question about castings

By welder40 Date 07-11-2010 15:29

Hello;
I have a question about castings. I need to determine exactly what type of casting I have.

I need to repair four holes that are stripped of the threads and also have two broken studs in them. The holes are about one inch dia.
The casting is part of a backhoe. It is the main pivot that houses the hydraulics swing motor. The swing motor has a large spline located on the bottom.

Here’s the problem.

This spline fits into a piece (which ,incidentally, is also threaded for some unknown reason)that is then bolted onto the cast part with four bolts and, in turn, moves the backhoe arm left or right in about a 180 degree arc.. It is an older backhoe, a Massey Ferguson. The piece and the casting are both threaded. There are no nuts as the bolts thread through the top of the splined piece and thread down into the casting.

The swing motor is bolted to the tractor side, while the spline and bolted assembly is on the backhoe boom side. Without this, the hoe does not turn, and it also takes a sever amount of strain as it moves the load.

I’m looking to determine what the cast is comprised of in order to determine how to repair it. The casting is one and one half inches thick where the holes are located. The holes are threaded and go completely through the casting. The splined piece is about three quarters of an inch thick. The bolts thread into the top of this piece and down into the casting.

I’m considering;

1.Silver soldering the holes and re-tapping but I am unsure if there will be enough strength for the threads.
2.Failing this I am considering making a unit out of steel plate with the dimensions of the cast unit, but this is quite a bit of work and expense if I can repair it another way.
3.Drilling the holes to a larger diameter and re-tapping to larger bolt. I am nervous of doing this as I am unsure if the remaining metal will be strong enough. If this would work it may be the best way out.

My main question is how I determine what material I have for a casting.

Are there any other methods besides a spark test? I have never been able to make use of the spark tests very well.

Any ideas on how I could fix this would be greatly welcomed.

Thanks very much in advance.

welder40

By welderbrent (*****)

Date 07-11-2010 15:49

Welder40,

WELCOME TO THE AWS WELDING FORUM!!

You will more than likely find that part to be a cast steel, not cast iron. It should be weldable using 11018 and plenty of pre-heat. Also many good cast rods, I beleive Nickel 99 is a good one, will work well for that. While they are mainly used for cast iron, they work well on cast steels also.

I'm on my way out the door. Hopefully others will chime in and give you more detailed repair possibilities and processes/procedures.

Have a Great Day, Brent

By welder40 Date 07-11-2010 16:13

Hi Brent,

Thank you so much for the warm welcome. I really appreciate your time and others as well, in answering my concerns.

I note that there had been a quick welding job performed on the two pieces to try and weld them together along two outer edges using 7018. The complete weld didn’t just crack; it just broke out completely, leaving a large V where the weld once was.

In the past, it had been welded along the sides at one time which actually did hold. I don’t believe that weld was a Ni rod though, as the color looked and rusted like the parent metal.
In regards to welding with a 11018 or a Nickel 99 rod, the four holes that are stripped are about one inch diameter by one and one half inches deep. Are you thinking that I should fill the holes completely, and then redrill and tap them? If so, do you have any suggestions on how I should proceed, i.e. preheat, procedure for filling hole, actual rod to be used, etc?

If this is cast steel, are there different types that I need to know about before I proceed?

Attachment: IMG_0581trim.jpg - what type of cast? (0B)

By welder40 Date 07-11-2010 18:08

See attachment for picture of assembly

Attachment: IMG_0581trim.jpg - what type of cast?

Attachment: IMG_0581trim.jpg (0B)

By DaveBoyer (*****)

Date 07-12-2010 03:54

Is there a clearance issue that prevents You from drilling the holes through and using nuts? It looks like it in the pic.

My preference would be to drill out to 1 3/64" and then tap 1 1/8"-12 tpi. That is a standard fine thread, but You might not be able to get the tap & bolts easily, probably need to order both. Of course You need to open up the bolt hole to 1 1/8" too.