B670 backhoe boom cylinder

[JRHill]

I was filling in a trench with the loader when I backed into a tree. Oops - the darnest things happen in low range. The yoke on the boom cylinder broke loose from the ram. It looked like it had been welded before and whoever attempted the repair, they didn't get much penetration. Anyway, I have it cleaned up and ready to reweld and it looks like there is a steel piece that may be threaded into the end of the cylinder ram and that is then welded to the yoke. I've tried to unscrew it and before I get more aggressive with some heat, etc, I thought I'd ask y'all. It would be much easier and safer to set up on the bench rather than on the tractor (B7100 manual shift).

TIA,
JRH

 

[North Idaho Wolfman]

There isn't anything welded to the rod other than the end.

Extend the rod all the way out, wrap the rod, near the cylinder with a wet rag then weld the end back on.

 

[Lil Foot]

I agree with NIW, but post a couple pics if you think you have something odd.

 

[JRHill]

There isn't anything welded to the rod other than the end.

On the B219 loader you are correct. The yokes are welded directly to the ram.

But for Lil Foot, the B670 backhoe is different. There is a definite rim and "hub" extending from the ram. The hub/extension is definitely undersized by a bit and not hard chromed like the ram. Boom and dipper:

What do you think?
-----------------
The pictures were stripped out.

Can't paste, can't post a URL. So I guess we can just kill this thread.

 

[Lil Foot]

Shame about the pics. Sounds like someone has changed the cylinders- I have two B670s and have advised/consulted on the rebuild of at least a half dozen more. None of them has cylinders like you describe; all I have seen have cylinders exactly like the pics below. (virtually identical to the B219 cylinders, as they were built at the same time by the same company)

 

[Lil Foot]

You can peruse this thread, I think there are more pics that show the cylinders:
http://www.orangetractortalks.com/forums/showthread.php?t=5482&highlight=b670+backhoe+rebuild

 

[North Idaho Wolfman]

On the B219 loader you are correct. The yokes are welded directly to the ram.

But for Lil Foot, the B670 backhoe is different. There is a definite rim and "hub" extending from the ram. The hub/extension is definitely undersized by a bit and not hard chromed like the ram. Boom and dipper:

What do you think?
-----------------
The pictures were stripped out.

Can't paste, can't post a URL. So I guess we can just kill this thread.

You need 5 posts to upload pictures:

And Factory prints don't show any other variations in the rams, make a couple more posts then upload pictures.

 

[JRHill]

You need 5 posts to upload pictures:

And Factory prints don't show any other variations in the rams, make a couple more posts then upload pictures.

Thanks for that hint. Here is post 5 - hopefully replies count. I'll know in a moment.... (wink)

 

[JRHill]

And here is post 6. Just to be safe I always try to exceed minimum requirements. It almost always works except when the wife is involved.

So here is the picture. Yeah, I slipped with the hand grinder and hit the hard chrome but it's still above the seal when retracted:

 

[JRHill]

Darned if I didn't do it again - working in a cramped space and backed into a tree in low range. You'd think I had time to watch but I had to watch the bucket and trench. But popped the yoke off again again.... Its time for a new cylinder. I looked up the part: 70050-00003

But my GOSH! $850 to $900 for a single 2" cylinder?!?

I've got a 410J but the 'lil Kubota has gone where no backhoe has gone before. The 'ol guy is getting tired over all. Whether the loader,cylinders xmission/rear and the backhoe I can't justify that for a single cylinder on the backhoe.

Any ideas?

Best, JRH

 

[Lil Foot]

I don't have mine here (it's 150mi from here) so I can't measure, but someone has got to make a cylinder that fits or can be adapted.
I'd start with Surplus Center.
http://www.surpluscenter.com
Have not used these guys, but they came highly recommended:
https://www.bbhydraulics.com/cylinder-repair.html

 

[JRHill]

I don't have mine here (it's 150mi from here) so I can't measure, but someone has got to make a cylinder that fits or can be adapted.
I'd start with Surplus Center.
http://www.surpluscenter.com
Have not used these guys, but they came highly recommended:
https://www.bbhydraulics.com/cylinder-repair.html

This is a curious issue. I'm sure I can find a cylinder with that diameter and stroke. But a cylinder with with that OEM yoke is a specialty as would be a threaded ram to accept the fashioned OEM yoke. Note that no break down shows the unit's threaded yoke as a separate item. I don't have anything to salvage from OEM cylinder.

I noted this years ago. Ya just can't reliably weld the mild steel yoke to the hard chromed strong and high carbon steel ram and have it reliable. That's why the yoke was threaded into the ram instead of welded.

I hate throw away stuff but I'm about there. I'd be better off pulling the backhoe and going back to 3pt attachments for the rest of this unit's life - which could be longer than mine as it has gone so far.

It's just such a waste of a fantastic machine. It was 35 years old when I got it. Yeah, I'm a bit older but to have a machine that still awakes a works... I have respect. Also for me '74 land cruiser.

BTW, I am a union machinist. Except for locomotives I haven't seen quality of materials and engineering like I've seen from the Kubota and the Land Cruiser (yeah, the LC used sourced and copied parts.)

 

[shootem604]

Local hydraulic shop probably can help you out.

 

[JRHill]

Local hydraulic shop probably can help you out.

(rolling eyes.) Ain't not way where we live. There is a CAT dealer an hour away but they won't screw with a Kubota. They're parts swappers and only want big stuff unless you're buying a hose or O-ring. I continued pondering a place to put depreciated implement ready for recycling. What a waste....

But you must be a prophet, shootem604. I saw a business feature in the local newspaper, right after reading your response about a specialty hydraulics shop in that same town. Heck, I didn't know they existed in all this time. Called 'em. "No, we probably don't need to make a new cylinder assembly. Let's put in a new ram, thread it's end, and buy a new yoke - probably all available. If not we'll make it."

The "moral" of the story is that this stuff can be restored. I had never even pondered a rebuild from generic parts with some modification. They are out there, even where I live.

So Mr. Shootem604, TY.

 

[JRHill]

Believe it or not there *is* a specialty hydraulic shop in the area. In fact they opened a 2nd shop about equidistant to me in a small town and the newspaper did a BIG news feature about the big grand opening. All they really do is make hoses - from the service truck. Anything else goes to the main shop. Anyway that's how I found out about them. They don't advertise and aren't searchable unless you get really specific. Anyway, I went in and dropped off the cylinder and lines which need to be replaced anyway. He said he hoped I wasn't in too much of a hurry 'cause he had to lay off his guys in the main shop during mandated closure time and none of them came back when allowed to reopen. Ah, the life of a sole proprietor trying to get by. But a decent shop with a good metal lathe and various machine tools and a specialized testing station. It was impressive.

When he arrived back from lunch I was admiring his pile of damaged/bent rams and good but short drops. And a big pile of compound, extending rams. Fortunately I had leaned my boxed cylinder up against his shop door so he had a hint I was a customer and not stealing scrap. Dang, he's a big guy - I humbled myself that I was admiring the scrap for other projects. He was good with that. In addition I shared I was an 'ol machinist a could help. I can cut single point threads in my sleep. He can't pay machinist wages but we parted ways to consider each other's priorities. I'm supposed to be retired but we will see. ( I always have home projects).

Anyway I'm still curious about welded shafts on this old B670 backhoe. They are definitely welded at the yoke but is it that to a welded stub that goes into the threaded ram? It's about impossible to see and mine has been cobbled too many times before I got it.

Ideas? Input?

(Oh gee, got a trophy. Errgh.)

 

[Lil Foot]

Again, someone has changed or altered your cylinders. The stock cylinders are welded only, not threaded. Beside my B670 qualifications mentioned above, I was a Toolmaker & Senior Research Technician, so I can tell welded from threaded, or both.
Find a replacement, or find a qualified welder to re-weld
yours.

 

[JRHill]

Folks, I screwed up. It took so long to get the rebuilt cylinder back that I can't recall the hose connections. There is an over-pressure valve between the operators legs. I can't recall if that was protection for the extension or retraction. I was going to diagram it but I thought it wasn't worth the time - besides the hoses were different lengths. Now that I have everything ready to reassemble and the hoses are equal length. What action is the valve protecting? Backing into something (extension) or pulling with the hoe caught (retraction). Gosh, I'm embarrassed. I'm thinking retraction....

BTW, the shop did an excellent job. New ram with a new yoke and all new seals for less than 50% of a new OEM unit. I specifically asked that they inspect the bore. They said they did some touch-up but wouldn't clarify. The only down side is the yoke wasn't perfectly square with the action. I adjusted by rearranging the shims and the pins went through the pins. It was that close.

Overall it looks to be a success except for my memory.

 

[Lil Foot]

I'd look at how mine is plumbed, but it's 150mi from here, and not sure when I can visit it next.
Hopefully someone will chime in on this. Glad to hear you got the cylinder repaired.

 

[Lil Foot]

Don't know if this helps, but copied these from the B670 manual:

 

[Lil Foot]

When I rebuilt mine, I marked & documented all the hoses and their connections, but I used the diagram above to double check everything. It is a PITA to decipher, but I used lots of copies & different colored pencils to trace everything, and that worked OK.