A Guide to Chassis Selection
APPARATUS & EQUIPMENT
IN 1906 WATEROUS delivered the first motorized fire apparatus— a 300-gpm dual gasoline engine pumping unit—to the Radnor Fire Company in Wayne, Pennsylvania. One engine powered the drive engine, the other the rear-mounted pump.
Like so many technological advances, the acceptance of motorized apparatus was neither immediate nor overly enthusiastic. In fact, many companies continued to use horse-drawn fire vehicles until the mid-1920s.
Since their humble beginnings, apparatus have undergone numerous modifications and improvements. Among the first of such improvements was the windshield. Chicago was one of the first cities to specify windshields on its apparatus in 1914. Firefighters who rode on apparatus equipped with such devices no doubt were ridiculed by colleagues. The fire service often has been slow to make changes, especially changes that affect the comfort and safety of firefighters.
Thirty-four firefighters were killed in apparatus and motor vehicle accidents in 1988, according to the NFPA. A number of these deaths involved falls from apparatus. Unfortunately, a visit to almost any area of the country will tell you that firefighters continue to ride on the back step, stand up while riding in jumpseats, or commit other equally unsafe acts. Therefore, it is best to have all personnel ride completely enclosed in the apparatus cab.
The concept of the enclosed apparatus cab has changed very little over time. Chief Hendrix Palmer of the Charlotte, North Carolina Fire Department ordered a fully enclosed cab from Mack Fire Apparatus in 1934. Chief Hendrix had read an editorial in Fire Engineering advocating such a safety feature. A year later Mack delivered a 750-gpm Fire Sedan with a completely enclosed van-type body. American La France followed Mack’s example in 1936, as did Seagrave with its Safety Sedans. Fourdoor varieties introduced by both American I.aFrance and Mack appeared as early as 1937.
Canopies and jumpseats are not new either. Pirsch built canopy cabs as early as 1942 and American LaFrance introduced the Model JOX aerial with a cabforward design and jumpseats in 1939.
COMMERCIAL VS. CUSTOM CHASSIS
In addition to deciding whether to fully enclose the cab, fire chiefs and apparatus specification committees also must make a number of other major decisions when purchasing apparatus. One is the type of chassis to specify: custom vs. commercial chassis. This age-old question has yet to be resolved.
Both commercial and custom chassis are available in a wide range of sizes, shapes, and price tags. Generally, all major ty pes of engines, transmissions, rear ends, and so on are also available in both styles of chassis. The choice is usually a matter of individual preference.
For the most part, the commercial chassis available fall into three categories: medium-range, tilt-cab, and heavyduty. Commercial chassis are popular with the fire service and often are less expensive.
Selecting a commercial chassis has many advantages:
- lower initial cost, with local vendors often offering considerable price concessions;
- local availability of parts and service;
- easier access to engine compartment on certain models;
- manufacturer’s successful track record with chassis model type;
- personnel more familiar with chassis, which helps in driving, operations, and in-house maintenance;
- improved visibility and handling, specifically on tilt-cab models; and
- often more economical to re-chassis.
The commercial chassis also has disadvantages:
— often more lighter-duty than custom chassis and will not hold up to use/ abuse by busy companies;
— limited seating capacity;
— limited visibility and turning radius on engine-forward models;
— engine compartment size on tilt-cab models limits horsepower and pump capacity;
— not conducive to aerial applications;
— height and overall length less desirable; and
— heavy-duty chassis are often as expensive as comparable custom chassis.
As the mission of the fire service changes and personnel spend more time in apparatus, the users expect more out of them. We also have begun to realize the hazards associated with the use of fire apparatus, such as excessive noise levels that result in the loss of hearing. The manufacturers of commercial chassis have developed several methods of enclosing cabs for safety and comfort. The European fire service uses fully enclosed commercial chassis from Ford, Magirus-Deutz, Volvo, Fiat, and Mercedes-Benz.
COMMERCIAL CHASSIS
TILT-CAB WITHOUT CANOPY
FOUR-DOOR ENGINE-FORWARD
MEDIUM-DUTY ENGINE-FORWARD
HEAVY-DUTY ENGINE-FORWARD
Custom chassis offer a wide variety of engines, transmissions, rear ends, and so on. They are typically available in twodoor models with either fixedor tiltcab configuration, four-door models, or more recently a rear-engine design.
Emergency One first introduced the rear-engine design with its Hush model. Spartan Motors also has developed a similar design. These models greatly reduce noise levels, have excellent visibility, and offer a variety of options for crew seating and other uses. They are, however, expensive.
Advantages to specifying a custom chassis include
- heavier-duty chassis and components;
- more appropriate for aerial applications;
- maximum flexibility for design and function;
- believed to have a longer life expectancy;
- specifically built for the fire service; and
- appearance.
Among the disadvantages are -higher initial costs;
— past history of manufacturers going out of business;
— unavailability of local parts and service; and
— higher repair costs.
A SELECTION THAT WORKS FOR YOU
I do not intend to recommend a specific type of chassis but rather to explore the various alternatives available to the prospective purchaser. Select a chassis that is appropriate to the task and affords the maximum safety and comfort to the personnel who will use the apparatus.
The city of Denton, Texas recently purchased the Peterbilt Model 377 chassis with a set-back front axle. Obviously, this is not the solution for everyone, but we based our decision on the following considerations:
- local manufacturing facility afforded significant price concessions;
- price concessions allowed us to purchase options not otherwise available because of budget constraints, such as roll-up compartment doors, flowminders, and an enclosed hosebed;
- successful performance of Peterbilts in the city’s solid waste fleet;
- design allowed for fully enclosed cab and met all NFPA 1500 requirements, and insulation in cowling reduces noise levels outside the vehicle;
- elimination of engine heat from crew area; and
- engine-forward design facilitates easy access to engine for service.
Our major concerns were that the length and height of the vehicle would increase the turning radius and that the engine-forward design would create a visibility problem. So far, the vehicles have performed as well as, if not better than, our existing fleet of more traditional custom vehicles. The set-back front axle and the seven-degree slope on the engine cowl have offset our original concerns.
The fully enclosed cab, complete with heating and air conditioning, has greatly increased both safety and comfort. The reduced noise levels, the ability of all personnel to have face-to-face communications, and the increased features on the apparatus body itself have reinforced our purchase decision.
