Truck & Off-Highway Engineering - August 2022 - 10

TECHNICAL INNOVATIONS
with features such as ECO drive, inching,
a variable creeping mode, different driving
modes and adjustable reversing behavior.
It is available either completely
pre-programmed or as an open system.
Rexroth states that customers can
Rexroth's open circuit
hydraulic architecture controls
hydromechanical functions via
software instead of pressure or torque.
productivity of the machine.
Rexroth also has upgraded its range of
axial piston pumps and added new functions,
such as dynamic control of pressure,
swivel angle and torque gradients.
Rexroth states that this allows the pump
to not only reach a specific target value,
but also determine the gradients that are
needed to achieve this pressure. The net
result is smoother and gentler motion,
especially at the start of a movement.
Another new function offered by the
eOC is auto-calibration. This feature
removes the calibration step from the
OEM's end of production line and the
system is calibrated cyclically while the
machine is operating. The eOC software
records specific calibration data when
the machine starts, as well as other
data whenever the operating conditions
allow. The data will account for factors
such as aging effects or temperature
differences, and automatically adjust
the operating parameters.
The system also features a secondary
logic system to control the hydraulic motor's
displacement and output torque to
achieve the desired rotational speed.
Rexroth claims that by moving the control
of the hydraulic system into the software,
fewer components are needed in
the machine and the overall architecture
is simpler. For example, travel direction
valves and brake valves are no longer
needed in this system. Additionally,
Rexroth states that the combination of
working and travel functions in one hy10
August 2022
draulic circuit allows the recovery of hydraulic
energy during braking or lowering.
This ensures that the optimum use is
made of available drive power.
BODAS-drive
Rexroth also offers an electronic variant
of its hydrostatic travel drives. The
BODAS-drive eDA is aimed at industrial
machines such as wheeled loaders, telescopic
handlers and forklifts, but can
reportedly be utilized for any application
that previously used conventional DA
controls. The system consists of a an
electrified A4VG drive pump and A6VM
hydraulic motor. The nominal pressure of
the system is 400 bar (5800 psi) and a
maximum pressure of 530 bar (7690
psi). The eDA package also supports the
digital conversion of hydrostatic drives
integrate specific desired features, such
as operating functions of the travel
drive, working hydraulics or the vehicle's
electrical system. Alternatively,
they can also jointly develop them in
cooperation with Rexroth. The SRC-eDA
electronic control unit serves as the
central interface of the software and all
components in the BODAS-drive system.
The unit can reportedly be freely
positioned in the machine and is EN ISO
13849 compliant.
Radial piston motors
Rexroth has expanded its range of direct
drives for compact tracked loaders and
other tracked vehicles. One of its latest
products in this sector, MCR-T, offers up
to a 55% increase in maximum torque
and a 20% increase in flow capability
compared with the existing and dimensionally
similar motors. The new design is
offered in frame sizes 5, 6 and 10. It features
larger bearings that are flushed
with case oil as well as new seals to ensure
high levels of durability in harsh environments.
An integrated flushing valve
contributes to increased service life by
supporting the cooling of the oil when
used in closed hydraulic circuits. The control
valve is integrated into the motor,
enabling the operator to shift smoothly
between travel speeds via the soft-shift
mode in both directions of travel.
In high-speed mode, the motor runs
The MCR8T redial piston motor has an
output of up to 9,000 Nm (6640 lb-ft) and a
displacement range from 380 cc to 1,340 cc.
with a standard reduced displacement
of 66%, which is also configurable on
request, reducing oil flow in the circuit
and improving system efficiency.
Additionally, the direct drive design of
the MCR-T is said to result in greater
efficiency, longer service life and lower
noise than typical gearbox-based solutions.
The differential pressure of the
motor is rated at a maximum of 450 bar
(6530 psi) with the MCR8T version
achieving an output torque of up to
9,000 Nm (6640 lb-ft). The displacement
of the MCR-T product currently
TRUCK & OFF-HIGHWAY ENGINEERING
BOTH IMAGES: BOSCH REXROTH
Truck & Off-Highway Engineering - August 2022

Table of Contents for the Digital Edition of Truck & Off-Highway Engineering - August 2022
