Specifying a customized Class 8 vocational truck involves weighing various trade-offs between factors like driver comfort, weight distribution, performance, and vehicle dimensions. New specifying software from manufacturers helps dealers and customers evaluate options and ensure component compatibility to reduce delays. Producers must consider trade-offs like prioritizing driver comfort over weight to retain drivers, or choosing automatic transmissions for productivity despite their heavier weight. Rear-mounted PTOs and set-forward front axles allow for better weight distribution and driver ergonomics while keeping overall length down. Initial cost of options must be weighed against factors like uptime and customer service.

1. The trade-offs
in truck specifying
When 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.
By Don Talend
S
pecifying a Class 8 voca-
tional chassis that will
perform as needed is not
unlike ordering the right
concrete mix—a one-
size-fits-all approach doesn’t work. It
takes an experienced fleet manager and
dealer to specify a truck that will fit the
producer’s unique requirements.
However, technological advances
are making truck specifying easier
and more predictive of actual perfor-
mance. Several heavy truck manufac-
turers have made the process quicker
and easier by offering special soft-
ware to predict performance (see re-
lated article below), especially useful
when designing a vocational truck,
particularly a mixer, because many
variables are involved.
Ever-changing variables like state
laws, a new plant’s design or a new
market that affects the driving envi-
ronment conflict with the desire to
stay with a single chassis manufactur-
er. So the producer must change the
truck design, and that involves several
trade-offs.
What are some of the trade-offs the
producer encounters? They often in-
volve driver comfort, weight distribu-
tion, performance, truck length and
truck height.
A visit to Dallas Peterbilt, which has
sold as many as 300 mixer trucks in a
year, may provide a glimpse into the
future of heavy truck sales. As part of
Truck Centers of America, one of the
largest U.S. dealer networks, the deal-
ership offers everything from sales to
frame straightening—even a lounge
with leather recliners and a big-screen
TV drivers can use while waiting for
repairs. The dealer also offers comput-
erized specifying.
Leo Girtz, a sales representative who
specializes in mixers, says that, with all
the available options, manufacturers
are moving away from package trucks.
“There’s nothing wrong with them,
but they don’t offer any value-added
benefits,” he says. “You’re making the
business fit your truck instead of the
other way around.” Craig Scott, con-
crete production manager who over-
sees an eight-location, 200-truck oper-
ation for Lattimore Materials of
nearby McKinney, agrees. “(Package
trucks) are a crescent wrench,” Scott
says. “Now we can get the right size
socket for what we need to do.”
The trade-offs involved in obtaining
the right “socket” include, but aren’t
limited to, the following.
Driver comfort vs. weight distrib-
ution. Reducing truck tare weight is
the producer’s most important design
priority, isn’t it? Scott and Girtz say
not in Texas, where competition for
qualified drivers is intense. “We
looked at how we were treating our
drivers,” Scott says.“When they
changed the CDL requirement, all of
a sudden we were competing with
over-the-road freight haulers.” With
more marketable driving skills, mixer
drivers 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 2:30
and knows he’ll be in a truck he does-
n’t like on another 110° day, how’s he
going to feel about going out for an-
other long day?”
So the purchasing team reassessed
cab design and added more expen-
sive—and sometimes heavier—com-
ponents like “smart seats” with several
lumbar 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.

2. With so many factory options available, Class 8 chassis
manufacturers are providing dealers with specifying
software to eliminate parts incompatibilities and recalls.
Since the software detects most incompatibilities instantly, it
helps deliver trucks to producers quickly.
Traditionally, deviating from a standard design has meant
sorting through numerous spec sheets. After several
hours, the customer has a price quote and the salesperson
has 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 Volvo
GM 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 developing
its own interactive, Internet-ready version for release later
this year. Since vocational trucks are so customized, an ex-
act replica isn’t in the lot. The software enables the dealer
and customer to create a truck from the ground up and test-
drive it on the computer screen.
How it works
When using Volvo’s TruckMatch program, for example,
buyer and seller enter a “Vehicle Work Area” with several
pull-down menus that include chassis, engines, transmis-
sions, axles and cab interiors. In each submenu, a check
mark 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 not
enter”symbol pops up next to the main pull-down menu, and
a mouse click pulls down the menu and reveals which part is
incompatible.
Making all the parts compatible is only half the battle. The
test drive really begins with a mouse click on “Perfor-
mance.” Here buyer and seller can determine the truck’s
weight distribution, dimensions (height and overall length)
and turning circle, among other attributes (Figure 2). A
“Bridge Formula” screen reveals allowable weight per axle at
the chosen spacing and number of axles. “Gradeability”
shows how steep a grade a truck can handle in each gear of
a nine-speed transmission, for example. A “Top Speed” of
71 mph reveals that a producer has chosen too much engine
for 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 component
packages much like those offered by your local car dealer.
“We can probably satisfy 80% to 90% of our customers just
with the modules,” says Ed Kipley, sales manager at J. Merle
Jones & 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 study
The software was a big help last year to Bob Gartman, fleet
supervisor for Ferrara Bros. Concrete of Flushing, N.Y. New
York City had allowed a Federal Bridge Formula exemption of
84,000 pounds with an overweight permit about 10 years
ago before reducing it to 82,000 and most recently, 79,000
pounds. Ferrara Bros. reacted to the first change by reducing
maximum payloads from 12 to 11 cubic yards; the second
change 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.

3. automatic transmissions.
“Automatic transmissions are heav-
ier, but there’s a long-term payoff,”
says Scott. “We don’t have to teach
refuse or military guys to drive a stan-
dard.” Girtz says automatics aid in dri-
ver retention. “Number one, the driver
doesn’t want to go back to a manual,”
Girtz says. “Number two, it opens up a
new source for drivers, like college stu-
dents, bus drivers. Another thing is
productivity, which is intangible. You
might gain a load a day because there’s
no shifting from a dead stop when
you’re doing city driving.” Automatics
also help producers prepare for loom-
ing ergonomics legislation, Girtz adds.
To get more weight on the front axle
and redistribute overall truck weight,
producers may choose a cabover de-
sign. In some cases, the trade-off is
driver comfort and repairability.
Adding an air-ride cab suspension and
soundproofing to improve driver
comfort may increase initial cost, but
it may be worth it.
Axle, PTO configuration vs. over-
all length. The producer can increase
weight capacity by adding axles, in-
cluding a booster, increase axle spac-
ing or get more weight on the front
axle by setting it forward. But these
choices, in addition to the power
takeoff (PTO) mounting location, af-
fect overall truck length. Trade-offs
include potential conflicts with local
overall 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 a
longer wheelbase,” he says.
In recent years, rear-engine PTO
mounting has become more widely
available. A front-of-engine PTO
mounting, in contrast, sometimes
tears up the radiator if the shaft gets
damaged (since it runs through or just
beneath the radiator), reduces engine
cooling (since there’s less radiator
area), increases overall vehicle length
(because a pump that runs the PTO
lies ahead of the radiator, adding
length to the front of the truck) and
hinders drivers’ ability to judge the
bumper’s proximity to obstacles.
The combination of a rear-mounted
PTO and a set-forward front axle al-
lows a longer wheelbase (and thus a
greater payload), a shorter overall
length and improved driver visibility
and comfort.
Reduced height vs. reduced
ground clearance. This mainly affects
mixer chassis selection. Even though
some mixer manufacturers offer low-
profile mixers, chassis selection is still
important. If the producer lowers the
chassis 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 the
battery box and fuel tanks to com-
pensate, however.
Electronic engines vs. initial cost.
Environmental regulations and manu-
facturers’ increasing economies of
scale are making electronic engines a
standard item, but for now, producers
can 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 get
better mileage without bursts of
smoke.” Additional electronic engine
advantages include the fleet manager’s
ability to preset PTO speed, especially
useful for mixers, and cruise control
that allows fleet managers to set de-
fault top speeds, Kipley adds.
Other extras vs. initial cost, length
of service. Producers can increase
payload with lighter—and often more
expensive—rims, frame rails, alu-
minum cabs and water tanks. Some
dealers 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 way
around.”—Leo Girtz, truck sales
length to 33 feet. Ferrara Bros.’ trucks met the rest of New
York’s 35-foot limit, but not Manhattan’s.
Gartman wanted to get payloads back to 12 yards and
meet 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 with
an 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. The
set-forward front axles allow the minimum 171
⁄2-foot wheel-
base. Finally, the cabovers put about a ton of additional
weight on the front axle and reduce overall truck length.
Gartman and Stadler also made up at least 5,000 pounds by
specifying lighter rails, a relatively light rear suspension,
steel instead of cast-iron wheels, smaller fuel tanks and
200-gallon water tanks.

4. durability of aluminum cabs and
lighter frame rails, however. A tight
axle spacing may save wear on lighter
frame rails, but that strategy runs
counter to the typical goal of increas-
ing payload by increasing axle spac-
ing. One dealer says he’s seen cracks
develop in many aluminum cabs un-
der severe duty after only a few years,
while another says steel cabs are prone
to rust in wet environments.
Other extras are designed to im-
prove performance. A wheel-locking
differential transfers power from back
to front or side to side, an advantage
to producers who commonly operate
mixers off road.“We feel it allows us to
get out to the job quicker after it rains,
a service we offer customers,” says
Scott. Jacobs brakes, a k a “Jake”
brakes, may reduce maintenance costs
for producers in mountainous or hilly
regions. When the driver eases up on
the accelerator, the engine releases
compressed air prior to the piston
power stroke, preventing combustion,
slowing engine rpm and reducing
wear 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 make
that possible.
“Upfront costs are very deceiving,”
says Scott. “I might have saved
$10,000, but did I lose a customer this
morning because I had three trucks in
the garage? That truck costs me the
same amount whether it’s delivering
concrete or sitting in the garage—I’m
still making payments on it.” s
PUBLICATION #J980258
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