Crush testing of cribbing

[rmoore]

An Illinois fire officer is concerned about hard or soft wood for vehicle rescue cribbing. Here's his question...

Ron,

Recently 2 of our firefighters went to the Vehicle Machinery Ops class and came back claiming that we have to remove all hard wood cribbing and replace it with soft wood.The instructor informed them that hard wood fails without without warning and that soft wood with start to splinter before failing and gives you advanced warning. Its been years since I had the class, but I remember that soft wood was NOT to be used as cribbing. Do you have any knowledge of recent changes?

My response is....
I can't explain exactly what those particular instructors in the class your guys took were getting at. I favor hardwood but have used soft wood then thrown it away if it breaks. Hardwood is sometimes difficult and expensive to buy.

What I can say though is that there is a lot of use of soft wood now for cribbing because US&R teams use it for their building collapse incidents. They actually have a guide written that gives ratings of box cribs and sets a mazimum height for certain loads.

In my seminar, I allow soft or hard wood. I do not allow plastic cribbing other than stepchocks. I don't like or trust any plastic 2x4 or 4x4 stuff even with the notches in the ends.

Visit a website that is from a friend of mine in VT. He is a "genius" in my opinion when it comes to wood. He has some training stuff online where he crush tested cribbing with amazing results.

http://www.sover.net/~branch/Safety.html

Check out the "destructive testing" link he has there on the left.

[Rescue101]

Yep,Frank Malteze,The WIZARD OF WOOD,Certified genius.Frank has crushed more wood in a 100 ton press than most folks have seen.And if you want to see some REALLY nifty cribbing packs of quality wood:Well, Frank would love to set you up with some.For a nominal fee of course but considering the quality of his product a very good investment.I'd like to know HALF of what Frank has forgotten about wood,and you'll be surprised at the results of his testing. T.C.

[MetalMedic]

What is wrong with plastic cribbing if it is stacked properly? We carry a mix on our rescue truck and while I prefer the wood cribbing, I am not opposed to using plastic when it can be done properly.

[KenNFD1219]

We have had issues with plastic cribbing (Turtle Blocks). The cribbing works well unless the loads shift or the forces are not perpendicular to the cribbing. This has caused the cribbing slide apart. We switched back to wooden cribbing last year-no problems.

[mcaldwell]

That is certainly interesting.

I did not find it clear however, if they stopped testing the hardwood at 60 tons, or if the wood simply yeilded at 60 tons, and would not take any additional weight.

Either way, I think you would be hard pressed to produce the supposed catastrophic failure we hear about with a 60 ton capacity.


I also like the little crib-pac bag they offer on that site. I may have to look into a couple of those. Better than our milk crates.

[Rescue101]

They're some slick.Study it carefully the first time before you dump it out or you'll be a half hour repacking it(Frank does it in two minutes),ask me how I know.A place for everything and everything in it's place.But if you make a mistake,it's like a Rubicks cube. T.C.

In regards to plastic cribbing. Ron, This is something that needs to be discussed further.

I am currently teaching a vehicle rescue course at a department that has all plastic cribbing. I have made a few suggestions during the class that they also should have some wood cribbing onboard. I told the class I prefer wood.

One thing I have found with the plastic cribbing is hard to move into position. The plastic cribbing has the rough knobby surface so you cannot slide the cribbing in without possibly putting your hands in an unsafe position under the vehicle. If the plastic were smooth, as some is, then the surface will not allow a firm contact until say you let the air out of the tires (many departments do not use the controlled deflation method of cribbing.

The Lincoln log plastic would give you a more secure crib box, but, is difficult to put the rear pieces into the slots when boxxing up to the vehicle. I'm also not sure as to how strong the notch would be ?

Does anyone know what ton capacity the plastic will withstand before failure ?

[Rescue101]

Here's a hint for placing things in harms way.Use a retractable boat hook.Short money and they work great.We use 'em for setting recovery straps but they work just as well for setting crib stacks. T.C.