Locomotive SKODA ES 499.0 (350 series)
This article presents locomotive SKODA ES 499.0 (nowadays 350 series). It was a crown jewel of back then Czechoslovak Railways and despite its age of over 40 years remains operational until today as four-axle express locomotive.
Background of locomotive SKODA ES 499.0
Concept of new traction locomotives of second generation was influenced by four major factors: (i) for increasing power density the transition between AC and DC traction systems was becoming a bottleneck; (ii) effort to interconnect railway networks in western and central Europe, (iii) weight of intercity trains and international fast trains were increasing (iv) power rating of DC locomotives became insufficient.
Initial requirements
The task from Federal Ministry of Transportation dated back in 1969 was very demanding. Key requirements were:
– continuous power 4’000 kW
– maximum speed 160 km/h
– chassis and mechanical parts constructed for up to 200 km/h
– electrodynamic brake
– total weight less than 88 t
– wheelset arrangement Bo’Bo’
Four-axle as well as six-axle locomotives were initially considered. Afterwards, four-axle design was selected.
Challenging task was finished already in 1973 by delivering two prototypes. It was necessary to develop a new driver’s stand and button control (for 150 series replaced by ‘joystick’ control).
Both prototypes were purchased and commissioned after difficult and long trial operation. Serial locomotives were manufactured in SKODA Plzen in last quarter of 1975.
Cabinet four axle locomotive of that time modern edge design utilizes recently proven chassis that was tested in Velim up to speed of 218 km/h and passed all tests. They feature two-stage suspension with screw springs with lateral and vertical damping by hydraulic dampers. Transmission of traction and braking forces is realized by pivot in ball bushing located in smallest possible distance above top of the rail. Such construction shall minimize the differences in axle pressure.
Newly developed 6-pole DC traction motors AL 4741 Flt, each rated 1’000 kW, were equipped with compensation windings for a better commutation. Traction motors use external ventilation and suck the cooling air through blinds on one side of locomotive body.
Electrodynamic brake (EDB) works in resistor braking mode. EDB uses smooth pulse control and can be used in speed range 160-60 km/h.
Two basic concepts were considered in development of traction equipment:
(a) regulation on AC side
This concept would require a development of inverter section.
(b) regulation on DC side
Such concept could only be realized with resistive control back in early 1970s.
Finally the latter concept was chosen, using resistors with continuous capability and 56 regulation stages with bridge transfer from serial and parallel re-connection of motor groups. Dynamic brake is rated 3’600 kW and can be used for speeds above 60 km/h. At lower speed, the dynamic brake is automatically disconnected.
Painting of the prototypes did significantly differ from serial locomotives.
Main data of locomotive SKODA ES 499.0
International designation: 91 54 7 350 xxx – x
Original designation for Czechslovak Railways: ES 499.0
Current designation: 350 (series)
Locomotive type: four-axle cabinet express locomotive
Operator: ZSSK
Manufacturer: SKODA Plzen (Czechoslovakia)
Beginning of deliveries: 1974
Number of manufactured locomotives: 20
Wheelset arrangement: Bo’Bo’
Wheel diameter: 1 250 mm
Length over bumpers: 16 740 mm
Minimum track radius: 120 m
Axle gear ratio: 1 : 2.162
Permanent traction force: 126 kN
Specific weight: 22.4 kg/kW
Continuous power: 4’000 kW
Hourly power: 4’200 kW
Maximum speed: 160 km/h
Service weight: 87.4 t
Traction systems: 25 kV AC/50 Hz, 3 kV DC
Nickname for locomotive SKODA ES 499.0:
◊ Gorilla (because of high power and robust construction)
◊ Rat (because of beveled fronts of locomotive body and recessed signal lights)
◊ Cockatoo (according to the colorful paint of refurbished locomotives)
References
[1] E-mobility series, https://mb-drive-services.com/category/e-mobility/
[2] Skoda Transportation, https://www.skoda.cz/en/
