448 BH woops (whine whimper)
- Thread starter Cidertom
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ORCM
Silver Member
Unless you guys hit the cylinder rod with something, there is no reason why it should have done that. The BH should be Engineer so it can't tear it self apart with its own power. If these rods were not hit, and it was just pressure from the bucket or cylinder that bent them, I would say that their defective, or too small.
I would go to JD for a warranty claim...
I would go to JD for a warranty claim...
dfkrug
Super Member
- Joined
- Feb 3, 2004
- Messages
- 7,602
- Location
- Santa Cruz Mtns, CA
- Tractor
- 05 Kioti CK30HST w/ Prairie Dog backhoe, XN08 mini-X
I agree with ORCM. No way this should happen in "normal" use.
When digging stumps where the dipper is below ground out of
view, it is easy to get some root or other debris pinched betw
the curl cylinder and the dipper. It takes just the slightest
sideways force when the cylinder is at full extension and under
full pressure to buckle the rod.
It is sometimes hard to track down the cause. The other 2
possible causes I am aware of include extremely high pressure
(4700 psi cuz the relief was set wrong and the owner used a
PTO pump), and a slightly mis-aligned pin. The latter condition
caused slight sideways forces (bad!).
When digging stumps where the dipper is below ground out of
view, it is easy to get some root or other debris pinched betw
the curl cylinder and the dipper. It takes just the slightest
sideways force when the cylinder is at full extension and under
full pressure to buckle the rod.
It is sometimes hard to track down the cause. The other 2
possible causes I am aware of include extremely high pressure
(4700 psi cuz the relief was set wrong and the owner used a
PTO pump), and a slightly mis-aligned pin. The latter condition
caused slight sideways forces (bad!).
Keoke
Gold Member
Hi folks, both the backhoe and tractor relief valves would need to be stuck closed for extreme pressure alone to have done that damage. In most systems using tractor hydraulics, the spread between the tractor relief and hoe relief valves is seldon more then 200psi.
It looks like ram was trying to curl buckect (pushing forward) when it bent. In a well desinged system, regardless of why bucket did not move, relief valve should have blown off head before the pressure got high enough to bend that piston rod.
Bottom line, a stronger rod then shown, or a lower blow off setting at hoe relief valve may have kept this from happening.
cheers,
keoke
It looks like ram was trying to curl buckect (pushing forward) when it bent. In a well desinged system, regardless of why bucket did not move, relief valve should have blown off head before the pressure got high enough to bend that piston rod.
Bottom line, a stronger rod then shown, or a lower blow off setting at hoe relief valve may have kept this from happening.
cheers,
keoke
dfkrug
Super Member
- Joined
- Feb 3, 2004
- Messages
- 7,602
- Location
- Santa Cruz Mtns, CA
- Tractor
- 05 Kioti CK30HST w/ Prairie Dog backhoe, XN08 mini-X
CIDERTOM, with a great CUT like your JD4520, I assume you are NOT
using a PTO pump, correct?
using a PTO pump, correct?
Phil2005
New member
ducati996,
The first time it happened was when I was digging out a stump and trying to maneuver it out of the hole. It started to fall back in and I tried to re-grab it with the BH. I think it was the momentum of the stump and the force of the hydraulics that worked together to bend the rod. I cannot rule out that the stump was touching the rod and helping start the whole process. The rod did not bend as far as Cidertom's and I was able to straighten it out. The seals were not leaking and the BH worked although the rod had a slight bend.
The second time it happened I was also digging out a stump. I think the rod not being as straight as it should contributed this time. Again, I was able to straighten it out and tried to get it as straight as possible. It came out pretty straight this time. This all happened last year and I continue to use the BH to dig stumps, although I try to be more careful.
I talked with the dealer (after the fact) and he said it would not be covered under warranty. Based on the size of the stumps and what I am asking the BH to do I am not sure I could argue the point.
In hindsight I should have taken pictures but in the heat of the battle all I wanted to do was fix it and defeat the stump. The 46 BH is a little worse for wear but still undefeated.
Phil
The first time it happened was when I was digging out a stump and trying to maneuver it out of the hole. It started to fall back in and I tried to re-grab it with the BH. I think it was the momentum of the stump and the force of the hydraulics that worked together to bend the rod. I cannot rule out that the stump was touching the rod and helping start the whole process. The rod did not bend as far as Cidertom's and I was able to straighten it out. The seals were not leaking and the BH worked although the rod had a slight bend.
The second time it happened I was also digging out a stump. I think the rod not being as straight as it should contributed this time. Again, I was able to straighten it out and tried to get it as straight as possible. It came out pretty straight this time. This all happened last year and I continue to use the BH to dig stumps, although I try to be more careful.
I talked with the dealer (after the fact) and he said it would not be covered under warranty. Based on the size of the stumps and what I am asking the BH to do I am not sure I could argue the point.
In hindsight I should have taken pictures but in the heat of the battle all I wanted to do was fix it and defeat the stump. The 46 BH is a little worse for wear but still undefeated.
Phil
dfkrug
Super Member
- Joined
- Feb 3, 2004
- Messages
- 7,602
- Location
- Santa Cruz Mtns, CA
- Tractor
- 05 Kioti CK30HST w/ Prairie Dog backhoe, XN08 mini-X
Phil2005 said:
That is plausible.
I have an hyd cyl (for my concrete mixer) that I have bent and
straightened twice. The rod, that is. I am able to get it very
close to straight with my press and it has worked fine afterwards.
It was certainly not bent like a pretzel, though.
Chris2520
Platinum Member
Phil2005 said:
I like the way you think Phil....
Chris.....
ruglad03835
Silver Member
Guys,
This is not as uncommon as you think. I know of at least 3 people who have bent cylinders on the John Deere industrial line of backhoes as well as other manufactures equipment as well. A lot of it has to do with physics and leverage. If you get the bucket to a certain place (ie angle) and are trying to use multiple cylinders to accomplish a task such as pulling a stump you can create a situation where the mast cylinders as well as the dipper cylinders can bend a bucket cylinder. Granted it is rare but so is winning the lottery!!!
This is not as uncommon as you think. I know of at least 3 people who have bent cylinders on the John Deere industrial line of backhoes as well as other manufactures equipment as well. A lot of it has to do with physics and leverage. If you get the bucket to a certain place (ie angle) and are trying to use multiple cylinders to accomplish a task such as pulling a stump you can create a situation where the mast cylinders as well as the dipper cylinders can bend a bucket cylinder. Granted it is rare but so is winning the lottery!!!
OP
Cidertom
Gold Member
- Joined
- Dec 14, 2005
- Messages
- 478
- Location
- Benton Co Oregon
- Tractor
- JD 4520, 2305 Aktive snow-trac ST4
Stock tractor power beyond. I don't think I got anything between the boom and the cylinder, that should have caused the bend the otherway.
I may have a problem with the relief valve, but I thought it was the otherway. I had an instance a while back where the BH was very slow for a minute with no power. The FEL still had full power. I figured the BH relief valve had stuck open. Since it never happened again, I didn't think much of it.
It may have been the combination of boom action at the same time I was curling. Or I might have nudged the cylinder at some point in the tree project, but I certainly don't remember it. That could have set me up for this failure.
What I'm going to do (next steps)
I am building a pressure tester. I got a set of male-female quick disconnects and a high pressure T fitting. I am going to get a 0-5000 PSI gauge and a short hose and make a remote reading test. That way I can put it inline occasionally, or when something isn't working quite right. The QD fittings will allow me to use it to test not only the PBY but the other remotes as required. I also am installing a test port I can plug it into on the boom. If I can find a very small gauge I might install it permanently If I can make it where it won't get damaged. It isn't so much the damage to the BH I am worried about, but the possibility that I could be doing something and losing the BH could become dangerous... Such as having 3 sides of a tall trees roots dug out next to your house, unable to pull it over, with a storm approaching. BT-DT.
I agree with the comments: It should not have been able to do that. I have worked around a lot of equipment, I am familiar with the geometry of the bucket, and there is no way the forces should have been in other than direct alignment.
So, we have heard of others with bucket issues. Has there been any reports of dipperstick or boom cylinder damage?
I may have a problem with the relief valve, but I thought it was the otherway. I had an instance a while back where the BH was very slow for a minute with no power. The FEL still had full power. I figured the BH relief valve had stuck open. Since it never happened again, I didn't think much of it.
It may have been the combination of boom action at the same time I was curling. Or I might have nudged the cylinder at some point in the tree project, but I certainly don't remember it. That could have set me up for this failure.
What I'm going to do (next steps)
I am building a pressure tester. I got a set of male-female quick disconnects and a high pressure T fitting. I am going to get a 0-5000 PSI gauge and a short hose and make a remote reading test. That way I can put it inline occasionally, or when something isn't working quite right. The QD fittings will allow me to use it to test not only the PBY but the other remotes as required. I also am installing a test port I can plug it into on the boom. If I can find a very small gauge I might install it permanently If I can make it where it won't get damaged. It isn't so much the damage to the BH I am worried about, but the possibility that I could be doing something and losing the BH could become dangerous... Such as having 3 sides of a tall trees roots dug out next to your house, unable to pull it over, with a storm approaching. BT-DT.
I agree with the comments: It should not have been able to do that. I have worked around a lot of equipment, I am familiar with the geometry of the bucket, and there is no way the forces should have been in other than direct alignment.
So, we have heard of others with bucket issues. Has there been any reports of dipperstick or boom cylinder damage?