Most of the 21 LC 660 flat top crane’s design is based on the successful 21 LC 750 model but it also includes new improvements.Linden Comansa completes its LC2100 series with the 21 LC 660 tower crane, designed under the EN 14439 European standards, and available in four versions, depending on the maximum load: 18, 24, 36 and 48 tonne (39,680; 52,910; 79,360 and 105,820 lb). The crane, whose commercialisation will start in July 2012, includes the Spanish manufacturer’s most recent features, such as the Effi-Plus high speed hoist mechanisms, or the PowerLift system.Due to its characteristics, this new model is especially useful in public works, industrial construction, mining and infrastructures, and allows Linden Comansa to complete its already wide range, as this new crane covers the space between the cranes 21 LC 550 (18 and 24 tonne) and 21 LC 750 (24, 36 and 48 tonne).The 21 LC 750 tower crane, launched in 2009, has been one of Linden Comansa’s most successful models, mainly due to the innovative design of the slewing part, and the easiness of its assembly. A similar design has been applied in the 21 LC 660 tower crane, which doesn’t have the apex element either, as the first jib and counterjib sections are assembled together directly over the slewing platform through fast conections, which saves time, reduces costs in auxiliary equipment, and improves the safety.Both jib and counterbib sections that form the slewing head of the 21 LC 660 are, which provides an easier assembly of the crane, and shortens the counterjib of the 21 LC 660 three metre in comparison to the 21 LC 750. Most of the jib sections of the 660 are the same of the 750, which increases the modularity and the possibilities of section interchangeability between both cranes.For the tower of the 21 LC 660, a new mast section has been designed, named D35, which is more economic than the tower section at the 21 LC 750 (D36). Both have the same dimensions (5.5 m high and 2.5 m wide - 18 ft high and 8.2 ft wide), which makes them compatible and able to share the same hydraulic jacking cage. The D35 mast sections can be divided in four panels, are easy to assemble and transport, and are easily joined to other sections by pins.Two standard tower configurations have been created: the first one uses only D35 tower sections, allowing the crane to achieve a freestanding height of 73.3 m on fixing angles (240 ft), or 69.9 on stationary or travelling base (229 ft). The second configuration combines D35 with D36 sections, and allows the 21 LC 660 to reach a height of 78.8 meters on fixing angles (258 ft), and 80.9 on base version (265 ft). Furthermore, the enormous modularity of the different tower sections from Linden Comansa allows many alternative configurations, which makes possible to the 21 LC 660 to reach a freestanding height of 124.8 m (409 ft).Compatibility is one of the characteristics that Linden Comansa stamps on all of its cranes, and the trolley-hook set of the 21 LC 660 is a new example, as it is the same as the 21 LC 550 or the 21 LC 750, depending on the model: the 18 t version of the 21 LC 660 has the set of the 21 LC 550 18 T, and the other three versions use the same set than the three versions of the 21 LC 750: 24, 36 and 48 T.The experience acquired with the 21 LC 750 has led to some improvements on the new model, such as expanding the transit zone at the slewing part, or placing all the electrical components and converters in a single cabinet, at the platform of the cabin, which allows easy maintenance labours.