Using Cribbing to Rig Machine Off Trailer
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    Default Using Cribbing to Rig Machine Off Trailer

    This is really more of a question of general interest, not something that I am planning to do in the near future...

    I've seen people mention that they use cribbing to remove a machine from a trailer, either using beams and cribbing to span the trailer as in this post http://www.practicalmachinist.com/vb...3/#post2077993, or using cribbing at the end of a trailer and rolling the equipment onto it.

    The question I have is, in the case of cribbing at the end of the trailer and rolling the machine onto it, what prevents the cribbing from tipping, sliding, or collapsing when the machine rolls onto the cribbing? Is the cribbing placed slightly underneath the back edge of the trailer so that when the machine rolls to the back of the trailer, the trailer lowers and puts weight on the cribbing to prevent tipping?

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    You are on the right track. You only need the trailer to block the ramps and cribbing from any forward movement. Just enough interference to accomplish this will work. I use plastic coffee container (Folgers) lids under the load to aid the slippage while going up the ramps. Careful jacking and blocking is required when raising the load to ramp level to prevent tipping and serious falls. Regards, Clark

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    Quote Originally Posted by zipfactor View Post

    The question I have is, in the case of cribbing at the end of the trailer and rolling the machine onto it, what prevents the cribbing from tipping, sliding, or collapsing when the machine rolls onto the cribbing? Is the cribbing placed slightly underneath the back edge of the trailer so that when the machine rolls to the back of the trailer, the trailer lowers and puts weight on the cribbing to prevent tipping?
    The answer to your question varies with the size/weight of machine you are dealing with.

    The only time I have cribbed under the back of a trailer is to load something light (say under 6k lbs) from the rear with a forklift. Have to do this when somebody shows up with a trailer with sides that can't be loaded from the sides with forks. The cribbing is just to keep the back of the trailer from dropping and lifting the back of the tow vehicle.

    It's a lot safer/simpler to use a truck/trailer that lowers to the ground or span the trailer with beams.

    The trailer has suspension and cribbing is not rigid. Everything moves around. If you don't have a sound handle on what's going to happen when you rig a certain way it isn't safe.

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    If you look at how house movers use cribbing they tend to assemble stacks that are more like a box than a wall. This prevents the stack from falling sideways. In the case of machinery and a trailer it probably wouldn't hurt to toenail the ends of the blocks to prevent them from sliding apart. If you can kick it over when it's unloaded the odds are it could slide and collapse if something shifts.

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    Pin the cribbing, with rebar, threaded rod, etc.

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    Quote Originally Posted by Garwood View Post
    The answer to your question varies with the size/weight of machine you are dealing with.
    Hypothetically 8,000 lb.

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    Quote Originally Posted by Scottl View Post
    If you look at how house movers use cribbing they tend to assemble stacks that are more like a box than a wall. This prevents the stack from falling sideways. In the case of machinery and a trailer it probably wouldn't hurt to toenail the ends of the blocks to prevent them from sliding apart. If you can kick it over when it's unloaded the odds are it could slide and collapse if something shifts.
    That's how I've understood it as well, arranged as in the attached picture below. Though the base would be significantly longer and wider, with more intermediate members.

    train1-1209fe.jpg

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    Quote Originally Posted by zipfactor View Post
    Hypothetically 8,000 lb.
    Lathe? Mill? Press brake? Makes a huge difference.

    An 8000 lb lathe is very easy to move. A press brake or mill, not so much.

    Over concrete, asphalt, dirt? Basic ground pressure is no more than 1500 PSF. Exceed that and your cribbing will sink.

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    Quote Originally Posted by Garwood View Post
    Lathe? Mill? Press brake? Makes a huge difference.

    An 8000 lb lathe is very easy to move. A press brake or mill, not so much.

    Over concrete, asphalt, dirt? Basic ground pressure is no more than 1500 PSF. Exceed that and your cribbing will sink.
    It is a CNC lathe, and will be moved over concrete (~5" thick).

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    Quote Originally Posted by zipfactor View Post
    It is a CNC lathe, and will be moved over concrete (~5" thick).
    You mean it's "Hypothetically" A CNC lathe right?

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    Quote Originally Posted by zipfactor View Post
    That's how I've understood it as well, arranged as in the attached picture below. Though the base would be significantly longer and wider, with more intermediate members.

    train1-1209fe.jpg
    That's what we call "pig pinning". It is a lot stronger than one would think. With weight forcing down on the stack, you can't hardly knock it over.

    As to the original question, you have to crib under a trailer anytime you are moving a heavy object from trailer to something solid or just the opposite.

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    Quote Originally Posted by m16ty View Post
    That's what we call "pig pinning". It is a lot stronger than one would think. With weight forcing down on the stack, you can't hardly knock it over.

    As to the original question, you have to crib under a trailer anytime you are moving a heavy object from trailer to something solid or just the opposite.

    So, in this hypothetical situation , is there a rule of thumb for where the cribbing should be initially loaded for the transfer such as 1/3 of the length of the cribbed "frame"?

    In all seriousness, this is more a question of general interest as ideally there will be a forklift available for unload. I enjoy gaining the understanding of how these methods work in practice, particularly because heavy lifting equipment isn't always available. Information like this is always useful in unexpected ways down the road.
    Last edited by zipfactor; 02-22-2018 at 09:42 AM.

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    Since you're in Ohio, go to Sunbelt or HERC and rent one of their drop-deck trailers. Use only enough cribbing to raise it to pallet jack height, and place one on each end. When unloading, pick it up only 1" to clear average terrain, and roll it out. Steering will require some thought, but probably safer than machine skates.

    Or engage your forklift from the side, if access permits. Pick up 2", drive trailer away, set down. Move in closer, pick again and place. Forks beneath legs, or straps from above, in that order of preference.

    Hypothetically, of course.

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    Quote Originally Posted by Chip Chester View Post
    Since you're in Ohio, go to Sunbelt or HERC and rent one of their drop-deck trailers. Use only enough cribbing to raise it to pallet jack height, and place one on each end. When unloading, pick it up only 1" to clear average terrain, and roll it out. Steering will require some thought, but probably safer than machine skates.

    Or engage your forklift from the side, if access permits. Pick up 2", drive trailer away, set down. Move in closer, pick again and place. Forks beneath legs, or straps from above, in that order of preference.

    Hypothetically, of course.


    Using a drop deck trailer is the plan. The issue is that last time I tried to rent one, they were unavailable, so I ended up using a tilt deck. That was a bit more challenging when the equipment got to the bottom of the ramp as the pipe rollers being used weren't tall enough. I didn't have my small forklift at the time or a pallet jack, so there was a lot of cussing involved while using a car jack as a machine skate

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    Firefighters regularly crib loads, often while lifting those loads off someone who is trapped. There is good discussion here with simple example calcs involving 4x4's, and good links to excellent resources:

    Cribbing and their weight limits - Firehouse Forums - Firefighting Discussion

    From that discussion, these two are excellent reading.


    US Army Corps of Engineers Shoring Operations Guide. Cribbing is on page 56.

    http://www.disasterengineer.org/Link...bid=57&mid=394

    FEMA US&R Response System/US Army Corps of Engineers Urban Search & Rescue, Structure Specialist, StS1 Training

    http://www.disasterengineer.org/Link...bid=57&mid=395

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    dscn1799.jpgdscn1804.jpgdscn1800.jpgdscn1806.jpgOh goodie, I can post more of my pictures. I moved my Devlieg off my trailer with cribbing and toe jacks, 22,500 lbs.dscn1807.jpg

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    dscn1819.jpgdscn1821.jpgdscn1824.jpgdscn1818.jpg
    Once we got it off the trailer we lowered it one 4 x 4 at a time until we had it on the floor. then we used a 6-ton come-a-long to drag it over where I wanted it. We anchored off my big forklift. I rented the toe jack system and it worked very well, though it was a sphincter tightening experience. Patience is a virtue I am short on, and one that is required when using this type of system.
    Attached Thumbnails Attached Thumbnails dscn1815.jpg  

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    Here is another one I brought home a few weeks ago.
    http://www.practicalmachinist.com/vb...7/#post3092387

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    Most of the machines I have moved are set up to be lifted by 3 toe jacks. I have usually found openings or slots in the base where they fit and center the load properly. I picked up 4 ten ton toe jacks at an auction awhile back for a great price, $400. You will choke on the price for new ones.

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    Quote Originally Posted by zipfactor View Post
    So, in this hypothetical situation , is there a rule of thumb for where the cribbing should be initially loaded for the transfer such as 1/3 of the length of the cribbed "frame"?

    In all seriousness, this is more a question of general interest as ideally there will be a forklift available for unload. I enjoy gaining the understanding of how these methods work in practice, particularly because heavy lifting equipment isn't always available. Information like this is always useful in unexpected ways down the road.
    I’m not 100% sure I understand your question but I’ll take a stab at it.

    Once you get past one side of the cribbing square, it’s stable enough. Of course the closer the cribbing is to the center of the weight, the more stable it will be.

    When building your “pig pin”, just make sure it stays level and shim if needed. Also, the cribbing is only as strong as as what is under it, make sure it’s built on a solid footing.

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