Apparatus Load Balance Guidelines

BY BILL ADAMS

It is exasperating when fire departments pub- lish apparatus purchasing specifications mandating requirements they do not understand. It is troublesome when some manufacturers and their dealers encourage potential customers to specify those same requirements when they too cannot fully explain what they mean. Examine “load balance guidelines,” a requirement referenced in National Fire Protection Association (NFPA) 1901, Standard for Automotive Fire Apparatus, 2009 edition. In particular, look at “front-to-rear-axle weight distribution.” Everyone has an idea of what it means, but few people can really explain it. The significance of proper load and weight distribution is emphasized throughout NFPA 1901. Purchasers should recognize what load balance guidelines are, who establishes them, why they are important, and who must adhere to them. Not following them could cause an accident. It would be unsettling to be responsible for causing an event you could have or should have prevented. Could you be held accountable for inaction? Claiming ignorance may not be an adequate defense if challenged. It is frustrating when you cannot readily find the answer to what appears to be a simple question: What is the proper front-to-rear-axle weight distribution for the fire truck I am buying? To avoid complicating the topic, only NFPA requirements—not governmental mandates—on chassis components are discussed below.

It is imperative to note when the NFPA 1901 says “shall,” the requirement is cast in concrete; when it says “should,” it means you ought to comply with the requirement. Whether a purchaser complies with some or all of NFPA’s “shoulds” and “shalls” is best left to the jurisprudence of the authority having jurisdiction (AHJ). Equally important, note that NFPA 1901 mandates not just physical items (e.g., nozzles, lights, and similar accoutrements); it also requires purchasers and manufacturers to follow “guidelines”—regardless of how nebulous they may be. Deciding whether a purchaser should not follow a guideline or a procedure is another call best left to the AHJ and not the fire department.

In both cases, you may consider seeking legal advice prior to making those decisions. Some day, you may have to professionally, morally, or even legally substantiate why you chose only to accept the parts of an NFPA standard you like and understand while ignoring others you dislike or do not understand. Good luck. NFPA 1901 is technical and detailed in many areas; however, it is not when addressing the front-to-rear weight ratio portion of load distribution guidelines.

Chapter 3 of the standard lists definitions applicable to terms used throughout the document. Surprisingly, the standard does not provide load balance guidelines or define front-to-rear weight distribution. NFPA 1901 tells you what may cause an accident with your apparatus if they are not followed, but it does not appear to give an adequate description of them.

(1, 2) According to NFPA 1901-4.13.1.1(1), “The apparatus shall remain stable to 26.5 degrees in both directions [i.e., driver’s side and passenger side] when tested on a tilt table.” Although NFPA 1901-4.13.1.1.1 says compliance with side-to-side vehicle stability can be certified by calculating or testing the actual or a similar vehicle, a computerized calculation may not depict the reality of a physical test of the actual vehicle. Purchasing specifications requiring photographs of the actual tilt-table testing may be beneficial to the end user. (Photos courtesy of CustomFIRE Apparatus, Inc.)

In this narration, load balance guidelines are separated into side-to-side and front-to-rear categories. The first is well defined; the latter is not. NFPA 1901 Section 4.13 “Vehicle Stability” addresses rollover stability, weight distribution, and load distribution. It is unequivocal in addressing side-to-side weight issues such as determining the vertical center of gravity, stability control systems, and testing methodology using a tilt-table (photos 1-4). Section 4.13.1.1(1) states, “The apparatus must remain stable to 26.5 degrees in both directions when tested on a tilt table ….” Section 4.13.3.3 states: “The apparatus, when loaded to its estimated in-service weight, shall have a side-to-side tire load variation of no more than 7 percent of the total tire load for that axle.” The 7 percent maximum weight variance and the minimum 26.5-degree stability angle are precise and explicit. They can’t be more than 7 percent or less than 26.5 degrees. Neither is subject to negotiation by a fire department, personal interpretation by a chassis builder, or subjective analysis by the apparatus manufacturer.

(3) This vehicle exceeds the NFPA requirements by more than 14 percent.
(4) Weights are distributed in compartments to approximate the typical in-service use of the apparatus, per NFPA 1901-4.13.1.1.3.2.

Concurrently, front-to-rear weight ratio requirements are ambiguous. It is challenging to determine what they are. They are important because the NFPA says the manufacturer “shall” build the rig to meet them and you “shall” adhere to them now and after your new rig is in service. Professional input was randomly solicited—in writing—from more than three dozen manufacturers including commercial and custom fire apparatus chassis builders, apparatus manufacturers that build their own custom chassis, and those that outsource their chassis requirements. Industry professionals, a commercial truck association, and fire apparatus dealers were contacted for feedback. The response was disappointing. Some would not comment on the record. Others expressed concern of liability issues. Amazingly, some would not or could not give definitive answers and, disappointingly, some answers appeared to be contradictory. Asking manufacturers to comment on load balance guidelines appeared akin to asking them to play catch with a live hand grenade. Off-the-record statements from manufacturers are not addressed herein—it is not fair to them. After this article has been published, any manufacturer opining in writing on the subject or responding to our questionnaire will be acknowledged and addressed in a future issue.

Several decades ago, apparatus manufacturers and dealers referenced a publication called the National Truck Equipment Association’s (NTEA) Handbook, which had “recommended” or “allowable” weight distribution by percentage of gross vehicle weight (GVW) per axle for various types of commercial chassis such as conventional, tilt-cab, tandem, and so forth. It is unknown if apparatus manufacturers reference the handbook today. The NTEA did not respond to a request for information. Several old-time dealers recall the front-to-rear-weight ratio being in the neighborhood of 30 percent weight on the front axle and 70 percent on the rear axle (30/70). With the introduction of nonmetallic apparatus bodies, nonmetallic booster tanks, and apparatus similar to nonwalk-in style rescue trucks, manufacturers seemed content to meet a 35/65 ratio, then 45/55, with some struggling to maintain a 50/50 ratio. It was not unheard of for builders to add weights to achieve a weight balance ratio. The introduction of rear-engine and mid-engine fire apparatus chassis further clouded the weight ratio debate. It is unknown if any custom fire chassis manufacturers use or refer to the NTEA Handbook. Another unknown issue is whether or not the front-to-rear weight distribution varies with the application of the apparatus—i.e., pumper, tanker, aerial, and so forth. Ask your sales representative what the front-to-rear weight ratio is for your new apparatus. Demand it in writing. Require it in your specifications.

Below, statements in quotes are from NFPA 1901. Comments, interpretations, and questions are mine.

In Annex A, “Explanatory Material,” Section A.4.13.2.1 states, “The distribution of the weight between the front wheels and the rear wheels should be a major consideration ….” It goes on to give the reasoning for this. Too little weight on the front end can cause a front-end skid; too little weight on the back causes a rear-end skid. If you are buying or planning to drive a fire truck, you ought to read that section. The reasoning concurs with other publications concerning driving and vehicle-handling characteristics. Search for it on the Internet.

Section 4.13.2.1 states, “When the apparatus is loaded to its estimated in-service weight, the front-to-rear weight distribution shall be within the limits set by the chassis manufacturer.” Buyer beware: This statement says that when you load your fire truck, you have to meet the front-to-rear weight ratio set by the chassis manufacturer. What is the ratio? Is it documented?

Section 4.13.3.2 states, “The manufacturer shall engineer the apparatus to comply with the gross axle weight ratings (GAWR), the overall gross vehicle weight ratings (GVWR) and the chassis manufacturer’s load balance guidelines.” This statement, directed at fire apparatus manufacturers, says the apparatus builder must build in accordance with the chassis manufacturer’s requirements. If a cab with chassis is purchased on the open market and the apparatus manufacturer builds on it, whose guidelines are followed?

Section 4.13.2.2 states, “The front axle loads shall not be less than the minimum axle loads specified by the chassis manufacturer under full load and all other loading conditions.” When you took delivery of your new rig, were you told there has to be a minimum weight on the front end? Is it in writing? What does “other loading conditions” mean? If you take nine people out of your 10-person cab and weigh the rig, does it still have to meet the minimum front-end weight requirement?

Section A.4.13.3.1 states: “It is critical that the purchaser provide the manufacturer the equipment inventory and mounting locations for equipment on the apparatus. This information should include existing equipment and estimated future equipment to be carried.” The section further elaborates the purchaser’s responsibilities, stating, “The projections of total equipment payload and mounting locations are essential for proper engineering of a new fire apparatus. It is the responsibility of the purchaser to properly load the fire apparatus and place equipment to comply with the GVWR, the front-to-rear weight distribution, and the right-to-left load balance requirements of this standard.” This section is definitive in stating the purchaser must conform to the ambiguous front-to-rear weight distribution as well as the explicit side-to-side requirements. There is no doubt this means after the rig has been placed in service, it must comply. Does yours? It also places the responsibility on the purchaser to inform the manufacturer of what equipment is going on the rig. For all potential bidders to have a fair and equitable opportunity to properly design your apparatus, the equipment list should be included in your purchasing specifications. Are they?

Annex B, “Specifying and Procuring Fire Apparatus,” is not officially part of the standard’s requirements; it is included for informational purposes only. It is, however, a basic primer in the purchasing procedure, especially useful for those new to the process. As mentioned, the document emphasizes the proper weight and load distribution, especially the front-to-rear ratio. Another example under B.5, “Acceptance,” Section B.5.1, states the purchaser is responsible for “verifying that the gross vehicle weight and axle weight distribution are within the chassis and axle ratings.” Again, the NFPA places the onus of responsibility to follow load balance guidelines directly on the purchaser—the fire department. If your fire truck is involved in an accident, you may have to legally prove the rig was not overloaded and it met the front-to-rear-axle weight ratio. Good luck again.

BEFORE THE BID

As previously mentioned, purchasers should inform all prospective bidders of what equipment will be carried and where it will be carried. Doing so ensures each bidder has an equal opportunity to engineer chassis components designed specifically for your apparatus. If the purchaser does not supply an equipment list with actual weights or a specific miscellaneous equipment list (in pounds), the manufacturer is only obligated to engineer and design the apparatus to carry the minimum equipment allowance predetermined by the NFPA in Table 12.1.2., “Miscellaneous Equipment Allowance.” Does the NFPA’s allowance meet your needs?

Almost every set of purchasing specifications published by fire departments specifies the chassis components and ratings. Who in your fire department has the engineering qualifications and expertise to specify the axle ratings, suspension, tires, and so forth in your purchasing document? Were the figures solicited from your local sales representative, an industry consultant, or a good buddy? Is that person qualified to engineer your chassis components? Would it be wiser for a purchaser to specify what is to be carried on an apparatus and where it is to be carried and let the manufacturers design, engineer, and propose chassis components to meet load balance guidelines?

Specifying and operating safe fire apparatus is important. If the fire service can be held accountable for “maintaining a front-to-rear weight distribution ratio,” whatever entity mandated that requirement should be equally accountable in clearly explaining what it means and how to find it. No fire department should be subjected to intense public scrutiny because of unavoidable circumstances.

“Village Rocked by Lawsuit”

Read the following fictitious newspaper article:

A Notice of Claim has been filed in County Court by Mrs. Olelady Smith’s attorney. Smith was involved in a crash three weeks ago with the Village’s newest fire engine. The accident occurred Monday morning on Main Street where it curves south toward Maple Avenue. According to police witness statements, when the fire truck approached with its lights and siren on, Mrs. Smith pulled her vehicle to the side of the road and stopped, yielding the right-of-way. The police report stated the firefighter who was driving the two-week-old truck claimed “the back end of the rig broke loose” as he was going through the curve. It rolled over and struck Mrs. Smith’s vehicle.

Because of the number and severity of injuries, the State Police Accident Reconstruction Team and the State Department of Transportation were called in to investigate. One investigator, speaking under the condition of anonymity, said there appeared to be no apparent equipment failures, nor was excessive speed or the weather a factor. The fire truck was equipped with a vehicle data recorder, similar to an airplane’s black box, which has been impounded by the state police. Both vehicles were damaged beyond repair. As of publication time, no criminal charges have been filed.

The Notice of Claim, the first step in filing a civil lawsuit, names numerous people and entities including the Village, the fire department, the fire chief, as well as the local commercial truck dealership that supplied the cab and chassis to the fire truck builder. Named was the Bigfire Truck Corporation, which mounted the fire apparatus body, the fire pump, and the water tank on the cab and chassis. The Village contracted with Bigfire for the completed vehicle. Bigfire’s local sales representative was also named. According to anonymous sources within the fire department, the sales representative assisted the fire department in writing the specifications for the new truck. One anonymous source contends the fire truck was poorly designed and did not meet nationally recognized safety standards.

The Notice of Claim specifically alleges “the actions or inactions of the individuals and entities named helped create a state of danger that was a direct cause of the accident.” Court employees said other respondents may be named at a later date because the notice also named “John Doe members of the named entities who are unknown at this time, all in their official and individual capacities.” Court employees confirm subpoenas have been issued for the fire department’s purchasing specifications, Bigfire’s contractor specifications, the Village’s legal contract with Bigfire, and all paperwork and correspondence concerning the fire truck from the local truck dealership and Bigfire’s local sale representative.

BILL ADAMS is a former fire apparatus salesman, a past chief, and an active member of the East Rochester (NY) Fire Department. He has more than 45 years of experience in the volunteer fire service.

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