Everywhere we look the economy is forcing us to change how we think and how we do things. Even the tradition-bound fire service is being affected by shrinking budgets, and additional forces of change are increasing the popularity of a new kind of wildland-like apparatus.
Many volunteer departments are having trouble recruiting and training firefighters, and paid departments are facing personnel reductions or hiring freezes. Training requirements continue to expand, and the new generation looks at the world through computer screens rather than through the contents of their toolbox. There is a growing emphasis on safety issues and the need to deal with increasing traffic congestion. But above all, American fire service needs are changing.
In many communities, we are seeing fewer structural fires and more emergency medical responses, auto accidents and wildland fires. Since every community is different, each one is searching for the best apparatus mix to match its individual run needs, personnel and environmental conditions, and is attempting to reduce the cost per run.
Some communities are deciding the best mix is a wildland-type of apparatus with structural initial attack, auto-extrication, and EMS capabilities—a compact, easy-to-use, two- or three-person multipurpose apparatus that should lower operating costs.
There are two basic chassis sizes for this type of apparatus. The bigger one is commonly an International, Freightliner or F650 Ford; the other is either a F550 Ford or a GMC 5500.
On the smaller chassis, the most common body configuration is a flatbed/platform with compartments and tank on top, but a full body similar to a mini-pumper is also available. On the larger chassis, the full body is the most common, but a flatbed/platform configuration can also be used.
The difference between the smaller chassis and the larger chassis goes beyond bigger compartments, more hose and equipment capacity and a bigger water tank. Various pump systems can also be selected.
With the F550 Ford chassis, the options are very limited. The diesel particulate filter (DPF) and the chassis electronic control system makes a PTO pump or split drive line pump almost impossible. That leaves direct engine-driven pump packages as the only other choice, and performance depends on the weight the apparatus design will accommodate.
Generally, the bigger the engine, the bigger the pump size, the greater the weight. The most common package has an 18 to 26 hp engine pump, but engines up to 60 hp have been used on an F550 Ford chassis apparatus. Regarding weight, the 60 hp engine over the typical 23 hp engine will cost about the equivalent of 50 gallons of water.
With the GMC 5500 chassis, the PTO is blocked by the diesel particulate filter, but installing a split drive line pump drive is possible as long as the pump/pump drive gear box is behind the DPF. This requires a longer chassis wheelbase/cab to axle length; a 120-inch cab to axle length is needed on a two-door chassis and an 84-inch cab to axle length on the four-door chassis.
Midship-mounted pumps rated at 750- to 1,000-gpm are common, but you lose pump and roll capability. To have pump and roll, add a portable pump mounted over the main pump and piped together to support some of the discharges from either pump. Additionally, a direct engine-driven pump package can be used as the primary pump system. Once again, performance depends on the weight the apparatus design will accommodate.
The bigger International, Ford and Freightliner chassis offer many pump drive options—front engine PTO, transmission PTO, split drive line, transfer case PTO and separate direct engine drive.
Front-mount pumps are uncommon today. Many apparatus manufacturers do not like to build them, and very few chassis are set up for front-mount installations. Currently, the best chassis for this application is the International 7400. A pump rated at1,000- or 1,250-gpm will work on that chassis and will provide a big water supply, a short wheelbase and pump and roll.
The most common setup for this class of apparatus is a transmission PTO drive with an Allison Transmission. The EVS2000-style transmission is more limited, with the PTO only able to handle a pump rated at 500-gpm. The EVS3000 transmission has two versions—one that limits the pump size to 1,000-gpm and another that allows a rating up to 1,250-gpm. The EVS3000 package can provide pump and roll depending on the operational application and pump package.
Some 4×4 transfer cases have an optional rear-facing, shiftable, full-power PTO that can be used to drive a fire pump up to 1,750-gpm, depending on the engine size. On the down side, these PTOs will not supply usable pump and roll performance, are not available on all transfer case models and require special transfer case oil circulation systems and oil cooling.
Split Drive Shaft Pumps
A split drive shaft-driven pump is also possible on these bigger chassis. The pump size is limited to the engine size, but forget any pump and roll unless a small PTO-driven pump or a small engine-driven pump package is added to the apparatus. Split drive line applications don’t always work with a 4×4 chassis and a short wheelbase.
As with the smaller chassis, a direct engine-driven pump package can be used as the primary pump system, and performance depends on the weight the apparatus design will accommodate. On the bigger chassis, the engine/pump package can be larger, and 60 to 120 hp are not uncommon.
When buying a National Fire Protection Association standard1901-rated pump, the expected performance ranges and chassis drive requirements are well known and are usually more than what is needed for most fire applications. Most apparatus have plenty of engine power for pumping, and given a pressurized water source, a very big pumping capacity is available.
When using an engine-driven pump package, performance capabilities can be limited. In the end, it comes down to horsepower, hose size and length and nozzle design. An 18 to 26 hp engine will commonly support a couple of one-inch lines or one 1.75-inch line; a 31 to 34 hp engine can support up to two 1.75-inch lines; a 60 hp engine will drive a NFPA 1901-rated 250- or 300-gpm pump; and a 110 hp engine will drive a pump rated at 500-gpm.
Pump and Roll
What constitutes a good pump and roll wildland attack set up? In short, there are three basic types of apparatus: walk-along rough-terrain pump and roll; in-cab, somewhat level ground pump and roll, also may have a bumper turret, and Midwest-style fast-moving prairie land fire pump and roll. Each has its own performance requirements and can be best achieved using specialized specific pumps.
Most West Coast departments, including state and federal wildland agencies, buy a separate engine-driven pump package for pump and roll. Often this is in addition to a bigger primary pump, which commonly is PTO-driven, and which itself could provide pump and roll.
Why are they buying both pumps? The engine-driven package will provide constant pressure and flow no matter how the apparatus is being driven, whereas the performance of the PTO pump changes with drive-engine speed changes. Additionally, when pump and roll operations are being deployed on a grade, engine power at low speeds can quickly run out.
For some departments, the flexibility of these apparatus and their ease of operation, compactness and lower purchase cost are key reasons to have them in their fleets.
Editor’s Note: Gary Handwerk is global pump product manager for Hale Products. He has been involved with the fire service industry for 37 years working for various fire apparatus or pump manufacturers and has been a member of the National Fire Protection Association (NFPA) Fire Apparatus Standards Committee for 17 years.