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Beej50
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Engineering Fields - Piping Design Engineering - New Member Australia - Member - New Member

Join Date: Aug 2007
Location: Childers, Queensland
Posts: 412
Good Answers: 5

JCB 4CX Backhoe

03/01/2016 3:58 AM

Hi all, I have a question regarding the kingpost on my backhoe. Previous to my ownership, the backhoe had been used with a hammer. This has created a lot of play in the pivots. They are basically "birdmouth" clevises where the middle part pivots and has a steel bush and greasing. The top and bottom part of the pivot locate the pivot pin and is prevented from turning (and falling out) with a standard bolt. It is the play (about 1-2mm) in the top and bottom part of the clevis that I would like to eradicate.

If I could drill and tap a grease nipple into these parts and pump in some liquid metal it would be what I was thinking of except I don't know if a suitable product was available and could be used in this way.

I also have exactly the same problem with the slew cylinder (two off) pivots. All pins and bushes have been replaced but a new king post assy' would cost about AUD 3k. I have attempted to make bushes (much like those speedy seal sleeves) but they always fail when I try to re-assemble the pivot.

Line boring and fitting oversized pins and bushes would be the go but......in the bush there is never a line boring machine around when you need one!

Any thoughts would be greatly appreciated.

Beej50..........is back!

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Pathfinder Tags: Backhoe JCB Pivots
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spades
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Join Date: Aug 2014
Location: Port Macquarie N.S.W. Australia
Posts: 1071
Good Answers: 225
#1

Re: JCB 4CX Backhoe

03/01/2016 4:46 AM

Have you considered expander pins, they are often used in such circumstances for heavy equipment.

Remove the old pins and bushes, fit the correct size expanders and tighten them. They crush the bush to conform to the ovoid of the worn part, and you're back in business.

Edit:- Here's a link to one manufacturer
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Beej50
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Engineering Fields - Piping Design Engineering - New Member Australia - Member - New Member

Join Date: Aug 2007
Location: Childers, Queensland
Posts: 412
Good Answers: 5
#2
In reply to #1

Re: JCB 4CX Backhoe

03/01/2016 5:43 AM

That's awesome Spades! Never heard of them before. Had a look at the link and the "Expander" is exactly the answer! I'm stoked! definitely worth a GA.

Cheers mate!

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 "A common mistake people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools!" Douglas Adams 1952-2001. E&OE!
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Brave Sir Robin
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Hobbies - DIY Welding - Wannabeabettawelda

Join Date: May 2007
Location: Annapolis, Maryland
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#3
In reply to #1

Re: JCB 4CX Backhoe

03/01/2016 3:33 PM

Necessity is truly the Mother of Invention. GA.
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Beej50
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Engineering Fields - Piping Design Engineering - New Member Australia - Member - New Member

Join Date: Aug 2007
Location: Childers, Queensland
Posts: 412
Good Answers: 5
#5
In reply to #1

Re: JCB 4CX Backhoe

03/02/2016 3:39 AM

Ok.....bad news! I have just priced up ONE expander pin and it came to $870 + GST. By the time I have replaced enough pins to make a difference, I will be about up to the same cost as a new kingpost!

Damn good idea though! Thanks.

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Deefburger
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Join Date: Mar 2011
Location: Sebastopol, California
Posts: 1205
Good Answers: 54
#4

Re: JCB 4CX Backhoe

03/02/2016 12:55 AM

Wow that is cool! I'm not qualified to judge a GA for something like this, but I like this as a solution to a big problem.

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welderman
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Hobbies - DIY Welding - New Member

Join Date: Sep 2007
Posts: 1601
Good Answers: 58
#6

Re: JCB 4CX Backhoe

03/03/2016 8:51 AM

I had a similar problem with an old shotgun with a worn pivot. My gun smith has a process to flame spray hard bronze-like metal on the old surface so the pivot can then be reamed and scraped to a custom fit. I think he charged me $300.00 for the whole job. An advantage is that the new metal has a low coefficient of friction an seems to last longer than the original steel.
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ozzb
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Hobbies - Fishing - Old Salt Hobbies - CNC - New Member United States - US - Statue of Liberty - New Member

Join Date: Mar 2007
Location: Rosedale, Maryland USA
Posts: 5197
Good Answers: 266
#7

Re: JCB 4CX Backhoe

03/03/2016 12:52 PM

Don't know if it will work in your application. Once had an elevating dock used to lower pallets of groceries from trailer height to the ground. Bushing was gone and they had egged out the hole. Cleaned and rough up the hole. Spread J B Weld all the way around. Then painted the back of the replacement bushing with something that would release it from the J B weld if necessary to remove it. Pushed in place. Installed a new pin. Let it set up with no load. Worked just fine. Had check on it every time I was called to the customer location. After 5 years it was still holding up.

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Beej50 (2); Brave Sir Robin (1); Deefburger (1); ozzb (1); spades (1); welderman (1)

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