FEATURE | GANTRY CRANES
KONECRANES
Konecranes are known for their RMG and RMTG port and dockside gantry cranes; but they also manufacture more standard types. Their design concept, they say, is for simplicity, compactness, and of buildings and work areas both indoors and outdoors. “A compact hoist makes the most of existing workspace, providing an extensive work area around the crane” is their view. Lifting heights up to 10 meters and spans of up to 20 meters are available.
developed and manufactured in-house, as well as options for rope hoists when installed on their gantries give a lifting capacity of vertical movement and smart features such as snag prevention, hook centring and Follow Me. This last allows the operator to speed loading-up operations by simply guiding the hook, by hand, over the load. The crane and trolley automatically follow along overhead. The hoist gives similar lifting capacity and features but uses wire rope. and emergency stops, and safety loops to avoid collisions; the semi-gantry cranes have derailment catches and rail cleaners for smooth movement. Those destined for outdoor applications have storm locks and tiedown to prevent sliding or falling in heavy winds, and windspeed meters that give an audible signal to prompt safety actions. For reasons that we have seen, Konecranes gantry structures
gantries are generally manoeuvred along the ground by hand. They run on four wheels, usually small casters. If the hoist lifting the vehicle engine is not positioned in the middle of the beam, the load is not centralised; then if the gantry is unduly rigid, the wheels will carry uneven loads. Worse: if the floor is anything but completely flat – and concrete floors in repair shops are frequently chipped and uneven – then one of the wheels may lose contact with the ground completely. As well as making it harder to push, the gantry may tip or tilt; with obvious risk to safety. So, again, over-rigidity is to be avoided.
It may be simply that the beam can flex a little, enough to generally compensate in most cases for mild unevenness of the floor; it may be more sophisticated than that. Thus, Pennsylvania makers Wallace, who have been making small gantry cranes since 1954 and who claim to have more gantry cranes in use than any other manufacturer, have their patented pin-joint design. A pin-jointed four-bar link joins the legs to the beam; the beam in effect is hanging from the apex of an A-frame. The arrangement allows it to swing slightly and makes it self-centering upon the legs. The legs at their lower end are also pin-
28 | March 2025 |
www.hoistmagazine.com
jointed, to the frame holding the casters. The arrangement serves several purposes. The self-centering beam reduces torsional, or off-angle loads in the legs, so stresses there are reduced. The casters and frame flex, so that the four wheels are always in contact with the floor. Not only that, but the
A gantry crane at Vejle harbour in Denmark. Credit: Alf van Beem
design ensures that the load is distributed among all the casters. Even if the load is entirely at one end of the beam the load is evenly distributed between the four wheels. Wallace Cranes do have a word of caution about the surfaces that portable gantries are run on. Because the load of the
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