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GMC Previews Truck Future

A PICKUP truck that turns as tightly as a Honda Civic and a hybrid pickup that generates enough electricity to power a small construction site were among the technologies that GMC plans to include in its truck lineup as early as October. The truck manufacturer made the announcements during a press conference June 27-28 in La Jolla, California.

Oh, and by the way — GMC also unveiled its new line of commercial trucks ranging from Class 4 models to those rated at 61,000 pounds GVW.

While the advanced technologies such as the tightly turning QuadraSteer Denali pickup and the Parallel Hybrid Truck that combines a V-8 engine and electric motor captured the imagination of the audience, it is the broad lineup of new medium-duty commercial trucks that promises to get the attention of truck equipment shops.

Code-named the GMT 560, these new vehicles will consist of the C4500/5500 (Class 4 and 5 trucks), along with the Class 6 C6500, the Class 7 C7500, and the Class 8 C8500. They will be introduced during the first half of 2002, designated as early 2003 models.

The C4500/5500 are new from the ground up, according to GMC. Designed as replacements for the 3500HD, these new models are available with GVW ratings of 16,000, 18,000, and 19,500 pounds. They will be available in a variety of two-wheel-drive configurations, including regular cab and crew cab models, along with commercial and RV cutaway chassis cabs. The initial product offering will be two-wheel-drive regular cab and commercial cutaway chassis cabs, with crew cab and four-wheel-drive models arriving shortly after the initial product launch in the 2002 and 2003 model years.

The C6500/7500/8500 Series replaces the current Chevrolet and GMC C-Series in Class 6-8. GM will begin production of two-wheel-drive regular and commercial chassis, adding crew cabs during the 2002 calendar year. They will cover the GVWR spectrum from 19,500- to 61,000-lb ratings.

Niche Markets

GMC is taking particular aim at six niche markets in introducing the C4500/5500 Series. Six vocational packages designed to simplify truck body installation will be offered: ambulance, fire and rescue, school bus, shuttle bus, snowplow, and wrecker.

Higher up the GVWR range, the C6500/7500/8500 Series also will be segmented. Among the variations will be low-profile chassis, tandem-axle models, and a tractor.

Each of these niche markets should be able to take advantage of the improved visibility and maneuverability built into the new trucks. New steering geometry on GMT560 models has made a marked difference in turning radius. For example, a regular cab GMT560 with an 84" CA can turn in 40.74 feet. Other factors contributing to the increased maneuverability include a set-back front axle and new front springs. A new ZF S-2 steering gear offers standard variable ratio steering, improved durability, and high output-to-torque ratios.

A sloping front hood enhances the driver's ability to see the road. The angle enables the driver to see the ground as close as 14.8 feet in front of C4500/5500 models. Visibility distance is 18.8 feet in front of the C6500/7500/8500 models because of their slightly higher frames and cabs.

Straight Frames

The GMT560 models share a stamped, straight C-section frame that provides a clean back-of-cab interface for truck body installations. The frames will come in three variations:

  • 6 mm-thick rails made of 50,000-psi steel will be offered on school bus chassis. They will have a resistant bending moment of 356,000 lb-in.

  • 6 mm-thick rails made of 80,000-psi steel will be offered on school bus chassis. They will have a resistant bending moment of 570,000 lb-in.

  • 8 mm-thick rails will be offered for long-wheelbase conventional cab models. These rails have an RBM of 736,000 lb-in.

The stronger frames are needed to handle the longer wheelbases GM will be offering. The C4500/5500 will be available with wheelbases up to 235 inches, while the maximum wheelbase for the C6500/7500/8500 Series will be 296 inches for single-axle models and 308 inches for tandems. According to GM, even single-axle models will be able to be equipped with 30-ft bodies without requiring frame extensions.

Engine Choices

The GMT560 will offer a choice of diesel or gasoline engines. Powering the C4500/5500 Series will be the Duramax 6600 diesel, which will be available with 300 hp @ 3100 rpm and 520 lb-ft of torque at 1800 rpm. C4500/5500 customers also may choose the standard Vortec 8100 V-8 (325 hp @ 4000 rpm and 450-lb-ft of torque @3200 rpm).

Either of these engines can be mated to the standard ZF S6-650 six-speed manual transmission or an optional Allison five-speed automatic. The Allison automatic offers PTO capability in a GM Class 4-5 conventional cab truck for the first time.

The C6500/7500/8500 Series will be powered by either the new Duramax 7200, the 7880 Duramax, or the Caterpillar 3126E diesels or the Vortec 8100 V-8 gasoline engine.

Allison 2000 Series transmissions will be standard in the C6500 and 7500 Series. The Allison MD 3000 Series will be standard in the C8500. Optional manual transmissions will include a range of Eaton five-, six- nine-, or 10-speed models and two TTC seven-speed gearboxes.

GM's New Technology

The new truck line-up was only part of what GMC had to show. The company displayed an array of technological developments, including the radical Terradyne concept full-size pickup and the Terracross concept SUV.

The technology scheduled to hit the market first is its four-wheel steering system that will be standard equipment on the GMC Sierra Denali pickup beginning in October. Other applications are expected to follow.

A product of Delphi Saginaw Steering Systems, the Quadrasteer all-wheel steering concept will enable the full-size pickup to turn in a 37.4-ft diameter, rivaling the maneuverability of compact cars.

The rear wheels can turn in the same or opposite direction as the front wheels. When in “negative” phase, the rear wheels steer opposite the front wheels. This is what creates the extremely tight turning radius.

However, the rear wheels also may steer in the same direction as the front. This “positive phase” improves the truck's ability to make high-speed lane changes — particularly when pulling a trailer. In effect, the rear axle becomes the articulation point for the trailer, reducing the amount of swing.

Electronic controls determine which direction the rear wheels steer, based upon wheel speed.

Further into the future, GMC is scheduled to introduce a combination electric and gasoline powered truck in the 2004 model year.

While hybrid power is expected to reduce fuel consumption by as much as 15%, perhaps the biggest application for the commercial truck market is what the truck can do while sitting still. With the 5.3-liter Vortec V-8 gasoline engine running, the truck can produce 4.8 kilowatts of electricity, enough to power a remote job site from a pair of 20-amp 110-volt electrical outlets in the cab and sidewall of the pickup box. Upon arriving, the driver can hit a button, pull the keys out of the ignition switch, lock the cab, and walk away — leaving the engine running and the electricity generating.

The electricity that the truck generates also can be stored in a 42-volt battery pack. GMC chose to use advanced lead acid batteries to keep cost and battery size low.

According to GMC, more 42-volt systems will be introduced as vehicle electrical requirements increase. These 42-volt systems tend to be smaller, lighter, and more fuel-efficient.

City Fuel Economy

The parallel hybrid truck (PHT) achieves most of its fuel economy gains in city traffic. When the vehicle is stopped, the gasoline engine stops running. Most of the accessories, however, continue to operate on stored electrical power. When the driver presses the accelerator pedal, the electric motor kicks in to restart the gasoline engine.

The electric motor takes the place of a standard starter and alternator. The motor is integrated into the drivetrain between the gasoline engine and transmission.

The hybrid is expected to be offered initially on the full-size Chevrolet Silverado and GMC Sierra pickups (no pickup box removal, though). Curb weight of the vehicle will be 4800 pounds, including 250 pounds of advanced lead acid batteries mounted beneath the seat.

GMC also displayed some concept trucks that have produced ideas, some of which will become regular production options before the end of this year.

The GMC Sierra Professional concept vehicle is designed for contractors who run their businesses from a construction site. It will be based on the 1500 and 2500HD Series.

Working in conjunction with Lear Corporation, GMC will offer the Sierra Professional with items such as personal computer interface that retracts into the dashboard, global positioning system, cellular phone in the center console that provides Internet access, voice recorder, color printer, and hanging file folder storage.

Outside the mobile office environment, the Sierra Professional will offer such equipment as Trac Rac ladder rack system, Case DMI receiver hitch, Putco stainless steel crossover toolbox and running boards, Warn winch, and AuraGen underhood generator.

The Terradyne and Terracross concept vehicles reflect GMC long-term thinking. But even there, some of the design ideas are beginning to show up — at least in modified form — in vehicles such as the new Envoy.

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