Extensive underground railway networks are an essential component of large cities worldwide. The metros in Beijing or New York City cover distances of over 400 kilometres. In their tunnel tubes they move millions of people every day – quickly, without pollution and much more safely than by road traffic.
In order to remain this way, the tunnels must be cleaned at regular intervals, as the fine dust in particular, which is deposited over years, has a negative impact on machinery wear and tear and on the health of passengers and train staff. A new kind of tunnel cleaning train has been built for this task. This is equipped with the latest servopneumatic drive technology from Festo.
The 85-tonne tunnel cleaner
The tunnel cleaning train weighs an imposing 85 tonnes and is 40 metres long. The cleaning unit is in the middle of two locomotives. There is a driver's cab at each end of the train. This means that the tunnel cleaning train can change direction without having to turn round. The units for the hydraulic drive are located directly behind the driver's cabs. This can be finely controlled even at low speeds.
Putting dirt under pressure
On each half of the train, three ventilators are used with a suction performance of six cubic metres per second. They generate the compressed air, which is used to help the suction nozzles to blow the dirt off the tunnel walls, and the vacuum, which immediately sucks in the dust stirred up and feeds it to the filter systems. These are located above the drive system. Containers for coarse dirt are followed by fine dust filter systems, which are blown out once a predefined level of contamination is reached. The dirt falls down into collecting bowls.
Five clean kilometres per hour
In many underground rail networks, cleaning work is still done manually. This takes a lot of time and labour and is therefore cost intensive. The tunnel cleaning train is much faster: its innovative dry cleaning technology removes dirt from up to five kilometres of tunnel per hour. When not cleaning, it can travel at up to 70 kilometres an hour.
Servopneumatics creates more safety
Modern servopneumatics from Festo take care of the fast and safe movement of the suction nozzles and feet. This is cleaner and safer than hydraulic solutions. What is more, no contamination from possible leaks is incurred. The Festo components used in the tunnel cleaner are responsible on the one hand for the air preparation. On the other hand they ensure that the suction nozzles and feet move quickly and flexibly to the prescribed positions. In this way, even large loads are accelerated or slowed down dynamically and precisely. The supply and exhaust air in the cylinders is also controlled by Festo technology.