strength of inch plate?

I'm glad it wasn't just me that was confused. Cribbing is the material of choice for most large load temporary support. If it will hold up a freeway section or a ship keel, I'm sure it would work for 60 tons.

Sounds like they point load an individual timber while tipping over and dropping 60 ton load. It will indeed literally 'explode', splinter city is more like it. Building moving, railroad trestles, and your ship cribbing come to mind as proper application of timbers.

I have a hunch the > Shaun Van Poecke wrote:

"Jim Stewart" wrote

I'm sure, though, that certain woods are better than others. I know some of the lighter stuff crushes easily. Oak palettes are certainly better than pine ones. Someone who's really familiar with shipyards ought to know that.

Steve

Shaun: Some thoughts / questions:

1. How do you propose to get the dump off the truck without a crane or other lifting device? (I must have missed that part of the thread.)

1. Your analysis of the fact that the truck can support the dump at only four points when loaded is essentially correct. A suitable stand can be designed if given a little thought.

2. For a 80 ton (assume 2200 lbf. ton) dump, that's about 200,000 lbf. total. Most steels can carry 200,000 psi in compression. So if your "stand" was simply steel plates stacked up to the height you needed you would be fine from a compression stand point. Simply make the footprint of the stand big enough to reduced the floor weight to an acceptable level while assuming each stand takes the full 200,000 lbf.

1. Side loads, as stated preveously, will kill you. Literally. Keep the stands low as possible. Tie the stands together with rod or cable to prevent them from sliding out with respect to each other. Consider safety cables attached to the building if you don't have a crane in case the dump decides to move off the stands.

2. Consider renting the crane to proof your design. Lower the dump and balance it on a single stand. If the stand supports the weight for 15 minutes you're probably OK to use them 4 at a time.

1. If you are going to use a truss design (tripod) then the legs of the tripod should be made from material no smaller in diameter than the diameter of the pivot pins when the dump is attached to the truck. Hollow tubing is Ok, but the wall thickness should be at least 20% of the OD (SWAG). It should go without saying that the legs of the tripod should be welded or otherwise connected together to a common base so they can't splay out.

Hope you can find some useful nuggets here. Good luck.

Okay, but IMO the tone everyone here read into your initial posting was "No Worries, we just need to prop it up on a couple of sawhorses, and it's good to go!" And since we have a pretty good idea just how heavy the beds on a mine dump truck are, you can see why we got just a wee bit concerned... ;-)

DISCLAIMER: I've dealt with this kind of problem, but not anywhere near on this scale. My 'big gun' is only a ~225A MIG.

I would approach this as a one-piece frame that hits all four truck chassis mount points at once with round tubing saddles hitting the same contact points, vertical square/rect tubing posts down, and a simple square tubing frame flat on the floor.

Some big pieces of heavy plate to spread the weight out onto the floor slab evenly at each corner would be prudent, and put two knee braces at 90-degrees on the outside angles of the posts to leave the inside work area clear.

ASCII Art, sectional view:

DUMPTRUCKBED O O | | /| |\ / | | \ =======ADJ======= ______ _______ concrete floor slab or compacted gravel base

If they make different sized beds (or different truck makers that use different bed dimensions) and the one work stand needs to be adjustable to fit them, cut the four base frame tubes at the four (ADJ) points and make slide joints that will couple any torsion across.

I was going to say nested 'seamless' square tubing (like a trailer hitch receiver), but I don't know how big they make it. If the tubing is big enough, you can get your arm in there with a small 4" angle grinder and knock the inside seam flat.

And put a 'floor' of thin plate or heavy expanded metal on top of the workstand's base tubing as a walk surface for the workmen.

If it's a one piece braced stand and overbuilt by a decent margin, that will greatly reduce the odds of the loaded stand unintentionally turning into a parallelogram. || to // to _ _ with lots of screaming and running like a bad Godzilla movie...

(Oxymoron - Like there's ever been a good Godzilla movie?) :-P

Oh, and if the stand is square and sturdy the truck bed should stay square too, which is kind of important if you find you have to cut the entire bottom sheet out and start over. At this scale you can't just "warm it up with a Rosebud, get out the Big (Fine) Hammer and give it a whack" to get it back on the truck chassis.

-->--

Shiver my timbers!

S.

Shaun Van Poecke wrote:

Ive read all the posts so far, and it comes to mind as a metal worker used to either making one offs to production runs of hundreds. How many dump truk bodies can you get in this contract? cos if its many then its worth making up the tooling/ stands or manipulators to make the work much easier. Im also interested in the make of these dump trucks? Euclid? or Cat? or what ever? How do they get to the mine? overland from a port? of importation? are they roll on roll off cargo? where from or imported as ckd parts ans assembled at the mine? Someone has the job of doing all this as well as putting the bodies onto the chassis. So theres no need to reinvent the wheel. Id ask all these cquestions first.

Of all the answers so far the one I like the best is where you drive the truck up to a purpose made staging and use the trucks own hydraulics to tip up the body enough to get a steel beam across the chassis at its balance point. unbolt the pivot bearing and lower the hydralics. this will balance the body on the beam. put in place your railway of beams and rollers and winch onto the staging. Thiscould be made up of steel girders or be an earthwork above ground level. Much easier than making a pit. the dump body stays on its railway carriage till the welding is done then reverse the process to put it back. No crane needed. I wouldnt ask my welder to work underneath such a weight. Id think up away of turning it over so its upside down thens he works from above at all times. a betterweld in anycase. Id use the dump truck and some heavy cables over the body. with it up against a pair of steel girders set in the ground. you should be able with the dumptrucks pull roll over the body, so far up against a frame work to support it.say at 60 degrees.before pulling it down from the other side. Hope you follow. I had the task of inventing a way ,simgle handed without cranes to move my 1 ton drop hammer bae/anvil from the back of my truck onto its working bed when im away at exhibitions doing demonstrations then getting it back again.. Its all done with a trolley,a railway and a simple block and tackle. To long a tale to relate here. Lets have some more info so we can help you resolve this interesting problem.

The trucks are Komatsu 830E's, the trays made locally in bribane by Kato. They are bought into brisbane by ship, partially assembled by Komatsu in townsville, then trucked up to the site with the trays trucked seperately. They are then fully assembled and commissioned on site. I think they have about 50 of these trucks. There's a write up of the story in one of the mining magazines on line with a few pictures. We dont get the whole truck, just the tray since we are about 500 miles from the site and the trucks arent allowed off the site. They'll probably come to us on superliners. Lifting them off isnt too much of a problem - we have a few cranes that can handle it. The question is more about where to put them once they are off.

While ideas of sliding them/rotating them/dragging them etc sound good in theory, Im not sure what the rules say about stuff like that nowadays. Im sure things are about the same now in the states as they are in aus (ie. everything covered by regulations) which means that you dont have too much of a say in how you go about stuff, but this is probably as it should be. There would be specs and rules covering how a load this size can be shifted, and thats more up to the master rigger/crane drivers. My side of it is deciding where they are going to put it.

Rotating/turning them isnt really practical... the time/cost involved is too great and with modern wires, you can get a lot of vertical up done in less time than what it used to be. The idea is get the tray in, pick it up, put it down on something solid, brace as required, cut out wear package, weld in new plates. Sounds easy enough ;-) Im sure we'll work it out eventually. While the idea of welding underneath a heavy truck might sound a bit unsafe, huge ships are chocked up in much this way with guys all over them, as someone else mentioned. In comparison to that, this is a pretty small job.

Ive got a few ideas about different stand types that I'm going to run by an engineer, then develop it a bit further, get it signed off. Will let RCM know how it progresses.

Shaun

Why dont you get in touch with the fabricator of these units and see what they recommend?

John

Hi Shaun, thanks for the completrewd picture. Makes all the difference.!! Im in the UK by the way, and get into several steel fabrication shops. We too have health and safety regulations but once at the shop what goes on inside is really up to the boss and how he sees each job. Only if any one is injured does the H&S get nosey and start being difficult. I know i sounds daft but what about going to the mine and setting up shop there? for the contract? theyll have suitable lifting gear to service the trucks. Might make economic sence. Ships go into dry dock right next to the water, so why not repair at the mine? theyll have acres of space. If you get the contract how you manage it will depend on you, One needs to consider every option even just to rule it out .We live on the biggest onshore oil field in Europe and always have big stuff moving around. As to where to put them? you only want to move this size unit once! it comes on the superliner lifed off. The repaired one lifted on and back it goes. Stacking them like skips is not so easy!!.Is this the largest project youve undertaken? Perhaps its time to think about one of those shipyard arch cranes that run on rails. Best known one is the biggy at the Harland and Wolf shipyard in Belfast. Keep us posted!!. Nice project!

What if instead of setting these on stands for access to th' top and bottom, you were to shore/cradle it up laying on a side? Access would be via vertical instead of horizontal, so some ladder work may be required. Stabilization with appropriately sized chain, shackles and turnbuckles, attached to D-rings anchored in a manner and pattern to keep them from tipping over wouldn't be very difficult to figure out.

Pick it with your crane, rigged to lift from a side, and set it in your cradle, lash it, weld, pick it when done, repeat as necessary.

We used to lash Manitowac 4000 W track cranes with a 150 ft boom and D-10 Cats, etc., to steel decked barges headed from Seattle to Pt. Barrow, AK (and points between) all th' time. If those can make it through th' weather/seas from hell we'd tow 'em through, you could certainly do it on land.

Making a crib to set them in would also be a fairly easy undertaking as well. Think a concrete form that matches a side profile. For that matter, th' cradle could be deep enough that having it tip over wouldn't even be possible. Make th' floor large enough for whatever scaffolding th' welders would need and go to town.

No flipping, nobody under it or in th' bite, cheap, safe and quick.

Snarl... that'll be $8.00 bucks