Three Point fatique

   #1  

TWINKLE_TOES

Veteran Member
Joined
Sep 3, 2000
Messages
1,373
My dealer sent a mechanic out last night to give my B21 a once over before the warranty expires next month.

While he was here, I asked what kind of problems he has to deal with from abuse and misuse of tractors. The one that he mentioned, which I thought was most interesting, was three point hitch failure from heavy loads, like tillers and box blades when your not using them but traveling with them raised on bouncy terrain. As I understand what he said, inside on a yoke, a rod connects to the hydraulic piston and through the yoke is a roll pin holding the rod.
The pin can fatigue under impact loads, (bouncing attachments), break, the yoke/rod falls into the gears and major bucks drop out of your wallet./w3tcompact/icons/frown.gif

His solution was to adjust the lowering speed to fully closed and go slow on rough terrain to minimize the impact loading. I've explained this as best I can and I know a lot of use use box blades, among other things for ballast. Maybe kubmech or others can confirm this failure mode or better explain it.

BTW B21 is fine and dandy/w3tcompact/icons/smile.gif

Al
 
   #2  

StanInCalif

Silver Member
Joined
Jul 16, 2001
Messages
198
Location
Northern Sacramento Valley, Calif.
Tractor
JD 300B, JD 4310
Al -
The people that operate equipment in this manner are generally the ones that are tearing it up. Mechanics have little respect for this type of operator. But I doubt that many of us fall into that category, as we are gentlemen.
I can see how lowering the drop speed would cushion the fall, and maybe you've brought up an exiting new topic "adjusting your 3ph". My JD manual covers it and it is not difficult - I just need to get some of those "round to-its".
- Stan
 
   #3  

kubmech

Platinum Member
Joined
Jun 2, 2001
Messages
711
The best ballast is in the rear wheels or attached to the rear rims, Even in this case if your hummin' across a wide open field you're still going to stress the axles some, so try not to humm alot.

If you're using a rear implement for ballast and your hummin' across a wide open feild you are stressing the (O.k. kubota calls it a "hyd. cylinder" and JD calls it a "rockshaft", I like JD's nomenclature better 'cause there's only one rockshaft on the tractor, so I'm gonna use it) rockshaft rod and pin as well as the under side of the piston where the rod sits (it actually just lays in a recess in the bottom of the piston) It's kinda hard to explain exactly how its all linked together (John Miller, got any cool rockshaft breakdowns?). Anyway if you're doing alot of bouncing with the rear implement raised,try not to do that alot either.

I,m not really sure what closing off the drop rate valve is going to do for you since the piston is still jammed up against hyd fluid and the implement is still bouncing, pushing the rod against the piston and pin, and if your bouncing enough, repeatedly slamming against the rod and piston. / Try this:
With the rear implement removed (unless your pretty strong)
lower the hitch about half way down (now shut off the tractor, I don't want anything goofy happening while your doing this) Now lift up on the lower links a little and let go, hear that noise? Know why it stopped, That's the rod hitting the bottom of the piston. Now can you picture that big old brush hog coming up and then slamming down (at this point I'm seeing alot of these /w3tcompact/icons/shocked.gif /w3tcompact/icons/shocked.gif while you're reading this) Now while you're their, start the tractor back up and lift the hitch all the way up, shut 'er down, go 'round back and lift the lower arms up again. Should be a little play at the top, not rock solid, if you don't have any play, and you're 'hummin it will now attempt to either rip the back of the rockshaft cover off or blow out the front of the cover(the cyl. itself). Which has been done on a number of occasions.
(more of these/w3tcompact/icons/shocked.gif/w3tcompact/icons/shocked.gif) So if you don't have the play, you need to adjust the feed back linkage. (We'll leave that procedure for another post, not that hard, just depends on the tractor).

Now for you guys with post hole diggers, if the auger gets stuck, please don't try to rip it out of the ground by jamming forward and reverse (think about what that's doing to your rockshaft assy.)

If you are ever unfortunate enough to break the internals of your rockshaft and you notice soon enough, stop driving it, don't let the guy who picks it up drive it, hang a BIG sign on it so nobody at the dealership drives it, because there's some parts floating around in some very expensive areas of your differential, you're already having a bad day, but it could be a whole lot worse.
 
   #4  

gtg

New member
Joined
Aug 3, 2001
Messages
9
hi, I'm new at this but wanted to agree with stanincalif and his gettoits'!!!
 
   #5  

Anonymous Poster

New member
Joined
Sep 27, 2005
Messages
0
Partial Rockshaft assembly breakdown from JD4500/4600/4700

http://wpc-customers.deere.com/images/MP23/MP23483.gif

18-35196-JDMFWDSigJFM.JPG


<P ID="edit"><FONT SIZE=-1>Edited by Muhammad on 08/06/01 10:47 AM (server time).</FONT></P>
 
   #6  

kubmech

Platinum Member
Joined
Jun 2, 2001
Messages
711
You are the man.........

O.K., imagine #16 repeatedly pounding into #15, notice the hole in the bottom of #16. That's where the roll pin attaches the rod #16 to the rockshaft linkage.
 
  
  • Thread Starter
#7  
OP
T

TWINKLE_TOES

Veteran Member
Joined
Sep 3, 2000
Messages
1,373
/w3tcompact/icons/smile.gif/w3tcompact/icons/smile.gif

kubmech, what can I say "you da man" belongs to Lance Armstrong "you are the man belongs" to John Miller. I guess THANKS will have to do. This is a trap that would have caught me, I'm pretty slow. The picture ( THANKS Incredible John) and the words make this problem easy to understand. The Kubota inerds in my manual look a lot like the Deere.

Al
 
   #8  

woodstock

Gold Member
Joined
Jun 21, 2001
Messages
342
Location
Winnipeg, Canada
Tractor
BX2200
Old Idea Resurrected

kubmech, My old B7000 has a neat fixture that is missing on the new BX.
It is a chain that you can attach to the 3 point attachment, in this case a tiller, where by once attached you can relax the hitch and the tiller is suspended by the chain.
I always use this when transporting the tractor or moving around the property when not tilling.
Am I wrong in assuming that this chain would eliminate the problems you are describing,
If so I think its time to resurrect a good idea?
Obe One Kubote what saw you?

Bx2200-(Altered,-Crop).jpg

Winnipeg, Manitoba
freebie-maple-leaf.gif

2001 BX2200 (23 hrs) All Kubota FEL,Tiller, box blade, blower w/elec shute, 60 mid mt deck, Ag tires.
Grey market B7000 w/Tiller (120 hrs)
 
   #9  

r0GuE

Veteran Member
Joined
May 9, 2001
Messages
1,333
Location
West PA
Tractor
ex-Bota Owner
Re: Old Idea Resurrected

Wouls hooking the 3ph links to the stowed (fixed holes) and then just ading weights totally eliminate the problem. I realize this does no good if you have a heavy implement but for me (trying to decide on tiller or just weights) this is a possible way to "stay out of trouble".
BTW excellent info to have, thanks for the post. I WAS going to hang the heaviest tiller I could find and leave it on.

Rogue
 
   #10  

kubmech

Platinum Member
Joined
Jun 2, 2001
Messages
711
Re: Old Idea Resurrected

It would definitely help your situation. But to be totally safe (from the internal damage at least) You would have to lift the implemant manually a little higher, then hook the chain. At this point you'd just want to watch the stress yor putting on the top link bracket and what its bolted to.
 
 
Top