Melbourne based overhead crane manufacturer Modular Cranes were recently presented with an unusual problem to solve for one of their customers.
Their customer, a heavy truck trailer manufacturer, already had two 22 metre wide overhead cranes installed in their factory which ran on the same set of rails.
These cranes were rated at 12.5 tonnes each, and had given reliable service for many years. They were identical in their specification and were synchronised with both their slow and fast speeds, and also the elapsed distance they traveled to slow down and stop.
However, the customer’s new production process now required a third crane to be installed on the same set of rails so that long and heavy trailers could be moved through the factory with the load being shared between two of the cranes at any one time.
A wireless handheld remote control would actuate the pair of cranes simultaneously as required.
However, the cranes that were already installed were no longer available so a modern alternative needed to be found, installed and synchronised to match the existing cranes.
This all needed to happen within a tight budget.
Modular Cranes sought the expertise of German Helical geared motor and frequency inverter manufacturer NORD Drivesystems for the two travel drive Helical geared brake motors on the new crane.
To solve the synchronisation problem, NORD Drivesystems’ utilised de-centralised frequency inverter technology.
To further enhance the economy requirement, NORD Drivesytems proposed a conventional 4 pole electric motor with a 10Nm electromagnetic brake mounted to each of the NORDBloc.1 series inline Helical geared brake motors.
The NORD SK205E series de-centralised frequency inverter was also included, complete with internal 24 Volt power supply cartridge, and an external brake resister to accommodate the re-generative current produced by the cranes’ weight when slowing to stop.
The high precision accuracy of the NORD Helical gear set and the flexibility of the de-centralised frequency inverter software permitted this new crane to synchronised with the existing cranes without the requirement of rotary encoders.
By enlisting the two de-centralised frequency inverters they eliminated the need or any shielded cable in this installation.
Modular Cranes commissioned the new crane in 2012 and succeeded in meeting their customer’s expectations regarding their requirement for an economic solution.