Apparatus, Pumpers

Rear-Mount or Midmount Pump: It Depends on How You Use the Truck

Issue 3 and Volume 20.

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By Alan M. Petrillo

Fire pumps have been mounted in the front, rear, and center of fire vehicles, but mainly the midmount fire pump has been the clear favorite of fire departments over the years.

Front-mounted pumpers seem to have dwindled to very low numbers in department fleets, while rear-mount fire pumps have experienced a resurgence in popularity in recent years. The reasons some departments are choosing rear-mount pumps instead of midmounts revolve around the pros and cons of each pump location on the vehicle as well as how firefighters plan to use the pumpers.

Rear-Mount Pumps

Scott Oyen, vice president of sales for Rosenbauer, says there are a number of advantages to mounting a fire pump at the rear of a vehicle. “A rear-mount pump allows a smaller envelope truck with the same amount of compartmentation,” he says. “Plus, access to the hosebed is generally better.”

Grady North, product manager for pumpers, tankers, and aircraft rescue and firefighting (ARFF) for E-ONE, thinks the number one reason fire departments spec a rear-mount pumper is to get a shorter vehicle. “Taking the pump module away from the center of the truck and putting it at the rear means you shorten the vehicle the width of the pump module,” North says. “That’s more in line with an urban interface vehicle, which is highly maneuverable.”

Mike Harstad, Rosenbauer’s aerial and pumper products manager, notes that rear-mount pumpers offer significant advantages in terms of maneuverability, safety, and increased compartment space. “Rear-mount pumpers are typically three to four feet shorter than a standard pumper, which makes them more maneuverable. The space where the pump house would have been in the center of the truck becomes a transverse compartment that allows a significant increase in compartment space.”

Chad Trinkner, director of fleet management for Pierce Manufacturing Inc., believes that a rear-mount pumper has the advantage of greater compartmentation. “With the pump at the rear of the vehicle, the pump house doesn’t take up as much valued space on the pumper as a traditional midship pump,” he says. “The disadvantage is that the driveshaft is longer when the pump components are placed in the rear.”

Jim Kirvida, president of CustomFIRE, says the rear-mount pump concept is more beneficial on a custom chassis or two-door commercial chassis. “That allows you to shorten the truck dramatically,” Kirvida says. “With a 1,000-gallon water tank and a 40-inch pump module, you can get a 120-inch cab-to-axle measurement on a typical pumper. If you put the pump in the rear, you can move the water tank forward and balance the load better while you’re maximizing the amount of water you carry.”

Kirvida says that Freightliner and Kenworth chassis are very popular for rear-mount pumpers. “We are able to get a decent compact overall length on those chassis, with 1,000- to 1,500-gallon water tanks and 1,250-gallon-per-minute (gpm) pumps at the rear,” he says. However, compartmentation is generally greater on a rear-mount pumper, Kirvida maintains. “You lose the rear compartment, but you can have a large transverse compartment that’s 96 inches deep that you can’t do on a side-mount pumper,” he says.

Rick Suche, president of Fort Garry Fire Trucks, says his company has seen “a small move toward fire departments using rear-mount pumps, but generally they want big 2,000-gpm pumps with large suction for industrial use with big rear intakes to use with portable water tanks.” He says that approximately 10 percent of the pumpers Fort Garry builds are rear-mounts and that the company has built multistage rear-mount pumpers. “We’ve put two-stage pumps on for ultra-high pressure,” he says, “and also multistage pumps for urban interface pump-and-roll capability.”

Bill Scherer, an engineer with 4 Guys Fire Trucks, says the company has seen a lot more interest in rear-mount pumpers in the past year or so. “It depends on the congestion in the area where the fire department runs,” Scherer says. “With a rear-mount pump, the preconnects are generally in the back so everything comes off the rear of the pumper, which means you don’t have to dodge parked cars if you go into a shopping area parking lot to deal with a car fire. With a side-mount or top-mount, the discharges and intakes are on the side of the truck, taking up more space.”

Scherer says fire departments in heavily populated areas and rural agencies both use rear-mount pumpers. “In rural areas, it’s easier to set up portable tanks and drop a suction off the rear of the pumper and still keep the operation in one lane, allowing the second traffic lane to remain open,” he notes.

Between 85 and 90 percent of the rear-mount pumpers built by 4 Guys are in the 1,500-gpm pump range, Scherer points out. “That’s generally the maximum you can get out of a suction hose by drafting,” he says. “If you try to do multiple suctions on a rear-mount, you have a lot more intake plumbing to mess around with compared with a midmount, where there’s usually a main and an auxiliary suction on the two sides of the vehicle.”

Midmount Pumps

A midmount pump has advantages of its own, Oyen says. “Typically, it’s easier to build a midmount pumper, and the serviceability of the midship pump is much easier for the department mechanic,” he points out. “The midmount also allows for easier access to light towers and generators in the dunnage area over the pump module.”

North believes that E-ONE hasn’t seen so much of a resurgence of rear-mount pumpers because of the popularity of its eMax pumper with a 24-inch-wide pump panel. “It makes for a short truck with a midmount pump and lots of compartment space, including a large rear compartment, which you would lose on a rear-mount pumper,” he says. “The eMax also can be built with pump-and-roll capability.”

One of the big advantages to a midship pump, Kirvida says, is that the driveline is less expensive. “The pump is in the middle of the driveline with a midship pump,” he says. “With a rear-mount you have to interrupt the driveline farther back, under the water tank, which raises the tank between four to six inches higher.”

Doug Kelley, product manager for KME, adds, “The drivelines on a midship pump are much better, in general, while the driveline for a rear-mount has more complexity,” making a rear-mount pumper a little more difficult to build as well as slightly more costly.

Joe Messmer, president of Summit Fire Apparatus, thinks the biggest advantage to a midmount pump is that it typically costs less to build. “In today’s climate, the most important factor is the expense,” Messmer says, “and a midmount pump is less expensive than a rear-mount. That’s probably the biggest thing.”

Operator Location

Harstad says scene safety is greater with a rear-mount compared with a side-mount pump because the pump operator is either at the rear of the vehicle or often at a pump panel in a curbside rear compartment.

E-ONE makes rear-mount pumpers in a couple of configurations, North points out. “One version puts the controls at the rear of the pumper, which gets the pump operator off the traffic side of the truck,” he says. “But, he has to contend with hoses back there, and some people believe it’s a more exposed position. The other version we make mounts the pump and discharges at the rear, while the pump controls are placed in either the left or right rear side compartment, where they typically take up half of the compartment.”

One of the advantages to a rear-mount, Suche points out, is seen when operating on narrow two-lane roads. “On a small two-lane road, you would close down the road with a side-mount,” he observes. “That won’t happen with a rear-mount if it’s placed correctly.”

Trinkner agrees that a rear-mount pump allows a pump operator greater visibility at a fire scene but feels that a pump panel located at the rear of a vehicle means the operator is more exposed to traffic. “In terms of where the operator is located, the advantage goes to the midmount pump, where the operator is in a more sheltered position compared with a rear-mount,” he observes.

Other Considerations

Another disadvantage of a rear-mount, Trinkner says, is that “the height of the hosebed is increased because the water tank has to go over the pump, meaning firefighters would be pulling handlines from a higher location.” Trinkner adds that the New York-style hosebed that uses an L-shaped water tank and puts the hosebed between 50 and 60 inches off the ground isn’t possible with a rear-mount pump.

Messmer notes, “A rear-mount can disrupt laying hose when fighting a fire, and there’s always the question of where to put the attack lines on a rear-mount.”

Discharge and intake placement can be problematic for rear-mount pumps compared with their midship counterparts, North says. “With a side-mount, discharges can be located almost anywhere,” he notes. “With a rear-mount, the discharges are usually all placed at the back. If you want a discharge at the side, you have to pipe it below the compartments from the rear. And, a front suction placement also is more of a problem with a rear-mount pump.”

Kelley says the majority of pumpers KME builds carry midship pumps, although it has made some rear-mount pumpers. Kelley acknowledges that a rear-mount pumper can be made smaller and more maneuverable by eliminating the pump house space but notes that “most departments usually make the body longer and put compartments where the pump module had been.”

Trinkner adds that as a counter to a rear-mount pumper, Pierce makes the Pierce Ultimate Configuration (PUC) pumper, where the pump is located between the frame rails and the pumper is set up with a traditional midship pump panel location, allowing more compartmentation on the vehicle.

“Whether midmount or rear-mount, it all comes down to how fire departments are going to use the pumpers,” Kelley points out. “If they have a standard operating procedure (SOP) for how to position the vehicle, which is key, they can have a better placement with a rear-mount pumper. There’s also better visibility with a rear-mount.”

Trinkner says the decision of midship vs. rear-mount pump always comes down to the individual fire department. “At the end of the day, the fire department will spec what it needs,” he says, “and we build what the end user wants.”

ALAN M. PETRILLO is a Tucson, Arizona-based journalist and is a member of the Fire Apparatus & Emergency Equipment editorial advisory board. He served 22 years with the Verdoy (NY) Fire Department, including in the position of chief.