Programmable Train Doors

Internal passenger rail doors that meet the U.S. Department of Transportation's Buy America requirements integrate a flexible control system that provides light weight, a compact design and programmable operation. Talgo, a leading manufacturer and operator of innovative high speed passenger trains, will use the doors in its new Intercity Series 8 train platform in the United States.

More than 14,000 unique internal door systems designed and developed by Norgren have been installed in rail cars worldwide since the solution was introduced in 1987. The system's light weight design includes an integral controller that provides passenger detection and anti-entrapment features. Its compact design fits into many applications with limited space and is available in both electric and pneumatic versions. Long service life and ease of maintenance help reduce the total cost of ownership.

"We have been supplying a number of high speed rail customers this type of actuator for a number of years in Germany," says Mark Densley, business development manager for Norgren Americas. "We started out with a pneumatic version but the demand in the rail industry has moved to electric doors."

The Norgren electric system uses a lightweight aluminum extrusion which is based on the company's pneumatic LINTRA rodless-style cylinder. One advantage of the electric doors is that using programmable operation, no regulators and valves need to be changed in the field. Once they are set, electric doors are ready to go.

"We use the electric motor in conjunction with a toothed belt which runs around the extrusion," says Densley. "In the extrusion, there is a carriage attached to roller bearings with rubber wheels on them. As the motor turns and the belt moves, it pulls the carriage which is holding the door panel to the actuator."

One unique benefit of the product is an integrated binary encoder that the controller is constantly monitoring as the door is travelling. If there is a jam or someone standing in the doorway, the controller will detect that to provide important obstacle detection and anti-entrapment features that are very important in the rail industry.

All of the operation of the door controls is programmable including the amount of time the door goes back into the pocket and waits, and the amount of force acting on any obstacles. In calculating the force, the system can use the current sent to the motor to calculate the required force to be exerted on the door leaf.

The door control mechanism is fully integrated with a standard footprint controller attached to the actuator. Typically, the controller is matched with an I/O card which provides the interface to the train's diagnostic system. If there is a jam or problem with the belt, a signal communicates the problem back to the train management system. The I/O card also allows the system to use IR sensors on either side of the doorway for detecting traffic and, if a person walks up to the door, automatically opens as well.

"A key to the system is its compact design," says Densley. "Many customers have space limitations in the area above the doorway and obstacles such as HVAC piping and electrical wiring that get in the way. To deal with those problems in the past in Europe is cut out areas in the actuator to make it fit.

Because Norgren is supplying the door actuator and controls as a custom system, it makes it easy to add specific customer requirements and components such as locking mechanisms, detection systems such as sensitive edges and latches to keep the door open, for example, if there is a power failure.

Norgren transferred the technology to the U.S. in 2010 to work on this project for Talgo. The U.S. market is slightly different because of the forces involved to open the door and A.D.A. standards are slightly lower than what is required in Europe. But by re-parameterizing the controller, those adjustments can be achieved very easily.