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Heavy equipment for bridge maintenance

Fast service for railroad hydraulics

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March 2016

 

48 hours. That’s how much time the Bosch Rexroth service team in China had to do the maintenance for the hydraulics at an important junction in the rail network. It was a job for professionals.

It is a great milestone in the history of the Chinese rail network: The Guangdong-Hainan Railway, connecting the rail networks of the two eponymous provinces by rail ferry and which, for the first time, includes the island of Hainan, was put into operation in early 2003. It was a big leap forward for the local infrastructure. The requirement: The ferries must be able to be loaded and unloaded in a reliable manner. Feng Wang, Head of the Management Department of the Guangdong-Hainan Railway Ferry, keeps a close eye on it – and not without good reason: “One can say that the ferry port of Hainan Island is the bottleneck of the railway. If a problem were to occur here it would affect the railway network!” A glance at the schedule confirms this prognosis: In the off-season, the ferry has to travel at least ten times every day, in high season, the frequency climbs to 20 to 30 trips per day.

The ferry port on the island of Hainan is the bottleneck of the Guangdong-Hainan railway. Magnifier

The ferry port on the island of Hainan is the bottleneck of the Guangdong-Hainan railway.

 

Involved from the outset

For loading and unloading the ferries, the ports are each equipped with one gangway for passengers and two landing stages, one for vehicles and one for trains. The gangway and landing stage for vehicles are both one-piece ramps, each one moved using two hydraulic cylinders. The 90-meter landing stages are suitable for handling all types of trains and are made of up three individual ramps joined together.

Movement is provided via three electronically-controlled, cardan-mounted cylinder pairs that move in sync. To this day, there has not been any downtime whatsoever. To keep it that way, there is a strictly-regulated maintenance plan. The cylinders are replaced according to a fixed cycle.

The clock is ticking

The cylinders are massive – the ones used weigh between 1.4 and 14 tons. For maintenance purposes, three cylinders are stored on site, which can be temporarily used as substitutes. Therefore, the service team in charge of the equipment has divided up the work into four phases. But that also means four times the risk for the railway company because rail traffic must be interrupted during each replacement. Those who are in charge estimate that every day of forced downtime would cost up to around 300,000 euros. That gives Jie Liu, Service Manager at Bosch Rexroth in China, little leeway: “Our target was that rail traffic could only be stopped for 60 hours. In order to have enough buffer for any unforeseeable situations, we wanted to get the work done within 48 hours at most.” For the local team that meant a race against time. Not only the cylinders themselves, but also 8,000 liters of oil and the corresponding lines had to be replaced.

The 90-meter landing stage for trains is made of three individual ramps joined together. The movements are carried out by three pairs of cylinders. Magnifier

The 90-meter landing stage for trains is made of three individual ramps joined together. The movements are carried out by three pairs of cylinders.

 
The stretch of track from Guangdong to Hainan connected Hainan Island to mainland China’s railway network. Magnifier

The stretch of track from Guangdong to Hainan connected Hainan Island to mainland China’s railway network.

Working for two days straight

The service team consisted of 12 engineers, more than 60 workers and electricians and heavy equipment, such as cranes and heavy loads. Removing the cylinders was hard work – but which required finesse at all times. The salty sea air had already taken its toll on the cylinders. More damage had to be avoided at all costs. Therefore, the team made sure that the individuals involved could always work fully focused and that they worked in shifts.

The removed cylinders came to the factory of Bosch Rexroth in Changzhou for overhaul as quickly as possible. For this purpose, the experts there analyzed first what items had to be replaced. “The piston rods were still in pristine condition, but seals and valves needed to be replaced,” says Lv Bin, Service Project Engineer. The functional capability of the cylinder was then ensured through several test procedures. Only two weeks after delivery, the transporter drove the serviced cylinder back to the landing site; time to start the next phase. “Apart from the technical issues, timing in particular was a major administrative burden,” says Bin. “The railway company had to laboriously find the right time for the installation and removal of the cylinders - and we had to respond flexibly.” And they succeeded: After the planned downtime, the railway resumed traffic in each of the four phases as usual.