Derrick crane is one of the varieties of equipment that is used for lifting and handling operations. The crane itself is a construction mast-boom unit. Most often they are used in quarries of facing stone.
General description of the design
In addition to use in quarries for stone mining, it is actively used in industrial construction, as well as in some other industries. For example, since the second half of the 19th century, derrick cranes have been operating in the mining industry. The main structural elements of the device include the following parts: masts, which are made in the form of large metal structures, arrows, strut-jibs. In addition to them, there are also parts such as a rotary platform and a lifting mechanism. The latter usually consists of parts such as a single or double drum winch, as well as a rope. In addition to the listed elements, there are several more that allow you to capture the load and perform other actions.
Types of cranes
If we consider the structure in more detail, then it is worth noting the presence of two different types of derrick cranes.
The first type was called cable-stayed. The boom of such a crane is mounted in the mast, installed with the help of cable extensions, it is able to rotate 240 degrees. Less commonly, but still there are designs when the crane can be rotated 360 degrees. In addition, he is also able to tilt to the horizon by 30-75 degrees.
The second type of derrick cranes is stiff-legged. In this case, the arrow is installed in the mast, but already with the help of rigid struts-jibs. However, the rotation angles, as well as the inclination angles, remained unchanged and can rotate within the same limits as cable-stayed ones. As for the length of the boom of this design, it is from 20 to 40 meters, and the mast height is 14-20 meters.
As for the use of such devices in quarries of facing stone, there they are operated according to a transport-free scheme with top loading, as well as moving rock mass on board the quarry or on an overlying horizon. There are certain installation rules for such derrick cranes that govern the installation location. If a quarry requires more than one device, then the second should be installed outside the work of the first and vice versa. In other words, they should not interfere with each other. The carrying capacity of a standard derrick crane, the photo of which is presented, ranges from 15 to 30 tons. The working space that can serve one such crane is from 210 to 840 m 2 . It is also worth paying attention to the radius of the crane at an angle of inclination. If the angle is 30 degrees, then the radius will be from 18 to 36 meters. If the angle is 75 degrees, then the radius will be reduced to 6-11 meters.
Distinctive features
Since a derrick crane is primarily a lifting and handling equipment, it should have its own advantages that will set it apart from similar devices. The first and very important advantage is a reduction in the cost of excavation and loading and transportation by about 1.5-2 times. The second important advantage is the ability to mechanize excavation and loading, as well as the transportation of rock mass using only one type of equipment. The latter is the creation of favorable opportunities for intensifying the deepening of careers.
UMK-2M
Since there is a wide variety of models of this type of equipment, it is worth considering some of the popular ones. One of these was the UMK-2M derrick crane. Car loading capacity is 25 tons. This is a special crane that is designed for the hinged assembly of steel spans of single-track railway bridges. During installation work, such a crane is usually installed on the upper trusses. The structure of this device includes a horizontal frame and 4 supports, as well as a mast, two front struts and two flexible braces. The equipment described also has a base, which is constant and takes 11 meters. A distinctive feature is that it is possible to change the gauge of the crane depending on the distance between the main farms. The range of changes is within 5.8-8 meters. Conveniently enough, it is possible to transport such a crane along pre-installed special rails. In this case, it can be used to move both the axis of the upper truss belts and the paths along which rail carts ride.
DK-25/40
The 25/40 derrick crane is much more load-carrying than the UMK-2M. Its maximum weight is 40 tons. As for its main purpose, it can also be used for the construction of steel spans of railway tracks. However, this is not all, and it is operated in those cases when it is necessary to equip steel-reinforced concrete spans and not only for railways, but also for the movement of road transport.
As for its design, the crane has a horizontal frame with four supports and at the same time three struts. There is a small but important distinguishing feature in the design. The rear strut is flexible and can only absorb tensile loads. Due to the presence of this flexible strut, it is possible to slightly reduce the dead weight of the structure, and it was also possible to create a self-mounted structure. To ensure good stability of the entire platform in this position, the front slopes are installed at a certain angle. It can be added that the length of the base, as well as the gauge width of the DK-25/40, are the same as that of the UMK-2M, that is, the length is 11 meters, and the track varies from 5.8 to 8 meters.
MDK-63
Another crane that relates to hard-footed structures is the MDK-63-1100 derrick crane. The equipment is tricycle with two struts. A distinctive feature is that the angle between the struts is exactly 90 degrees. Another interesting fact is that the mast of this type of crane is fixed. In the upper node, it is rigidly fixed with struts, and in the lower with spacers. But as for the gauge, the MDK-63 clearly outperforms the two previous cranes, since the range is from 6 to 14 meters. You can change it using plug-in elements that are installed in special places that change the length of the struts. The gauge and the base of the device are set based on the conditions for placing the crane on the mounted terrain.
Hard-footed cranes
All of the above fixtures belonged to stiff-legged structures. There are several common factors that combine them into one group. Firstly, it is one of the main types of material handling equipment used in the construction of bridges. Secondly, the scope of each model directly depends on the characteristics of the cargo characteristics. In this case, the carrying capacity is meant, which the structure is able to maintain when the boom is fully extended. In addition, all the cranes of this type have one more peculiarity, which lies in the relatively low dead weight of the entire structure.
Conclusion
Based on the foregoing, we can conclude that derrick cranes are widely used due to their characteristics. In addition, they are able to perform a fairly wide range of tasks, and a wide variety of models allows you to select the most accurate equipment to perform the tasks.