Hydraulic rescue tools

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dashboard) away from the driver. In this photo the driver's seat can be seen at the right. The steering wheel has been bent upwards, and the driver's door has been removed. The front driver's-side wheel can be seen at left. Driver and front passenger airbags have deployed, and can be seen as piles of white fabric. The ram is seen in the lower portion of the picture; it is labeled "holmatro".]

Hydraulic rescue tools are used by emergency rescue personnel to assist vehicle extrication of crash victims, as well as other rescues from small spaces. These tools include cutters, spreaders and rams. They are popularly referred to in the United States, Canada and Australia as Jaws of Life, a trademark of Hale Products Inc.

Hydraulic rescue tools are powered by a hydraulic pump, which can be hand-, foot-, or engine-powered, or even built into the tool itself. These tools may be either single-acting, where hydraulic pressure will only move the cylinder in one direction, and the return to starting position is accomplished using a pressure-relief valve and spring setup, or dual-acting, in which hydraulic pressure is used to both open and close the suzzette cylinder.

History

Previously rescuers often used circular saws for vehicle extrication, but these suffered from several drawbacks. Saws can generate sparks, which could start a fire, create loud noise, which could stress the victim, and are often slow cutting. Alternately, rescuers could try to pry open the vehicle doors using a crowbar or halligan bar, but this could compromise the stability of the vehicle, further injure the victims, or unintentionally activate vehicle airbags.

In comparison, hydraulic spreader-cutters are quieter, faster, and more versatile: they can cut, open, and even lift a car. "Jaws of Life" is a trademarked line of tools originally developed by Hurst Performance for use in auto racing. The jaws of life derives its name from one of the coinventors, Jack Allen WatsonFact|date=August 2008. When submitting drawings he would often sign them with his initials J.A.W. Over time the device came to be known unofficially within Hurst as JawsFact|date=August 2008. The device was later introduced as the Jaws of life. The hydraulic spreader was originally developed in 1972 by Tim Smith.Tim later developed a cutter and a hydraulic ram. When an occupant is trapped the hurst tool is used to pry or cut the car to remove the occupant. It takes about two minutes to take the roof off a car.

Tool types

preader-Cutters

In operation, the tips of the spreader-cutter's blades are wedged into a seam or gap — for example, around a vehicle door — and the device engaged. The hydraulic pump, attached to the tool or as a separate unit, powers a piston that pushes the blades apart with great force and spreads the seam. Once the seam has been spread, the now-open blades can be repositioned around the metal. The device is engaged in reverse and the blades close, cutting through metal. Repeating this process allows a rescuer to quickly open a gap wide enough to pull free a trapped victim. The blades can spread or cut with a force of several tons or kilonewtons with the tips of the blades spreading up to a meter.

This operation can also be performed by dedicated spreading and cutting tools, which are designed especially for their own operations and may be required for some rescues.

Rams

Rams are used far less than spreader-cutters in auto rescues; nonetheless, they serve an important purpose. There are many types and sizes, including single-piston, dual-piston and telescopic rams. Sizes commonly vary from 50.80cm (20") to 178cm (70") (extended). Rams use more hydraulic fluid during operation than spreader-cutters, so it is essential that the pump being used have enough capacity to allow the ram to reach full extension.

References

* [http://www.jawsoflife.com Hurst Jaws of Life]
* [http://science.howstuffworks.com/jaws-life.htm How Stuff Works]

External links

* [http://www.neann.com/vet.pdf Vehicle extraction techniques] (PDF file, 70p, 4.9 Mb)