A truck of their own: steering manufacturers toward productive truck configurations.

Normally the sight of state DOT enforcement agents setting up portable truck-weighing scales under the watchful eyes of the state transportation agents would have signaled a bad day coming for Graham Poole. But on this warm fall day, it was an opportunity for which he had been waiting for several

Poole knew that things were going to work out, but there still remained the threat of the unexpected. When the mixer truck pulled up under the batch plant's discharge spout, Poole's plant operators asked in a quiet voice if he should batch the full 10 cubic yards. Poole nodded his head in reply. The plant roared into its familiar hatching sequence.

A few minutes later, with the truck fully loaded, Poole and his group of important visitors knew the moment of proof was about to happen. The driver cautiously approached the scale. Following the direction of the state scale master, he properly positioned the new twin-steer axle mixer on the scale load pads.

Poole positioned himself so that he could share the view with other members of this inspection team of the scale's LCD indicator. And he later said that he exhaled a cleansing breath when the scale readings confirmed what the truck-design engineers had predicted. The twin-steer axle track will legally scale at its full-rated drum capacity load of 10 cubic yards of standard-weight concrete.

Poole's mission, initiated by Bryan Pfohl, Sunrock Concrete's owner, to create a safer rear-discharge truck configuration was accomplished with the result of the scale test. With this proof, Sunrock is committed to building a ready-mixed truck fleet of rear-discharge, twin-steer mixers and in time eliminating their use of a trailing-arm axle.

Poole had arranged the early morning weight test with the North Carolina Division of Motor Vehicles--Enforcement Section as a courtesy to eliminate any further problems in field enforcement as his new fleet additions hit the street. The scale test was the first step in the department's process to create a new procedure for weighing trucks with this new axle configuration. Once approved, the new procedure would be distributed to all state DMV officers.

But the vice president of Carolina Sunrock, Raleigh-Durham, N.C., knew that the real benefits of the new truck configuration were the increase in fleet safety and driver comfort. And just as important, the success fulfilled a promise that Pfohl and Poole had made to their employees to create a safe company.

Weighing in on productivity

Graham Poole has been around concrete trucks for a long time. As a kid, Poole shared many a ride with his father in the family ready-mix truck fleet. And then he made a more formal commitment to the industry following graduation from the Citadel in 1983. While he had been involved in a number of industry-wide efforts to make concrete production safer and more productive, one problem still nagged his conscience.

Poole had always wondered why someone hadn't done anything to design a fully loaded rear-discharge ready-mix truck that would meet federal bridge laws without using what he describes as "the high-maintenance and cumbersome" trailing axle.

"When I first saw ready-mix trucks with these trailing axles, my father told me that this 'invention' was a temporary fix and that someone would come up with a better idea soon," said Poole. But that has not proven to be the case. According to Poole, the concrete industry has accepted this awkward "fix" as a permanent solution to meeting bridge laws.

But according to Poole, acceptance doesn't imply satisfaction. "I've never met anyone in a state operating under bridge-weight law requirements who wouldn't welcome a new configuration that would eliminate this albatross," said Poole.

Armed with the lifelong conviction, Pfohl, Poole, and their management team at Sunrock studied truck configurations that were used in other countries to meet severe axle-weight load limits. The team discovered that truck users in Europe and Canada had already solved the problem in principal. The team even traveled to Montreal to look at some twin-steer ready-mixed concrete trucks in operation.

With the help of Cooper Sykes of Cooper Kenworth, their local truck dealer, Sunrock's team configured the truck that was eventually to pass the scale test conducted early this fall. "I think I attribute a great deal of this success to Cooper Sykes, who worked diligently with Kenworth engineers on the final design," said Poole.

Three units were custom built for Sunrock by Kenworth and were delivered in late fall of 2002. Throughout the design phases, it was understood that the trucks would have to haul the same payload as a track using trailing axles.

The field tests of the concrete proved that the configuration met with North Carolina DMV weight and payload regulations. In tact, Sunrock management worked with the state authorities from the very start of the design process. Poole found the authorities to be very helpful. "Many suggested that the new configuration will cause less wear and tear on surfaces and thus reduce roadway repair costs," said Poole.

The end result is that Poole's team is convinced that this new track design will revolutionize ready-mix truck designs in other states. And to prove it to the industry, they've scheduled delivery of 12 more units in late winter and early spring of 2003.

Configuration innovation

The key to the innovations is the twin-steer front-axle design. Sunrock's new mixers have two sets of front-steering axles. With a better distribution of the loaded weight over 6 axles and 16 wheels vs. 5 axles and 14 wheels, the unit meets stage bridge weight laws at full capacity.

Under North Carolina's weight laws, the allowable weight a truck can haul is determined by axle group weights and the overall gross weight of the truck. In this configuration, axles 1 through 6 are considered a single "group," meaning the entire length of the truck is a single "bridge." Therefore, only the total gross weight of the truck is considered for compliance--unlike conventional ready-mix trucks that can have weight limitations on various axle groupings.

The configuration also works for secondary roads. Under North Carolina's weight laws for low-tonnage roads, the allowable weight a track can haul is based upon the average weight of any axle within a group. Again, since the twin steer is considered a single axle group (or a single "bridge"), the weight calculation used is based upon the total weight of the truck divided by six axles. Because of this configuration, the twin steer can haul 10 cubic yards on the state's low-tonnage roads.

With the mixer more centrally located on the truck, more weight is forward, making the truck less susceptible to rollovers. And when the weight of more equally and uniformly distributed payload is combined with a larger "footprint," trucks are less susceptible to getting stuck in adverse jobsite conditions. And Poole expects to have less rear-d problems because there is no sudden weight transfer to the rear-axle assembly on poor soil conditions as there is when the driver raises the trailing arm on the standard truck.

There is also the advantage of increased braking capacity. "With the twin-steer design, we have doubled the sets of front-braking wheels," said Poole. This feature is even further enhanced because the anti-lock braking system applies to all 16 wheels vs. 14 wheels of a standard chassis.

Driver-friendly

Poole feels that his drivers will find the new configuration to be a benefit. "We anticipate that these trucks will result in higher driver retention due to a more comfortable driver-friendly design," said Poole. "We have even gone so far as to specify automatic transmissions for driver safety and convenience."

Along with convenience, these trucks offer some safety considerations. With a more even weight distribution across the whole frame, the truck is more stable and thus easier for the driver to handle. Having dual-steering axles increases turning grip and thereby reduces sliding while turning on wet or otherwise slick roadways.

With no trailing axle (a cumbersome mechanical device), the driver can concentrate more on the safe, expeditious delivery of concrete rather than having to deal with ancillary equipment. "Our configuration has eliminated accidents from errant or erratic movement of the tag axle up or down, which can occur due to mechanical malfunctions," said Poole. He points out that there aren't any tag axle fenders to break off to become potential road hazards.

Poole has found drivers to be more productive using the new truck. First, there's less downtime due to the common tag axle repairs from malfunctions of hydraulic and electrical systems, crushed or smashed discharge chutes, and other problems, such as fender repair/replacements.

Second, Poole is finding truck cycle times are decreased, thus increasing the number of loads per truck per day. At the plant, these trucks load faster and are easier to wash down following drum charging. And on the job, there's no longer time taken to lower the axle when arriving on a jobsite.

Third, there are savings in the tire repairs. Poole is anticipating less tire wear since weight is better distributed on all axles without overloading any single axle or group of tires.

Long-term benefits

By reducing the weight from truck overhang, Poole also expects a number of tangible and intangible advantages. Since Sunrock is planning to lease these trucks for 5 years, they have opted to include features such as a heavier-than-normal engine and suspension.

The new design allows such plans because these trucks can be used as dump trucks. As dump trucks, they will be able to haul as much as a tractor-trailer. Sunrock management views design as a potential great return on investment, as trucks purchased with trailing-axle configurations aren't normally used in retirement or find value in the resale/secondary market as dump trucks, since the tag axle reduces payload capacity.

RELATED ARTICLE: Casting gains in productivity.

When Robert Affenita sold his fleet of six 12-yard mixers to focus on his 20-year-old precast concrete business about a year ago, he never thought he'd be back behind the wheel of a mixer. But he recently changed his mind.

Affenita was having operational problems in purchasing concrete for his own needs at All County Block and Supply, the building supply yard located in Bohemia, Long Island, N.Y. The daily order quantity from the small operation, which casts septic system covers, extension collars, and survey monuments, created delivery problems for his ready-mixed concrete supplier. The high-volume producer had a policy that 4 cubic yards was the smallest delivery load without an additional charge. "If I only needed 2 yards, I still had to order 4," said Affenita. All County workers often had to pour forms they didn't really need.

But when Affenita purchased a 3.5-cubic-yard, class-7 mixer truck, he solved the production problem. Since using the truck's agitating capacity of about 3 cubic yards, All County now buys fresh concrete at a low price and just as importantly can balance plant work activity. "My decision has proven to be very cost-effective," said Affenita. "I can still pour 4 yards a day if I need to, but I can do it in two shifts, which is easier on my employees."

Recently, Affenita found another application for the mixer, servicing the short-run, short-load customer. And he has found the Mitsubishi Fuso FM-MR concrete mixer to be ideal. "We've sent the mixer out to pour patios, sidewalks, and cobblestone curb work," he said, "and the contractors are more than willing to pay the premium price to get the short load delivered right where they need it.

"I don't want to be doing what everybody else is doing," he said, "and I don't want to compete with the guys who have the 10- and 12-yard mixers."