Maintenance-free shaft guides in doors of high-speed train

Completed in 2012, these high-speed trains connect Beijing and Shanghai. They are intended to meet the high demand for transport on the busy route. The trains, some of which travel at more than 350km per hour, are not only subjected to heavy loads every day due to their high speed. The side doors of the carriages also have to move reliably during the countless opening and closing operations at stations while requiring as little maintenance as possible. Doors that get stuck or even break down would be devastating on the tightly scheduled route. The two linear guides whose job it is to ensure smooth movement on each door are thus extremely important. However, there were other requirements of the linear technology: It had to work reliably even when it was moving quickly, be able to withstand strong vibrations, and allow reliable operation under fluctuating ambient conditions and temperatures as low as -40°C.
The design had previously used metal bearings in tests, but they were too noisy and did not always ensure smooth movements during opening and closing. As the bearings had to be lubricated at regular intervals, the grease caused problems with dust and dirt, which increasingly collected at the door bearing points.

Today, train door movement uses drylin R shaft guides. Since the liners in the linear plain bearings are made of the lubrication-free material iglidur, they require no maintenance. This also makes them less sensitive to dust and dirt, which can get into the bearing points when the train doors open. iglidur J is optimised for coefficient of friction and wear, which extends the service life. In tests, the drylin linear plain bearings proved satisfactory in terms of noise and temperature behaviour as well as frictional resistance. In the drylin R bearings, the JUM-02 and JUM-01 guide systems are used - 5,000 of them in 120 trains. They both are made of iglidur J. 
Another important consideration is that the drylin linear bearings have low acquisition costs: They are as much as 40% lower than those for linear solutions with rolling elements.