The trade-offs in truck specifyingWhen it comes to building a Class 8 vocational truck from the ground up, there’s no avoiding customization.Some issues to consider—and new tools that make the process quicker and easier.

B y D o n Ta l e n d

Specifying a Class 8 voca-tional chassis that willperform as needed is notunlike ordering the rightconcrete mix—a one-

size-fits-all approach doesn’t work. Ittakes an experienced fleet manager anddealer to specify a truck that will fit theproducer’s unique requirements.

However, technological advancesare making truck specifying easierand more predictive of actual perfor-mance. Several heavy truck manufac-turers have made the process quickerand easier by offering special soft-ware to predict performance (see re-lated article below), especially usefulwhen designing a vocational truck,particularly a mixer, because manyvariables are involved.

Ever-changing variables like statelaws, a new plant’s design or a newmarket that affects the driving envi-ronment conflict with the desire tostay with a single chassis manufactur-er. So the producer must change thetruck design, and that involves severaltrade-offs.

What are some of the trade-offs theproducer encounters? They often in-volve driver comfort, weight distribu-tion, performance, truck length andtruck height.

A visit to Dallas Peterbilt, which hassold as many as 300 mixer trucks in ayear, may provide a glimpse into thefuture of heavy truck sales. As part ofTruck Centers of America, one of thelargest U.S. dealer networks, the deal-ership offers everything from sales toframe straightening—even a loungewith leather recliners and a big-screenTV drivers can use while waiting for

repairs. The dealer also offers comput-erized specifying.

Leo Girtz, a sales representative whospecializes in mixers, says that, with allthe available options, manufacturersare moving away from package trucks.“There’s nothing wrong with them,but they don’t offer any value-addedbenefits,” he says. “You’re making thebusiness fit your truck instead of theother way around.” Craig Scott, con-crete production manager who over-sees an eight-location, 200-truck oper-at ion for Latt imore Materia ls ofnearby McKinney, agrees. “(Packagetrucks) are a crescent wrench,” Scottsays. “Now we can get the right sizesocket for what we need to do.”

The trade-offs involved in obtainingthe right “socket” include, but aren’tlimited to, the following.

Driver comfort vs. weight distrib-u t i o n . Reducing truck tare weight is

the producer’s most important designpriority, isn’t it? Scott and Girtz saynot in Texas, where competition forqual ified drivers is intense . “Welooked at how we were treating ourdrivers,” Scott says.“When theychanged the CDL requirement, all ofa sudden we were competing withover-the-road freight haulers.” Withmore marketable driving skills, mixerdrivers had an alternative, so Latti-more wanted to provide more com-fortable cabs, Scott says. “Down here,if one of our drivers wakes up at 2:30and knows he’ll be in a truck he does-n’t like on another 110° day, how’s hegoing to feel about going out for an-other long day?”

So the purchasing team reassessedcab design and added more expen-sive—and sometimes heavier—com-ponents like “smart seats” with severallumbar adjustments, larger cabs and

Producers can build several types of trucks with a Class 8 chassis, including end dumps, bulk

haulers, flatbed haulers and mixers. It’s important to weigh design factors to maximize the truck’s

performance in a given operation.

W ith so many factory options available, Class 8 chassismanufacturers are providing dealers with specifying

software to eliminate parts incompatibilities and recalls.Since the software detects most incompatibilities instantly, ithelps deliver trucks to producers quickly.

Traditionally, deviating from a standard design has meantsorting through numerous spec sheets. After severalhours, the customer has a price quote and the salespersonhas a factory order. An engineer at the factory double-checks the order for parts compatibility, sometimes delay-ing delivery for weeks.

To make the process easier, CWC Inc., Mankato, Minn.,has developed performance-predictive software for VolvoGM Heavy Truck, Paccar’s Kenworth and Peterbilt divisions,Freightliner and for component manufacturers Meritor, Alli-son Transmission, Caterpillar and Hendrickson. Navistar In-ternational offers its own program, and Mack is developingits own interactive, Internet-ready version for release laterthis year. Since vocational trucks are so customized, an ex-act replica isn’t in the lot. The software enables the dealerand customer to create a truck from the ground up and test-drive it on the computer screen.

How it worksWhen using Volvo’s TruckMatch program, for example,

buyer and seller enter a “Vehicle Work Area” with severalpull-down menus that include chassis, engines, transmis-sions, axles and cab interiors. In each submenu, a checkmark indicates the default component, and a minus sign in-dicates one the user cannot choose with the currently select-ed menu item (Figure 1). When the program detects an in-compatibility with a previously chosen component, a “do notenter”symbol pops up next to the main pull-down menu, and

a mouse click pulls down the menu and reveals which part isincompatible.

Making all the parts compatible is only half the battle. Thetest drive really begins with a mouse click on “Perfor-mance.” Here buyer and seller can determine the truck’sweight distribution, dimensions (height and overall length)and turning circle, among other attributes (Figure 2). A“Bridge Formula” screen reveals allowable weight per axle atthe chosen spacing and number of axles. “Gradeability”shows how steep a grade a truck can handle in each gear ofa nine-speed transmission, for example. A “Top Speed” of71 mph reveals that a producer has chosen too much enginefor trucks that will be assigned to that downtown plant.

Navistar’s Truck Order Processing System (TOPS 3) in-cludes the Diamond Spec program, which offers componentpackages much like those offered by your local car dealer.“We can probably satisfy 80% to 90% of our customers justwith the modules,” says Ed Kipley, sales manager at J. MerleJones & Sons, Joliet, Ill. The transmission module, for ex-ample, offers various clutches and speeds for a manual.Even if the customer must deviate from a module, the sys-tem at least reduces the number of potential incompatibili-ties that need checking.

A case studyThe software was a big help last year to Bob Gartman, fleet

supervisor for Ferrara Bros. Concrete of Flushing, N.Y. NewYork City had allowed a Federal Bridge Formula exemption of84,000 pounds with an overweight permit about 10 yearsago before reducing it to 82,000 and most recently, 79,000pounds. Ferrara Bros. reacted to the first change by reducingmaximum payloads from 12 to 11 cubic yards; the secondchange would have required a further reduction to 10.

Furthermore, the producer sought work in booming mid-town Manhattan, where the city restricts overall vehicle

High-tech truck specifying software tools eliminate delays in order processing

Figure 1. Truck-specifying software detects component incompatibilities,

ultimately reducing delivery time. In this case, the selected transmission

doesn’t fit the previously chosen engine model.

Figure 2. The “Performance” menu reveals whether an under-construc-

tion truck meets desired criteria like wheelbase and weight distribution.

automatic transmissions.“Automatic transmissions are heav-

ier, but there’s a long-term payoff,”says Scott. “We don’t have to teachrefuse or military guys to drive a stan-dard.” Girtz says automatics aid in dri-ver retention. “Number one, the driverdoesn’t want to go back to a manual,”Girtz says. “Number two, it opens up anew source for drivers, like college stu-dents, bus drivers. Another thing isproductivity, which is intangible. Youmight gain a load a day because there’sno shifting from a dead stop whenyou’re doing city driving.” Automaticsalso help producers prepare for loom-ing ergonomics legislation, Girtz adds.

To get more weight on the front axleand redistribute overall truck weight,producers may choose a cabover de-sign. In some cases, the trade-off isdriver comfort and repairability.Adding an air-ride cab suspension andsoundproof ing to improve dr ivercomfort may increase initial cost, butit may be worth it.

Axle, PTO configuration vs. over-all length. The producer can increaseweight capacity by adding axles, in-cluding a booster, increase axle spac-ing or get more weight on the frontaxle by setting it forward. But thesechoices, in addition to the powertakeoff (PTO) mounting location, af-fect overall truck length. Trade-offsinclude potential conflicts with localoverall length limits and a concur-rent increase in wheelbase and turn-ing radius.

Setting the front axle forward not on-ly puts more weight up front, it increas-es the wheelbase, to the driver’s benefit,says Scott. “Ride comfort comes with alonger wheelbase,” he says.

In recent years, rear-engine PTO

mounting has become more widelyavailable. A front-of-engine PTOmounting, in contrast, sometimestears up the radiator if the shaft getsdamaged (since it runs through or justbeneath the radiator), reduces enginecooling (since there’s less radiatorarea), increases overall vehicle length(because a pump that runs the PTOlies ahead of the radiator, addinglength to the front of the truck) andhinders drivers’ ability to judge thebumper’s proximity to obstacles.

The combination of a rear-mountedPTO and a set-forward front axle al-lows a longer wheelbase (and thus agreater payload), a shorter overalllength and improved driver visibilityand comfort.

Reduced height vs. reducedground clearance. This mainly affectsmixer chassis selection. Even thoughsome mixer manufacturers offer low-profile mixers, chassis selection is stillimportant. If the producer lowers thechassis for greater clearance and tip-over prevention, the trade-off is re-duced ground clearance, an undesir-able attribute for the producer who

supplies a lot of tract housing pours,for example, requiring a lot of off-road driving. The factory can raise thebattery box and fuel tanks to com-pensate, however.

Electronic engines vs. initial cost.Environmental regulations and manu-facturers’ increasing economies ofscale are making electronic engines astandard item, but for now, producerscan choose often less-expensive me-chanical engines, with which their me-chanics are likely more familiar.

Besides meeting emissions stan-dards, electronics benefit producers.“The No. 1 advantage is diagnostic ca-pability,” says Ed Kipley, sales manag-er at J. Merle Jones & Sons, Joliet, Ill.“Also, electronic fuel systems inject fu-el with precise metering so you getbetter mileage without bursts ofsmoke.” Additional electronic engineadvantages include the fleet manager’sability to preset PTO speed, especiallyuseful for mixers, and cruise controlthat allows fleet managers to set de-fault top speeds, Kipley adds.

Other extras vs. initial cost, lengthof service. Producers can increasepayload with lighter—and often moreexpensive—rims, frame rails, alu-minum cabs and water tanks. Somedealers and producers question the

Craig Scott: Driver comfort is worth the cost.

“There’s nothing wrong with (package trucks), but they don’t offer any value-added benefits. You’re making the business fit

your truck instead of the other wayaround.”—Leo Girtz, truck sales

length to 33 feet. Ferrara Bros.’ trucks met the rest of NewYork’s 35-foot limit, but not Manhattan’s.

Gartman wanted to get payloads back to 12 yards andmeet Manhattan’s restriction. So he and his truck dealer,Bruce Stadler of Milea Truck Sales, Bronx, N.Y., relied heav-ily on specifications software to design several trucks withan unusual combination in their market—pusher axles, set-forward front axles and cabovers.

“No one likes change, but we were forced to deal with it,”

says Gartman. The pushers increase weight capacity. Theset-forward front axles allow the minimum 171⁄2-foot wheel-base. Finally, the cabovers put about a ton of additionalweight on the front axle and reduce overall truck length.Gartman and Stadler also made up at least 5,000 pounds byspecifying lighter rails, a relatively light rear suspension,steel instead of cast-iron wheels, smaller fuel tanks and200-gallon water tanks.

durabili ty of a luminum cabs andlighter frame rails, however. A tightaxle spacing may save wear on lighterframe rails, but that strategy runscounter to the typical goal of increas-ing payload by increasing axle spac-ing. One dealer says he’s seen cracksdevelop in many aluminum cabs un-der severe duty after only a few years,while another says steel cabs are proneto rust in wet environments.

Other extras are designed to im-prove performance. A wheel-lockingdifferential transfers power from backto front or side to side, an advantageto producers who commonly operate

mixers off road.“We feel it allows us toget out to the job quicker after it rains,a service we offer customers,” saysScott . Jacobs brakes, a k a “Jake”brakes, may reduce maintenance costsfor producers in mountainous or hillyregions. When the driver eases up onthe accelerator, the engine releasescompressed air prior to the pistonpower stroke, preventing combustion,slowing engine rpm and reducingwear on brake parts.

Does initial cost really matter?For the producer, keeping a truck

running may outweigh its initial cost.

To Scott, truck utilization is the No.1 priority, and extra options makethat possible.

“Upfront costs are very deceiving,”says Scott. “I might have saved$10,000, but did I lose a customer thismorning because I had three trucks inthe garage? That truck costs me thesame amount whether it’s deliveringconcrete or sitting in the garage—I’mstill making payments on it.” ■

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