Deliberating Custom Versus Commercial Chassis

With stagnancy in the economy amplifying the tug-of-war between municipal budgets and fire apparatus purchasing, debate over the traditional “what worked in the past will for us again” attitude is bound to take on new meaning as fire departments struggle to upgrade their fleets in the face of dramatically rising chassis costs.

The new EPA emissions standard, which became effective Jan. 1, requires severe restrictions on carbon and noxious emissions, which must be cycled through particulate filters and, in many cases, treated with a liquid before discharge into the environment. The cost to engineer these motors and the subsequent re-tooling of chassis, cooling packages and testing are passed on to customers. Custom chassis for aerials can now exceed $300,000.

In our present economic climate, departments will likely be restrained in upcoming purchases due to the burden of added cost and may need to look at sacrifices to what has been tradition. While there are benefits and drawbacks to both the custom and commercial chassis platforms, it is up to the fire department – through research and deliberate evaluation – to rationalize and justify the appropriate chassis platform in the face of funding limitations. It is, therefore, imperative for you enter the evaluative process with as open a mind as possible.

Difficult times translate into difficult decisions, which is sure to cause heartburn for many apparatus committees in the coming months.

The obvious difference between custom and commercial chassis is architectural design. Custom chassis offer shorter wheelbase minimums, more spacious interiors with seating for up to 10 firefighters and wider latitude for exterior cab storage options.

The commercial platform, on the other hand, offers an engine-forward design, which results in longer wheelbase minimums. Crew-carrying capacity is generally limited to five firefighters with a smaller interior footprint placing limitations on storage cabinets and equipment mounting.

From a construction standpoint, custom cabs are fabricated primarily of aluminum plate with a small segment of the market still using stainless steel. On the commercial side, most cabs are fabricated of steel, which are made corrosion-resistant through a double-sided electronic galvanized coating process.

Limited Production

Because the custom chassis is built specifically for the fire service, there are only 2,800 to 3,000 of them made annually – roughly 55 percent of the market. This can result is inefficiencies of production with resultant long-term maintenance issues, especially in the area of electrical, due to limited production numbers.

By comparison, the commercial chassis is but a fraction of a commercial builder’s annual production of hundreds of thousands of chassis for many diversified severe-duty environments. All of them are intrinsically engineered to precise tolerances and built in world-class manufacturing centers.

Properly maintained, each platform can enjoy a life-cycle of at least 15 years, though the custom chassis is likely to last upwards of 20 years or beyond without major refurbishment. The fallacy to this life-cycle, however, is that in 20 years, we will have been through at least five updates to the NFPA 1901 standard, which means a chassis purchased today will be well-beyond its point of obsolescence by 2030. Let us not forget where apparatus standards were in 1990.

One of the most misunderstood and misinterpreted myths in the fire industry today is that those companies that build their own custom fire chassis are somehow of greater importance under the moniker of “single-source” than those who simply are final-stage manufacturers.

What is noteworthy about the “single-source” theory, beyond the obvious marketing strategy, is that “single-source” simply does not exist in our industry.

To be a single-source entity, a manufacturer would need to build, fabricate and assemble each and every component on the apparatus. There is not a manufacturer doing this in the industry today.

The Same Components

Be it custom or commercial, each chassis furnished to the fire industry uses virtually the same components and systems of consequence to the safe operation of fire apparatus. These include engines, transmissions, axles, alternators, drivelines, brakes, hoses, suspensions, steering gears, HVAC systems, seat belts, 9G equipment mounting hardware and seats. The major systems carry warranties not from the apparatus builder, but the component manufacturers, such as Cummins, Allison, ArvinMeritor and Hendrickson. Further, warranty repair on major components is required to be performed by the component manufacturer’s authorized service provider, not your apparatus dealer.

Viewed realistically and considering no one manufacturer makes every component on fire apparatus – an important criterion for any company making the “single-source” claim – one could successfully establish that what “single-source” really means is “single point-of-contact” relative to engineering and production oversight, customer support and warranty repair. Under this heading, almost all of North America’s fire apparatus builders fall into this category.

Custom chassis builders ensure their platforms are complaint to the current National Fire Protection Association standard for automotive fire apparatus (NFPA 1901). Waivers are permitted, by choice, to various parts of the standard, though liability concerns abound if you – or the manufacturer – agree to deviate from the standard.

The commercial platform poses some challenges with NFPA compliance, especially in the area of the Society of Automotive Engineers J1939 standard for interfacing with the vehicle data recorder (VDR) and the seat belt recognition system. Several manufacturers do not permit such an interface with the vehicle electronic control module (ECM) and have stated they will nullify warranties if you do. However, efforts by fire apparatus trade groups are bearing fruit in remedying this situation.

Where engines are considered, you face major changes with the departure from “dirty” motors that were bountiful until the end of 2009. Cooling packages are larger today to accommodate hotter-burning motors working double and triple-time to burn diesel emissions particulates before they enter the atmosphere. Achieving this requires either exhaust gas re-circulation (EGR) or selective catalytic reduction (SCR). In using an SCR motor, you have the addition of diesel exhaust fluid (DEF) – also known as urea – which must be held in a tank separate from the exhaust system.

Motors supplied to both custom and commercial chassis manufacturers will use either the EGR or SCR systems, so there is no real difference between the two platforms.

There are some key differences in cab design beyond the obvious cab-over versus conventional cab designs. Custom chassis tend to have wider door openings at shorter step heights, thus making entry/egress easier. Also available on the custom platform are cabs which allow for raised roofs in the crew area and notched roofs for lower bedding of an aerial. Legroom may be slightly more ample. Finally, there are exterior storage options on custom cabs – such as EMS cabinets behind the front seats and large storage areas in extended cab lengths which cannot be designed into a commercial cab.

Commercial chassis, on the other hand, tend to be higher from the ground, thereby making entry/egress a little challenging, though certainly not insurmountable. Exterior storage options are limited, but there is plenty of space beneath the crew doors of a four-door cab to permit mounting of booster reels, hydraulic/electric/air reels, and storage compartments that are low to the ground and extremely accessible.

Roll-stability, electronic-stability and traction control are standard features on both chassis platforms, as is some variation of crash-testing – be it the United Nations Economic Commission for Europe ECE-R29 test or SAE J2422.

One of the most notable differences between custom and commercial chassis is that the custom platform offers both frontal and side-impact airbags, whereas they are absent in the commercial. Seat belt sensors – in compliance with NFPA 1901 – are also found on custom chassis, while commercial chassis manufacturers have been slow to allow integration of such after-market systems within their ECMs.

Multiplexing Systems

Some custom manufacturers utilize their own multiplexing systems, which allow specific functionality control for their chassis, thereby affording those builders a competitive advantage. Other custom chassis builders, as well as the commercial manufacturers, use off-the-shelf multiplexing systems, such as those manufactured by Weldon or Class 1.

There are no discernable differences in the utilization of front bumpers on either platform. Extendable to a point that ensures staying within an effective angle-of-approach window, the front bumper on both chassis types may be used for hose wells, hydraulic rescue tool storage, reel mounting, front intakes, winches and bumper-mounted turrets. The one area where a fire department can run into a problem is bumper height, which is an issue on the commercial platform, especially if the chassis is a 4×4.

Regardless of chassis style, the typical general warranty on a chassis is for one-year. Other custom chassis warranties vary in terms, depending on the manufacturer. Care must be exercised in understanding, however, precisely what your warranty covers. While chassis frame rails may carry a lifetime warranty for a custom application, some builders only offer a 5-year warranty on their cross-members, which can be strengthened with costly extended warranties. Paint warranties range from 5 to 10 years.

Commercial chassis warranties are weaker than their custom counterparts, outside of the general one-year workmanship warranty. Frame rail and cross-member warranties typically run between 5 and 7 years, and paint warranties last no more than 3 to 5 years. Cab perforation warranties on the commercial platform equal those of the custom version at 10 years.


More importantly, there is no distinction between the warranties for your major systems, such as the power train and axles. These warranty terms are explicitly defined by the component manufacturer, with the caveat that warranty repair be performed by its authorized service centers. Most fire apparatus dealers do not fall into this category, unless they are tied directly into a heavy-truck dealership.

The most telling bottom-line difference between the two chassis types is price. A custom chassis can range – option content dependent – from $160,000 for a bare-bones model with a small-block motor to well beyond $300,000 for an aerial chassis. On the commercial side, a chassis can cost between $80,000 on the low-end to $150,000 for a platform with a big-bore motor.

Only recently have fire departments consciously looked at the European fire service for ideas. Roll-up doors were the bane of many departments when first introduced in North America, yet they have become the door-of-choice on more than 80 percent of new apparatus built in the U.S. European-style chevron striping is now a NFPA 1901 requirement on all new apparatus, and there is least one manufacturer making great strides marketing a European-built multi-stage pump offering simultaneous normal and high-pressure fire flows with an integrated foam system.

Looking At Europe

When it comes to chassis selection, there is not a single major fire department in Europe using a custom fire chassis. Mercedes and Scania – prominent European commercial chassis manufacturers – rule the fire apparatus chassis market with their two and four-door chassis offering 52 to 55 percent cramp angles, short wheelbases and – in the case of the two-door versions – crew modules seamlessly integrated into the body affording comfortable seating for 4 firefighters. Cabs are ECE-R29 crash-tested and are chock-full of relevant safety features. Apparatus functionality with the body and installed components take precedence over the platform which gets firefighters to their destination.

The point here is with fire professionals in other parts of the world, chassis are treated more like a commodity and not the chrome chariots we’ve come to expect in North America. They are a means of transportation to an emergency. It is the functionality of body design and integration of on-board suppression systems which drive the design processes.

Delicate evaluation in determining the best-practical application of chassis platforms for your environment will mean approaching it with an open mind. Be realistic in looking at what can be sacrificed and what are the “must-have” features.

Tradition notwithstanding, practical logic must be at the heart of any chassis selection discussion relative to your specific function and operational requirements. Can you make a compelling case for using either a custom or a commercial chassis? Do your standard operating procedures best suit the custom platform, where EMS equipment and other critical tools are best kept within arm’s length inside a spacious custom cab? Can you realign equipment layouts and utilize “dead” space in a body to accommodate your department with a commercial chassis? With cities focused on being “green” friendly, what options exist that forestall your contribution to your department’s carbon footprint?

A word of caution: When finalizing your chassis decision, look deep inside your psyche and question whether you are justifying one chassis platform over another because of vanity for marketing-driven brand loyalty or genuine utility. Untold tens of thousands of dollars in added cost or savings stand in the balance.

Considerations In Chassis Selection

  • Engine
  • Application
  • Seating
  • Safety and innovation
  • Maneuverability
  • Weight and balance
  • Affordability
  • Functionality
  • Tradition

Custom Chassis Overview

  • More expensive
  • Built for the fire service
  • Logical choice for aerial
  • Greater seating and storage options
  • Chassis storage design options
  • Greater GVWR for multi-purpose
  • ECE-R29 crash testing
  • Warranty repair may be limited
  • Proprietary parts
  • Friendly for daily checks
  • Custom is the fire service tradition

Commercial Chassis Overview

  • Price competitive
  • Fits most applications
  • Engine limitations
  • Seating limitations
  • Customization limitations
  • Good off-road use
  • Longer wheelbase
  • Parts and service availability
  • Maintenance friendly
  • Engineered for other vocations

Editor’s Note: Sean P. Duffy, a 27-year veteran of the emergency services, is the eastern regional sales manager for Rosenbauer America, technical committee co-chair for the Fire Apparatus Manufacturers’ Association (FAMA) and FAMA’s alternate voting member on the National Fire Protection Association (NFPA) 1901 technical committee.


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