Lift and Stabilize, Volume 1 by 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” x 4”, 4” x 4”, 4” x 6” and even 6” x 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 xxxxxx, while six by six cribbing is rated for a xxxxx 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. You will find that wood cribbing blocks will last fairly long and are relatively inexpensive. Your timber step cribs and wedges do not hold up as well, as I prefer plastic for these. There are also plastic cribbing on the market that is fully load rated and petroleum resistant. There are basically two types, the “Lincoln Log” style by Turtle Plastics and the “Lego” style by Res-Q-Tec. Both get the job done and both have distinctive advantages.
Now, let’s look at what our goals are when we stabilize a vehicle(s). This is when the physics kick in. We have to consider weights, gravity, forces, and “where there is an action, there is an opposite and equal reaction.” There are five movements we want to overcome. The first is “vertical movement” where in relation to the ground, the vehicle moves up and down on its vertical axis. Next is the horizontal movement, where the vehicle moves forward or backwards on its longitudinal axis or side to side on its lateral axis. The third consideration is the pitch, where the vehicle moves up and down its lateral axis causing the front end to rise and fall. Yaw is the next movement to look at, as the vehicle twists or turns on its vertical axis causing the front and rear end to move left or right. Then last is roll, where the vehicle rocks side to side while rotating about its longitudinal axis and maintaining a horizontal orientation. I am sure you are now somewhat confused.
However, these are the movements we should be looking for and considering when doing our stabilization. Do we always consider all of these? We probably do not. Perhaps we should look at stabilizing the vehicles like trying to stabilize a ball, or at least concentrating on preventing most all types of movement. If the vehicle slips a couple of inches, is that a real problem? It is, if one of your rescuers has a finger or hand in the wrong place. So spend that extra minute to make sure that all the vehicles are stabilized and extrication work can be done safely.
We will talk more about stabilizing next time and as always, be safe, train hard, and don’t be afraid to think outside the box. Feel free to email me at Reds100@aol.com or visit our website at www.RedsTeam.com. See you next time…….
David Pease, Chief The Reds Team