Whether electric, pneumatic or manual, rail door systems must combine reliability and cost efficiency to be successful. Chris Lo asks Norgren's Mark Densley about the challenges and opportunities in this technical market.

Rail doors have seen a gradual evolution since the days of bulky, hand-operated door panels linking carriages. Pneumatic systems control the speed of doors opening and closing, and modern electrical systems simplify the process to the touch of a button or the activation of an infrared sensor. Manufacturers of rail door actuators and door systems are now working on achieving greater integration of rail doors to the rest of the train through improved interfaces and LAN connections.

Norgren have been operating in the rail door market since 1987, and currently has more than 14,000 door systems installed on rail cars all over the world, from Siemens’ Desiro and ICE fleets to Shanghai’s Transrapid maglev train. Railway Technology talked to Mark Densley, business development manager for Norgren’s rail division, about the company’s approach to manufacturing, testing and installing door systems.

Mark Densley: Sure. We’ve been in the industry for over 30 years, and a lot of the products that we sold begin with pneumatic versions of the actuator that we have today. And then moving on from there, we had a need to move to an electric actuator because although the pneumatics are great, they have a lot of other products to control the speed and the forces and the pressures involved, like regulators and valves. So, by using an electric version, we can program the forces involved; the timing, the speed of the door, all electronically into a controller.

We’ve got a lot of door systems out in the field; I think about 14,000 of them in operation today. We have products in China, for instance; they have our door actuators on the Transrapid maglev there, which I think is the fastest train in the world. Although in this case we’ve provided a solution which includes the actuator and the door, we’ve also focussed on providing an actuator solution that could include sensors to open the door, such as IR sensors, and the actual buttons to open the door, and so on.

MD: Reliability seems to be at the top of the list. They want a low life-cycle cost from a door system. You hear a lot of scary stories about doors not closing when the car’s leaving the station, and they want to get away from that risk. They want a reliable product that is also going to have a low life-cycle cost.

MD: That’s a good question. When we design any new door or make a new door for a customer, we do a lot of different testing.

Obviously, first-time article inspections, as well as first article sign off with the customer, but the other big thing we tend to do is a lot of cycle testing. Typically, on every door we sell, we reach 1.5m cycles before we say that door is ready to be used in the application.

When I say cycles, that’s with the actual door leaf it’s going to be controlling on the train, all the weight and everything as it would be used on the train. So we have rigs where we can simulate the door opening and closing. Once we achieve that 1.5m cycles we don’t just stop, we tend to carry on and leave them cycling even longer.

The other thing we do is supply extensive documentation that we supply with the product. This documentation is about how to install it properly; it gives you a graphic pictorial view of the product. The maintenance manual also tells clients what to do at the service intervals, what to replace. Typically, within the first seven years it’s more of an inspection, or maybe a tightening of the belt or a greasing of the roller bearings. After seven years, it’s typically replacing parts that wear like the belt or the rollers.

MD: Pneumatic does still have its place. Electric is typically used for external and internal vestibule doors, where there is going to be a high-traffic area. While we do see some areas that use pneumatic cylinders, they’re very few and far between. The main application for pneumatics is manual doors, when there’s no electricity to be supplied to the door.

It’s typically a cylinder with some cushioning inside it to dampen the door as it closes – it could be a body end door which isn’t opened frequently, so a fire door for instance. A toilet module door is another typical one where we’d use a pneumatic actuator.

MD: We don’t actually manufacture external doors. What we do is manufacture and supply a solution for internal doors and body end doors. We don’t actually get into the external area. What we do supply to external doors is actuators and locking mechanisms. We’d sell that typically to Tier 2 suppliers.

MD: Yes, that’s typically the first challenge. You always want to know what the space restrictions are – if there’s panelling in the way, or pipes for the HVAC system running overhead, or electrical cables. We have made actuators where we’d have to cut out little areas within the actuator to allow piping or cabling to go across it.

So we have done that in the past, but typically, space is the number one challenging area.

MD: Not really internally, no. The only thing we’ve been asked in the past is, for instance on the ICE product in Germany, that it be very quiet. If you’ve got somebody paying for a first-class ticket to travel across Europe and you want it to be a nice setting within that car, a big noisy door actuator is not going to work. As I’ve said, the electric doors can be programmed to open at various speeds and forces. By doing that, we can achieve a nice quiet actuation of the door panel, whether it is a glass or aluminium-framed panel.

MD: Sure. We’ve worked with Talgo extensively to design a door actuator and door panel, which is the vestibule door between the external doors and the internal carriage. It’s an electric system that comes with a Norgren controller, which is linked up to some IR sensors that Norgren is supplying to detect the traffic. We’re also doing the emergency stop system as well, so that’s wired into the actuator with some buttons to enable passengers to egress out of the car should something happen.

We’re interfacing the actuators to the train management system, so if something does go wrong – if the belt comes off, for instance – it will actually signal that to the train management system to send an alert that there’s an error with the door.

MD: We’re looking at different developments. We’re developing a new controller which has things like CAN and a LAN system built into it. So, you get faster transmission of data and more interfaces, along with Ethernet as well. We’re working on a controller that can do that.

Another area we’re looking into is a more rugged external door actuator. One of the big problems in the US is the dust, like the Arizona dust, getting into the screw of the external door operator. So we’re looking at a way to encase the screw using some of the technology we use in pneumatics to keep the dust out of the actuator and lengthen the life of the product.

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