Hydraulic Cylinder Repair

[granitepeak]

Hello all, new to this forum.

I have a Davis 185 Backhoe with a leak on the dipper cylinder. The leak is in the hard tube that runs from the fitting housing up to the other end. The leak is on the underside so access is difficult.
Have a call into a bone yard to see if they have a replacement cylinder. However because of time first, money second, I would like to repair it.

Can the tube itself be replaced? Cut out a section and replace it using compression fittings with either tube that meets specs or hose?

All ideas appreciated.
Thanks,
Don

 

[RNeumann]

Uh no- you aren’t going to have success with a compression fitting on a cylinder......

Remember a cylinder has the full hydraulic pressure multiplied by the surface area. So just the force opposite the piston is over 7000 pounds. Then you have the force pushing out on the walls. If the cylinder has a crack it’s new cylinder time. If you have more time than cash I’m sure you can round up a used one, maybe even one with bad seals. An old one that needs some internal seals replaced should be cheap.

 

[granitepeak]

It is not the cylinder itself. It is the hard external line that supplies fluid to the upper end of the cylinder. See attached picture.

 

[Shaneard]

Take the line off, clean it super good and braze it.

 

[granitepeak]

How is the line removed from the cylinder body?

 

[Shaneard]

How is the line removed from the cylinder body?

I don't know on that one, is it welded to the fitting in the front? If it isn't, the cap on the end may be holding it with just o-rings on each end.

 

[RNeumann]

Ok I’m with you know. I’d cut the line below the split and silver solder or braze a fitting on. As an example- buy a JIC plug (male threads), drill the plug end center to the pipe OD (tight fit) and solder/braze it. You now have something to attach a new hose to.

I’ve done this on some custom steering components for a vehicle. It was about 15 years ago and is still in service now. Mine is silver soldered but either will work.

 

[granitepeak]

I don't know on that one, is it welded to the fitting in the front? If it isn't, the cap on the end may be holding it with just o-rings on each end.

I do not see any signs of the end that mounts to the side of the body being welded. I don;t see how it could, but maybe there is a nut on the inside of the cylinder body that once removed allows the tube to be pulled?

 

[granitepeak]

Ok I’m with you know. I’d cut the line below the split and silver solder or braze a fitting on. As an example- buy a JIC plug (male threads), drill the plug end center to the pipe OD (tight fit) and solder/braze it. You now have something to attach a new hose to.

I’ve done this on some custom steering components for a vehicle. It was about 15 years ago and is still in service now. Mine is silver soldered but either will work.

It is one option I am thinking of.
Thanks

 

[nyone]

Why bother making your self a bigger leak by cutting it off? Personaly i would just find the leak and weld it shut.

I had the same cylinder leak at the hard line on my mini ex. A new $700 cylinder wasnt going to happen. It originaly started leaking because its kind of out in the open and the pipe was welded on the cylinder to keep it in place. Many bumps and dropped trees it got hit enough that the pipe started to leak. I spent about 1hr with the tig welder chaising the leak at the back of the pipe but its fixed and now has a bash plate. So once you fix it make sure it dosnt happen again.