Where do I ask about welding o1 pin to loader arm on here?
What are you trying to do? Pictures would help tremendously.
Pins aren't normally welded in but need some pics. or more details of what you want to do.
I don't know what steel cat used for arms, pins are annealed o1. Someone said use 7018 rod. To best of my reading was preheat to roughly 1500 cool to roughly 930, weld and quench in oil for awhile. Concerned about cracking at weld and wish to harden pins. Thanks for any help.
Or is annealed o1 hard enough for loader arms?
If it's off a Cat and is welded Cat will have a procedure. I'd guess just weld it with 7018 but should be easy to check with Cat or post what machine it's for and one of the people with access to SIS may be able to post the welding procedure.
What model of Cat machine is it from and what exactly are you trying to do..?
It looks like the linkage for bucket cylinders to me.
I agree with the bucket linkage cylinders. If there is clearance why not weld bosses to those plates and make slightly longer pins with thru holes. More support on the pins and then the pins can be hardened.
939c piece of junk front engine loader (943 fan, but it needs final bearings and this is all I could get as a spare). Way too much movement in arms. I'm assuming Cat welded as there isn't much clearance between side panels and arms. No wonder they stopped making these fronts, doesn't make a good loader.
Seems like maybe the weld also gives arms more stability
Seems to me that hardening the pin and the arm would make a brittle weld . You need some ductility.
I need to do some digging. I’ll get back to you tomorrow. I assume it is a 6DS-prefix machine..?
I think the pins would just get welded in. Don't think Cat would weld them in and then harden them.
5xk38441 Yes I suppose brittle comes with hardening, just don't know how annealed o1 would hold up, but would be easier to weld and be done
That's the engine Serial Number. The machine is 6DS01814. I'm assuming that you are trying to replace the pins in the 108-5672 Lever As, Item 10 in the illustration below, correct..? For a kickoff the plate will be nothing super-special, probably no more than a good-quality 28mPa yield strength structural steel. Neither will the original pins be case-hardened for that size of a machine, unless I am mistaken. They will simply have been manufactured from a good-quality steel for manufacturing pins. What material did you use to manufacture the replacement pins.? So I'm going to defer to Welder Dave & the weldor as regards detailed welding technique, but IMHO E7018 should be fine for this job. It's probably what the factory welded it with in the first place although they would've probably used wire. Something like an 8-12mm (3/8"-1/2") 45-degree chamfer on both ends of the hole in the plate then fillet weld the pin to the plate on both sides would be my thought. I'll see if I can't knock up some sort of sketch to give you an idea. Pre-heat ought to be no more than 60-70 DegC, just enough to keep the moisture out, then to maintain a maximum interpass temperature of possibly 120-130 DegC during the process. The complicated part will be to grind the inside surface so that the weld ends up smooth and the finished repair will not rub on the tilt cylinder rod end or on the tilt lever when everything is assembled.
Here's the sketch. Sorry my drawing skills are not that great This is a section through the joint where the pin installs in the end of the plate. RH side is as it is right now, LH side as you want to make it. The pin should be a tight fit in the hole. TBH if you had to heat the plate a hair to install the pin it wouldn't be the end of the world. Chamfer the plate as shown on the left side at 45-deg. all the way round both inside & outside. You could also chamfer the end of the pin at 45-deg to give you a v-groove on the outside. Weld up to the red line. Don't start all the weld beads in the same place. Stagger the stops & starts around 360 degrees of the hole. For stress-relief a needle peening giun after each weld pass would be the best idea. Depending on what material was used I wouldn't have though any surface hardening of the pins would be necessary
Looks like the pin is already chamfered a bit and if you set the pin in from the edge of the plate about a 1/4"-5/16" would make for a good deep penetration fillet weld. You wouldn't have to chamfer the plate this way but could if you preferred. Pins that have a bolt on retainer are often done this way. I wouldn't weld the pin inside the arm. Warm it up to drive any moisture out and 7018 should be good to go. How the pin is secured on the other arm might be the deciding factor on how far the pin extends into the arm where it's welded. Personally I would add a shim/washer on the loose plate (if required to take up slop) and have a fillet weld rather than have the pin flush for welding. The most important thing is to have a good sound weld so hire a welder if need be.
Dave, there are all sorts of shims, washers, etc in that assembly. I just didn't include them in the snip I posted above. I'm not too sure how much space there is on the outside of the assembly to let the pin protrude and fillet weld it 100% externally. I think the critical thing is the fit of the pin into the plate. To me it ought to be either a press or a shrink fit. That would significantly reduce the bending stresses in whatever weld was used.
I was saying to have the pin recessed a little in the plate for a fillet weld that would end up flush with the plate when finished. In your diagram above, imagine the pin is the plate you show beveled and the blue line is edge of the plate. Move the chamfered pin a 1/4" to the left and recess it in the plate for a fillet weld with a groove for deeper penetration. I'd run a hot 5/32" 7018 in there. The pin wasn't welded on the inside from the factory. The one pic. shows a bunch of shims and stuff. Adding another shim on the outside to take up slop I don't think would be problem and it would allow for a better weld. I think it's important those pins be kept greased so there is never a lot of stress on the welds. I wish my machine was close, I'd take a look as I think it's similar.
Here's a few more snippets of information about the 939C in question.
I think that the reason for the lever assembly is installed "inside to out" with the flush face on the inside is probably the lack of clearance between the inside face of the lever assembly and the outside face of the hood of the tractor.
I was thinking the same and the outside with the removeable plate has more clearance. Recessing the pin a bit just allows for a stronger weld.
Would a full 90-deg v-groove (45-deg on both plate and pin) not achieve the same objective.? Are we agreed that a shrink or press-fit for the pin into the bore in the plate would be the best way to go, whatever design of weld was used.?
A V groove on both the pin and plate would add strength but recessing the pin would add more strength in my opinion. A compromise might be to V both and recess the pin about 1/8-3/16". I don't think the pin would need to be a press fit because it's welded anyway. It should be a real close fit to keep the pin aligned though. As long as the hole on the other plate isn't wallowed out and is also a very close fit I think would work fine. The pin may be a tight fit to begin with. The outer plate just adds support and doesn't allow the arms to twist. That's part of why I think it's important to keep the pin greased. I think it's very similar to a cylinder pin and they normally just slide right in. They have bushing but I think take more of the load and have more movement. There wouldn't be a lot of force on the weld unless the pin was dry and seized in the bore. I think I'd put the 2 arms together spaced apart with all the pins aligned before tacking the pin(s) in just to insure everything lines up. I'd put 3 or 4 tacks on the pin. The last thing you'd want is to weld the pin up and it's off a few thou. and the assembly won't go together. I found a pic. of a Case pin that shows the recess I was talking about. Click on the 2nd pic. https://www.minnpar.com/product.asp?PartNbr=105752A1&StockNbr=QR6881820&ProductCode=550901
I get what you're saying, but IMO there's a difference between the function of the two piins. The type of pin in your photo is being pretty much entriely held against rotation by the weld on the flag (locking plate) with very little in the way of side to side forces being applied to it. Also the plate to which the pin is being welded is not that thick. If the pin was left shy of the outside by even a 1/4" it would IMO increase the bending moment on the plate significantly. The pin in that 939C Tilt Link has to be held against both rotational and significant side-to-side forces because of the loose plate #12 on the outdie of the assembly. That's why I suggested an interference fit of both pins into the lever. Also having an interference fit between the pin and the plate will IMO largely stop the pin from moving while it is being welded and help to maintain alignment. For correct alignment it would be necessary to assemble everything with both the inside (fixed) and outside (loose) plates in position then weld the end of the pins to the plate. At each stage of the welding the outside plate could be checked to ensure that it was still free to move on the pins. Here's another thought. Are both the inside and outside plates still true (straight in other words)..?
Would be good to fit everything together and see how the pins fit. Maybe Cat designed the pin to be slightly recessed? If the pin was recessed a little (not as much as the Case pin) the weld would bring it out to the thickness of the plate anyway. The pin is already chamfered. If the pin is recessed is still a loose fit at the outside of the plate. I think with both arms connected (boxed) the plates are already extra thickness to resist bending. Whether the pin was flush with the edge or recessed with the weld going to the edge I don't think would make any significant difference as far as bending. With no side forces I'd bet 3/8" plates would handle the lifting force. I tried to find a clear pic. online but can't tell for sure. It looks close to flush but could have a slight recess. I think the upper and lower pins are designed to hold the two arms tight so they can't spread apart. That's why it would be good to make sure the retainer on the loose plate will fit after the pin is welded. Adding a shim/washer is better than having it too short. If it was a 977 might be more critical. The original 931 clamped the pins on the plates on both sides instead of welding the pin on the inside plate. I might go out to my property this weekend and see what my 931B looks like. Interesting discussion. This loader will be better than new once we figure it out.
I would agree with Welder Dave as far as welding just the outside with 7018. Put a bit of a bevel on both the pin and the plate both on the outside. The hole in the plate should be a nice fit to the pin. I am not sure it needs to be a press fit but it should be snug for alignment purposes and to get all the support possible on the pin.
Thanks a ton guys, really appreciate it. It will be a press fit and then weld, the other side is a hair loose so should slide on. The pin is annealed o1
Here's a question. Are you doing just one side or both.? If you're only doing one side then I would suggest to use the Tilt Link on the other side as a pattern to get accurate centre-to-centre measurements for welding. If you don't do that there could be a risk of the linkage trying to twist in operation because one link is slightly different mechanically to the one on the other side.
My thought was to assemble them with the outside plate and use some spacers (pipe, tubing, even wood blocks) so they are the same width as when installed on the machine. The cylinder pin could also be used for alignment. You could use a couple clamps to hold the mock up together for welding. The 3 pins should keep it in alignment. The pins being a press fit shouldn't move and having the whole thing clamped together should prevent any twisting. Just make sure to clamp them so they are flat and the same distance apart on all sides. Leave them clamped till the weld(s) cool enough to handle them with bare hands. Should be a fairly simple repair. A good weld is essential for it staying together.
I finally went out to my property to pump water. I looked at the bucket arms on my 931B and the pins are clamped on each side. The retainer plates on all the bolt on cylinder pins are recessed some for welding. Not as much as the Case pin I showed but down about 1/8" and the weld just out a little past flush. The recess likely gives more surface area for the weld without having to bevel the plate. I wouldn't be surprised if the pin had a slight bevel as that would be easy when it was made.
Thanks for all your thoughts, I really appreciate it. Welds seem decent. Not I have to decide if I want to hear and put in oil or just put them on unhardened
I don't think they require hardening. I think if they did they would attached a different way so Cat wouldn't have to harden them after welding into the arm. Being they were a press fit the arm would take a lot of heat away from the pins.
Yeah your probably right