DEVELOPMENT OF DESIGN OF SHIP-TO-SHORE CONTAINER CRANES: 1959-2004 Nenad Zrni ü University of Belgrade, Faculty of Mechanical Engineering, Dep. of Mechanization 11000 Belgrade, 27 marta 80, Serbia and Montenegro E-mail: [email protected] Klaus Hoffmann Vienna University of Technology, Faculty of Mechanical Engineering Inst. for Engineering Design and for Transport, Handling, and Conveying Systems A-1060 Wien, Getreidemarkt 9, Austria E-mail: [email protected] ABSTRACT- The paper presents the historical development of mechanical and structural design of ship-to-shore (STS) container cranes, from 1959, when the first crane was built, up to now. The paper gives a short survey of the evolution of the container crane industry, the state of the art in modern container cranes, and focuses particular attention on mechanical design of trolleys and evaluation of the existing structures. The analysis of historical development and state of the art in modern container cranes enables us to analyze future trends in mechanical and structural design. KEYWORDS: History of STS container cranes, design, trolley, construction INTRODUCTION The method of handling ship cargo in the early 1950s was not very different from that used during the time of the Phoenicians, Figure 1 >6@. The time and labor required to load and unload ships increased substantially with the size of the ship, requiring more time in port than at sea, Figure 2 >6@. The problem “how to lift a load” is as old as humankind. From the earliest times people have faced this problem. The first written information on the use of hoisting mechanisms appeared around 530 BC, mainly concerning the construction of the first temple of Artemis in Ephesus >13@. The forerunners of modern cranes in the ports were the wooden slewing cranes developed in the middle Ages, Figure 3 >20@. The slewing level luffing crane was the main means of cargo loading and unloading between ship and shore up to the end of 1950s, Figure 4 >20@. Through the 1950s, general cargo continued to be handled as break-bulk (i.e. palleted) cargo. Pallets were moved, generally one at a time, onto a truck or rail car that carried them from the factory or warehouse to the docks. Each pallet was unloaded and hoisted, by cargo net and crane, off the dock onto the ship. Once the pallet was in the ship’s 229 230 hole, it had to be positioned precisely and braced to protect it from damage during the voyage. This process was then reversed at the other end, making the marine transport of general cargo a slow, labor-intensive, and expensive process. All this began to change in 1955. Believing that individual items of cargo needed to be handled only twice - at their origin when stored in a standardized container box and at their destination when unloaded, Malcolm McLean purchased a small tanker company, renamed it SeaLand, and adapted its ships to transport truck trailers. The first voyage of a SeaLand container ship commenced on April 26, 1956 between Newark, New Jersey, and Puerto Rico. In the years that followed, standardized containers were constructed, generally twenty or forty feet long without wheels, having locking mechanisms at each corner that could be secured to truck chassis, a rail car, a crane, or to other containers inside a ship’s hole or on its deck. The idea of shipping cargo in locked containers has been widely accepted, resulting in an uninterrupted worldwide growth of about 8% a year at the beginning of this century >16@, >21@. Fig.1: Beginnings of handling ship cargo. Fig.2: Past of handling ship cargo. Fig.3: Wooden slewing crane. Fig.4: Development of slewing cranes 1856-1956. 231 One of the major problems facing the containerization concept was that during the mid- Fifties most ports were not equipped to handle the heavy containers except by mobile revolving cranes and even then many of the cranes did not have the capacity to lift containers. These cranes were extremely inefficient, in that at least two to three minutes of loading cycle was lost due to poor control at the points of pickup and discharge. In July 1957 the engineering staff of Matson company, under the leadership of Mr. Les Harlander, commissioned a study of existing crane types, to determine the state of the art and identify the type which best met the general requirement for loading containers between ship and shore and keep turnaround time of container ships to a minimum. The study concluded that no crane then on the market satisfactorily filled this requirement, and that an ore-unloading type crane with a horizontal boom and through-leg trolley came closest to meet this requirement. Early in 1958, performance specifications were finalized and put out for bid >6@. PACECO, one of eleven biddres, pioneered the first container crane for Matson in 1958 >4@. PACECO philosophy was that the best design has the fewest number of pieces, and developed the conceptual drawings paying particular attention to aesthetics. Trusses, used at that time by most manufacturers, were replaced with all-welded box girders wherever possible. This resulted in unique and extremely clean-looking A-frame configuration. The A-frame gantry crane takes its name from it’s “A”-shaped noticeable when observed from the bridge. On 7 January 1959 the world’s first container crane was put into service at the Encinal Terminals in Alameda, California, Figure 5. The original container crane set the standards for dozen of manufacturers around the world. Although there have been many significant improvements, all modern cranes are direct descendants of this first crane, and the design of later cranes has reminded relatively unchanged >6@. In the meantime, to keep up with the growth of container traffic, container ships and container cranes are getting bigger and bigger. During the first 45 years since the first container crane was designed, the size of container cranes and lifting capacity have more than doubled, Figure 6 >5@. Fig.5: First container crane. Fig.6: Growth of container cranes 1959-1995. 232 EVOLUTION OF CONTAINER CRANE INDUSTRY At these early 1960s a crane container purchaser could call up a PACECO (at that time a US company) representative in any part of the world and order STS cranes. Around the same time, European manufacturers entered the market, offering improved and standard design, good quality and competitive prices. The Japanese entry into the container crane industry in the late 1960s presented some opportunities and, for the first time, some challenges for the purchasers. Japanese consumer and industrial products were introduced to the world market at significantly lower prices. The first reaction in the Western world was “No such thing as a free lunch – you will pay for it one way or another” >4@. But, some large shipping lines saw opportunity in the new competition and decided to give the Japanese a try. The Japanese provided good quality cranes, and within a short time they were in the same category as the Americans and Europeans. With the growth of the economy and domestic demand increasing, Japanese cranes ceased to be a bargain. The concept of purchasing cranes with the “Tailor-Made” specification was born. The “Tailor-Made” philosophy requires the detailed performance specifications and very competitive bids. A larger number of cranes brings economy of scale and favors this concept. Tailor-made cranes require high expertise, whether in-house or through outside consultants >4@. Korean STS container cranes manufacturers were next with the lower-priced cranes, starting from 1970s. Now, at the beginning of 21st Century the Chinese manufacturer ZPMC, Shangai, has made the most significant impact on the container crane industry, and may further increase its share of the world market during the coming years. The actual situation is that PACECO could no longer compete with the overseas suppliers, some European suppliers have merged or quit manufacturing STS cranes, and the Japanese suppliers retracted from the international market and remained focused on their protected domestic market. To compete in the current market, established cranes builders have shifted fabrication and assembly to remote plants with cheaper labor, purchased electrical components and integrated them in-house, used standardized components and reduced profit margins. The use of standardized components favors the “Off-the-Shelf” approach in design of STS cranes. The aim of this strategy is to emulate the early purchasing strategy of issuing a brief technical outline and inviting proposals from two or more crane suppliers >4@. DEVELOPMENT OF DESIGN OF STS CONTAINER CRANES The basic structural form of STS container cranes (A-frame) remains practically unchangeable compared with the first structure built in 1959. Of course some modifications are done. The basic structural shape of STS cranes can be divided into two groups: 1. Conventional or modified conventional cranes, Figure 7 >15@; 2. Low profile cranes, Figure 8 >1@. Conventional STS cranes are used for servicing the following ships: 1. Panamax ships: III-generation ships with a beam of less than 32.3 m (width of Panama Canal) – their structure was developed from end of 1960s up to early 233 1980s, and they operate with up to 13 containers abeam on deck and with maximum capacity of 4,700/4,900 TEU (Twenty Equivalent Unit); 2. Post-Panamax ships: IV-generation ships, developed from 1984, whose beam is greater than the width of the Panama Canal – they operate with up to 20 containers abeam on deck and with a maximum capacity of 7,000 TEU; 3. Mega ships or Jumbo ships: Ships of the most recent generation, pioneered in the last years of the 1990s, they operate with more than 20 containers abeam on deck and with a capacity of more than 7,000 TEU.