guidelines.. .. just as long as i realize why/what/wehn i'm doing so.. etc.

soundguy

 

[Soundguy]

Well, after reading this entire thread... I need to make some updates on my cutter I've used for the last 6 years. It didn't come with the "U" bracket or lower chains so it was solid mounted. It's done a pretty good job of knocking the high spots down in the field!

i'd for sure get or make a flex link for it..

soundguy

 

[LD1]

I still dont consider 540 a high speed that would cause EXTREME wear. The MFG's are probabally just playing it safe.

The u-joints on my bushhog are about the same size as the ones found in my truck.

So... If 15 degree angle, 2000RPM, and 300+HP is ok in my truck.....

....I dont think 15 degrees, 540RPM, and 30HP out of my tractor is going to cause EXTREME wear, even if I go a tad over on the angle.

But I guess everyones definition of EXTREME could be different.:confused2:

 

[Soundguy]

I still dont consider 540 a high speed

ever seen someone wrapped up in a pto shaft moving at 540... it's fast..

t

hat would cause EXTREME wear. The MFG's are probabally just playing it safe.

they wrote the manual.. they are responsible for reasonably safety usage and warranty.. so if they want to be a lil safe.. it's thier product. I'm not here to 2nd guess the team of engineers and fabricators that designed the driveline, and due tot he inherrant dangers with a driveline.. I'm guessing they actually did some testing on it, not just slapped it and 'that's good' and went on...

you are free to do what you want with your equipment.. however I think you are doing a dis-service to your fellow man by waving your hand and saying the industry standard specs on driveline anges and wear are hogwash.

unless you are perhaps implying you are going to warranty the labor and materials for the asker ?

soundguy