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- Hydraulic rescue tools come in a couple of varieties:
- Single Acting : Hydraulic pressure will only move the cylinder one way. The return to starting position is accomplished using a pressure relief valve and spring setup. A good example of this is the port-a-power used in the Auto Body trade.
- Dual Acting : Hydraulic pressure is used to both open and close the hydraulic cylinder. Excavators, JCBs, and any other hydraulic construction machinery use this system.
Single Acting Hydraulics
History
Use
Components
Dual Acting Hydraulics
History
Previously rescuers often used circular saws but these suffered from drawbacks such as lots of sparks, which could start a fire, lots of noise, which could stress a victim, and slow cutting. Or rescuers could simply try to pry open the doors using a crowbar or halligan bar but this could compromise the stability of the vehicle, further injure the victims, or unintentionally activate airbags. In comparison, hydraulic spreader-cutters are quieter, fast, 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, later owned by Hale Products, for use in auto racing. A hydraulic spreader was originally developed in 1972. "Because the tool reduced the time to extricate a victim from a car crash, literally snatching them from the 'jaws of death', the tool earned the name Jaws of Life."* Hurst later developed a cutter, and a hydraulic ram.Use
A hydaulic pump is essential to the operation of hydraulic rescue tools. The pump can be hand, foot or engine powered. The tips of the 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 a trapped victim free. 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.System Components
Pump
The hydaulic pump is essential to the operation of hydraulic rescue tools. The pump can be hand, foot or engine powered.Cutter
Spreader
Ram
A ram is a tool that is only used about 10% of the time during auto rescue. There are many types and sizes. There can be single piston, dual piston or telescopic rams. Sizes commonly vary from 20" to 70" (extended). Rams use the most hydraulic fluid during operation so the pump being used must have enough capacity to allow the ram to reach full extension.
Combination Tool
Also known as a combi-tool / combo-tool. This tool is essentially a cutter with a set of blades on it that has spreader tips built on to them. It does both spreading and cutting but it does neither as well as the dedicated tool. In spreading mode the tool doesn't have as much spreading distance, the forces are less than a dedicated spreader and the narrower tip can tear metal when spreading. In cutting mode the dissadvantage over a dedicated cutter is that the spreader tips touch causing some cuts not to go to completion (a full shear is stopped because the blades do not overlap as much as they are able to on a cutter). That said, the combination tool is a good choice where space is limited, as a rapid attack tool or as a backup tool for your main system.
References
See also
External links
- Vehicle extraction technics (PDF file, 70p, 4.9 Mb)
- Hydraulic Tool Manufacturers
"Hydraulic Rescue Tools"