Jaws of Life

A ram used to push the forward block (motor and 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 Hurst Performance Inc. The Jaws of Life was first used in 1963 as a tool to free race car drivers from their vehicles after accidents.

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

A hydraulic spreader in use

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. Alternatively, 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 in partnership with Zumro resQtec for use in auto racing, with Hurst targeting the American market and resQtec targeting the European market. The jaws of life derives its name from one of the co-inventors, Jack Allen Watson^{[citation needed]}. 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 Jaws^{[citation needed]}, and was later introduced as the Jaws of Life. The hydraulic spreader was originally developed in 1972 by Tim Smith, who later developed a cutter and a hydraulic ram. When an occupant is trapped the 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.

Other manufacturers (including Holmatro and Lukas, amongst others) make equivalent tools.

Tool types

Cutter

The cutter is a hydraulic tool which is designed to cut through metal. It is often called a crab-cutter, owing to the shape and configuration of its blades. Sometimes specified as to its capacity to cut a solid circular steel bar, these are most commonly used to cut through a vehicle's structure in an extrication operation.

Spreader

A spreader is a hydraulic tool designed with 2 arms which come together in a narrow tip. The tip of the tool can be inserted into a narrow gap between two vehicle panels (such as between 2 doors, or between a door and a fender) - when the tool is operated, the arms are opened, drawing apart the metal in the panels. Spreaders are used to "pop" vehicle doors from their hinges.

Spreader-Cutters

A combination spreader-cutter with a built-in, manually operated pump

Detail of a combi-tool's blades.

Whilst a cutter or spreader tool is designed for a particular application, a combination tool is also available which combines the cutting and spreading functions of separate tools into a single tool. 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. These tools sometimes have lower capabilities when compared to the dedicated tool (e.g. a smaller spreading range) but may be useful where space is at a premium on fire and rescue vehicles.

Rams

An Amkus Ram

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.

Power

The tools operate on the basis of hydraulic oil pressure of up to 720 bar, which must be provided from a power source. At present, there are 3 different means of generating the pressure. The most commonly used source is a separate power unit, which is a small petrol (gasoline) engine connected to a hydraulic pump. The oil is pressurised in the pump, and conveyed in a hose under pressure to the tool.

Alternative power sources are a small electrical pump in the tool powered by a heavy duty rechargeable battery, and a hand-operated pump also connected to the tool directly. These are useful for lighter-duty and do not require the storage space taken up by the separate power unit and associated lengths of hose.

References

• Hurst Jaws of Life
• How Stuff Works
• http://www.phoenixrescue.com/about.htm

External links

• Vehicle extraction techniques (PDF file, 70p, 4.9 Mb)
• Hydraulic Rescue Tool Manufacturers
  • Amkus
  • Genesis
  • Holmatro
  • Hurst
  • Lukas
  • Phoenix
  • TNT
  • Weber