Equipment
PROFIT-PROVED VARIANT. FAST-ERECTING TOWER CRANES
Vladimir Novoselov
As of today fast-erecting tower cranes have strengthened their hand outside of Europe – they became very popular in Asia too. Such types of cranes are used according to the design philosophy of the erected building or installation (relatively low altitude and weight of lifted construction). The main application field is: low-rise construction (usually 5-7 stores) – mansion houses (cottages, etc), shopping malls, administrative and public buildings, warehouses, multilevel parking; assembly/disassembly of constructions in straitened circumstances; bridge building; handling operations; installation of antinoise screens, etc. Such cranes could be exploited at the primary stage of high-rise construction or in the capacity of temporary elements under high-altitude cranes.
Russian customers began to use such tower cranes recently. Compared to the stationary tower or wheeled mobile cranes, their total sales volume is low, but this market is constantly developed. Such companies as Liebherr and Potain had strengthened their hand in this section. Day by day there appear new manufacturers – namely Terex, Raimondi, Alfa. Russian companies also have their own producers, such as Yunikran, Nyazepetrovsk crane factory (NKSZ), Klintzovsk autocrane factory (KAZ), Uhtinsk mechanical factory (UMZ).
Let us consider the constructional characteristics of fast-erecting tower crane models, presented at the Russian market.
The family of Liebherr tower cranes numbers 14 models. They can be divided into three groups – cranes of the K and TT series (non-self-propelled, transported by means of a tractor) and crawler cranes of the R series (self-propelled within the building site). There are also fast-erecting special truck cranes of the MK series.
The fast-erecting crane program of lattice construction extends from 26 to 120 mt. These cranes have various jib lengths and hook heights as well as simple erecting kinematics. Due to the 34 K to 120 K.1 cranes' quick-climbing system, complete tower segments can be installed quickly and easily, with the under-hook height adjusted to suit the construction site. These cranes have both the 45° obstruction-avoidance angle and the 30° raised-jib working angle. The 26 K.1 is equipped with the practical 160° obstruction-avoidance angle and the 40° super-raised-jib working angle. All driving units of cranes are electronic. Slewing gear has a swinging load damping system and a wind load regulation. Hoist gear has a frequency converter. Crane tower slewing has no rotation limit due to the skate. Crane construction provides an opportunity of separated and tracked crane travel.
Severe Russian exploitation conditions are taken into account in the construction of an electrical cabinet with a function of microclimate maintenance. They also have a patented automatic re-reeving device (double/quadruple).
Crane is managed by means of a remote control (wire or wireless). Also crane can be equipped with an operator’s cabin with a post, all-round glaring, heater, screen wiper and screen washer. There is also possible an installation of an operator’s platform at the crane bottom with steps and rops.
Crane disassembly is executed by one operator from the remote control. Self-contained ballasting can be executed by means of a semi-automatic ballasting tongs and automatic self-centering ballast slabs. Ballasting by means of foreign lifting devices is also possible.
For the transportation there are used various drives like double/triple pole-changing hoisting gears, double pole-changing trolley travel gears with 25 km/h speed (within building site) or 80 km/h (on public roads). Transportation by means of foreign transportation devices is also possible.
The 32 TT is the representative of the TT series. Its main distinction from the K series is the telescopic construction of tower and jib. Crane tower has box sections and jib is latticed (both are 2-sectional). The jib of the 32 TT offers seven different jib lengths and can be positioned at two-metre extension intervals to provide a fixed working radius. Load moment ranges: 30 mt - 57 mt. Crane has the 20° raised-jib working angle. Other constructional characteristics are similar to the K series.
The crawler-track undercarriages of the R series are produced by Liebherr to be used in conditions of a complex relief and rough terrain. They are the already known models of fast-erecting cranes of the TT and K series - 32 TTR (look the main picture at the beginning of the article), 42 KR.1, 120 KR.1 (crawler transported). They provide maneuverability and high mobility.
Crane can work independently due to the presence of an integrated generator with a diesel engine for the base mounting, crane installations and other current consumers. Besides, it can be connected to the external power supply. Crawler track provides a crane travel at the speed of 25m/min. Crane can be transported as in transport position, as in unfolded position with a complete ballast set. The conveniences of a crawler track are necessary at the objects with a high travel rate. Base mounting has a telescopic crawler trolley, what provides the compactness during its transportation and stiffness at working position. Telescopic hydraulic mountings are also used for the stiffness growth. Base mounting and crane installation management is executed by means of a remote control. Aside from that, this crane installation is similar to the corresponding fast-erecting crane.
Liebherr also provides such types of fast-erecting cranes as track-mounted cranes of the MK series. In terms of erection speed these cranes fully justify their name – their transfer to the working position is executed by one operator by means of a remote control. However, this crane installation is based on the expensive and complicated chassis, that’s why it is not as cheap as other fast-erected cranes. In turn, cranes of the MK series excel in their characteristics the main part of such models as non-self-propelled and crawler cranes of the K,T and R series, and also they do not create the conditions for the internal competitiveness, they gather the mobility of a classical self-propelled crane with the functional advantages of a tower crane. Such cranes are convenient, first of all, in cases, when there is a necessity of their usage on different building sites within one day. They are provided with modern wheeled chassis, contributing to a high mobility of a crane. Their exclusive maneuverability is conditioned by the usage of an active back axle steering, and also several bridge management programs. Crane is transported in a fully assembled and fully equipped condition. Cranes of the MK series have latticed or box telescopic towers (subject to model). Mobile construction cranes are also fitted with the 45° super-raised jib angle. Cranes of the MK series have hydraulic stabilizers like all classical mobile cranes (with an automatic crane leveling). Operator’s lift-cabin can be fixed at any level.
Company Potain offers the widest family of fast-erected hydraulic cranes, which consists of 23 models: from the very small cranes with 16m lifting height, 16m jib height and maximal 1.3t lifting power to the most powerful models with 51m lifting height, 50m jib height and maximal 8t lifting power. These cranes are very popular both in Russia and other CIS countries.
Potain cranes have a traditional construction for the machines of this type. They can be provided with different axis types for transportation (within building site and public roads). They can be transported on the drop-frame semitrailer. Cranes of the Igo series have a box unfolded tower with a profiled piped cut. The special tower cut increases the rigidity of construction and allows considerable decreasing of crane weight. Cranes of the IgoT series have a latticed and telescopic tower, a latticed jib, whose length can be specified during the crane erection (using additional jib sections) or during the working time (having folded a jib to the specified length by means of its own mechanisms). Cranes are provided with the mechanism of a jib angle adjustment. Crane folding and unfolding are executed by means of hydraulic devices, working operations are executed by means of electric drives.
Crane assembly and disassembly are executed at minimal time. Total Igo series crane assembly can last no more than 2 hours. IgoT series crane assembly is executed within 6 hours. Assembly is executed by 2-3 people with the implementation of an additional crane of without it, as fast-erected cranes are provided with beam cranes for the installation of own counterweight and telescoping mechanisms. Additional crane increases the speed of assembly. Stabilizer substantial stroke allows crane erecting on the uneven ground. Besides, crane installation ground doesn’t need a special preparation due to its large bearing area, whereupon crane ground pressure is minimal and the crane can be placed at softer soil.
Cranes are provided with frequency converters on electric drives of all main mechanisms, what increases the productivity of an operational cycle, controls ride, freight positioning accuracy and needs low starting current (additional energy saving). Crane management system allows working of all three main mechanisms at the same time. Cranes are computerized in order to increase the productivity and allow operator managing at a safe mode, while the service engineer can execute the installation, doctor and maintain cranes at minimal time. Cranes are managed by radio remote controls (wire). Indication of an operating crane is printed at the liquid crystal display. All crane models in their standard versions are provided with coordinate parity systems and parameter register. Rational location of safety elements eliminates equipment errors, produced by the dynamic effect during crane travel.
Cranes, imported by Potain to Russia, are provided with heating of mechanisms and cabin and with a thermostat. The latter controls the bottom temperature limit of working regime (–25 ÎÑ) and blocks crane work at lower temperature. All crane reducers are maintained with oil, which should not be changed during the whole exploitation period.
Among Russian producers of fast-erecting tower cranes we can mention group of companies “Yunikran”. Recently they developed the manufacture of cranes under license of the Italian company FmGru S.r.l. at the factory “Stroytekhnika” (Tula region). Today they offer one 4-ton model, which has Russian name KB-235. All main crane components are delivered from Italy, and fabricated metals are produced at “Stroytekhnika”.
Construction KB-235 is a traditional machine of the corresponding type. Crane is provided with running chassis, which is transporting within the building project. Tower presents itself a two-wheeled folding construction, which is produced with the help of a box girder. Jib presents itself a truss construction consisting of three elements. The mechanisms of the erecting crane are hydraulic. Crane can be assembled by its own mechanisms, however, in order to minimize time it is recommended to use foreign auto cranes to install a counterbalance block at the rear console. “Turnkey” crane assembly by two people lasts 4 hours. Electrical drives of working operations have frequency converters (with all advantages of this construction – look above). Crane can be managed as by means of a cable remote control, as by means of wireless control. Functioning of crane in conditions of a restricted space is provided by the alteration of jib length from 35m to 30m or 14m. KB-235 can work at the temperature not lower than -25ÎÑ, due to the implementation of cold-resistant steel of crane construction, and also to control cabinet heating. One of the important advantages of Russian cranes can be the fact that their price is 1.5 times lower than the price of similar models of foreign production, and also we can mention short delivery terms (5-10 working days) and the presence of spare parts at the factorial warehouse.
This year two Russian manufacturers – KAZ and NKSZ – presented to the specialists their fast-erecting tower cranes. Presentation of new products was held at the exhibition “STT’2009”. Actually it was the presentation of new fields of activities of such famous domestic companies. Indeed, there was a misunderstanding related to the production of NKSZ as their crane was presented at the exposition of the Chelyabinsk mechanical factory. Consequently, we’ve learned that the Nyazepetrovsk crane factory is the producer of the crane, and the Chelyabinsk mechanical factory is the seller of this product.
Constructors of Klintsovsk autocrane factory focused their attention on the segment of low-tonnage fast-erecting cranes. The presented model KB-108 (KBSM-16) is characterized by its maximal lifting power of 1.6t and 1.8 m long jib reach (maximal reach 24m long – 800 kg). Folding double-elbow crane tower 16.7m long has a box cut; it was made from bent semi-boxes. Jib is latticed double-elbow construction 24m long. These cranes have 14° raised-jib working angle. The driving units of these cranes are typical for the cranes of this type: crane mechanisms have electromechanical units (motors are unattended); lifting, tower drop and jib folding mechanisms have hydraulic ones. Hydraulic kinematics of assembly allows quick and safe crane installing by one person. High assembly curve allows jib unfolding at the level of 17.5m and above the obstacles. Foreign lifting vehicles are used only for the assembly of additional counterbalances. Crane construction provides an opportunity to work with freights inside 360Î circular zone. Crane management is executed from the cable operator remote control or by means of radio control. Installed safety vehicles apart from lifting restrictor have parameter register, hook lifting restrictor, cable reeling restrictor, lifting indicator, crane inclination indicator, moto hour counter, audio signal device, anemometer (automatically turning audio signal with the achievement of wind speed, mentioned in the passport for the working condition of crane). KB-108 is intended for work at the temperatures from +40 to -40 ÎÑ. Crane is provided with its own carrier, maintaining its transportation within the building site with the help of towing by transport vehicle with the speed to 15 km/h. At the public roads the crane is transported on the platform with folded assembly ballast. Additional ballast blocks are transported on a separate transport vehicle.
NKSZ, being a part of the Industrial group “Kranov” produced its first fast-erecting crane KB-314 of 5t maximal lifting power under license of the German company KSD Kransysteme GmbH. Crane has a latticed telescopic tower, which can have two fixed height positions – 23 and 29 m. Jib is also latticed, its main length is 34 m. Jib can be extended to 40 or 43 m by means of 3 and 6 m inserts. These cranes have both the 45° obstruction-avoidance angle and the 20° raised-jib working angle. All working operations of crane are executed by means of an electric drive (motors are unattended). Speed regulation for such cranes is traditional (frequency type). Crane is assembled and disassembled by two specialists within 4 hours without the implementation of foreign lifting vehicles. Crane can be managed from the portable cable remote control or radio control. KB-314 is provided with dollies, allowing tractor towing of cranes (with disassembled counterbalances) at the public roads at the speed of 80 km/h without the special permission of traffic police. Nyazepetrovsk crane can work at the temperature from +40 to -40 ÎÑ. Today HKSZ continues it work for new models of fast-erecting tower cranes. Its constructors plan to produce two models of 3 and 4t maximal lifting power.
Recently the official site of Uhtinsk mechanical factory published a piece of information about their new fast-erecting crane KB-202UHL with maximal lifting power of 3t. This crane can be exploited in regions of moderate climate, as well as in regions of utmost North, at the ambient air temperature from -60 till +40 ÎÑ. It is a track-mounted travelling crane and there can be also a stabilizer (non-carriage) variant. This crane is assembled by means of its own mechanisms.
Unfortunately, we couldn’t manage to get more detailed information about new cranes of UMZ and such foreign companies, as Terex, Raimondi and Alfa.
BY THE WAY
Special auto cranes with a tower-jib equipment KST-7 (on the picture) and KST-5AM1 of 7 and 5 t lifting capacity, respectively, produced by “Ivenergomash” factory, can be considered to be the relatives of fast-erecting tower cranes (especially Liebherr cranes of the MK series). Cranes have a hydraulic activator of all executive devices and can work with the help of both base unit engine and external power supply network. No additional lifting devices are necessary for their unrolling. The lifting height admit of KST-7 is 23.5 m, its boom-out is 12 m, as for the KST-5AM1 these parameters are 17.6 and 8 m, respectively.
