What happened...

[NOTV8]

I was having a good time digging when this thing happened :mur::mur:. I tried to think what I did before but could not come up of anything aside from maybe I back up on a stump when I positioned my self but it's not possible because I'm already halfway on the stump that I was digging when I smelled the hydraulic fluid and saw it spewing out coming from the cylinder. Any idea how this thing could had happened? How can I prevent it in the future? I just did a lot of work on this backhoe with the new paint, all of the hoses are new and swing bumpers. Is it possible to bend the rod back? Probably the seal are shot... or new cylinder should be added on my lists....

 

[oldnslo]

Did this happen while digging or while repositioning the tractor?

If while digging it would look like you was pushing down with main mast while the crowd boom was partially extended.

Rod is shot. If you did not try and cycle the the cylinder you hopefully save the rod cap bearings.

Roy

 

[jake98]

That's not supposed to happen..

 

[leonz]

That's not supposed to happen..

Neither is the poor design of the dipper boom or the fact that the hydraulic system depends on the main relief valve of the tractor.


In order to prevent it happening again a bronze stop tube must be installed
in the space between the packing gland and the cylinders piston
in a NEW cylinder.

The packing gland cannot be used again because the cylinder barrel has become egg shaped and fully distorted and none of the old parts can safely be used.


the other issue with this back hoe model is something I have described in detail previously as the building of the upper boom and its contruction with the weldments in the picture are the reason this damage always occurs with these back hoes.

I have labored in described how exactly the problem can be resolved with a needle valve on the dipper boom cylinder at the cylinder or on the valve if room is available to install the needle valve.

The back hoe builder installed a longer cylinder to allow a larger travel arc of the dipper boom which is a massive mistake and a common problem with it which could be resolved with a cylinder that has a much shorter stroke if desired.

 

[NOTV8]

Neither is the poor design of the dipper boom or the fact that the hydraulic system depends on the main relief valve of the tractor.


In order to prevent it happening again a bronze stop tube must be installed
in the space between the packing gland and the cylinders piston
in a NEW cylinder.
QUOTE]

Soooo, if I buy a new cylinder I should ask to have the one with "bronze stop tube"? Or that is something I should do my self? The backhoe is made by Woods and it is the BH7500. I just painted it with "Bobcat orange paint like the rest of my implements... most of it anyway.

 

[leonz]

OK if you call a cylinder manufacturer-which I strongly suggest you do-

First:

The stop tube slug is 1/64 of an inch larger in diameter than the rod outside diameter and

1/64 of an inch in diameter smaller than the Inside diameter of the cylinder

barrel.


The stop tube MUST be one inch in length for every 12 inches of extended rod length PLUS an addtional inch for

the partial measurement if less than 12 inches.

You will not lose that much stroke in the scheme of things believe me and the issue will be resolved for you.

Preferably the stop tube slug should be made of bronze to avoid damaging the cylinder and it components being the piston rod, piston, piston packing, the valve body and pump.

You will be slightly more dependent on the main boom but that will be a minor issue in the scheme of things.

 

[shaley]

The woods BH has a relief valve for each circuit which should prevent that from happening. Call Woods customer service and send them a picture.

 

[Egon]

I bent one of the stabilizer cylinder shafts on my #7 JD backhoe. One of the local shops straighted it all out with no problem. They do have some large presses to work with.

End result getting the stabilizer brackets straightened and welded back up along with some new pins and fixing the cylinder cost $140.00 as compared to seven hundred plus for a new cylinder.:thumbsup::thumbsup:

Catching the dipper on the ground while going forward may have caused the bent cylinder??

 

[mooseracing]

Rod is shot.

Fixable if you have access to a good press. I would buy a new one though on that size, wouldn't expect it to be worth the cost to fix it.

 

[pycoed]

Blimey, I've just done exactly the same thing on my 45 year old Twose backhoe on a 45hp UTB tractor (sold as a Long 445 over there)!

I did a much better job than you though, mine was bent through 50 degrees :ashamed:
Mine didn't leak any fluid at all, so existing seals are sound.

I extended the cylinder fully & took it off the backhoe (make sure it's securely propped in position) & dismantled the cylinder. I took the seals off the ram rod & took it to a hydraulic shop. Mine was 30" long & 1 1/4" rod with pin diameter also 1 1/4". They priced the rod (no seals) at GBP 135 (say $200), but I bought a length of rod from them for $50 & will turn a shoulder & thread one end to suit on my lathe. The other end I'll shoulder down & fit to the old pin housing, bored to suit. I'll tack weld together & take it to my mate ( a welder) to weld it "right".

If you don't have access to a lathe/welder, take it to a hydraulic shop & ask just for a new rod & seals to be fitted - it'll be way cheaper than a whole new cylinder.