In short:Motion components on a train have to meet rolling-stock rules before anything else: EN 50155 for the electronics and supply, EN 61373 for shock and vibration by mounting position, EN 45545-2 for fire and EN 50121-3-2 for EMC. Within those limits, electric actuators are appearing in wheelset steering, brakes and doors, and the same actuator families drive the rigs that test rail components.
Typical requirements
| EN 50155 operating temperature | OT3 −25 to +70 °C (common default for cabinets); OT4 to −40 °C; OT6 −40 to +85 °C |
|---|---|
| Rolling stock battery voltages | 24, 72 and 110 V DC recommended; 0.7–1.25 Un continuous, 0.6–1.4 Un briefly |
| Supply interruption (EN 50155 class S2) | Normal operation through interruptions up to 10 ms |
| Shock and vibration (EN 61373) | Category 1 body, 2 bogie, 3 axle mounted; severity rises with category |
| Fire protection (EN 45545-2) | Hazard levels HL1 to HL3 |
| Electromechanical brake trial (EU-Rail) | 180 brake cycles up to 160 km/h on a test vehicle; TRL 7 |
| Active wheelset steering trial (UK) | At least 50% less contact-patch frictional energy; up to 30% longer wheelset maintenance intervals |
Machinery we specify motion for
- High-speed train wheelset steering
- Rail vehicle linear actuators
- Electromechanical brake actuators
- Passenger door drives
- Ramps, steps and gap fillers
- Railway maintenance and railroad equipment
- Rail component test rigs
What rail demands from motion components
Rail is a market where the qualification file matters as much as the product. Anything mounted on a vehicle has to show evidence against a set of rolling-stock standards, and the vehicle builder will ask for it before an order. The table below summarises what the main ones ask of a motion component, drawn from Bel Fuse’s railway FAQ and Televic’s standards overview.
| Standard | What it sets | Key figures |
|---|---|---|
| EN 50155 | Electronics on rolling stock | OT classes (OT3 −25 to +70 °C; OT4 down to −40 °C; OT6 −40 to +85 °C); battery 24–110 V; 0.7–1.25 Un continuous; S2 interruptions up to 10 ms |
| EN 61373 | Shock and vibration | Category 1 body, 2 bogie, 3 axle; severity rises with category |
| EN 45545-2 | Fire behaviour of materials | Hazard levels HL1 to HL3 |
| EN 50121-3-2 | EMC of rolling stock apparatus | Emission and immunity tests |
| EN 14752 | Bodyside doors, steps and ramps | Closing force, kinetic energy, obstacle detection, egress |
Evidence from component makers is thinner here than in most industries. Thomson lists train manufacturers among its actuator customers, and its Electrak HD actuator names railroad equipment among its uses. Tolomatic publishes one rail application in detail. Beyond that, most of what follows is about how to specify for the environment rather than lists of machines.
Where electric actuation is used on rail vehicles
Wheelset steering
Tolomatic describes a modified IMA44 integrated servo actuator used to steer the wheels of a high-speed train car and reduce the wear caused by curves. The IMA is a rod actuator with a built-in servo motor and ball or roller screw. The benefit of active steering is well documented: the UK LiCAS trial by Liebherr, Newcastle University and Grand Central, funded by RSSB, reported at least 50% lower contact-patch frictional energy and wheelset maintenance intervals up to 30% longer. LiCAS used compact hydraulic actuators, so this is a case where electric and hydraulic designs compete. Bogie-mounted equipment sits in EN 61373 Category 2, so screw, bearings, encoder and connectors must be chosen for that vibration level.
Electromechanical brakes
EU-Rail reports that Knorr-Bremse has developed electromechanical brake actuators that can directly replace electro-pneumatic brake calipers, tested to technology readiness level 7 with 180 brake cycles on a 45 km track at up to 160 km/h, and that Wabtec Faiveley built a lab prototype with more accurate braking force control. The open issues it lists are useful for any electric actuator on a train: the vehicle power supply must be adapted, the whole air system does not necessarily disappear, and high safety integrity is needed in the electronic control.
Passenger doors, steps and ramps
EN 14752 limits the kinetic energy and static force a closing door can exert, requires doors to stop and reopen when they detect an obstacle, and sets emergency egress rules that must work without the main door supply. Crouzet points to brushless motors as the way to remove brush wear over a door’s very large number of cycles and to tune acceleration and deceleration. Steps, ramps and bridging plates covered by the same standard must stay closed while the vehicle moves.
Pantographs
Pantographs are a common search, but the published designs we found rely on springs and air bellows as much as on motors. Schunk, for example, offers its metro pantograph as a spring-electric version with an electric drive for lowering, and as an air-bellows version in which the bellows replaces the drive spring and lowering cylinder. If you are designing an electric raising or lowering drive, treat it as a roof-mounted actuator: EN 61373 body category, OT class for roof temperatures, high-voltage clearance, and a defined state on power loss.
Rail test rigs
Off the vehicle, rail suppliers test doors, couplers, suspension parts and brake equipment on rigs. These are ordinary industrial machines, so EN 50155 does not apply, but loads and duty are high. Roller-screw actuators such as the RSX or the SRB Linear Servo Actuator (up to about 49 kN) replace hydraulic cylinders for endurance work where a quiet, oil-free rig is wanted. See ball screw vs roller screw.
EMC on rolling stock
EN 50121-3-2 sets emission and immunity tests for rolling stock apparatus: bursts, surges, electrostatic discharge, radiated fields and conducted disturbances on the ports. A servo drive switching tens of amps next to train control and passenger information systems is a likely source of trouble. Plan screened motor cables, filtering on the supply input and a bonding scheme agreed with the vehicle builder, and ask the supplier for test reports rather than a declaration alone.
How to specify a rail actuator
- Mounting location first. Body, bogie or axle sets the EN 61373 category and much of the mechanical design.
- Supply and interruptions. State the nominal battery voltage and design for 0.7–1.25 Un continuous, brief excursions to 0.6 and 1.4 Un, and 10 ms interruptions (class S2).
- Temperature class. OT3 suits many cabinet locations; outdoor and underframe equipment usually needs OT4 or wider.
- Materials. Ask for EN 45545-2 evidence for housings, seals, cables and connectors at the hazard level the vehicle needs.
- Fail-safe state. Decide what the actuator must do on loss of power or signal: hold, return or free-wheel. Brakes and doors have very different answers.
- Life. Specify cycles and years. Door and brake actuators can see far more cycles than general industrial actuators.
- RAMS and software. Vehicle builders work to EN 50126 and, for on-board software, EN 50657. Ask what failure data and documentation the supplier provides.
Worked example: supply range for a 110 V door drive
A door operator will run from a nominal 110 V DC battery.
- Continuous range: 0.7 × 110 = 77 V to 1.25 × 110 = 137.5 V. The drive must operate normally across this band.
- Brief excursions: 0.6 × 110 = 66 V to 1.4 × 110 = 154 V. The drive must survive these; Bel Fuse quotes ±40% for 0.1 s.
- Interruptions: under class S2, normal operation through 10 ms with no supply. Size hold-up capacitance in the drive or converter for that time at full load.
- Motion check: for an 80 kg leaf (assumed) opening 650 mm in 2.5 s on a triangular speed profile, peak speed is 2 × 0.65 / 2.5 = 0.52 m/s and acceleration 0.42 m/s², so about 33 N to accelerate the leaf plus seal and guide friction. Kinetic energy at peak speed is ½ × 80 × 0.52² ≈ 10.8 J. Compare that with the EN 14752 closing limits for your door type; the closing profile is often slower than opening for this reason.
Few general-purpose servo drives are EN 50155 qualified, so the practical choices are a qualified drive, a qualified DC/DC converter feeding a wide-input drive such as DigiFlex Performance, or a qualification test programme.
Typical pitfalls
- Treating a bogie like a car body. EN 61373 Category 2 and 3 vibration breaks parts that survive happily in Category 1.
- Testing at nominal voltage only. Faults appear at 77 V or during a 10 ms dropout.
- Leaving fire evidence until late. Seals, cable jackets and plastic housings all need EN 45545-2 data.
- No defined fail-safe state for doors, brakes or steering.
- Specifying cycle life from industrial norms. Rail duty adds up over decades.
Send us the function, mounting location, supply, temperature class and required evidence, and our specialist engineering and supply partners will propose actuators, motors, encoders and drives, and say what qualification data exists.
Linear actuators for rail vehicles and rail test rigs
Electric linear actuators on rail vehicles replace hydraulic or pneumatic cylinders in steering, braking, doors, steps and ramps. On the vehicle, the actuator's electronics must meet EN 50155, its mechanics the EN 61373 category for where it is mounted, and its materials EN 45545-2. Specify force, stroke and speed, the battery voltage and its tolerance, mounting position (body, bogie or axle), fail-safe behaviour, IP rating and design life in cycles. On test rigs the rules relax, but force, speed and duty rise: roller-screw servo actuators reproduce track and service loads for long endurance runs.
- Wheelset steering: electric actuator steering a high-speed train's wheels to cut curve wear
- Brakes: electromechanical calipers in place of electro-pneumatic units
- Doors, steps and ramps: deploy and lock
- Test rigs: fatigue and endurance loading of rail components
Available through our supply network
Train door motors and auxiliary drive motors
Passenger door systems have moved from brushed to brushless motors, which remove brush wear over a very large number of cycles and let the controller shape acceleration and deceleration. A door drive must hold the EN 14752 limits on closing force and kinetic energy, detect obstacles and stay closed and locked while the train moves. Specify door leaf mass, opening width and time, supply voltage, brake or lock arrangement, temperature class and cycle life. Low-voltage brushless servo motors on a 24 V or 110 V derived supply suit door, ramp and auxiliary axes.
- Passenger doors: brushless sliding and plug door drives
- Boarding ramps and gap fillers: deploy and retract
- Auxiliary systems: dampers and covers
- Test rigs: servo-driven rotary axes
Available through our supply network
All servo and stepper motors →Specify servo and stepper motors for rail →
Encoders for rail actuators and test rigs
Rail actuators need position feedback that survives the EN 61373 shock and vibration category for their mounting point, wide temperatures and dirt. Non-contact inductive and capacitive encoders with no glass discs are a good fit. Specify absolute or incremental, interface, resolution actually needed, operating temperature, IP rating and the vibration level it must survive, which is far higher on a bogie or axle than in the body. On test rigs, linear encoders measure displacement under load and feed the rig's closed-loop control.
- Wheelset steering actuators: stroke feedback
- Door drives: leaf position and closed confirmation
- Brake actuators: clamping position
- Test rigs: displacement measurement
Available through our supply network
All encoders and feedback →Specify encoders and feedback for rail →
Servo drives for rail auxiliary systems and test rigs
A drive on a train runs from the vehicle battery, typically 24, 72 or 110 V nominal, with continuous variation of −30% to +25% and brief swings to ±40%, and must ride through 10 ms interruptions under EN 50155 class S2. Few general-purpose servo drives are qualified to EN 50155, so either choose a qualified product, use a qualified DC/DC converter in front of a wide-input drive, or plan qualification testing. On test rigs, standard AC servo drives with STO and EtherCAT are the norm.
- Door and ramp drives: low-voltage servo control
- Brake and steering actuators: force and position control
- Test rigs: multi-axis servo loading
Available through our supply network
Gearboxes for railway auxiliary drives
Auxiliary rail drives and test-rig axes use planetary gearboxes to match small servo motors to high output torque. On the vehicle, check the gearbox against the EN 61373 vibration category, lubricant temperature range for the OT class, sealing for washing plants and the maintenance interval the operator expects. On rigs, the key checks are peak torque during load reversals, torsional stiffness and backlash, which affect how well the rig follows a recorded load profile. Ask for the gearbox efficiency at the rig's real speed, because a long endurance run turns small losses into heat.
- Door and ramp drives: compact reduction
- Test rigs: high-torque rotary loading
- Maintenance equipment: drive reduction
Available through our supply network
All gearboxes and harmonic drives →Specify gearboxes and harmonic drives for rail →
Motion controllers for rail test rigs
Rail component rigs, from door endurance rigs to bogie and suspension test frames, run several synchronised servo axes that replay load or displacement profiles and log the results. An EtherCAT motion controller programmed in IEC 61131-3 coordinates the axes, I/O and data logging. Specify axis count, cycle time, the profiles to replay, sensors to read and how test data leaves the rig. Keep emergency stop and safe torque off in rated safety hardware, separate from the motion program, and log every cycle so a failure can be traced to the load that caused it.
- Door endurance rigs: repeated open-close cycles with force logging
- Suspension and bogie rigs: multi-axis load replay
- Actuator qualification: life and performance testing
Available through our supply network
All controllers and plcs →Specify controllers and plcs for rail →
Standards to have in view
- EN 50155:2021 (railway applications: rolling stock electronic equipment)
- EN 61373 (rolling stock equipment: shock and vibration tests)
- EN 45545-2 (fire protection on railway vehicles: material requirements)
- EN 50121-3-2 (railway EMC: rolling stock apparatus)
- EN 14752 (bodyside entrance systems for rolling stock)
- EN 50126-1 (RAMS for railway applications)
- EN 50657 (software on board rolling stock)
- IEC 60529 (IP codes)
Which standards apply depends on the end product and its market. Your engineer will confirm what the component itself needs to meet.
Frequently asked questions
Which standard applies to electronics in a rail vehicle actuator?
EN 50155 covers electronic equipment on rolling stock: operating temperature class, supply voltage range and tolerance, interruptions, humidity and dielectric strength. Shock and vibration are tested to EN 61373 by mounting category, fire behaviour of materials to EN 45545-2 and EMC to EN 50121-3-2. An actuator with on-board electronics needs evidence against all four for the vehicle it goes on.
What do EN 61373 categories 1, 2 and 3 mean?
They describe where the equipment is mounted. Category 1 is body-mounted, Category 2 is bogie-mounted and Category 3 is axle-mounted, and test severity increases from 1 to 3. An actuator on a bogie for wheelset steering or braking therefore faces far harsher vibration and shock than a door drive in the car body, which affects screw, bearing, encoder and connector choice.
What supply voltage range must rail equipment tolerate?
EN 50155 lists nominal battery voltages from 24 to 110 V, with 24, 72 and 110 V recommended. Equipment must work continuously from 0.7 to 1.25 times nominal and survive brief excursions to 0.6 and 1.4 times nominal. At 110 V that is 77 to 137.5 V continuous. Class S2, the default, also requires normal operation through interruptions up to 10 ms.
Are electric actuators used for train wheel steering?
Yes, in some designs. Tolomatic describes a modified IMA44 integrated servo actuator steering the wheels of a high-speed train car to reduce wear in curves. In the UK, the Liebherr LiCAS trial used compact hydraulic actuators instead and reported at least 50% lower contact-patch frictional energy and up to 30% longer wheelset maintenance intervals, which shows the benefit of active steering whichever actuator is used.
What is a train door motor and what standard covers doors?
It is the motor in the door operator that drives the leaf through a spindle, belt or rack. Brushless motors are increasingly used because they avoid brush wear and let the controller set speed profiles. EN 14752 covers bodyside entrance systems, including closing forces, kinetic energy, obstacle detection, emergency egress and keeping doors, steps and ramps closed while moving.
What should I send for a rail actuator or test rig enquiry?
Send the function and mounting location (body, bogie, axle or rig), force or torque, stroke, speed, duty and cycle life, supply voltage and tolerance, EN 50155 temperature class, EN 61373 category, EN 45545-2 hazard level, IP rating, feedback and interface, fail-safe state, envelope and the qualification evidence the vehicle builder requires.
Sources
- Tolomatic: Automotive and transportation applications (high-speed train wheel steering)
- Thomson: Industry applications (rail vehicles)
- Automation.com: Thomson introduces Electrak HD linear actuators (railroad equipment)
- Bel Fuse: Railway FAQ and glossary (EN 50155, EN 61373, EN 45545)
- Televic: Standards overview (EN 50155, EN 61373, EN 45545-2, EN 50121-3-2)
- International Railway Journal: Active radial steering suspension system reduces wear
- EU-Rail: In search of more efficient braking systems
- Schunk Transit Systems: Pantograph metro SBE/SBL
- Crouzet: Train doors, how can reliable and safe opening and closing be ensured?
- Railway News: EN 14752, Europe's blueprint for safer, accessible rail doors
Figures are summarised from the sources above and from manufacturers' published data on the date shown. Always confirm against the current datasheet for your exact part.