Liebherr Reveals ‘Hybrid’ CFRP Cylinders and Parallel-Pump Concept

February 1, 2023

Ryan Gehm

Reducing weight from components and systems is a major trend in passenger vehicles to boost fuel efficiency and driving range — it’s not a strategy typically associated with construction machinery and stationary applications. Liebherr Components contends that such off-highway applications also can benefit from utilizing lighter-weight components and has spent years developing the expertise and production capabilities to add them to its hydraulics portfolio.

Liebherr recently revealed “hybrid” hydraulic cylinders — components made of steel but wrapped in carbon-fiber-reinforced plastic (CFRP) — that can be up to 50% lighter than traditional all-steel cylinders. If a weight-optimized product is already available, the use of CFRP can lead to a further weight reduction of 10-20%, the company said.

“At Liebherr, we focus primarily on the construction of an optimized product, especially with regard to its cost-effectiveness,” a spokesperson shared. “This means that a decision about whether to implement a lightweight variant depends on the requirements of each particular application and aims at finding the best possible solution.” Depending on the application and customer preference, the weight savings can increase operating speeds, allow larger attachments and booms, and raise payloads – or, as in road-going vehicles, reduce CO2 emissions and fuel consumption during operation, the company said.

Initially introduced at Bauma 2019, Liebherr’s work with fiber composites at its Components site in Kirchdorf an der Iller, Germany, has progressed, focusing on transferring the technology into its established product lineup. The company says that following preliminary development and targeted design, all its traditional hydraulic cylinders can be wrapped with CFRP. The hybrid-cylinder variant has been integrated into Liebherr’s 380-bar (5,500-psi) series-production range and is available as a separate option in its online configurator for hydraulic cylinders.

For certain applications, hybrid solutions can be implemented without fundamental modifications to the machine, according to Liebherr. Performance of the cylinders is maintained or enhanced, the company says, due to the stiffness, strength and density attributes of fiber composites. Another stated benefit is reduced cylinder-tube expansion during pressure peaks.

Liebherr plans to implement its CFRP technology for other hydraulic components — for example, piston accumulators can be wound from CFRP and are being tested. Its hybrid-material solutions have already achieved “noteworthy results” in field test trials in mining and earthmoving sectors. Material handling and crane construction are other suitable applications.

The company’s goal is “full-fledged” CFRP components — not just hybrid variants — but says there are still several steps to be taken before this can be achieved.

Digitalization of pumps

Liebherr took steps toward the “digitalization” of its hydraulic pumps with a recent concept study and an expanded axial-piston line. Liebherr’s concept consists of a compact parallel pump with an electrohydraulic control (EHC) system, merging mechanical features with electronics.

The parallel-pump system offers the possibility of different gear ratios and is especially suitable for machines with conceptually different drive speeds, said Albert Bertschi, sales manager at Liebherr Machines Bulle SA. The software-based EHC can provide the oil volume flow in an optimized, efficient and highly dynamic fashion, Bertschi said. “Accordingly, the concept creates a prerequisite for future application with condition monitoring of the component,” he said, noting that this technology will pave the way for new applications and industries.

The Liebherr Components product segment also added to its axial pistons by two hydraulic pumps with nine nominal sizes. The company says that the new product developments stem from the mining and industrial sectors, as well as maritime applications, placing increasing demands on the availability and longevity of machines and technology. To keep up, the Components product segment in Bulle, Switzerland, is expanding its portfolio of open circuit pumps by the nominal size of 550 cm3, which also can be used as a double pump of 1100 cm3.

“Like all pumps in this product family, the DPVO 550i is characterized by a particular robustness. In the view of digitalization, this product is ready to incorporate various sensor technologies,” said Guillaume Bonnetot, general manager systems at Liebherr-Mining Equipment Colmar SAS. “We are looking forward to see Liebherr components in use on our own machines.”

The LH30VO family, with nominal sizes of 28, 45 and 85 cm3, now includes a pump of 100 cm3. The LH30VO100 consists of a modular system of eight controllers with a variety of combination options. The variable drive-through concept allows the selection and addition of further pumps, when installing them on the machine. The LH30VO pump family offers a range of applications from mobile machinery and stationary hydraulics for primary work functions to secondary applications such as in fans, auxiliary drives or steering systems.