How to Optimize Mechanic-Truck Design

By Walt Moore, Editor | November 19, 2012
How to Optimize Mechanic-Truck Design

Dan Root, president of QT Equipment, a builder/distributor of service trucks in Akron, Ohio, sees several developing trends among the company’s customers for mechanic trucks.

“The shortage of good mechanics is a growing problem for many of our customers,” says Root, “so experienced, older technicians are an appreciating resource for them. As a result, we’re seeing an increased concern among buyers to make life easier for these experienced people, who maybe aren’t quite as agile as they were 20 years ago.”

This concern, says Root, is translating into requested features such as ergonomically designed steps, hand rails that assist in accessing work areas, and pneumatic tool lifts that ease the strain of the job.

Another trend Root sees in the design of mechanic trucks is, in his words, “safety, safety, safety.”

“Requested safety features tend to be customer specific,” he says, “and often result from a concern to rectify a design element that’s been suspected of contributing to an accident.”

Those concerns, says Root, might mean positioning steps and handrails for three-point contact and integrating design elements that discourage working from unsafe areas of the truck, such as not installing tread plate on top of side compartments, “because the material might be considered a non-slip surface and would signal that it’s okay to walk there.” In addition, Root notes that new regulations in the Canadian market might find their way into U.S. regulation, citing specifically provisions for venting compartments used for storing oxygen/acetylene tanks.

Buying basics

Root says that most of his customers are quite knowledgeable about what they need in mechanic trucks, but Dennis Seyller, president of Original Seyller Bodies, Oregon, Mo., cautions that buyers sometimes have preconceived notions about the truck’s design, which must be evaluated with the vehicle’s application in view.

“A buyer might come to us, for example, and tell us that his truck needs a 6,000-pound crane,” says Seyller, “but you have to probe statements of that sort—in this instance, to determine weights to be handled and at what distances from the truck. The more information we can gather, and the better that information, the better the end result—a more useable product.”

Tim Davison, Stellar Industries’ product manager for bodies and cranes, says that the initial step in the buying process is analyzing what expectations the customer has for the truck—best determined by thinking through basic questions.

Those questions might include, says Davison: What type of equipment will be serviced? Is a crane required, and if so, what will it be handling and at what radii? What types of services will be performed? What tools are required? How far from the shop will servicing take place? What type of welding or cutting will be done, and how frequently? What are electrical-outlet needs? What are compressed-air requirements—capacity and pressure? How much payload capacity is needed, based on the size and weight of items transported? Are commercial driver’s license requirements a consideration?

Seyller adds that buyers also should assess what supplies the truck will carry and how often it will be restocked. A truck that is frequently restocked might get by with a smaller chassis, he says, compared with a truck that stays out for extended intervals.

Seyller makes another basic observation: “Mechanics have a large investment in tools to be accommodated, so the truck needs adequate drawers, bolt bins and storage space. Spending 30 minutes pawing through cluttered compartments at the job site just adds to the cost of downtime. An important aspect of what we’re selling is organization.”

Crane considerations

Deciding whether the truck needs a crane is a primary consideration, says Tim Worman, product manager of commercial vehicles for IMT (Iowa Mold Tooling).

“If you don’t need a crane, then look at buying just a service body,” says Worman. “The crane is one of the least-used tools on the truck, and it requires a body that is fundamentally different from a service body. The crane body needs an integrated structure to handle the crane, as well as an integrated structure to handle the stabilizers.”

But that said, most mechanic trucks are fitted with a crane, says Worman, and once a crane of adequate capacity and reach is selected, then an appropriately sized body can be matched to it. Crane and body selection, taken together, will be a primary determinant of chassis size, he says.

The most common crane selected for mechanic trucks is an all-hydraulic telescopic, but an electric/hydraulic model might be a viable alternative if lifting duties are less severe. These cranes might use a 12-volt electric winch and an electrically driven hydraulic power unit for boom-raise and rotation functions. Compared with an all-hydraulic, says Stellar’s Davison, electric/hydraulic models, although less expensive, typically don’t exceed 6,000-pound rated capacities, have a limited duty cycle (because electrical components need time to cool), and generally do not have the reach, speed, and proportional control systems found on all-hydraulics.

In most instances, all-hydraulic cranes require a chassis with a power take-off and a wet kit (a PTO-driven hydraulic pump, fluid reservoir, and related plumbing). These items add expense, says Worman, “but you’re paying for productivity—the ability to work more efficiently, faster, with greater lift capacity and reach.”

 In some instances, buyers might also consider an articulating crane.

 “The predominant crane is the corner-mounted telescopic,” says Worman, “but an articulating crane can be paired with a mechanics truck for more reach and capacity. The drawback is cost—an articulated crane is substantially more than a telescopic. And because these cranes typically are mounted behind the cab, the truck usually gets a longer wheelbase, and coupled with an already large body, turning radius might be an issue. But, a truck handling components like dozer roller frames or working with mining equipment might benefit from this type of crane.”

Accessories and packages

Air compressors, powered hydraulically or directly from the chassis PTO, along with engine-driven or hydraulically driven welding units and generators, have long been staple accessories for mechanic trucks. When selecting and sizing these individual units, buyers are advised to carefully analyze anticipated needs and to pay particular attention to duty cycles (the number of minutes out of 10 that the unit can operate before needing cool-down time). Seyller also suggests that buyers solicit the experience and expertise of their mechanics, who might be aware of inadequacies in present equipment that can be redeemed in new trucks.

Although these stand-alone accessories are widely used, combining the welder/generator or the welder/generator/air compressor into a single module, driven hydraulically or with its own small engine, is an approach some buyers are taking in the interest of overall efficiency, including saving space on the truck.

IMT’s Worman sees a move toward engine-driven combination units, which use only a fraction of the fuel needed by the truck engine to power these functions. He cautions buyers, however, to make certain that the capacities of the combination unit will match or exceed those of stand-alone units that might be presently used—the air compressor in particular.

“The air compressor is probably the most used accessory on a mechanics truck,” says Worman, “because of all the pneumatic tools. Buyers should carefully assess air requirements, so as not to undersize the compressor. If you oversize it, that’s a good thing—you’ll always have more air than you need. Undersize it, and the truck becomes an under-utilized asset.”

Worman suggests also that buyers evaluate the merits of both reciprocating and rotary-screw air compressors, saying that the general trend is toward the rotary screw, because it produces air on demand and eliminates having to sometimes wait for the reciprocating compressor to catch up. But on the positive side for the reciprocating, says Stellar’s Davison, are a lower initial price, greater tolerance of intake-air contaminants, and a generally “bullet-proof” design.

Miller Electric added another dimension to the combination concept with its EnPak, which combines a rotary-screw air compressor, generator, hydraulic pump, and 27-horsepower diesel engine. With hydraulic power as part of the package, the truck’s crane can be operated without using the chassis engine. According to Christopher Wierschke, product manager, the EnPak can power portable welding equipment capable of stick, TIG, and MIG/Flux-Cored applications at amperage levels suitable for most field repair. In addition, an available control package allows the EnPak to power hydraulic tools.

“The mechanics truck operator can run all of these off the 27-horsepower engine built into the EnPak—not the 200- or 250-horsepower engine in the truck,” says Wierschke. “This eliminates the need for a PTO, extends truck-engine life, and reduces idling, fuel usage, and emissions.”

According to Vanair’s Dean Strathman, the company’s just-released Air N Arc I300 combines a 40-cfm rotary-screw compressor, 7kW AC generator, 300-amp welder, battery booster, battery charger, and a 10.5-gpm hydraulic pump—all driven by a single 25-horsepower diesel. The system ties directly into the truck’s electrical system, says Strathman, allowing the battery to be charged to operate work lights, and the system also shares the truck engine’s fuel source. The I300, he says, reduces chassis fuel consumption, noise, and engine maintenance, while supporting anti-idling laws.

Seyller does note, however, that not all mechanic-truck buyers are sold on combination units and are skeptical about using a small engine to reliably power multiple functions. But fuel costs and emissions regulations, in his view, will drive the use of such combinations.

IMT’s Worman leaves mechanic-truck buyers with a final thought: “Aside from the technical analysis of designing a service truck, there’s also a financial analysis to be considered—utilization. When you’re putting together an expensive truck, you have to ask whether its utilization will allow recouping the investment in a reasonable time. Keep asking what you need to do in specifying the truck to make sure it will be fully utilized.”