Hydraulic rescue tools

File:Desincarceration demibloc avant.jpeg

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 Holmatro ram can be seen in the lower portion of the picture.

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 English speaking Commonwealth nations and the US as the Jaws of Life, a trademark of Hurst Performance, Inc. The Jaws of Life were first used in 1963 as a tool to free race car drivers from their vehicles after crashes.

Hydraulic rescue tools are powered by a hydraulic pump, which can be hand-, foot-, or engine-powered, or even built into the tool. 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 hydraulic cylinder.

History

Hydraulic cutter in use during a demonstration at the Monterrey Institute of Technology and Higher Education, Mexico City.

File:Spreizer schlossoeffnung.jpg

A hydraulic spreader in use, seen here widening a window on the door of a Volkswagen Golf Mk2 to allow fire crews access into the vehicle.

The Hurst Rescue Tool was invented by that company's founder, George Hurst, after he viewed a stock car race accident in which it took workers over an hour to remove an injured driver from his car. That was about 1961 and the tool reached the prototype stage of development in 1971. Previously rescuers often used circular saws for vehicle extrication, but these suffered from several drawbacks. Saws can conduct sparks, which could start a fire, create loud sounds, stress the victim(s), and often cut slowly. Alternatively, rescuers could try to pry open the vehicle doors with a crowbar or Halligan bar, but this could compromise the stability of the vehicle, injure the victims further, or inadvertently trigger the airbags of the vehicle.

In comparison, hydraulic spreader-cutters are quieter, faster, stronger, and more versatile: they can cut, open, and even lift a vehicle. Jaws of Life is a now trademarked line of tools originally developed by Hurst Performance. Hurst Performance began to export parts to a European company, Zumro resQtec, to avoid import duty. Zumro resQtec was interested in developing these tools for use in auto racing, with resQtec targeting the European market and Hurst targeting the American market. The hydraulic spreader was originally developed in 1972 by Tim Smith and Mike Brick, 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. Mike Brick coined the phrase "Jaws of Life" after he observed people saying that their new device "snatched people from the jaws of death." Later Brick went on to develop a single rescue tool that could perform all the functions of rescue — push, pull, cut and spread. His patent for this unique design eventually led to the Phoenix Rescue tool, which incorporates his design to this day. Other manufacturers (including Holmatro and Lukas, amongst others) make equivalent tools.

Tool types

Cutter

Hydraulic shears

The cutter is a hydraulic tool which is designed to cut through metal—a pair of hydraulically powered shears. It is often called the jaws of life, 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 extraction operation. Cutter blades are replaceable, and blade development progresses as vehicle technology progresses in order to be able to cope with the new car protection technology.

Spreader

A spreader is a hydraulic tool designed with two arms which come together in a narrow tip, and which uses hydraulic pressure to separate or spread the arms. The tip of the tool can be inserted into a narrow gap between two vehicle panels (such as between two doors, or between a door and a fender) — when the tool is operated, the arms are opened, pushing apart the metal in the panels. Spreaders may also be 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, or combi-tool as popularly referred to by the fire department, 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 metre.

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. Spreader-cutters 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, or when the budget does not allow for a separate cutter and spreader tool.

Many manufacturers utilize the body of their dedicated cutting tool for the combination tool. Specially engineered combination blades that are designed to spread and cut are used on the cutter body. If the end user decides later to add a separate cutter and spreader, the blades of the combination tool can be changed to make it a cutter only.

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 50.80 cm (20") to 178 cm (70") (extended). Rams use more hydraulic fluid during operation than spreader-cutters, so it is essential that the pump being used has enough capacity to allow the ram to reach full extension.

Power

The tools operate on the basis of hydraulic fluid pressure of up to 720 bar (10,000 psi), which must be provided from a power source. At present, there are three different means of generating the pressure. The most commonly used source is a separate power unit, a small petrol (gasoline) engine connected to a hydraulic pump. The hydraulic fluid 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- or foot-operated pump also connected to the tool directly. These are useful for lighter-duty use and do not require the storage space taken up by the separate power unit and associated lengths of hose.

See also

• bolt cutter

External links

• Bonsor, Kevin (August 24, 2001). "How the Jaws of Life Work". HowStuffWorks