By DOUG KELLEY
One of the key interface zone challenges is getting the right apparatus for the job. The problem is that, by definition, any fires there have both a structural and a wildland component. At the same incident, the department may be tasked with exposure protection, structural pretreatment, water supply, interior and exterior attack, and true off-road brush firefighting—frequently against fast-moving fires with large flame fronts.
Generally speaking, there are two apparatus types: structural pumpers, which usually have poor pump-and-roll or off-road capabilities, and wildland apparatus, which often carry limited water with limited pump capacities and are poorly suited for structural attack. It’s rare to find a piece of apparatus comfortable in both worlds.
Through discussions with fire departments, it became clear that the fire service needed a vehicle that could perform well in both structural and wildland components without sacrificing performance in either. As a result, KME developed the Ridgerunner series of interface/multipurpose firefighting vehicles, designed to provide a Type 1 pumper with the functionality and performance of a Type 3 wildland.
The design’s heart is the pump. For wildland effectiveness, pump-and-roll is absolutely necessary, which means good operating pressures at low revolutions per minute (rpm). Structural pumpers require higher capacities for effectiveness, which means high-volume capabilities. Unfortunately, the nature of an impeller means that a single pump can do one or the other but not both at the same time.
KME collaborated with Hale Products to develop the Interface Pumping System, which combines two components—a low-volume impeller with good pump-and-roll performance and a high-volume impeller for stationary pumping. KME’s goal was to achieve 100 gpm and 200 psi at a low engine speed and up to 1,500-gpm National Fire Protection Association (NFPA)-compliant stationary performance.
The pump-and-roll performance definition was vital because many pumps can stay in gear while the truck is moving. But frequently, their performance at low speeds is poor because the engine has to rev up to build appreciable pressure. As a result, they are really “stop-pump-then-roll” because the operator must hold the brake while pressing the accelerator to raise the engine speed. In fact, larger volume pumps cannot build up the higher pressures at low engine speeds. By ensuring that the pump will have good flow and pressure when the engine is close to idle, there will be no appreciable loss in performance as the truck moves, especially if the truck is in low gear.
As the operator/driver, you can completely control both impellers from inside the cab. On arriving at an incident, you can quickly determine which impeller is best for the job. If using pump-and-roll, a flip of a switch engages the low-volume side. Another flip of a switch starts water flowing to the turret on the front bumper, and water is placed on the fire.
You can push another button to start Class A foam. If you stop the truck, there is no need to disengage the pump; the pump may continue to flow as you deploy additional lines. The low-volume impeller can flow up to approximately 400 gpm as you increase the engine speed. If you decide that flow is insufficient, attach a suction line and activate the high-volume impeller to maintain flow to all the discharges and bring the capability of additional discharges, including a large-diameter hose discharge and a full-size deck gun—all without deactivating the low-volume impeller.
The design’s second part involves the body. Again, to excel at the job’s structural component, the unit must have sufficient storage for the tools required. For a successful wildland component, package it in a short wheelbase for maximum maneuverability.
For the base package, the body is limited to 156 inches in length with an 88-inch cab-to-axle measurement (only four inches longer than many smaller brush trucks). The pump is mounted at the front of the body with the pump panel behind the left front compartment door, where it is protected from the elements. The rest of the body contains almost 200 cubic feet of enclosed compartment space, not including the extra storage in the hosebed, which contains more than 70 cubic feet with the capability to add more if required.
A full complement of NFPA 1901, Standard for Automotive Fire Apparatus, ladders can slide out from the hosebed, with additional storage for backboards. The dual preconnects are stored low at the front of the body for easy deployment and reloading, along with hosereel space in either the rear compartment or under the cab doors. The base unit includes 800 gallons of water and 20 gallons of foam.
The chassis is the last part of the design. The base unit is available on a four-door 4 × 4 Navistar chassis, which allows for the comfortable transport of up to five firefighters and their gear. Specialized wildland agencies and many larger wildland apparatus frequently use this chassis. If another commercial chassis is desired, however, KME can package the unit accordingly. In a custom cab, the unit may be mounted on any of KME’s custom cabs, with or without four-wheel drive.
KME believes this truck is useful for many missions. It has a short wheelbase, good mobility in poor terrain or weather, large compartments, high-capacity pumping for large incidents, and smaller-capacity pumping for most responses (as well as pump-and-roll) and meets all NFPA 1901 pumper requirements. In short, this truck’s goal is to fill a need not currently being met within the industry, and it expands the capability of the fire departments that use it.
The Ridgerunner series will be unveiled at FDIC.
DOUG KELLEY is the wildland product manager for KME Fire Apparatus.