WANDFLUH
New steering systems
98 iVTInternational.com September 2019
November 10-16, 2019
Wandfluh
Hall 17, Stand G08
AGRITECHNICA FLUID POWER
THE LOGISTICAL TASKS FACED AT PORTS EVERYDAY ARE BEING OPTIMIZED WITH
THE USE OF INNOVATIVE HYDRAULIC TECHNOLOGY, WITH IMPRESSIVE RESULTS
The so-called ISO or ship containers are
nowadays a standardized part of the global
supply chain. They are usually loaded directly at the
manufacturer, transported by truck to the next container
port and then tend to arrive on large container ships at
their destination port, where they are picked up by a
truck for final distribution.
For the entire system to function smoothly, it must
be ensured that exactly the right container is available
at the right place at the right time. This is one of the
classic logistical tasks of a port operator. In addition to
intelligent logistics software, this also includes loading,
unloading and transport systems that are optimally
integrated into the logistics concept. It is one thing to
know where a certain container is stored on the large
area of the port, but another is to find it and transport
it to a certain place in the shortest possible time in order
to load it onto a truck.
Working out logistics
For many years, Wandfluh has been involved in
providing such logistics systems for container ports
among its customers. Initially, valve technology and
electronics for the large harbor cranes were supplied.
With proportional hydraulic valves and corresponding
mobile electronics, the containers are held exactly
horizontally on the four ropes of the crane during
transport. When two containers are picked up, the
distance between the two containers is also controlled
by the hydraulics so that they are unloaded in parallel
and no transport damage occurs.
A similar electronic-hydraulic system is used for
self-propelled Automated Guided Vehicles (AGVs). Four
hydraulic cylinders ensure that the containers are lifted
horizontally and synchronously and are set down again
evenly after transport. From there, they must then be
stacked with manned large cranes in the intermediate
storage facility for sea freight containers.
The latest generations of these AGVs are selfpropelled
cranes called Straddle Carriers. These
move longitudinally over the containers, lift them and
set them down again directly at the desired storage
location. Up to three containers can be stacked on
top of each other. The logistics software controls
all processes and stores the exact location of the
individual containers.
With the constantly increasing transport volume
on the world’s oceans and the growing port facilities,
intelligent Straddle Carriers integrated into a logistics
system are among the transport systems of the future.
Wandfluh has developed the hydraulic concept for
ABOVE: AGV harbor cranes
BELOW: Straddle Carriers
controlling these innovative AGVs and has already
successfully implemented it in several prototypes.
Moving loads
The steering angle can either be taken over digitally by
a steering wheel on the vehicle, or it can be calculated
directly with the commands of the logistics software
and – depending on the steering mode – can be
individually adjusted via individual cylinders on the
six or eight wheels and monitored using angle sensors
on the wheels.
With partly heavy loads, these Straddle Carriers
have to be able to drive on the port site as efficiently and
safely as possible and they have to be able to maneuver
the loads in the tightest of spaces.
In order to fulfill both tasks, the vehicle distinguishes
between truck mode, in which only the front wheels
move with increasing steering angle in the curve, and
the so-called Ackermann mode, where the steering
angle of the front wheels is set in the opposite direction
to the rear wheels in order to be able to drive curves or
even circles in the tightest of spaces.
The proportional valves for the individual wheels
are controlled by the (SIL) steering controller. It was
programmed at Wandfluh in Frutigen, Switzerland
where an extensive test environment with steering
wheel, valves, cylinders and sensors was replicated in
the laboratory. In June 2018, the hydraulics were finally
installed in the first Straddle Carrier prototype in China.
Thanks to the close cooperation between Wandfluh
and the customer, the new steering system was – after
several optimizations and countless test-drives with the
various steering modes – successfully handed over to
the customer.
Just one year after commissioning the new
technology, series production of these Straddle
Carriers is already on the agenda.
The project has shown that there is great potential
for special vehicles in promising markets and that such
projects are being driven forward and implemented
with great commitment. iVT
By Adrian Feuz, head of electronics at Wandfluh AG
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