Lifting and Stabilizing: Cribbing Overview
A proper cribbing technique is demonstrated during a recent training exercise on lifting and stabilizing. (Photo: David Pease)
David Pease, Carolina Fire/Rescue/EMS Journal
I want to look at the “art” of stabilizing and lifting over the next few issues. I think we tend to spend a lot of time on the actual extrication techniques but sometimes overlook the stabilizing of the vehicles. How much time do we spend training on stabilization? I can do an entire weekend class just on stabilizing and lifting of vehicles.
First, let us take a look at what types of cribbing and stabilization devices are out there to be used. Standard lumber has been the norm for quite some time and continues to be used by many departments. This will usually consist of treated pine, yellow pine, or even oak and other hardwoods. The sizes vary from 2″ × 4″, 4″ × 4″, 4″ × 6″ and even 6″ × 6″.
Lengths tend to vary from eighteen inches, twenty four inches and even thirty six inches. The length of the cribbing does have a direct coefficient with the height you can stack it. The other type of cribbing we make from the timbers is the step crib and the wedge. Step cribs are usually 2"x 4" pieces that are cut from longer lengths to shorter lengths and then attached on top of each other to form a step type configuration. I always built mine using liquid nail and decking screws.
The other thing to do is to paint the ends of the cribbing different colors as to their sizes and attach straps for easy carrying.
In many training classes I have discovered that students need practice building a basic crib box. The timbers should be placed on top of each other so that the weight bears down on the cribbing block below. You don’t want the cribbing box to be one sided or pyramided upward. If the load were to shift, this could cause the cribbing box to fail.
Another thing to remember is that the cribbing box should not be stacked any higher than twice the length. If your cribbing is two feet long, then your crib box should be no higher than four feet. You may also want to know the weight ratios for the size cribbing your using. Four by four pine cribbing is rated for a horizontal load of 24,000 lbs, while six by six cribbing is rated for a 60,000 lbs load.
Keeping this in mind, you do not want to put heavy loads bearing on your step cribs either, as they are made of two by fours and have a lower load capacity. They are good for filling voids and preventing movements. They also make really good wedges if you turn them upside down and slide them in. Timber wedges should be cut from four by four’s or six by sixes.