World's largest luffers15 August 2006
Like big saddle-jib cranes, luffing-jib cranes over 1,000tm were developed to help build dams and power stations. Their popularity continues today in China, writes Heinz-Gert Kessel
Luffing jib boom tower cranes have a longer tradition than the now-common saddle-jib tower cranes (see ‘Super-size Me,’ CT July, pp. 29-32).
The initial growth of large towers in the 1970s and 1980s came from massive investment in the power generation industry following the energy crises in the 1970s. At that time large mobile crawlers were only beginning to be popular, and large scale tower cranes were seen as a sound alternative.
That popularity continues in China, which up until recently has lacked many of the large crawler cranes with superlift attachments that have taken over the heaviest power station lifting jobs in Europe and the USA.
The big, Chinese-built, luffing jib tower cranes can be divided into six categories according to their design. Many of these modern cranes work on the basic principles of designs developed elsewhere.
1 Stationary top slewing and climbing cranes with a cylindrical mast system. All Japanese-built climbing cranes over 700tm capacity are installed on strong tubular mast systems with diameters from 2.8m to 4.5m.
One 60t Mitsubishi with 35t capacity at 55m radius is still working in China. This became the yardstick for the Chinese built QTP 1350 climbing cranes with 50t maximum capacity, and the FZQ 2000, shortened heavy duty boom, with 140t maximum capacity .
In the 1980s and 1990s the Japanese market favoured far bigger cranes for a massive suspension bridge building programme. For the Akashikaikyo-ohashi bridge project, IHI developed its most powerful luffing jib climbing crane (see picture, p. 47).
It can lift 160t at 35m radius, and 90t at 44.5m at its maximum radius. Special earthquake buffers are integrated in the climbing frame and the counterweight carriage under the machinery deck to absorb any strong seismic forces, which are amplified by the pylon.
2 Rail going, middle slewing, bottom self raising models similar to Russian BK series heavy lift tower cranes, typically named DTQ series. The 1,000tm capacity BK 1000A series is still widely used in Russia. It travels on two 1.59m wide standard rail lines in a 10m wide, three leg, portal version. Maximum capacity is 70t, and 16t can be lifted at 45m maximum radius. A 10t capacity fly jib capacity extends the maximum working radius to 53m. The drive units of the self raising crane, where tower sections are inserted through the portal and slewing part, are located on the machinery platform above the portal.
The BK crane designs have their roots in central Europe. From 1928, Wolff manufactured heavy top slewing construction cranes with luffing jib, for large construction projects and ship yards. Wolff and their licencees have built more than 10,000 “Form” cranes. Today the Wolff WK60140B is the biggest top-climbing luffing jib crane built in Europe, with a 90m high free-standing tower and a maximum capacity of 45t up to 29m radius.
3 Rail going bottom slewing self raising cranes with top climbing frame. These cranes, called QTZ series cranes, are similar to some IHI designs from Japan. In order to insert extra tower sections through the turning table, and reduce the minimum working radius, the boom connection point with the machinery deck is located behind the slewing ring.
The JCC series raises its superstructure by inserting sections through the top-mounted machinery deck. In 1981, IHI found that it could not simply scale-up existing JCC series of cranes for heavier power construction jobs.
The solution was an all-new self-climbing crane design. The heavy machinery deck and turntable is placed on a ringer frame at the crane’s base. Additional tower sections can be inserted through the A-frame-like tower head with a climbing frame, which is connected by tension bars to the crane’s base.
These tension bars must be lengthened by the same amount as the height of inserted tower sections. When the crane is being climbed, the boom is raised to a steep angle and the tension bars are unbolted.
As soon as the required tower section is climbed in, the tension bars are extended to connect them again with the crane’s base. Now it can boom out again.
With this unique design, with a comparably lightweight upper section, the JCC 2000W offers a free standing tower height of 91.5m and a maximum outreach of 89m, at which 10t can be handled. The crane can lift up to 60t up to a radius of 40m.
A far bigger 8,000tm version with 135t capacity up to 60m and 45t up to 95m as well was also built, providing up 220m free standing working height when installed on a 58m high frame pedestal.
4 Rail going bottom slewing self raising cranes with bottom self raising facility, called QTS cranes. The Chinese-built QTS3150 with 125t capacity at 25.7m, and 32t at 50m maximum radius, followed in the footsteps of the large Peiner VM models.
Peiner gained a dominant market position during the 1980s with its mega-size bottom-slewing TN and M luffing jib cranes. The crane tower can be raised by inserting additional sections at the bottom. With a maximum lifting capacity of 58t for the M13000 and 102t for the M2000, these cranes are not only suitable for dam construction sites but for boiler house construction, shipyards or heavy steel erection.
The bottom-slewing Peiner cranes with up to 95m tower height and a maximum outreach of 95m set a standard. In the VM version the rail going giants are mounted on a portal, allowing vehicles to pass underneath.
Peiner’s competitor Liebherr had a similar crane, the bottom-slewing, rail mounted, 1000A crane series. Several units were delivered to Brazil at the beginning of the 1980s, for the construction of large hydroelectric power stations. Normally the crane would handle 3 or 6m3 concrete skips out to 76m maximum working radius. A special design feature of the cranes still in use today are the buffers under the counterweight eliminating horizontal movement of the crane tower during heavy cycle operation.
5 Rail going, portal mounted, slewing crane with a main boom and luffing jib combination similar to German style lattice boom mobile cranes, like the Demag TC4000, called DBQ and BTQ cranes.
6 Rail going high frame, top slewing, cranes with bottom self raising facility of the MQ range, generally used at large dam projects for concrete delivery with extreme outreach realised by single boom or articulated jib designs both providing horizontal load movement.
The number behind the series name indicates the lifting capacity of the Chinese crane in tonne-metres. All rail going cranes use two standard railway tracks to spread the load of the portal mounted heavyweight cranes, allowing vehicles to pass through the 8-12.5m wide undercarriage. At least one model size of every series will provide a maximum hook load greater than 100t. For the large rail going versions, a free travelling under hook height of 100-130m, a maximum outreach of 50-71m and a maximum capacity of 60-125t ,as well as a runner for small lifts up to 12 or 16t, can been indicated as standard features.
Specially designed heavy lift units on short stationary towers following the Chinese top slewing luffing jib design are purpose built, in order to unload vessels at river quays, like the QT10500 with 450t capacity up to 22.5m radius and 260t up to 35m radius.
The number of giants fabricated is impressive. For example the Hangzhou Guodian Dali Mechanic & Electric engineering Co. Ltd. alone delivered ten units of the massive 3,150tm QTS3150 and 12 units of the DBQ2000 luffer.