SCA - Preventive maintenance at the world's largest container terminal

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Immediately after the container ship from Singapore ties up at the 1,400-metre quay of the Altenwerder container terminal in Hamburg, a race against the clock begins. After all, ships don’t generate revenue for their owners when they aren’t underway. Short layovers are therefore essential, but it’s still necessary to transfer 7,000 standard containers. Stevedores are ancient history. Nowadays this previously backbreaking work is handled by sophisticated, computer-controlled transport systems. 

Container Terminal Altenwerder (CTA) is one of three container terminals operated by Hamburger Hafen und Logistik AG (HHLA) in Hamburg Harbour. HHLA is one of the world leaders in harbour logistics. CTA is designed for the efficient handling of large container ships, and its high level of automation makes it the world’s most advanced container terminal. Here it is not uncommon to see three or four large containers being loaded or unloaded simultaneously. The average ship has 4,000 to 5,000 containers of various sizes on board, and seven million containers on average are moved each year. The ship layover time is around 30 to 50 hours. The current record was set by CTA in January 2008, when the Colombo Express with its 8,750 twenty-foot equivalent units (TEUs) was processed in just 50 hours.

On the harbour side, fifteen gantry container cranes stand ready to unload cargo. Three to five cranes are used for each ship. On the quay side, 84 automated guided vehicles (AGVs) take over the containers. These fully automated transport vehicles operate without drivers and navigate under wireless computer control. No rails are necessary at Container Terminal Altenwerder. A network of more than 16,000 transponders (electromagnetic beacons) is embedded in the ground. As if controlled by an invisible hand, the AGVs travel to the intermediate storage areas specified by their transport orders, without ever getting in each other’s way. Their priorities are clearly regulated, and the AGVs obey the right-of-way rules without fail. As soon as an AGV reaches the intermediate storage area with its load, a stacking crane takes over the container. Probably no other bulk storage site in the world is as fast as this one. CTA developed a highly unique concept for optimal utilisation of its fleet of 52 stacking cranes. In each instance, a large gantry crane travels above a smaller crane. Their different heights allow them to work independently, which dramatically boosts productivity and flexibility.

Next to the storage area, there are four large free-standing cranes for loading containers onto railcars.

The AGVs move back and forth tirelessly. They pick up incoming containers at the quayside, and they bring other containers from the storage area to the ships. These high-tech vehicles are a product of Gottwald Port Technology GmbH (Düsseldorf, Germany), a member of the Demag Cranes AG group of companies. The automated guided vehicles pick up 20-foot, 40-foot and even 45-foot containers, and they work quickly, almost silently, and with three-centimetre precision. They can move forward, backward and sideways, and they can even overtake each other. If a person enters the large working area of the AGVs while they are active, the entire system is stopped automatically. The vehicles have diesel–hydraulic drive systems. The fuel tank holds 1,200 litres of diesel fuel. When its tank is nearly empty, the AGV travels to a filling station. Naturally, refuelling is also performed automatically by a robot.

Every 600 operating hours, each AGV heads to the shop for scheduled maintenance. Here the AGVs are checked thoroughly by the staff of Service Center Altenwerder.

SCA Service Center Altenwerder GmbH is a subsidiary of Hamburger Hafen und Logistik AG. Its 130 employees are exclusively responsible for the maintenance of all CTA facilities. OELCHECK lubricant analyses are a vital part of mandatory scheduled maintenance for the AGVs. Oil samples are taken every 600 operating hours. The analyses encompass the HVLP 46 hydraulic fluid, the low-friction SAE 10W-40 motor oil for diesel engines operating under heavy load, and the GL 5 SAE 85W-90 multigrade gear oil used in the two drive axles of each vehicle.

Philipp Mühlenhardt, SCA Technical Manager: “We change the lubricants according to their condition as determined by OELCHECK in their lab. After all, each AGV holds around 360 litres of hydraulic fluid, 25 litres of gear oil, and approximately 30 litres of motor oil. However, we regard early detection of damage as almost more important than the cost savings from condition-dependent oil changing. Our system is highly networked at the logistics level. If any component fails, there is a direct impact on the entire process. If we have a failure and the system does not operate as planned, the ship loading and unloading processes slow down. Especially in the shipping business, time is money, so every minute of extra layover time leads to lost earnings. Consequently, absolute reliability and maximum operational security of the facilities are our top priority. We definitely practice predictive maintenance at Altenwerder.” 

OELCHECK cooperates closely with the AGV manufacturer. Our experienced tribologists are familiar with the situation at SCA GmbH and check their oil samples accordingly. In the lab, the motor and gear oils and hydraulic fluids are examined meticulously for the presence of metallic wear particles that may indicate possible damage, as well as for water or dust contamination. The general condition of the oil or fluid is also determined. Has the viscosity changed? Are the additives still effective? Has the aging process progressed? How good are the sludge-carrying properties of the motor oil? What purity class does the hydraulic fluid achieve? In short, a large number of properties are determined, compared with each other, and diagnosed by experienced tribologists at OELCHECK. The verdict is not always negative. If it is, the lab report is marked immediately with a warning symbol and suitable comments from the tribologist are included.

Philipp Mühlenhardt: “We take action if there is even the least suspicion. The oil is changed immediately. We take the next oil sample when the AGV makes its next stop in the shop. If the lab report again indicates high wear or other irregularities, we investigate the case thoroughly. Although we operate right next to the harbour, the occasionally high humidity or water in the air hardly affects our equipment. However, wear can always occur at any time with an AGV. When this happens, the OELCHECK lab detects fine metal flakes or wear particles in the hydraulic fluid or motor oil sample. Soft wear particles in the hydraulic fluid are typically a sign of worn seals or hydraulic hoses. Thanks to the lubricant analyses, we usually have a head start in early damage detection. We can take action before an AGV is crippled by damage and disrupts the entire process.” Tip: On 24 May 2009 the ARD German television network broadcast a report on CTA. The video clip can be viewed on the Internet <link http: wwiewissen _blank external-link-new-window externen link in neuem>here

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