By Bill Adams
Part 1 described the development of custom fire apparatus cabs.
Part 2 described how safety standards developed for the commercial trucking industry were adopted by reference in National Fire Protection Association (NFPA) 1901, Standard for Automotive Fire Apparatus. All fire apparatus manufacturers that build their own cabs and chassis were invited to explain how their products are constructed. Their responses follow my questions.
![1 Cab skins, including doors, are constructed from 3⁄16-inch aluminum plate. Also shown is the engine tunnel sidewall, which is constructed from ¼-inch aluminum plate and welded to the front wall, floor, and vertical roof support posts. (Photos 1-5 courtesy of E-ONE.)](/content/dam/fa/print-articles/volume-22/issue-4/1704FA_Adams1.jpg) |
1 Cab skins, including doors, are constructed from 3⁄16-inch aluminum plate. Also shown is the engine tunnel sidewall, which is constructed from ¼-inch aluminum plate and welded to the front wall, floor, and vertical roof support posts. (Photos 1-5 courtesy of E-ONE.) |
Describe your Cab Substructure.
Mark Bartlett, engineering manager, Spartan Motors: “Cab designs are an extruded aluminum substructure platform, using a dual-roll-cage design with aluminum flat panel outer skins.”
Dave Reichmann, national sales manager, Rosenbauer: “Extruded aluminum design, using 6061-T6 extrusions. Our 3⁄16-inch-thick extruded design creates an extremely safe environment for our customers.”
Yoseph Setiadi, operations manager, Sutphen Hilliard, Ohio, facility (cab and chassis plant): “The Sutphen cab is designed similar to a roll-cage design. While strength is a very important design factor, weight is also a great design consideration. We want to design a cab that results in a lower center of gravity for the overall truck. We have chosen aluminum as the primary material used in the construction. The frame construction all around the cab uses extruded 6061-T6 aluminum, which is stronger than the 5052-H2 aluminum we typically see on a sheet metal part.”
![2 The 3⁄16-inch cab sidewalls and cab roof are welded to the perimeter roof extrusions. Slots are CNC-machined into extrusions for wiring.](/content/dam/fa/print-articles/volume-22/issue-4/1704FA_Adams2.jpg) |
2 The 3⁄16-inch cab sidewalls and cab roof are welded to the perimeter roof extrusions. Slots are CNC-machined into extrusions for wiring. |
Joe Hedges, product manager, E-ONE: “E-ONE cabs use a combination of 6061-T6 and 6063-T6 high-strength aluminum extrusions and 0.188-inch 3003-H14 aluminum plate to create an extremely durable structure. The cab foundation features a wishbone style floor substructure that measures 3.0 inches à 2.25 inches with a substantial 0.435-inch wall thickness. The cab also features two centrally located 3.0-inch à 3.0-inch à 0.188-inch wall vertical posts that support a 3.0-inch à 3.0-inch à 0.375-inch wall roof crossbeam. The vertical posts are also welded to the 0.25-inch engine tunnel side plates that extend all the way forward to the front cab wall. At the rear of the cab are two 6.0-inch à 1.438-inch rear wall extrusions that are also welded between the floor substructure and roof extrusions. The roof structure consists of a perimeter extrusion measuring 4.125 inches high à 7.5 inches wide with an internal grid of 1.5-inch à 3.0-inch x 0.188-inch wall rectangular tubes to suppor