The popularity of the TV series Emergency boosted the recognition of rescue trucks. The show was about two Los Angeles County Fire Department paramedics and the staff of Rampart General Hospital's emergency department. Each episode centered on a disaster or medical emergencies. It took viewers from the genesis of the paramedic program in early 1972 and showed their truck, Squad 51, a small rescue, in action during earthquakes, auto accidents, airplane crashes and fire fights.

The first rescue trucks in the early 1970s typically were built on a light-duty cab chassis with two-wheel drive and gasoline engines because rescue tools and equipment were simple: chains, come-alongs and hand-powered tools. But they evolved to small, lightweight, low-duty cycle vehicles to carry equipment to aid or support an emergency incident.

Speccing your rescue

Before you start specifying your light-duty rescue truck, you need to determine:

• Personnel requirements

  How many crew members will respond on the truck?

• Vehicle objectives

  Will the rig provide extrication, air supply, rehab, water or ice rescue, or a combination of all these?

• Equipment needs

  What additional equipment will you need to purchase to fulfill the objective of the unit?

• Onboard equipment weights, measurements and categories

  How much room will the unit need for major components such as generators, light towers, cascade air systems and hydraulic power units?

Consult NFPA 1901 for its guidelines. The standard can be purchased by calling 800-344-3555, or by visiting www.nfpa.org/catalog.

Rescue trucks fall under the “Special Service Fire Apparatus” portion of the standard. A minimum of 120 cubic feet of enclosed compartmentation is needed to meet the requirements. This should be an easy requirement to meet, as even the smallest bodies should have at least double the amount of this requirement. Also, there are some minor equipment requirements that will need to be considered, such as one SCBA for each seated position, but not fewer than two total, and one spare air cylinder for each breathing apparatus carried.

The first light-rescue trucks had gross vehicle weight ratings from 8,000 to 10,000 pounds and payloads of 2,000 to 4,000 pounds. At that time body manufacturers were building mostly from steel. When the body was fabricated and only a small amount of equipment added, the unit was overloaded.

Today the light-duty rescue can be built on a two- or four-door cab chassis with GVWR up to 19,000 pounds for two-wheel drive, and 17,500 pounds for four-wheel drive. This range allows for more options and greater flexibility.

Weighing in

The light-rescue truck will not work for everyone depending on how much equipment is going to be carried. A complete inventory of all equipment should be done with dimensions and weights. A great tool to help you with your inventory is available from the Fire Apparatus Manufacturer's Association Web site at www.fama.org, where you can download the Equipment Weight and Cube Calculator.

Even though the GVWRs of light-duty rescues are higher than they used to be, it's still very easy to overload the vehicle. The 2003 edition of NFPA 1901 tells us the equipment allowance for a special service fire apparatus from 10,000 to 15,000 GVWR is 2,000 pounds, and 15,001 to 20,000 pounds is 2,500 pounds. Another important consideration when determining your total weight load is your personnel. Unequipped personnel weight should be calculated at 200 pounds per person.

Most light-duty cab/chassis have standard cab-to-axle (CA) dimensions: 60, 84, 108 and 120 inches. The CA is the distance from the back of cab to the center of the rear axle. Typically the 60-inch measure is used for a 10-foot body, 84-inch for a 12-foot body, 108-inch for a 14- or 15-foot body, and 120-inch for a 15- or 16-foot body.

You can use a four-door, 4×4 cab/chassis up to the 84-inch CA, but beyond that you may run into an overload situation. Be very cautious with the larger 14- to 16-foot bodies, even with a two-door unit. Bodies are fabricated many different ways: formed or extruded construction; steel, stainless steel or aluminum; and varying thicknesses. All these things will have an effect on the weight of your body. Aluminum weighs approximately 40% less than steel or stainless steel, allowing for more equipment storage or personnel in the long run.

Required duty

The first light towers built were installed on rescue trucks and have evolved into being used on pumper and aerial trucks. Light towers are available from 3kw to 9kw using halogen or metal halide lights. Proper lighting is essential for emergency scene safety, where being seen is just as critical as being able to see. Lighting often is taken for granted because most training is done during daytime hours. Lighting should be put in to service automatically.

Light towers can be roof mounted or recessed for a lower profile if necessary. Light towers will help light all hazards and call attention to overhead power lines, holes and unsound structures. They light major access/escape routes and ensure safer, more efficient movement. Make sure your generator is sized to simultaneously operate light tower and any other devices, and allow for at least 20% more than anticipated load.

Warning light requirements for your light rescue will probably be the same as your pumper or aerial unless it's under 25 feet in overall length. This puts the truck into the “Small Apparatus” portion of NFPA 1901, which requires less lighting. While most would agree that more lighting is better, you could save some money and amperage in this area.

Speaking of saving amperage, consider some of the new warning light packages using light-emitting diode units. You can significantly reduce your amperage requirements compared to a halogen or strobe lighting package. Be prepared to pay more, but the payoff is that an LED will last for 100,000 hours — that's the equivalent of more than 11 years of continuous operation.

Power needs

Generators, too, have come a long way since the first light-duty rescue trucks were built. Built-in or portable generators still are an option, but the size, weight and cooling requirements should be considered in design and layout.

The center-rear location is typically the best spot, but the generator may be placed on the side of the body depending on weight. NFPA 1901 talks about load distribution and keeping the side-to-side load variation to no more than 7% of the tire or axle weight rating. Gas or diesel generators with fuel drawn from the cab/chassis fuel tank also are available.

If these generators take up too much weight and space on the truck, consider an under-hood belt-driven or power take-off generator. These generators are lighter and won't add noise on scene, create additional heat or take up usable compartment storage areas. Best of all, they require little or no maintenance.

Under-hood generators typically are rated from 5kw to 10kw. The generator is located in the engine compartment and belt-driven from the engine. Power can be used while driving or stationary. The only other component to the belt-driven generator is a control box, about the size of a computer tower that needs to be located in a compartment.

The PTO generator can be installed on a two-wheel drive light-duty rig if it's equipped with a PTO opening on the transmission. This typically is offered as a manufacturer option, but it needs to be added when the vehicle is ordered. A PTO generator can't be used on a four-wheel drive unit because of the location of the transfer case in relation to the PTO opening on the transmission.

Typically PTO generators can be operated up to 15kw. The torque rating is not sufficient to handle a PTO generator larger than 15kw, and unlike the belt-driven model, the PTO generator only can be used when the truck is stationary.

Another generator option is the hydraulic generator, which can be used while driving or stationary, and on two- or four-wheel drive up to 10kw. Although not as popular as the above generators due to its costs and maintenance requirements, this generator covers all the operational bases.

Air supply

Air systems on a light-rescue truck should be given careful consideration due to the substantial weight of most of the components. Air system storage choices should be matched to the output of the stationary air compressor. DOT cylinders with 4,500 or 6,000psi ratings weigh 144 pounds or 188 pounds each while ASME cylinders with 5,000 or 6,000psi ratings that weigh 400 pounds each.

The DOT cylinders need easy access for removal, as they will need to be removed every five years for hydro testing. The ASME cylinders never need hydro testing, so they can be located in areas where future access may not be of a concern. However, they cost more than DOT cylinders.

Fill stations are built in many sizes and configurations: one-, two- or three-bottle fill positions; drop-down or side-opening doors. Regardless of design, fill stations need to be built and tested to NFPA 1901. Fill stations weigh from 300 to 750 pounds and typically are side-loaded because the fuel tank is located at center-rear.

Offset the weight of the fill station with the weight of the air storage. A typical four-cylinder 4,500psi DOT system air storage with one-bottle fill station components would weigh about 900 pounds, and fill 39 2,216psi cylinders. The average 2,216psi aluminum SCBA cylinder weighs 30 pounds, and a carbon cylinder weighs 20 pounds.

In this example it would weigh more than the cascade system to carry 39 aluminum cylinders at 1,170 pounds, but it would weigh less to carry 39 carbon cylinders at 780 pounds. These are just some considerations when determining your air system. Again, work with your rescue truck manufacturer to determine the right system, and keep in mind the side-to-side load variation to no more than 7% of the tire or axle weight rating.

Storage issues

Hinged or roll-up compartment doors are available from all manufacturers. Hinged doors aren't as popular on a rescue truck because they can block access to the equipment stored in compartments and obstruct personnel from vision of oncoming traffic.

Roll-up doors are available with or without locks, and they can be painted to match the truck's exterior. Some of the roll-up door manufacturers even have designed compartment lights into the door track that allow for a more even lighting of compartment area, but these lights draw a lot of amperage. A lot of departments use LED-type compartments lights, but be prepared to spend about one-and-a-half times more than the cost of the built-in door track halogen lights.

Special compartment features that store equipment in place and prevent damage while the truck is moving are very important. Look for shelving that's easily adjusted, has a vertical lip in front or rear to hold equipment in place, and can stand up to the weight of the equipment that is going to be stored on it.

Slide-out equipment trays can have ratings up to 1,000 pounds and can slide out one or two ways on either side of truck. Make sure the equipment you intend to store on each tray is within the weight rating of the slides used and will fit properly. Slide-out tool boards are a one-way slide-out vertical panel used for storage of anything from hand tools to shovels to SCBAs. When used for SCBAs, mount at the right height level for easier donning.

Slide-out and drop-down trays are also a way of storing equipment. The trays usually are rated for loads up to 250 pounds, but that often is too much for the average person to pick up and push back into compartment. Special equipment items such as stokes basket, back boards, air bags, and spare SCBA cylinders usually require a special module to compartmentalize each unit for storage. You also may consider special storage boxes for storage of small items or for items that are difficult to carry, such as chains, and small hand tools.

Writing specifications for your rescue truck is the most important aspect of this process. This allows you to determine the quality you want before you go to bid. If you ask for an NFPA-compliant halogen lighting package, most manufacturers are going to give you the least expensive package they offer, because they want to be low bid. But if you ask for a specific lighting brand and include model numbers, then they all have to bid to that quality level.

The same can be said for the other major components specified on truck. After the bid opening, evaluate each proposal for compliance; don't assume you're going to get what you specified. A light-duty rescue truck can be versatile if the time is spent beforehand making sure the unit accomplishes the objective you set for it and holds all equipment you want without being overweight.

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Bob Sorensen is the vice president of SVI Trucks, a Loveland, Colo.-based company that specializes in building rescue, hazmat, air/light, command, bomb and initial-attack trucks for emergency services.

Equipment Requirements

	Weight load (lbs.)
	4×2	4×4
GVWR	19,000	17,500
2-door cab	7,300	7,500
4-door cab	7,900	8,250
10-foot body	4,000	4,000
12-foot body	4,800	4,800
Equipment	2,000-2,500	2,000-2,500
Each Member	200	200

This chart can be used to help you decide whether a light-rescue truck will fit your equipment requirements. One of the most common mistakes made when purchasing a light-duty rescue is that you end up with an overloaded vehicle that doesn't handle well, and is unsafe to drive.

A good rule of thumb when determining your light-rescue truck requirements is:

GVWR-cab-body-equipment-crew=leftover payload

Let's say your fire department is considering a 4-door, 4 × 4 with a 10-foot body to accommodate 2,500 pounds of rescue equipment and a five-person crew.

17,500-8,250-4,000-2,500-1,000=1,750 pounds

Of course, requirements will vary, so check with the manufacturer you're working with to verify all equipment and body weights before you purchase your truck.

Tools of the Trade

Rescue tool operation can be accomplished several different ways from a light-duty rescue. A portable gas-power unit can be stored on the unit or mounted on a slide-out tray for easy access, or a built-in electric-power unit can be powered from the on-board generator system.

Depending on your generator size and power unit requirements, you can operate one or two tools. The gas- or electric-power unit can then be connected to one or two built-in 100-foot hydraulic hose reels. This allows rescue tools to be stored in a compartment, pre-connected to the hose reels for quicker deployment. The advantage to the electric power unit is that it does not add additional noise onscene and is easier to start than some of the gas units that may be affected by weather and temperature.

A system also is available from many of the rescue tool manufacturers that is operated from the PTO opening, similar to the hydraulic generator system, and powers up to three tools simultaneously. This system can be installed on either a two- or four-wheel drive cab/chassis and takes up no usable compartment storage space. A drawback to the hydraulic system would be cost, typically one-and-a-half times the price of a dual electric-power unit, and the added maintenance.