Truck & Off-Highway Engineering - February 2023 - 8

TECHNICAL INNOVATIONS
HYDRAULICS
Liebherr reveals 'hybrid' CFRP cylinders and parallel-pump concept
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.
Wrapped in carbon-fiber-reinforced plastic, Liebherr's " hybrid " hydraulic cylinders reduce weight
as well as cylinder-tube expansion during pressure peaks.
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 offhighway
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 carbonfiber-reinforced
plastic (CFRP) - that
can be up to 50% lighter than traditional
all-steel cylinders. 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,
8 February 2023
all its traditional hydraulic cylinders can
be wrapped with CFRP. The hybridcylinder
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
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 hybrid-cylinder variant has been
integrated into Liebherr's 380-bar (5,500-psi)
series-production range.
TRUCK & OFF-HIGHWAY ENGINEERING
BOTH IMAGES: LIEBHERR

Truck & Off-Highway Engineering - February 2023

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