Nord releases customised solution for crane drive synchronisation

German manufacturer NORD Drivesystems delivered a customised solution to
enable an Australian overhead crane supplier meet the specific needs of their

Melbourne-based Modular Cranes Pty Ltd is one of Australia’s leading
overhead crane suppliers, offering modular packages for payloads up to 100
tons. The cranes are individually adapted to suit the particular factory layout
or application. Working with top crane technology manufacturers such as
Advanced Radiotech Corporation, Donati and Street, Modular Cranes supplies quality
material handling products to clients all over the country and also services cranes
throughout Victoria as well as New South Wales, South Australia, and Tasmania.

In this particular instance, the Melbourne-based Modular Cranes Pty Ltd
faced the challenge of synchronising a new bridge crane with two existing ones
for their customer, a manufacturer of heavy truck trailers.

The customer had been successfully using two 22m wide overhead cranes in
its factory. The traditional single-girder bridge design cranes rated at 12.5
tons each were installed on the same set of support beams spanning the entire
length of the factory. They were identical in their specifications and synchronised
for two speeds as well as for ramp-up and ramp-down times. A wireless handheld
remote control pendant simultaneously actuated the two cranes as required.

The truck trailer manufacturer now sought to install a third identical
crane on the same set of support beams, allowing for very long and heavy trailers
to be moved through the factory with the load shared between two of the cranes
at any one time.

However, the specific crane used in this application was no longer in
production. After many years of reliable service, the existing cranes had not
nearly reached the end of their lifespan, and therefore it was neither economical
nor environmentally sustainable to replace them. Modular Cranes needed to find
a practical and economical design alternative to match the performance and
synchronisation characteristics of the existing onsite cranes.

For the new overhead crane’s two bridge drives, Modular Cranes sought
the expertise of German drive manufacturer NORD Drivesystems. Annie McDiarmid,
Operations Manager at Modular Cranes explained that their challenge was to
ensure the new crane travelled exactly in synch with the existing onsite
cranes. NORD’s solution not only met the customer’s budgetary requirements but
also provided Modular Cranes the assurance that they could match acceleration,
deceleration, braking, and traversing speeds with the existing non-inverter
driven cranes.

NORD’s solution consisted of an efficient helical gear unit, a standard
four-pole electric motor with a 10 Nm electromagnetic brake, and a motor-mounted
frequency inverter with an external brake resistor. The two bridge drives were configured
to synchronise and match the existing cranes using a simple parameter set-up
procedure and were flange-mounted on the crane girder. The same remote control pendant
is used to operate the new crane with no additional configuration required. The
precision of the NORD helical gear set and the flexibility of the decentralised
frequency inverter software permitted the new crane to be synchronised with the
existing cranes without rotary encoders.

NORD configured the gear units using its UNICASE helical inline gearbox
series, which provides a wide torque range from 10 to 26.000 Nm and ratios from
1.35:1 to 14,340.31:1, enabling unique flexibility in the configuration of the
optimal drive train for any task and mechanical setup. The UNICASE housing design
provides long and trouble-free operation and allows for a highly robust
solution that can withstand extreme loads.

NORD recommended a motor-mounted frequency inverter for straightforward
installation that makes shielded cables unnecessary and resolves the synchronisation
problem. The manufacturer has a comprehensive drive electronics program with
graded performance and functional range options that allow users to choose suitable
compact solutions with the exact features they require for any given task, thereby
optimising budget and resource use.

NORD’s SK 205E inverter selected for this application realises drive
functions such as ramp-up where the inverter ensures the motor starts slowly
with high torque, thereby protecting the mechanics from the extreme loads that come
into play when the heavy overhead crane is started from standstill. An external
brake resistor accommodates the regenerative current when the crane is
decelerated. The inverter is also equipped with an integral 24 VDC power supply
to provide the internal control voltage, therefore requiring only a power
connection and no separate control cable.

Underlining the quality of NORD’s customer support, Modular Cranes’ Operations
Manager Annie McDiarmid said that NORD’s trained professionals provided
abundant amounts of support throughout the process, working with them to achieve
the best possible outcome.

To achieve this high level of support globally, the NORD Drivesystems Group
has established a large network of subsidiaries and service centres including
in Australia, where its subsidiary, NORD Drivesystems Pty Ltd boasts a
state-of-the-art geared motor manufacturing plant with production and quality
assurance processes that comply with the standards of the German parent company.
NORD maintains sales branches in the port cities of Sydney and Brisbane while regional
sales managers serve all States and Territories in Australia as well as New
Zealand. NORD supplies motors conforming to the relevant Australian energy
efficiency specification MEPS High Efficiency and frequency inverters with
C-Tick certification.