Heavy lifting drills can be an absolute blast for rescue professionals. There is something extremely satisfying about lifting an object of considerable weight with the simple press of a button. However, there is a lot of knowledge, skill, and attention to detail that goes into these evolutions.
Do you know how much weight your box cribbing can safely carry? Typical 4″ x 4″ cribbing made of softwoods (i.e., Douglas Fir) will provide you 6,000 lbs. of carrying capacity per contact point. That means, when you stack two pieces of cribbing per layer, you have a total of four contact points for 24,000 lbs. of carrying capacity. The maximum height of a crib stack is relative to the length of the pieces of cribbing, but the recommended maximum height of a crib stack made of 4″ x 4″ cribbing is 4 feet.
It is critical that all layers of the crib stack are aligned perfectly. The transfer of weight through the crib stack is dependent on all of the connection points being in line. If one of the layers of the crib stack is off centered, the entire operation can be compromised. It is also important to maintain at least 4″ of overhang on the edges of the crib stack. Finally, when lifting with high pressure air bags on top of a crib stack, the top layer of cribbing has to be a solid layer or else inflating the air bags will cause the entire stack to fail.
High Pressure Air Bags
The high pressure air bags pictured here are operated at 118 psi, but you have to be familiar with the correct operating pressure of your bags. Some newer models operate at higher pressures. Try to use the biggest air bag you have for your lifting evolutions to ensure you get maximum lift height and capacity. Remember, as the bag inflates, its lifting capacity decreases due to the bag’s shape becoming rounder.
A maximum of two bags can be stacked (again, this can differ between makes and models), and when that is done the lifting capacity is equal to that of the weakest air bag. We recommend always stacking two bags if you have the space, even if you don’t think you will need to use both of them. It slows the whole rescue scene down when you realize one air bag isn’t giving you enough lift height and you have to scramble to add a second bag in after the fact.
It is important to remember that stabilizing and lifting are two different operations. The priority is stabilizing the object to prevent the load from shifting and making the situation worse. Then, we can set up our lifting operation. When we lift, we always follow the object up with our stabilization system. We refer to this concept as, “lift an inch, crib an inch.”
Assign a supervisor to oversee both the stabilization and lifting operations to ensure they are on the same page and coordinating their efforts. The supervisor should also give all lifting commands. A safety officer is also an important position to fill during these evolutions. Keep the number of personnel near the object during the lifting operation to the bare minimum (typically just those adjusting the stabilization system). For those who must remain close to the object during the lift, ensure they are wearing appropriate PPE and always have an “exit strategy” should they need to remove themselves from a dangerous situation.
Lastly, you must coordinate the lifting operation with EMS! Crush syndrome treatment has to begin before the lift and its imperative EMS is ready to provide follow-up treatment as soon as the patient is extricated. We’ll talk about this more in our next blog post.
Owner / Lead Instructor
Elder Technical Rescue Services, LLC