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Stabilizing Heavy Trucks

Tue, 16 Aug 2011|

Steve White explains why firefighters can't take a small vehicle approach to large vehicle stabilization and examines common cribbing and methods of stabilization. Sponsored by Holmatro.



[BLANK_AUDIO] [MUSIC] [MUSIC] Welcome to Fire Engineering's Training Minutes. I'm Steve White, Battalion Chief, Fishers Fire Department. In this segment we're gonna talk about stabilizing heavy trucks. The one thing we really wanna emphasize throughout this whole program is that you can't take a small vehicle approach to a big truck rescue. We're dealing with vehicles that are taller. Vehicles and their loads that are heavier. And to be able to accomplish this, we have to have good, solid stabilization. We're not capturing the weight of a car. We're gonna start off by talking about four by four cribbing. Four by four cribbing is the most common used cribbing in the fire service. Now technically we know that it's really three and a half by three and a half. For this segment we're gonna call it a four by four. Another key component is the length of the cribbing. We're gonna be dealing with 24 inch long cribbing. When we build our box cribs theres are two critical factors that we want to make sure that we're getting correct. And that is how much weight this crib box can support. And how high we can safely and effectively build this box crib. When we build the box crib we want to ensure that we have four inches of overhang everywhere theres a point of contact. Anything greater than that makes the box unsafe. To be able to figure how much weight we can [UNKNOWN]. We're gonna talk about points of contact, and a point of contact is every the curbing comes across the top of another piece of curbing. Each point of contact can support or capture 6000 pounds. So when we have four points of contact, 6000 pounds times four, is 24,000 pounds. So, as long as the entire load is resting across all four points, we can capture 24,000 pounds of weight. When it comes to height, there's two factors we have to understand. If we capture all four points, okay? We can go up to. 48 inches tall. And we figure that because we're looking at 16 inches from outside to outside, times three, is how we come up with 48. So it's not the dimension or the length of the 24 inches, it's the 16 inches. From where our points of contacts are. So, 16 times three is 48. Four points of contact. We can build this box 48 inches tall. Now we know, in some situations, based on the positions of the vehicles, we may not be able to capture all four points. We maybe only able to capture. Just two points so that takes our weight to six and six, 12,000 pounds but it's gonna have an impact on our height. When dealing with the same 16 inches, it's 16 times one and a half. That comes to 24 inches. So when you're only capturing two points of contact. We can go up to 24 inches and no more, because then when we build it beyond the safety factor, then it can sway and is no longer safe. To capture the points of contacts, it's effective to use. Wedges in various positions. And again, the key point is, we wanna make sure where we capture the load. We wanna distribute it down, and keep our system in line, at all times. Here we're gonna build the box crib, starting with a good stable base. Now we understand that, normally there would be a trailer in the way. We've removed the trailer, so that we can demonstrate clearly. What our task is. Understand too that we have to do a size up to our load and understand what can impact at the end where we go to tighten the system up with our wedges. It could be various bolts, mudflaps, and hoses and other items that are in the way. If we can move the hoses out of the way without cutting, that would be perfect. But any aluminum or metal objects are in the way, we can simply cut off with cutters, chisels or sawzalls so that we can gain good positive contact. Here with this box crib, we're capturing two points of contact. So we're stabilizing 12,000 pounds. At the back points of contact. Using the wedges we're able to tighten that box core back. Now we have an effective means of stabilization for the back of this frame rail. Now we know that in every rescue situation we're not always going to have the perfect scenario. Sometimes it's safer to build the box tower outside of an area and slide it in. Working as a team, using four by fours to push it, we can get it in place safely and effectively. When we tighten it we want to double check because typically our vision is gonna be the front. In order to make sure that we are maintaining that four inches of overhang correctly and keeping all of our points of contact in line. It's critical that we check the two points of contact that we're capturing in the box. So when we slide the box, it doesn't get out of frame. Here we're dealing with an air-ride cab. On size up, it's easy to identify by looking at the back of the cab. Here, we have two cushions. That helps the cab rest. The problem is it makes the cab very unstable during extra casing operations. So, what we want to do is capture the space between the cab and the frame rail, stabilize it so that now, the cab is resting on our cribbing. And not the unstable air ride cushions. [BLANK_AUDIO] As another alternative for stabilizing the air ride cab. We're gonna use side buttress stabilization, also known as crutches. This is an option for stabilizing, if you have the ability to, otherwise, you can simply just use the cribbing and wedges that we just covered. One thing that we wanna stress. Is that we are not supporting the load of the entire tractor. We are just simply stabilizing the aluminum cab for movement, taking it off the air cushions and putting it on our system that doesn't move during extrication operations and patient removal. During this segment of the stabilization, what we're going to do is stabilize the large vehicle on top of a smaller vehicle. It's critical to point out that we have the car stabilized, [INAUDIBLE] it always has to stabilize from the ground up, having a good base, as well as chalking the tires of the truck. In this scenario, what we're gonna use is side buttress stabilization devices in two places to be able to stabilize the load. [FOOTSTEPS] The side buttress stabilization system that we're using is the holmatro power strut. It's a combination of making it a mechanical [UNKNOWN] after we put it in place with a hydraulic pump. A pump in this scenario is a manual pump. A critical factor is where the strut makes contact. Is at the frame rail on both sets of struts. [SOUND] We're simply stabilizing the vehicle. In this scenario we do not have the intent of lifting the vehicle. [SOUND] Once the strut's in place, we're gonna go ahead and back it up. And that makes a mechanical strut. Now, we're gonna put the drivers side struts in place. The struts we're using on this side are static struts. They're not put in place with a hydraulic pump. One critical factor in all rescue operations in particular the initial stabilization phase, we're always trying to strive beyond one name. By being on one knee, that allows us to quickly move out of the area in the event the load shifts. Becomes out of balance. It's also important when you're working on one knee to make sure that you always have a means of egress clear behind you. You don't want any tools or equipment in your way if you wanna move out from the load quickly. [SOUND] The principles of the struts are the same as if you were stabilizing a car. It's an A frame. We're trying to maintain and stay within a 45 degree angle. Good solid positive contact. This is just to stabilize, not to lift or raise the vehicle. Again our strut is making firm positive contact, with the frame rail, and the ground, not to any moving parts on the truck. For this part of the stabilization segment we wanted to simulate a common accident with a car underneath a simitrailer known as an under ride. Looking at our stabilization we're sticking with our twenty-four inch long cribbing, building our solid base. All the way up to our points of contact which when it reaches the top, the outside section is what will be referred to as the rail. Underneath are actual floor joints that run from side to side. Typically, they're spaced anywhere from 10 to 16 inches apart, so it's pretty important that we either read the rivets. To where it's attached. Or we physically go underneath. Size up where those floor joists are, because the two outside points of contact will catch the rail. The back two points of contact, on the curb box, will catch the floor joist. By catching all four points, we are able to say that we are supporting 24,000 pounds without exceeding the max height of 48 inches. As we transition to the other side of the car, we utilized a strut system. One thing that we want to point out about the strut is the placement should also be at the floor joints. Good, solid, positive contact, main, maintaining a 45 degree angle, and we're tightening our ratchet straps. In this scenario we're using two ratchet straps between the struts on either side of the truck. As we close this stabilization segment, we just want to emphasize that we covered just a few basic scenarios. For simple stabilization, loads, weights can vary based on the size of the trucks. So being able to use these tools are a good starting point. We'd like to thank Colmatro, for sponsoring this section of training minutes. Thanks for watching.

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