Finding the perfect linear components for a railway plattform door

Eduardo, you talked about extraordinary applications for linear components, but is there also a very normal one?

At first glance yes. But if you take a closer look, every application has its specialties. Let me give you an example: We were asked to compete in a test for ball screws and linear guides for a platform door in a station of a subway line. These doors keep people from falling onto the rails when the station is crowded. The door system consists of two elements each sliding some 90 centimetres back and forth. A very simple application one might think.

But then again there are some implications: The system needs to work quietly for many many years without any service. Well, that is not so much of a challenge for our components. However if you then add the dust and dirt that will gather through the years, things become a bit tricky. Both the ball screw and the slider of the linear guide need to be kept dust free on the inside. Our linear components can be equipped with a number of different sealing measures to keep dust out. The question was: Which are the best ones for the job? After all, the expected contamination required more than just the standard seals but certainly not our high performance seals. So we set up a test arrangement with silica sand as an example for what was waiting for the sealing in real life. We did a 150.000 cycle test run which equates a travelled distance of 120 kilometres. Every stroke was 400 millimetres. Every 10.800 cycles we added another 400 grams of contamination to the test set up. At the end we figured out, that a side and a bottom seal together with a K1 unit, that provides a lifelong lubrication, is the right choice for the platform doors. Enough to keep the expected dust out and on the other hand keep friction to a reasonable level, as more sealing always means more friction.?

The customers uses this set up for years now and it works just fine. In more demanding environments we can have double (high performance) seals and additional protectors. Also the K1 lubrication units can be doubled or tripled if needed. So we can adapt the level of sealing to the conditions our components are used in.

So this is at first glance a more down to earth application. However, there has gone quite some consideration and testing into it, which in turn makes it interesting to consider. Good engineering and proper testing is a precondition to choose the right equipment. I think that that is true for many cases in which our material is used, so this is what we do.