The 350 horsepower hydraulic-assisted, hot-looking Tonka Truck

Ford’s bright yellow Tonka concept truck borrows heavily from the heavy-metal, sibling-bashing iconic toy that’s a toddler’s favorite. In one of the strangest ventures in reverse automobile engineering, Ford is expressing the workhorse theme embraced by the collectible Tonka toy trucks in a full-size vehicle based on the company’s super-duty F-350 pickup. (The deal with Tonka is for using the name on this concept only. Tonka may at some point want to adapt the design for a toy.) But despite styling and power ratings at the outer end of the Schwarzenegger scale, the concept truck is also a test bed for moderation and efficiency in heavy-duty pickups.

The squared-off exterior, with its prominent fender flares, is a strong hint at the future design of Ford’s pickup trucks. The interior, all rounded plastic and brushed metal, with lots of bins and a giant toolbox, is more far-fetched.

But the most dramatic innovation is a hydraulic hybrid drive system that promises 25 to 50 percent more efficiency. The 16 to 18 mpg or so that results is hardly as fuel-stingy as the 70 mpg claimed by, say, Honda’s lightweight aluminum gas-electric Insight hybrid. But the 350 horsepower and 600 pound-feet of torque produced by the new Navistar diesel would let the Tonka keep up in traffic with two Insights crushed and stacked in its bed.

Based on Ford’s 350-series Super Duty chassis, the Tonka concept is as muscular and weighty as a pickup gets. The vast majority of vehicles in its class are in commercial service, hauling dirt, cement, or refuse. But a fast-growing proportion of owners are employing these behemoths for personal use, ranging from hauling horses to towing RVs. Such work requires raw, fuel-consuming power. Until recently, the power demands made dramatic fuel savings seem unattainable. The Tonka’s new approach to conserving energy in stop-and-go driving promises to change that.

The key is recovering the energy normally lost while braking. The raw torque required to push more than 3 tons up to highway speed is quickly dissipated as heat by the brakes in bringing the same load to a halt. Up to now, most systems that recapture lost braking energy have relied on some kind of electric drive — using energy from a battery pack to assist while accelerating, then using the motor as a generator to recharge while slowing the vehicle. “The problem is that you change energy forms too many times, losing a little efficiency each time,” says Cliff Carlson, senior specialist of advanced technologies at Ford. “Mechanical energy becomes electrical, then electrical becomes chemical (in the battery). And then you reverse it.”

Ford has promised a 25 percent improvement in light-truck fuel efficiency in the next five years, partially as a reaction to pressure from federal regulators. Up to now, the company has directed its efforts toward gas-electric hybrids. In the heavier weight categories, both General Motors and Ford have been working on so-called mild hybrids, which use starter-generators that allow start-stop operation, killing the engine at idle and providing a limited amount of boost during acceleration. Some test results, however, have been casting doubt on the potential of such systems to achieve significant fuel economy.

Carlson points out the alternative Ford is pursuing: Mechanical energy can be stored directly, using a hydraulic accumulator. The accumulator is a high-pressure tank, partially filled with nitrogen. Hydraulic fluid is pumped into the tank, pressurizing the gas above the liquid as the tank fills. The hydraulic pressure can be quickly retrieved as shaft horsepower by running the pump as a hydraulic motor. “You can store lots of energy quickly, which is what you need while braking,” says Carlson. “It’s efficient: As much as 70 percent of the braking energy can be recovered. An electric hybrid is lucky to get 25 percent.”

Still, an accumulator tank with enough volume to launch a heavy truck up to speed is relatively bulky. The Tonka concept’s two tanks, housed between the frame rails, are each slightly less than a foot in diameter and about 2 feet long. They’re reinforced with carbon fiber to withstand pressures that can reach 5,000 psi, and lined with a material that absorbs the heat generated when the gas compresses. The pressure in such tanks is high, so safety testing has been thorough — similar to what storage tanks for compressed natural gas receive. The hydraulic motor itself, mounted midships alongside the tank, is compact, roughly the size of a standard differential.

With the tank charged, the system nearly duplicates the power of the primary diesel, adding another 600 lb.-ft. of torque to launch the truck from a standing stop. This is enough to let it drag race competitively with a BMW roadster, and also means that the engine doesn’t need to kick in until the vehicle is rolling at 20 to 30 mph, when it is operating at a more efficient rpm range. Brake life also benefits — with the system providing most of the stopping force, brake linings last three to five times as long.

The main drawback is noise: Hydraulic motors produce a ratcheting sound that is something like an air wrench. “We can get it to where it isn’t objectionable in a commercial truck,” Carlson says. “We think we can almost eliminate it with about five years of further development.”

The main drive engine, the new 6.0-liter Navistar diesel, will be available in Ford’s heavy-duty trucks next year. The production version will yield something less than the show truck’s 350 hp, but is more fuel-efficient and less polluting than its predecessor.

To its fuel efficiency gains, the Tonka adds a brace of new safety features. Safety and fuel economy have long been sticking points, and the problems have been exacerbated by rising curb weights and payloads. The looks of this concept Tonka may have been inspired by a toy, but it is likely to have a serious impact in the adult world.

A Kinder, Gentler Truck

Who among us has not, in our idle youth, gleefully sent two toy Tonkas into an intense, headfirst, frame-jarring collision? But Ford’s new concept Tonka, in addition to its fuel-saving capabilities, is designed to avoid crashes and minimize them when they occur.

The headlamps on the Tonka, for example, are a first effort to utilize LED light sources. Light-emitting diode technology has been used for brake lights for a decade or so, but the new generation of high-intensity white LEDs makes a compact headlamp, clustering 30 tiny LED searchlights so that they focus a solid beam pattern on the road ahead.

The Tonka’s installed image recognition system looks ahead to detect
possible collisions. When the system senses that a crash with a smaller vehicle is inevitable, it activates the vehicle’s air suspension to lower the front end in 0.3 seconds. That way, the heavy grille and bumper will hit the small car lower down and do less damage. This system also lets the truck “kneel” at
a curb when necessary, so you can swing up into the driver’s seat more easily.

It may be a monster, but it’s a sensitive, courteous one.

Illustration by Ula Puggard