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Worthington's concept Global Cab made entirely of advanced high-strength steels (AHSS) offers a 50-100% strength increase vs. typical ROPS cab materials. (Gehm)

Stronger, quieter cabs

Worthington expert sees AHSS and active noise cancellation making off-highway cabs safer and less-stressful places to work.

Worthington Industries made its first-ever appearance at bauma in April, showcasing the new Global Cab modular design along with its European manufacturing partner Fritzmeier. The cab’s length and width can be varied by using different modular parts and the ROPS (rollover protection structure) incorporated to meet varying requirements while optimizing the cab structure to increase visibility.

Aluminum extruded structures can be applied in weight-sensitive applications such as in crane construction, providing a ROPS loading capacity of up to 20 t. For heavier-duty applications, the cab can be reinforced with an integrated steel INNO-ROPS structure that increases the loading capacity to 50 t.

But the big news at bauma was a concept Global Cab made entirely of advanced high-strength steels (AHSS)—the first such structure produced in the industry, according to Matt Trippel, director of product development at Worthington Industries Engineered Cabs. These AHSS materials can offer a 50-100% strength increase vs. typical ROPS cab materials, and the company is exploring advanced materials that can provide an up-to-300% increase in strength compared to traditional materials.

“We’re one of the largest purchasers of steel in North America. We have unique relationships with steel producers,” Trippel said, noting that Worthington worked closely with U.S. Steel on this development project.

The typical ROPS material is 60 ksi (414 MPa). The Gen3 (third generation) AHSS materials supplied by U.S. Steel for the concept cab are 120 ksi (827 MPa) up to 240 ksi (1,655 MPa).

“The value proposition in the off-highway heavy-duty industry today is really about things like lines of sight, decreasing the structural sections, decreasing the part count in some cases, and solving those unique problems where you don’t have the space or geometry available to use traditional materials,” Trippel explained.

Lightweighting is not the motivating factor in most off-highway segments, he added. The concept cab structure weighs about 300 lb (136 kg), while the equivalent in traditional steel would be in the 500- to 600-lb (227- to 272-kg) range.

“So does 200 or 300 pounds [lighter] move the needle for the off-highway equipment industry when there’s 20-, 30-, 40-, 50-thousand-pound gross vehicle weight vehicles? Probably not. That’s the math we’re doing right now,” he said. “The goal here is to use less material to achieve equivalent strengths, or in some cases reduce the section of structural tubes to increase visibility. The strength-weight tradeoff is really what we’re trying to go after.”

Trippel acknowledges there’s not really a need for an all-AHSS cab right now. But implementing the technology in focused areas makes sense today, with further opportunities down the road.

“As more AHSS materials become available and volumes increase, the ability to expand from a cost perspective across other parts of the cab will become more prevalent,” he said. “That’s also going to spur steel manufacturers to develop stronger materials that are a little bit more applicable to the heavy-duty off-highway industry.”

Quiet, please
Worthington worked with Hamburg, Germany-based Recalm to integrate the start-up’s active noise cancellation (ANC) system in a cab demonstrator, which was drawing a lot of attention at the bauma booth, according to Trippel.

The system is attached to the headrest. Microphones pick up the sound frequencies, and software generates phase-shifted sound waves in real time and outputs them through speakers to cancel out the unwanted noise. Sensors detect where the operator’s head is to create a “quiet zone.” An app is used to configure the system to the specific cab during installation and also can be used to control it.

The ANC system targets low-frequency noise from about 80-500 Hz.

 “You hear collisions, things that your implements come into contact with, but the low frequencies of engine noise, for example, are damped out, providing an overall more-comfortable and safer environment that might be more productive if the operator can hear the things that they want to hear,” Trippel explained.

The noise level in the demonstrator was reduced by 8 to 10 dBA. Greater reductions can be achieved, depending on the sound being canceled.

The technology is still in development, but Recalm expects to start selling the system by year end, in the aftermarket and as original equipment.

Worthington also is working on more conventional ways to reduce noise in the cab, such as cab-mounting technologies, sound-absorbing layers within the glass and noise-insulating materials in the cab. The AHSS concept employed a rubberized coating on the entire interior of the cab that’s still in the experimental stage, Trippel said.

“There’s only so much we can do from a cab perspective. You’re really dealing with the symptoms of the problem,” he said. “Dealing with the noise-emission source is always where we’d like to start, but low-hanging fruit exists in the cab.”

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