YONGMAO TOWER CRANES
Yongmao is the leading manufacturer of large tower cranes in the world. In 2007, we brought the first Yongmao crane to Levi in Finland; at the time, it was the largest crane in Finland and capable of lifting a load of 18 tonnes. Currently, the lifting capacity of our largest crane is 750 mt and it is capable of lifting a load of 40 tonnes. All Yongmao cranes are modern flat-top cranes, meaning that several of them can easily be placed at the same construction site, as they do not require the same amount of space between the jibs as conventional cranes with tops.
Yongmao cranes are controlled using a frequency converter, which means that a construction site will save considerably on electricity costs compared to typical cranes. Yongmao cranes have an excellent free standing height; in other words, they can be placed at a height of more than 120 metres without stays. Another benefit of flat-top cranes is that their jib can be extended and shortened in the air, whereas the jib of cranes with a top has to be lowered to the ground. A tower crane can thus be made extended and shortened as the work at the construction site progresses.
Yongmao tower cranes consist of components from manufacturers that are well-known in Europe, such as Schneider, Electric, Yaskawa, Omron, Siemens and Flender. This will guarantee reliable operation and the fact that we have the most common spare parts, engines, frequency converters and logics in stock, and we can, therefore, prevent long breaks in operation at construction sites. The machinery of Yongmao cranes is, for the most part, compatible between various models, which reduces the number of spare parts in stock, and thus facilitates managing spare parts.
LOADING A CRANE
The lifting capacity of a crane is usually expressed in metric tons. This unit indicates the greatest permitted moment of a crane. For example, a crane of 200 metric tons is capable of lifting a load weighing 10 tonnes to a distance of 20 metres from the boom. A metric ton is not an exact unit, as the calculation of the greatest permitted moment must include the effect of the weight of the jib (which depends on the length of the jib) as well as the weight of the hoisting ropes, trolley and hook.
Another key figure of lifting capacity is the maximum load, which depends on the dimensioning of the lifting equipment. Usually, the lifting capacity is demonstrated by using a load chart. The chart indicates the largest permitted load at a given distance. It is easy to see from load charts that the lifting capacity is slightly greater when a shorter jib is used than with a long jib.
The height of the crane also affects the lifting capacity. When lifting is performed extremely high up, the weight of the hoisting rope increases significantly and reduces the useful load.