You've all seen those big heavy-rescue trucks with bodies designed to carry just about every piece of equipment imaginable. Have you ever wondered why departments specify such big apparatus and what they have under all that sheet metal?

Over the past 40 years, people have come to view their local fire departments as multi-function emergency service providers that can handle everything from fires and heart attacks to lockouts and building collapses.

As a result, many departments now specify very large heavy-rescue units simply because they have to respond to a lot of different types of rescue situations. For example, a growing number of departments regularly have to handle multiple-vehicle accidents, sometimes involving trucks, buses or farm equipment. Other departments need to deal with trench, confined-space, structural-collapse and high-angle rescues. Some have to handle specialized ice and water rescues. Each of these situations has evolved into a specialized function that requires specialized gear.

Interior design

To keep all of this diverse equipment secure and ready for use, the inside of large heavy- rescue units takes as much planning and design as the outside.

The walk-around body design with exterior compartment doors has largely replaced the walk-in design because it allows a more efficient use of space. Equipment used for specific types of rescues often are grouped together, and compartments are fitted with slide-out tool boards, trays and racks. Heavy items are mounted low on the body to make it easy to unload them.

Another reason departments specify very large heavy rescues is that some of the equipment can be quite large or require permanent installations. They aren't the sort of items you just throw in a compartment.

One of the larger items typically found on large heavy rescues is a generator. Many units are equipped with permanently installed 20kw to 40kw generators powered directly or indirectly by the transmission power take-off. Generators are used primarily for lighting, but they may also supply electrical power to drive hydraulic pumps for rescue tools. Other uses include power for communications equipment, hot water heaters, refrigerators, auxiliary air compressors, winches and other components.

Other large items found on large heavy rescues are hydraulic pumps and hose reels for rescue tools. Many departments have found that using two or more hydraulic rescue tools can speed automobile extrications to take advantage of the golden hour of survival. Multiple rescue tools also can help departments deal with extrications involving several vehicles in several locations. Installing the pumps on the apparatus and transmitting the power to the rescue tools through hose reels allows the use of larger pumps for faster tool cycle times. It also reduces the noise at the scene to improve communications and minimize patient trauma.

Some heavy rescues have a breathing-air compressor or cascade system with storage for spare air bottles. These typically are used for incidents in high-rise buildings, tunnels, subways and other confined spaces where personnel may be exposed to a variety of hazardous atmospheres. A few rescues are equipped with preplumbed hose reels to supply breathing air to locations far from the apparatus.

Finally, some heavy rescues are equipped with high-capacity winches or cranes to lift or stabilize heavy objects. These devices may be used for over-the-side vehicle accidents where the vehicle is on a slope and can't be stabilized by normal struts or cribbing. They also may be used for incidents involving heavy machinery or large rocks. Some rescue units use portable winches with multiple receiver points positioned around the chassis to allow operation from all sides.

Extended operations

Some departments specify very large heavy-rescue units because they want to include areas for command and communications or provide facilities to allow personnel to recuperate during extended operations.

Command and communications areas are usually positioned in the back half of the cab and may extend rearward into the main body. Several custom apparatus manufacturers have optional cab configurations that include a work area with a single rear door on one side and a blank wall on the other. These areas also can be equipped with a raised cab roof and a walk-through opening. Having separate areas allows incident commanders to formulate tactics in a quiet atmosphere and keeps sensitive communications gear out of the elements.

Facilities for recuperation during long-term incidents may be as simple as drop-down awnings or as sophisticated as fully equipped galleys and lavatories. They may include heaters, misters, benches or telephone connections. Some departments may incorporate semi-enclosed facilities outside the apparatus for patient triage and treatment.

In the end, every department has different target hazards and different operating conditions. One size of rescue apparatus doesn't fit all situations. In some cases, however, bigger can be better.