B670 backhoe boom cylinder

[JRHill]

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

Dang, thank you SO much. Its the reaction action (retraction of the cyclinder) - as if you drove forward with the bucket in a hole so you don't blow a line.

 

[Lil Foot]

Would I be correct in assuming you don't have the B670 manual? If so, I can try to send you a PDF copy.

 

[JRHill]

No Sir, I don't have the manual. I don't want to trouble you for that project but if you are available to ping if I have a question in the future that would suffice. I've had the tractor for 30 years and the backhoe for 27 and there's been very few times I actually needed the documentation.

I joke around at how long this unit and the accessories are going to last. Seems it'll all out last me (wink).

 

[Lil Foot]

OK, no problem.
I know what you mean about longevity, I'm sure mine will outlast me.

 

[JRHill]

What a hoot. Got the rebuilt cylinder in place and the new hoses. Fired it up and began to actuate the cylinders to purge the air. When I did the bucket a hose blew. And it blew in just the right place to spray me directly. Fortunately I wear glasses. This seems to be the project that just keeps 'giving" or, ahem, 'taking'.

Yeah, there were signs of UV deterioration on some hose jackets but I sure didn't expect the shower.

The continuing saga of the simple backhoe repair....

 

[JRHill]

Here's another question on the B670 backhoe (and I suspect others): The swing cylinders are pressurized on the back side only. The front side is open to the air. That means condensation or whatever can build up. The end cap is drilled through to vent the air on that side but is a source for moisture entry that *will* corrode the wall of the cylinder.

At the rebuild several years back I used a brake cylinder hone to clean them up. But they were pitted beyond any repair. I reassembled them with new seals and used them as is. They of course leak a bit from the vents and that's not all bad. At least some hydraulic fluid is getting in there to lube the vented portion.

So this: If you have a backhoe with this configuration do you push some kind of lube into the vent holes as a maintenance chore?

Lil Foot, is there any mention in the manual for maintenance of the swing cylinders? To me its an engineering failure. Ya just can't have precision surfaces exposed in a way that they *will* fail over time.

I compared this with our JD 410J. The swing cylinders are pressurized on front and back and on both sides - yeah, its a different critter and a bit more expensive machine. There is no intermediate swing arm. But on what we affectionately call the 'toy' tractor, as valuable as it is, this is a terrible thing.

 

[Lil Foot]

This cylinder design is the second most common failure of the B670.
(the first being the swing pivot bearing setup)
If you read the thread listed below, (posts #22-#24) you will find my solution to this poor design. My cylinders were pretty marginal, but they work and probably won't get any worse with this vent setup.
Pic shows the vent filter, connected to the swing cylinders with tygon tube & a tee.
This thread is a compendium of all things B670 related, lots of good info from lots of good contributors.
7 pages, 140 posts.

B670 Backhoe Rebuild

Does anyone have a working knowledge of the older B670 (KUW200) backhoes that were made for the older B6100 Kubota tractors. I am trying to rebuild one and have found that the area that the bottom pin of the swing weldment goes into is worn out and out of round. The raised round piece of metal...

www.orangetractortalks.com

 

[JRHill]

Yup, This is 'perfect.' (sorry)

I'm not looking forward to pulling those cylinders out again. But it would be worth it before things get yet worse (worser, sounds terrible)?

The center pin is in good shape judging from play. I've kept everything very well greased. Actually more than well greased. Even still I had a pin seize on the arm. I've tried to drive it out with a copper sledge. Still it only moves 1/4" side to side. Now the ends are mushroomed but can be ground down to exit - if I could get it to do so. It hasn't affected the cotter pin hole. Another winter project but I can't use it too much or it will wear at the wrong place.

Lil Foot, a 'field toolmaker'? I worked in a tool shop building and sharpening production tooling for hydraulics and other projects. I am a journeyman card holder. When people asked and I answered 'Tool maker' they thought I made wrenches. But a 'field toolmaker'? Gosh I'd like to suck down a few beverages with you. BTW, I got wary of being laid off and went to school. I got a BS in Mfg Eng but I went back to working with my hands. I just couldn't be happy otherwise.

 

[Lil Foot]

Lil Foot, a 'field toolmaker'?

I think there has been a slight misunderstanding.

I guess there are some advantages to being a toolmaker after 36+ years in the field.

I meant 36+ years in the field of machining /toolmaking.
I did 7+yrs in a production aerospace shop, then another 2+yrs training/working in a short order/toolmaking shop under some truly fine, old school toolmakers who pushed me hard and taught me well.
I then went to a pure research lab & became their toolmaker. While there, I tested out & got my Toolmaker Cert, as most of the work I did for them was far beyond normal machining tolerances.
We researched sensors- quartz, silicon, optical, & fiber optic.
I still cannot talk about most of it. Suffice to say the highest end stuff on the planet at the time.
I worked machining just about all metals including exotics, carbides, ceramics, glass, quartz, & silicon.
We built & operated, machining centers for non standard materials, vacuum metal deposition systems, fiber optic lapping, cleaving & splicing machines, E-beam systems, sputtering machines, electron microscopes, chemical cleaning & etching, hot deionized water systems, etc, etc, etc,. Very interesting, demanding & diverse work.

 

[JRHill]

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