How The "Jaws Of Life" Work

The Jaws of Life have been used to save thousands of lives after an accident, but just exactly how does it work?

When a serious accident has occurred and a driver or passenger have become trapped in a vehicle, the Jaws of Life might be used to rescue them from the wreckage. The Jaws of Life are actually a set of tools which are piston-rod hydraulics known as cutters, spreaders and rams. These various tools are used to pry or rip open the vehicle for passenger removal or to rescue a victim from under collapsed building structures due to earthquakes or other calamities.

Hydraulics work by using the transmission of forces from one point to another through fluid, such as oil. The Jaws of Life uses a phosphate-ester fluid which is fire resistant and will not conduct electrical current. This fluid is safer at a crash scene, where fires can be easily started. The workings of the hydraulic system are such that when a piston pushes down on the fluid, the fluid transmits the force to another piston, which is pushed up. When using the cutter and spreader, a portable engine is used to pump pressurized hydraulic fluid into the cylinder of the piston through one of two different hose ports. The Jaws of Life machine usually uses about a quart of hydraulic fluid, and a valve switch controls through which port the fluid enters. If it enters one port, the fluid forces the rod up and opens the arms of the spreader or the blades of the cutter. The operator of the Jaws of Life can then reverse this maneuver, causing the rod to retract and closing the arms or blades. These powerful operations can rip a car open in seconds. The spreader is used to pull pieces of the vehicle apart or it can be inserted in to the side of the car and tear out a chunk for easier access to the inside of the vehicle. The cutter of the Jaws of Life is used to cut into the metal, and often the cutter and the spreader are joined together in one machine.

The spreader consists of aluminum allow arms with tips that are made of heat-treated steel, and do exactly what the name suggests: spread the metal apart. The spreader can having a force of 16,000 pounds for spreading, over 14,000 pounds of pulling force and can open a space of between 2 and 3 feet. Different spreaders can accomplish more or less than this, depending upon the model. When the portable engine is started, the fluid flows through hydraulic hoses in to the pump. The operator of the spreader opens the arms by using a valve switch that allows the fluid to flow from one hose into the cylinder, pushing the piston and rod up. The rod is linked to the spreader's arms. The rod goes up, making the linkages rotate, therefore opening the spreader arms. The operator reverses the valve to close the spreader arms.

Cutters are usually aluminum-alloy housing with forged, steel blades which have been heat-treated. The piston and the piston rod are normally alloy steel. The cutter runs from a gasoline-powered unit. The cutter has curved extensions which are claw-like and come to a point. These work similarly to the spreader, with the hydraulic fluid flowing in to a cylinder, placing pressure on the piston. When the piston rod is raised, the claws will open, when the rod lowers, the claws will enclose around a structure and pinch through it. The cutters usually have over 12,000 pounds of cutting force at the blade center, over 20,000 pounds of cutting force at the notch and can make 4 inch cuts or higher, depending upon the particular design.

The ram is also a hydraulic system which uses the hydraulic fluid to move a piston head inside of a cylinder, therefore extending or retracting a piston rod. The ram serves to push apart sections of the vehicle or other structure, such as the dashboard. In an emergency, the Jaws of Life can be the only hope you have of getting out of a wreck, particularly if you have sustained injuries which prevent you from being able to leave the vehicle voluntarily. Seconds can make all the difference between death and survival, and the Jaws of Life have saved seconds, minutes, and lives.

© High Speed Ventures 2011