Repair a Cracked Caterpillar 789 Dump Truck Suspension Part | Machining & Welding

how you going guys Kurtis from cutting edge engineering tonight's job is a 789d front strut cap so this part is actually off a 789 d cat dump truck this is the top cap of the front strut of the machine the strut is bolted onto the shafts of the truck and it allows allows for suspension movement and steering of the truck this is just one of many components that go along with it it's coming from the customer with a crack in it we've also got a lot of excess wear on the top of the pin from the bearing that is also caused from incorrect fitment this has been repaired once before by someone else we do come across these quite a lot where someone's repaired them they generally always fail in the same place generally comes down from improper fitment to the machine after they've been been repaired people don't understand there's a few other steps that need to be taken when fitting these back back to the machine when they are a completed strut so we're going to chuck this in the lathe we're going to set it up we're going to see if there's any run out on this pin that will then tell us whether the pin was installed correctly and then welded in situ or it was machined after it was welded if there's any sort of run out there it's it's going to impact the life of this component so once we get it set up in the machine we'll see how true it's running if it's running pretty good we might be able to salvage the pin we do have a piece of material in stock that we're going to use if we need to replace it as it goes for repairing we're just going to get in the machine and see what this thing's doing righto so we've got this set up in the machine we're going to throw a dial indicator on it now to see how much run out this pin actually has in it if there's any run out in that pin that's going to give us a pretty good indicator that that was the reason the weld actually failed i need to be a little bit wary where we put the dial indicator as there is a bit of wear on the pin from the spherical bearing that that works up top here i'll get a dial indicator and i will set it up and see what it's doing so now that we've discovered there's run out on this pin first step is we're going to we're going to put a center up it we're then going to machine this weld out and try and get this pin out we'll then see what they've done inside here as we didn't do do this repair so after we machine this pin out we'll be able to see how they repaired it previously and make a plan of attack on how we're going to fix it properly right oh so we've uh we've machined out the crack uh found the base of the weld where the two pieces of material meet uh there's not a great deal of weld in there that would probably be some of the reason why the weld did actually fail so next step now is get it out of the machine and we'll try and remove this pin with a bit of heat failing that we'll just machine it out all right guys so we've removed the pin and found out exactly how they installed the new one a little bit different to how everyone else does it um it didn't work they'd actually threaded the pin and threaded the housing and then screwed it in and then welded it in uh we did find a lot of dirt and [ __ ] like that floating around in there which you know that's not usually a good thing it means there was dirt getting in from somewhere could have been going in through that crack the repair was only about 20 mil down inside this hole wouldn't have been enough strength or enough enough structure down inside the housing to actually make it all work so what we usually do is we'll bore it out we'll go about 60 mil deep open it up to whatever diameter we need to and then we'll machine our new pin so it goes all the way down inside and it's actually down inside this plate here a little bit as well so that that extra little support seems to help it really well so uh we're just going to finish this to size now and then we'll take it out of the machine and throw the piece of material in and start making the new pin so now that we know the pin is going to be replaced we're going to cut the new stock for the replacement pin so we've got our piece of material set up in the Everising saw uh it's a 360 horizontal bandsaw piece of material we've had in the container for a while so we dug that out this morning we've got to cut it to length it's a piece of 150 mil 4140 we need to cut it to 220 millimeters long right so we've machined everything everything's finished now we've got the plate machine to size we've got our new pin machine to size well only the bottom half of that pin we're going to finish that off once it's been welded just in case anything moves does anything weird like that so first step we're going to do now is we're going to preheat this plate and then we're going to try and fit this pin it is an interference fit of about 0.15 of a mil so that's about 6 thou in bananas if all else fails and it stops halfway down we've got the press sitting here ready to go so we'll just throw it straight in the press and push it home i've also drilled a eight mil hole all the way through this pin as a vent to allow any um any pressure that's built up inside to escape so we don't have any dramas with that so yeah let's let's get this thing hot that's already locked all right so that went pretty well as perfect as it could be got it preheated drop the pin in there and it instantly locked when it hit the bottom so that is a very tight neat fit we're going to let this cool off just a little bit oh the heat's already coming up into that pin we're going to let this cool down a little bit while that's happening i'm going to set up all the welding gear and we're going to set up a little rotator and weld this thing out righto guys so we finished the welding on this it's been cooling down for about seven hours now we've got it back in the machine uh we're going to start by turning off this weld uh we're going to machine a bit of this shoulder down put a radius in that corner we're then going to machine the pin to size it's going to be finished out at four inch exactly uh we'll then put a 22.25 mil hole in the end of it we're going to thread that with a one inch unc tap that's just for an eyebolt or lifting whatever the customer needs to do do with it after we do all that the job's finished a little bit of stuff once once we get that pin out we can see see what people are doing just a um rough [ __ ] which will tell us it might tell us strut connects to oh boy you where the bearing has been uh rubbing into the pin [ __ ] i'll get a dial going and um so i'll get a dial indicator we didn't do do this repair we're going to fix it again uh properly and start to put the the features back back onto this um this hat top hat cap strut cap strut cap try and get it running true to find out who is that hang up not tonight i bet they're watching they'll know it's them probably is that it oh that sounds right why is there hello well do you want to be by the saw in front of the saw i don't want to be by it here's good is here alright yep right here we go you going yep [ __ ] getting uncomfortable stop leaning i've got to do stuff just so we've got that set up in our new saw new to us saw here's our new well old right guys so we've got the bit of material set up in our new saw [ __ ] um so yeah let's let's get this thing hot pretty good oh let him have it he's getting annoyed drop it homeless drop it homeless drop it

Channel: Cutting Edge Engineering Australia

Views: 721,331

Rating: 4.9092026 out of 5

Keywords: cutting edge engineering australia, machinist in australia, machining, abom79, Repair a Cracked Caterpialler 789 Dump Truck Suspension Part, Weld repair, cracked suspension, broken weld, cracked weld repair, mig welding, dump truck, dump truck suspension, caterpillar dump truck, fixing bad welds, repair cracked welds, workshop asmr, workshop, machine shop, machining shop, the fabrication series, heavy machinery, lathe, caterpillar wrenching, cat 789, cat 789 dump truck, welding

Id: CfR94njAV2s

Length: 39min 0sec (2340 seconds)

Published: Thu Feb 18 2021