A lightweight high-strength-steel frame intended for use in long-haul transport is claimed to weigh 30% less than conventional frames. Developed and optimized by Engineering Center Steyr (ECS), Magna Powertrain’s R&D center for truck engineering in cooperation with Cosma International, Magna’s body and chassis systems operating unit, the modular frame concept is ready to be brought to market.
“The significant reduction in weight has been achieved by replacing the standard type chassis frame with a unique steel-monocoque structure, while maintaining the same or better technical performance and improving transport efficiency,” Franz Dorfer, General Manager of Engineering Center Steyr, said in a statement. “The production-ready concept utilizes Magna’s unique manufacturing excellence. In addition, by integrating our own fuel system, we can package up to 1500 L of diesel fuel—a clear advantage for transport companies.”
The new frame architecture is able to accommodate different tank designs with a volume of up to 1500 L (396 gal), and it is also suitable for alternative drive technology such as hybrid and CNG (compressed natural gas), according to Gregor Schwarz, Lightweight Design Vehicle Engineering, Engineering Center Steyr. “You can use a standard drivetrain and powertrain, and also standard suspension—you don’t have to develop anything new,” he explained to SAE Magazines.
Rigid front axle suspension with single leaf stabilizer and air spring rear suspension were shown in a packaging display for the frame concept. For a hybrid system, one tank module needs to be removed to accommodate the batteries, Schwarz said.
The frame consists of four modules, weighing a total of 595 kg (1312 lb): front end module (181 kg/399 lb), front axle module (127 kg/280 lb), middle module (127 kg/280 lb), and rear axle module (160 kg/353 lb). This compares to 850 kg (1874 lb) for a standard steel frame, according to ECS.
To offer different wheelbases, only the middle module needs to be replaced.
“The frame’s still steel, but the difference is that we reduced wall thickness,” Schwarz shared. “We have [sections] with a wall thickness of 1.5 mm compared to other frames that have 7, 8, or 9 mm.”
The middle module, with a paneling thickness of 1.5 mm (0.06 in) and structure thickness of 2.0 mm (0.08 in), features a rectangular shell shape with a tensile elastic limit of 380 N/mm2. The front and rear axle modules have a wall thickness between 2.5 and 3 mm (0.10 and 0.12 in).
“With the closed-box design—the geometry of the frame—we get the torsional stiffness,” Schwarz said. “The shape, of course, helps with aerodynamics as well.”
“We also checked other materials [including aluminum, composites, magnesium, and multimaterial] for the frame concept, but we decided to use steel again,” he continued. “The costs are much too high for carbon fiber, and also for maintenance we still need to check some things.”
For assembly, MAG and spot welding are used in all instances except for components that have to be removed for maintenance, in which case they are bolted.
The frame concept has been in development for about four years, according to Schwarz. Magna is currently in talks with truck OEMs regarding the solution.