Editor’s Note: In recent years, heavy rescue trucks have gone from walk-through units to predominantly walk-in or walk-around rigs. There are pros and cons for both designs and largely depend on what is best for the residents a department serves and what is most efficient for personnel. This month, Editorial Advisory Board members Bill Adams (left) and Ricky Riley (right) comment on these rescue truck designs.

Asking which is better is a loaded question - similar to asking whether mechanical sirens are better than electronic sirens or if single-piece engine companies are more efficient than two-piece engine companies. There is no correct answer unless the context in which the question posed is defined as well as the parameters in which the rescue is to operate. The debate should entail more than comparing physical attributes between two styles of rescues. Determining how it is going to be used, where it is going to be used, and how many people are going to use it should be the initial step in the evaluation process.

Commentators, vendors, and pundits are hard pressed to recommend either until pertinent facts are known. Remember: A vendor’s job is to sell product; hence, one’s recommendation may be slightly skewed. This is not a condemnation of apparatus salespeople. Their advice, product knowledge, and expertise are invaluable and should be actively sought. Prior to seeking outside guidance, objectively answering some basic questions in-house will help in the evaluation process. It may prevent apparatus committees from having “deer in the headlights” looks when vendors ask similar questions. And, make no mistake - competent vendors will ask them.

Factors affecting apparatus purchases are occasionally overlooked - sometimes to the embarrassment and humiliation of the fire department. What is the usable door width and height and length of the apparatus bays? Do apparatus bays have a maximum floor rating? What are the angles of departure and approach? Are there any bridge weight and travel height restrictions in your response district and neighboring districts? Are there any extraordinary governmental Department of Transportation or local vehicle road-use rules and regulations the apparatus must meet? Is there an established minimum wall-to-wall turning radius for your response district? Is the intent to pull a new rig out of the barn and back it in in one swing? Is there a size rig that may intimidate volunteer drivers?

Important is establishing a definitive job description for the apparatus. Purposely left out of this discussion is having a rescue truck pulling double duty such as a command post, urban search and rescue support rig, mobile communications center, or rehab vehicle. Will it be the proverbial toolbox on wheels that’ll bring everything needed to the scene? If so, what equipment will be carried now and what is anticipated in the future? Does the job description entail transporting firefighters to the scene? How many? Is the priority carrying equipment or people? You might not be able have it both ways.

A controversial subject is honestly determining how many firefighters the rig will carry. Career departments may have more stable estimations of crew size. Requesting seating for eight or 10 may be hard to justify to city hall for a rig consistently running with three or four firefighters - especially if staffing was agreed to contractually. What is the justification for extra seating, just in case the mayor asks in a public forum? Volunteers stating they expect to or hope to carry 10-plus firefighters on every response may be overestimating. Claiming to regularly respond with that number may be boastfulness. Reality is the actual number consistently riding on the apparatus. What are

By Bill Adams

The first equipment compartment on a fire truck located behind the cab on the driver’s side is often designated “L1” on manufacturers’ blueprints and in purchasing specifications - L1 obviously meaning left side, first compartment.

This article addresses L1 full-height compartments on traditional-style pumpers and rescue-pumpers equipped with conventional midship pump houses. What the compartment is designated or numbered and how it’s fabricated are irrelevant. How and why it is described in a set of purchasing specifications (specs) are important.

1 This traditional-style pumper body by HME-Ahrens Fox has a decent size L1 compartment. Note the yellow wheel chocks and uncluttered pump panel. (Photo courtesy of HME-Ahrens Fox.)

Technical purchasing specifications including compartment dimensional requirements are generated by three entities. The first is by the authority having jurisdiction (AHJ) or the fire department on its behalf. Writing effective purchasing specifications in-house is challenging at the least and intimidating at most. Fire departments commonly use outside sources for advice and technical expertise. The second is when the document is provided by a preferred apparatus manufacturer (OEM), which, as expected, ensures the verbiage totally favors the apparatus it builds. It is commonplace and understandable. When a manufacturer’s “standard” specification is published by the purchaser, it is readily obvious to other OEMs what the purchaser wants. It can influence their decision on whether or not to bid. The last are specs generated by a third party such as a local dealer or a consultant. Dealers’ specifications understandably reflect the product they sell. Although a dealer may tell a prospective purchaser a nonproprietary specification is being provided, experienced dealers can subtly skew verbiage and narrative to be self-serving. That’s business. It’s their job - get over it. Anticipate it. Some are better at doing it than others. Experienced dealers can look at a spec and immediately identify the dealer that wrote it. That can also influence whether or not to bid.

2 Two vertical dividers mounted on a slide tray on the floor of compartment L1 with an adjustable shelf above it. Note the vertical up and down handles on the pump panel’s discharges and inlet.

Most consultants and professional spec writers claim to write nonproprietary documents. However, some - and I emphasize some and not all - have preferences for specific manufacturers and will slant their verbiage accordingly. That is human nature, especially for those previously employed in the fire service or industry. Purchasers should read between the lines. Principles and ethics aside, there is nothing illegal when dealers and consultants write a proprietary purchasing specification. Sometimes end users will request a spec writer to do so. The AHJ promulgates the document; hence, the spec writer is not accountable or culpable - the A

By Bill Adams

The first equipment compartment on a fire truck located behind the cab on the driver’s side is often designated “L1” on manufacturers’ blueprints and in purchasing specifications - L1 obviously meaning left side, first compartment.

This article addresses L1 full-height compartments on traditional-style pumpers and rescue-pumpers equipped with conventional midship pump houses. What the compartment is designated or numbered and how it’s fabricated are irrelevant. How and why it is described in a set of purchasing specifications (specs) are important.

1 This traditional-style pumper body by HME-Ahrens Fox has a decent size L1 compartment. Note the yellow wheel chocks and uncluttered pump panel. (Photo courtesy of HME-Ahrens Fox.)

Technical purchasing specifications including compartment dimensional requirements are generated by three entities. The first is by the authority having jurisdiction (AHJ) or the fire department on its behalf. Writing effective purchasing specifications in-house is challenging at the least and intimidating at most. Fire departments commonly use outside sources for advice and technical expertise. The second is when the document is provided by a preferred apparatus manufacturer (OEM), which, as expected, ensures the verbiage totally favors the apparatus it builds. It is commonplace and understandable. When a manufacturer’s “standard” specification is published by the purchaser, it is readily obvious to other OEMs what the purchaser wants. It can influence their decision on whether or not to bid. The last are specs generated by a third party such as a local dealer or a consultant. Dealers’ specifications understandably reflect the product they sell. Although a dealer may tell a prospective purchaser a nonproprietary specification is being provided, experienced dealers can subtly skew verbiage and narrative to be self-serving. That’s business. It’s their job - get over it. Anticipate it. Some are better at doing it than others. Experienced dealers can look at a spec and immediately identify the dealer that wrote it. That can also influence whether or not to bid.

2 Two vertical dividers mounted on a slide tray on the floor of compartment L1 with an adjustable shelf above it. Note the vertical up and down handles on the pump panel’s discharges and inlet.

Most consultants and professional spec writers claim to write nonproprietary documents. However, some - and I emphasize some and not all - have preferences for specific manufacturers and will slant their verbiage accordingly. That is human nature, especially for those previously employed in the fire service or industry. Purchasers should read between the lines. Principles and ethics aside, there is nothing illegal when dealers and consultants write a proprietary purchasing specification. Sometimes end users will request a spec writer to do so. The AHJ promulgates the document; hence, the spec writer is not accountable or culpable - the A

By Bill Adams

The first equipment compartment on a fire truck located behind the cab on the driver’s side is often designated “L1” on manufacturers’ blueprints and in purchasing specifications - L1 obviously meaning left side, first compartment.

This article addresses L1 full-height compartments on traditional-style pumpers and rescue-pumpers equipped with conventional midship pump houses. What the compartment is designated or numbered and how it’s fabricated are irrelevant. How and why it is described in a set of purchasing specifications (specs) are important.

1 This traditional-style pumper body by HME-Ahrens Fox has a decent size L1 compartment. Note the yellow wheel chocks and uncluttered pump panel. (Photo courtesy of HME-Ahrens Fox.)

Technical purchasing specifications including compartment dimensional requirements are generated by three entities. The first is by the authority having jurisdiction (AHJ) or the fire department on its behalf. Writing effective purchasing specifications in-house is challenging at the least and intimidating at most. Fire departments commonly use outside sources for advice and technical expertise. The second is when the document is provided by a preferred apparatus manufacturer (OEM), which, as expected, ensures the verbiage totally favors the apparatus it builds. It is commonplace and understandable. When a manufacturer’s “standard” specification is published by the purchaser, it is readily obvious to other OEMs what the purchaser wants. It can influence their decision on whether or not to bid. The last are specs generated by a third party such as a local dealer or a consultant. Dealers’ specifications understandably reflect the product they sell. Although a dealer may tell a prospective purchaser a nonproprietary specification is being provided, experienced dealers can subtly skew verbiage and narrative to be self-serving. That’s business. It’s their job - get over it. Anticipate it. Some are better at doing it than others. Experienced dealers can look at a spec and immediately identify the dealer that wrote it. That can also influence whether or not to bid.

2 Two vertical dividers mounted on a slide tray on the floor of compartment L1 with an adjustable shelf above it. Note the vertical up and down handles on the pump panel’s discharges and inlet.

Most consultants and professional spec writers claim to write nonproprietary documents. However, some - and I emphasize some and not all - have preferences for specific manufacturers and will slant their verbiage accordingly. That is human nature, especially for those previously employed in the fire service or industry. Purchasers should read between the lines. Principles and ethics aside, there is nothing illegal when dealers and consultants write a proprietary purchasing specification. Sometimes end users will request a spec writer to do so.

By Bob Albano

Air-ride suspensions have steadily increased in popularity in nearly all segments of the trucking industry. Approximately 75 percent of the trailers manufactured today and almost all highway tractors use air-ride suspensions.

Air has even proliferated into the specialty segments of the trucking industry. It is not uncommon to find air-ride suspensions on heavy-duty vehicles that operate in extremely rugged environments - dump trucks, refuse, logging vehicles, and even concrete mixers. Following this logical progression, the migration from leaf spring suspensions to air ride is gaining momentum on fire and rescue vehicles. Specifying the right suspension should be a high priority for decision makers in this industry. Suspension systems affect the performance and life of the vehicle, frequency of maintenance, and comfort and safety of the operator. Upgrading to an air-ride suspension typically results in less than a one percent increase in the total cost of an apparatus, a great value for benefits gained.

What Factors Control Ride Quality?

Suspensions with a lower natural frequency reduce the force transmitted to the vehicle, which improves ride and vehicle protection when properly engineered. Natural frequency includes the spring rate of the suspension and the amount of weight supported by the suspension. The spring rate of the air springs is a measure of the vertical stiffness of the air springs or how much the suspension deflects for a given load being carried. The natural frequency of a suspension will increase if the suspension spring rate is increased or decreased. Because of a softer spring rate, air suspensions provide greater equipment protection over traditional mechanical suspensions. This is because of the air springs’ ability to cushion the equipment and passenger load. Outstanding ride produces superior driver and passenger comfort while helping to protect critical, lifesaving equipment and costly electronic components from excessive vibration and road inputs.

Understanding Roll Stability

Roll stability is a measure of how well the suspension and chassis resist rolling or swaying, especially when encountering a turn. A vehicle’s roll stability can be measured in two ways: (1) determining the maximum cornering speed before reaching the rollover threshold (when tires lift off the ground), and (2) measuring the amount of roll that occurs for a given turn at a given speed (the roll angle). Many elements of a vehicle’s design play a factor in determining its roll stability. Roll stability for a fire and rescue vehicle is influenced by the height of the center of mass of the truck body and the axle track width. These factors can have the greatest impact on the roll stability of the vehicle.

While suspension roll stiffness contributes to roll stability, it represents only one component of the equation. The chassis’s flexibility and tire stiffness, for example, must also be considered when determining the truck’s overall roll stability. Air-ride suspensions have come a long way over the past few decades, and we’re now at the point where properly engineered air-ride suspensions can deliver roll stability near that of a steel leaf spring suspension. For fire and rescue vehicles, higher rollover thresholds allow improved vehicle performance during the challenging, evasive maneuvers that are experienced when rushing to the scene of an emergency.

So, how can the vehicle’s suspension affect roll stability? The level of roll stiffness provided by a suspension is the best way to directl