Stripped hydraulic fitting threads - options?

[cgraham]

I'm using a Kioti KB1914 to dredge under a low bridge and I struck the pressure fitting for the bucket curl hydraulic line, which is on top of the dipstick, on a bridge beam, damaging the thread and the hose fitting; I had a new hydraulic line fitting made, but now have a worse leak due to the threads on the fitting welded to the hydraulic cylinder being very badly damaged. (I can operate the bucket, with some leakage as long as I keep the hyd. oil topped up).

What are the options for replacing/repairing the damaged fitting likely to be available in a small town shop? Saw off fitting and weld on a new one: saw and tap for a different fitting?

An old-timer suggested installing a coupling as there are 3 unused threads at the base of the fitting, and modifying the hose to mate with it. Would this approach seal properly?

Anyone happen to know what the thread type is on the KB1914?

I'm new to hydraulics repairs, and would like to be informed before driving 26 mi to the shop that has agreed to "look at it".

Accessibility to the fitting is not good, because I had a friend weld a vertical guard (steel plate) to the frame to which the cylinder is attached after the initial damage (too late!) Just room to get a wrench in there. Maybe I should get him to remove it with his plasma cutter before going downtown?

(Searched for similar question without success).

Suggestions and comments gratefully accepted.

Charlie

 

[tommu56]

I would cut guard off and if he is a good welder take cylinder apart and cut fitting off and weld a 1/2 coupling in place weld some tabs on cylinder and bolt guard on to tabs then reassemble cylinder.

Ironically I bent mine up the same way (digging under house and hit beam) its bent and isn't leaking so i wont kick a sleeping dog.
tommu56

 

[kennyd]

Without seeing it, it sounds like the striped bung needs to be cut off and a new one welded on. Remembers that the operating pressure is about 2500 pounds, and the shock loads can easily be 2X that, so the repair must be solid.

 

[john_bud]

Get a quote before you authorize any work. Cost to repair may be 2-3x the cost of a replacement generic cylinder!

If it's just a bung cut and reweld - a decent machine shop can do it for about 35-50 bucks. You will have to take the cylinder apart to get that price. Having them take it apart - clean it - do the repair - clean it again and put it together will run the labor up to 2 hours or more. Probably more.

Surplus Center - Hydraulic Equipment Electric Motors probably has your cylinder cheaper than the repair cost.

These people will have the threaded port. If you repair it - buy a port and take it and the dis-assembled cylinder to a welder.

Fittings

 

[cgraham]

Many thanks for the helpful comments and suggestions.

I'm taking photographs to the shop today to get a better idea whether they can handle it.

I have tried to attach a photo to show the problem here. The fitting in question is an elbow, and is next to the guard I described.

(To the left is a second guard that runs down the top of the cylinder to protect the metal line that runs there.) They would have worked nicely If I had installed them before the damage was done :-(


Charlie

 

[cgraham]

I forgot to ask - is rethreading and a new coupling a viable option? The thread diameter looks to be about 5/16"

Or will this weaken the fitting too much, given kennyd's comment about operating pressure?

Charlie

 

[cgraham]

I got an e-mail that stated JerryG asked "Is the elbow actually welded to the cylinder or is it screwed in and painted?"

The post has not appeared on the forum, so here is the answer, Jerry:

The elbow is welded to the cylinder and painted; some of these JIC fittings can have a thread or tap in fitting on the base (I think), so it could be anchored AND welded.

The shop says they will cut through the weld and see if the fitting will pull or screw out. If not, it's a new sleeve.

Charlie

 

[john_bud]

Can you take off the hose and give a close up of the elbow - couple views.

Thanks
jb

 

[pycoed]

Many thanks for the helpful comments and suggestions.

I'm taking photographs to the shop today to get a better idea whether they can handle it.

I have tried to attach a photo to show the problem here. The fitting in question is an elbow, and is next to the guard I described.

(To the left is a second guard that runs down the top of the cylinder to protect the metal line that runs there.) They would have worked nicely If I had installed them before the damage was done :-(


Charlie

Looks to be plenty of room without removing the guard, & also enough room for a straight female to male coupling. I'd try fitting that with Loctite (take advice from a hydraulic shop as to the grade) & give it plenty of time to set. Then carefully refit the hose without twisting the coupling. Suck it & see! All you have to lose is the price of the coupling. If it fails then take it to the experts, though personally I'd try welding a coupling to the elbow before I admitted defeat. But again, I am mean!! (Does that translate as "tightwad" over the pond?)
Cheers
JohnL

 

[cgraham]

John_Bud: I don't want to take off the hose until I commit to a repair - I can still get a little use out of the hoe; but I can tell you it is a JIC compression fitting almost totally stripped. I'll attach a close up. 3 good threads remain which might catch Pycoed's coupling.


Pycoed: are you suggesting a repair with the existing fitting -I am not clear? How about JB Weld? (We don't have any experts n my area; it's DIY or the dealer's expensive way.)

On this side of the pond ....... "frugal", perhaps
Mean = nasty/cruel

Thanks for the responses; Charlie