By Les Baker
Published Friday, August 5, 2011
| From the August 2011 Issue of FireRescue
The June edition of In-Depth Extrication challenged you to approach extrication tactics as precise, methodical processes that employ various hydraulic tools, and I offered tips for understanding the operational characteristics of your tools. In this edition, I will concentrate on how spreader-operator performance affects the ability to execute tactics, as well as the specifics of proficient hydraulic spreader use.
Respect the Force
Depending on design, hydraulic spreaders can have a spreading force of approximately 50,000 lbs. and a crush force of 25,000 lbs. This amount of force is more than sufficient to rip a vehicle apart in a haphazard or random manner. However, this approach is ineffective in achieving the best path of patient egress in a timely fashion. Extrication tactics using hydraulic tools should be based on a choreographed operation among the cutter and spreader operators, because for most applications, the spreader-operator is responsible for making room for the cutter to sever vehicle components. Because the spreader is actually displacing and distorting components, the spreader-operator can cause a significant vehicle reaction; as such, they shouldn’t displace or distort areas that haven’t been properly evaluated for potential hazards.
Anticipate the Effects
A spreader moves a vehicle’s weaker parts by using its stronger parts as a base from which to push. A spreader pushes in a one-dimensional line that extends in each direction, perpendicular to the tool. Responders can determine the movement of vehicle components by evaluating the strength of the material on each side of the tips. The weaker side will move in the direction of the perpendicular line. This is why relief cuts are sometimes important; they help ensure that the side moving is the one intended. In training sessions, we’ve even taped an antenna on the spreader handle to help students anticipate the direction of movement of the spreader tips. (See Photo #1.)
Think Flat First
Most manufacturers design spreaders with a feature within the arms or tips for crushing material. When completing a crush, the spreader arms have a tendency to move to a flat surface, much like the cutter. Several situations—including door squeezes, body panel crushes and certain third door tactics—require the spreader to be positioned on a flat surface. The spreader moves in one direction or the other until the arms are flat against the area being crushed. With this in mind, the best course of action is to position the spreader in line with the flat area at the beginning of the crush instead of dealing with the spreader movement later. (See Photo #2.)
Easy Does It
Many responders have been told that spreader tips move in an arc, and that they should anticipate this movement while completing tactics. Although this is true to some extent, the tips only move in an arc if the tool body is stationary. Otherwise, while the tips are spreading open, the body will move inward, allowing the tips to move in a straight line in relation to the spread. The shorter the spreader arms, the more pronounced this movement is.
Rescuers should anticipate the contact area of the tips and arms against the areas being spread. Two possible scenarios may develop: 1) The tips may have several inches of contact and as the spread begins, the contact area of the tips will slowly decrease to the point of the tip; or 2) If the arms contact the components being spread, they will have a tendency to pull the spreader into the area (this may be evident when conducting a vertical spread to create a purchase point). The best way to prevent this unwanted reaction is to spread only enough to accomplish the task. (See Photo #3.)
In Readiness & In Memory
The basis for the last three editions of this column has been the need for responders to apply the operational characteristics of both the spreader and cutter to any tactic requiring hydraulic tools. The spreader and cutter should be treated as a unit, with a coordinated effort geared toward the concept of spreading to cut and surgically completing tactics.
Note: This month’s column is dedicated to the memory of 343 brave members of the FDNY who were killed September 11, 2001. In their memory we continue to hone our skills, strive for surgical accuracy and demonstrate the core values of our profession. God bless the United States of America.
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