Background and overview
Japanese National Railways (JNR) planned to introduce newly built commuter trains on the Yamanote Line to replace the 103‑0 series EMUs then assigned to Yamanote Line services. The displaced 103‑0 series sets were to be reassigned to the Yokohama and Musashino Lines to increase capacity on those routes. JNR also considered deploying the high‑cost 201 series EMUs to the Yamanote Line; however, the chopper‑controlled traction system used on the 201 series made further cost reductions difficult, and JNR’s budget constraints prevented the construction of additional 201 series sets.
Meanwhile, JNR had achieved favourable results with field‑added excitation traction control and lightweight bolster-less bogies developed for the next generation of suburban trains. Building on these technologies, JNR developed the 205‑0 series DC commuter electric multiple units (EMUs) in 1985, featuring a stainless‑steel body and an electrically commanded braking system.
In the same year, four ten‑car sets—each consisting of six powered vehicles and four trailer vehicles—were built and allocated to the Shinagawa Depot.
Car body
The carbody of the 205‑0 series measures 19,500 mm in length and 2,800 mm in width, with a bogie centre distance of 13,800 mm. The structure is primarily composed of stainless steel, except for the bolster beams, the end sections of the centre beam, and selected cross beams, which are fabricated from weather‑resistant steel plate (Steel Plate Atmospheric). The exterior features unpainted bead‑stiffened stainless‑steel panels with olive‑green waistline and headline bands running the length of each car below and above the windows.
The non‑gangwayed cab ends, which have no gangway door, are framed with decorative FRP panels. The driver’s cab is elevated 300 mm above floor level to improve forward visibility and provide additional protection against obstacles at level crossings. The flat and slanted windscreens are divided into a wide glass pane on the driver’s side and a narrower pane on the assistant driver’s side. A destination rollsign is mounted centrally behind the upper portion of the wider windscreen, while an operation number indicator—displaying the trainset-level scheduling identifier—is implemented using a flip‑disc display located behind the upper portion of the narrower windscreen. End vehicles are equipped with a longitudinally arranged sealed‑beam headlight with a taillight positioned below.
Each car is equipped with four double‑leaf automatic sliding doors, each 1,300 mm wide. Between the doors, the side panels feature pairs of prefabricated double‑hung windows measuring 885 mm in width, with additional double‑hung windows provided at each end of the carbody. The upper sash slides downward, while the lower sash slides upward. Door operation is controlled by TK4J units installed beneath the bench seats. Door‑pocket windows adjacent to the doors are omitted. A destination rollsign is also mounted on each side of the carbody.
Each car is fitted with a roof‑mounted AU75G air‑conditioning unit rated at 42,000 kcal/h. Class Moha204 vehicles are equipped with four roof‑mounted draught ventilators; end vehicles feature five, while other variants feature six.
Couplers between married‑pair motored cars use drawbars, while all other connections employ tightlock couplers.
Bogies
The powered bogies are designated as type DT50, while the trailer bogies are classified as type TR235. Both types feature bolsterless secondary air suspension and conical multilayer rubber‑spring journal supports. Traction force is transmitted via the centre pin and multilayer rubber‑spring draw gear. The side beams of the bogie frame are straight in shape, and the bogie transom incorporates seamless pipes to achieve a lightweight and simple construction.
Power transmission utilizes a parallel cardan drive system with a hollow shaft. The gear ratio is 6.07, optimized to provide the same high‑acceleration performance at starting and the same maximum service speed as the 201 series EMU. Corrugated wheels are adopted for reduced weight, and a compound circular wheel profile is employed to minimize lateral forces exerted on the track.
The braking configuration varies by bogie type. Powered bogies are equipped with single‑tread brake rigging, while trailer bogies combine a single‑disc brake device with single‑tread brake rigging to enhance overall braking performance.
Powertrain and ancillary equipment
Series‑wound brushed DC traction motors (MT61), each rated at 120 kW, deliver high torque at both low and high speeds by expanding the field‑weakening ratio to 35%. The eight traction motors on Class Moha205 and Class Moha204 vehicles are controlled by the CS57 armature‑resistance traction control system, which incorporates field‑added excitation control. A naturally ventilated traction resistor unit designated as MR159 is employed. During the armature‑voltage control stage, armature‑resistance control and series–parallel control are applied. During the field‑weakening stage, the HS52 field‑added excitation system indirectly regulates the field current by controlling the current of the inductive shunt. Forced‑field control provided by the HS52 enables regenerative braking. At low speeds, regeneration voltage is maintained through series–parallel control, allowing regenerative braking to remain effective down to approximately 20 km/h. If regenerative braking performance falls below the required threshold, pneumatic braking is automatically applied to supplement braking force.
Current collection is handled by a PS21 lozenge‑type pantograph mounted on the roof of Class Moha205 vehicles. Class Moha204 vehicles are equipped with a brushless motor‑generator unit (DM106) delivering 190 kVA, and a motor-driven air compressor (MH3075-C2000M), both mounted beneath the floor. The brake system was changed from the electromagnetic straight‑air type—previously standard on JNR electric trains—to an electric‑command pneumatic system, resulting in improved brake response. End vehicles are equipped with onboard ATC signalling system beneath the floor.
Accommodation
The passenger saloon of the 205‑0 series EMU is configured with fully longitudinal seating to maximize capacity and facilitate smooth passenger flow during boarding and alighting. Each bench is fitted with end partition panels to delineate individual seating areas. Hanging straps are installed throughout the passenger compartment to support standing passengers in two parallel rows along the ceiling. The air‑conditioning ductwork is installed above the ceiling to maintain a clean interior profile, with slit‑type vents providing evenly distributed airflow. Illumination is provided by fluorescent fixtures arranged in two parallel rows along the ceiling. The master controller employs a lateral‑motion operating handle.
Additional delivery
JNR
JNR delivered thirty ten‑car sets to the Yamanote Line to release 103‑0 series sets for reassignment to the newly opened Saikyō Line in 1985. From this batch onward, pairs of drop windows were employed in place of the earlier double‑hung windows. The operation number indicator was upgraded to a flip‑disc display.
Vehicles manufactured from April 1986 onward incorporated improved bogies—DT50D and TR235D—featuring double‑collar sealed roller bearings for enhanced running stability.
In August 1986, JNR also delivered four seven‑car sets, consisting of four powered vehicles and three trailer vehicles, to the Akashi Depot to provide additional capacity for commuter services on the Tōkaidō–Sanyō Line in the Kansai area. This batch was equipped with the ATS‑S onboard signalling system instead of ATC. The headline and waistline bands were finished in light blue.
JR East
JR East continued to deliver twenty ten‑car sets of 205‑0 series EMUs to the Yamanote Depot to replace the remaining 103‑0 series sets operating on the Yamanote Line. Trainsets delivered from February 1988 onward incorporated the HS52A field‑added excitation system featuring half‑wave rectification, and one of the three motor‑generator units normally installed on Class Moha204 vehicles was omitted, as two units provided sufficient auxiliary power for a ten‑car formation, reducing overall cost. Overhead luggage racks were redesigned with pipe‑frame structures.
Subsequently, JR East delivered twenty‑five seven‑car sets—consisting of four powered vehicles and three trailer vehicles—to the Kamata Depot to replace the 103‑0 series on the Yokohama Line. From this batch onward, a roller‑blind train‑type indicator was added behind the upper portion of the wider windscreen on the driver’s side. The operation number indicator reverted to a rotary disc. End cars were equipped with onboard ATC and ATS‑S signalling systems mounted beneath the floor. In addition, the side‑door windows were extended downward. The headline and waistline bands were finished in a combination of olive green and green.
JR East also delivered sixteen six‑car sets to the Nakahara Depot for deployment on the Nambu Line between 1989 and 1990. End cars were equipped with onboard ATS‑B and ATS‑S signalling systems beneath the floor. The headline and waistline bands were finished in yellow, orange, and brown. During the same period, twenty‑five ten‑car sets were delivered to the Kawagoe Depot for the Saikyō Line. From this batch onward, the traction motors adopted an internal‑fan design. End cars were equipped with onboard ATS‑B and ATC signalling systems beneath the floor. The headline and waistline bands were finished in green. In addition, two ten‑car sets were delivered to the Toyoda Depot for Chūō–Sōbu Line commuter services. End cars were equipped with onboard ATS‑B and ATS‑S signalling systems and were provisioned for future installation of ATC equipment beneath the floor. The headline and waistline bands were finished in yellow.
Six ten‑car sets were delivered to the Urawa Depot for Keihin–Tōhoku Line commuter services between 1989 and 1990. End cars were equipped with onboard ATC signalling systems beneath the floor. The headline and waistline bands were finished in light blue. In the same period, twelve ten‑car sets delivered for the Keiyō Line featured cab ends fully covered with decorative FRP panels and vertical curved windscreens. Headlights were positioned lower than on earlier batches, and taillights were upgraded to externally mounted LED units. The traction‑motor inspection hatches on the floor were sealed. End cars were equipped with onboard ATS‑P and ATS‑S signalling systems and were provisioned for future installation of ATC equipment beneath the floor. The headline and waistline bands were finished in red. These sets were later retrofitted with pressure‑intensifying braking for operation above 110 km/h to reduce braking distances.
Finally, JR East delivered five eight‑car sets for assignment to the Musashino Line. The cab‑end configuration matched that of the Keiyō Line sets. Several improvements were introduced on this batch: sliding doors were actuated by TK112 units employing pneumatic direct‑drive mechanisms mounted on the door headers, and the operation number indicator was upgraded to a flip‑disc display. End cars were equipped with onboard ATS‑P, ATS‑B, and ATS‑S signalling systems.
Class Saha204-900
Background and overview
In 1990, JR developed the class Saha204-900 proto-type trailer intermediate vehicles to the relieve overcrowding on the Yamanote line during peak hours.
Car body
The carbody of the Class Saha204‑900 measures 19,500 mm in length and 2,800 mm in width, with a bogie centre distance of 13,800 mm. The structure is primarily composed of stainless steel, except for the bolster beams, the end sections of the centre beam, and selected cross beams, which are fabricated from weather‑resistant steel plate. The exterior features unpainted bead‑stiffened stainless‑steel panels with olive‑green waistline and headline bands running the length of each car below and above the windows.
Each vehicle is equipped with six double‑leaf automatic sliding doors, each 1,300 mm wide and 1,850 mm high—50 mm higher than those on standard 205 series vehicles. Between the doors, the side panels feature drop windows measuring 600 mm in width. The second doors from either end of the carbody can be placed in a “shut‑up” mode during daytime operation. The sliding doors are actuated by TK112 units employing pneumatic direct‑drive mechanisms mounted on the door headers.
Each car is fitted with a roof‑mounted AU717SX or AU717MX air‑conditioning unit rated at 50,000 kcal/h, along with six roof‑mounted draught ventilators.
Bogies
The TR241B bogies feature bolsterless secondary air suspension and rolled rubber‑spring journal supports. Traction force is transmitted via a Watts‑linkage draw gear. The side beams of the bogie frame are straight in shape, and the bogie transom incorporates seamless pipes to achieve a lightweight and simple construction.
Corrugated wheels are adopted for reduced weight, and a compound circular wheel profile is employed to minimize lateral forces exerted on the track.
Each bogie combines a single‑disc brake device with single‑tread brake rigging to enhance overall braking performance.
Accommodation
The passenger saloon of the Class Saha 204‑900 is configured with fold‑down longitudinal seating, which can be locked in the stowed position during peak hours and folded down for passenger use during off‑peak periods. Hanging straps are installed throughout the passenger compartment in three parallel rows along the ceiling to support standing passengers. Stanchion poles are also placed at the centre of the saloon.
For thermal comfort, each vehicle is equipped with floor‑panel heating, as the limited seating leaves insufficient space for conventional under‑seat heaters. The air‑conditioning ductwork is installed above the ceiling to maintain a clean interior profile, with slit‑type vents providing evenly distributed airflow. Illumination is provided by fluorescent fixtures arranged in two parallel rows along the ceiling.
Class Saha204-0
Background and overview
The Class Saha 204‑900 received generally favourable evaluations. As a result, in 1991 JR East introduced the mass‑production Class Saha 204‑0 trailer intermediate vehicles to relieve overcrowding on the Yamanote Line during peak hours.
Car body
The carbody of the Class Saha204‑0 measures 19,500 mm in length and 2,800 mm in width, with a bogie centre distance of 13,800 mm. The structure is primarily composed of stainless steel, except for the bolster beams, the end sections of the centre beam, and selected cross beams, which are fabricated from weather‑resistant steel plate. The exterior features unpainted bead‑stiffened stainless‑steel panels with olive‑green waistline and headline bands running the length of each car below and above the windows.
Each vehicle is equipped with six double‑leaf automatic sliding doors, each 1,300 mm wide and 1,850 mm high—50 mm higher than those on standard 205 series vehicles. Between the doors, the side panels feature drop windows measuring 600 mm in width. The “shut‑up” mode for the second doors from either end of the carbody was discontinued. The sliding doors are actuated by TK112 units employing pneumatic direct‑drive mechanisms mounted on the door headers.
Each car is fitted with a roof‑mounted AU717 air‑conditioning unit rated at 50,000 kcal/h and powered by 600 V DC, along with six roof‑mounted draught ventilators.
Bogies
The TR241B bogies feature bolsterless secondary air suspension and rolled rubber‑spring journal supports. Traction force is transmitted via a Watts‑linkage draw gear. The side beams of the bogie frame are straight in shape, and the bogie transom incorporates seamless pipes to achieve a lightweight and simple construction.
Corrugated wheels are adopted for reduced weight, and a compound circular wheel profile is employed to minimize lateral forces exerted on the track.
Each bogie combines a single‑disc brake device with single‑tread brake rigging to enhance overall braking performance.
Ancillary equipment
Each vehicle is equipped with a 30 kVA DC–DC converter that supplies 600 V DC to its own air‑conditioning unit, supplementing the existing auxiliary power capacity, which became insufficient due to the addition of one extra car to the trainset.
Accommodation
The passenger saloon of the Class Saha 204‑0 is configured with fold‑down longitudinal seating, which can be locked in the stowed position during peak hours and folded down for passenger use during off‑peak periods. Hanging straps are installed throughout the passenger compartment in three parallel rows along the ceiling to support standing passengers. Stanchion poles are also placed at the centre of the saloon.
For thermal comfort, each vehicle is equipped with floor‑panel heating, as the limited seating leaves insufficient space for conventional under‑seat heaters. The air‑conditioning ductwork is installed above the ceiling to maintain a clean interior profile, with slit‑type vents providing evenly distributed airflow. Illumination is provided by fluorescent fixtures arranged in two parallel rows along the ceiling.
Class Saha204-100
Background and overview
In 1994, JR East introduced the Class Saha 204‑100 trailer intermediate vehicles to relieve overcrowding on the Yokohama Line during peak hours.
Car body
The carbody of the Class Saha204‑100 measures 19,500 mm in length and 2,800 mm in width, with a bogie centre distance of 13,800 mm. The structure is primarily composed of stainless steel, except for the bolster beams, the end sections of the centre beam, and selected cross beams, which are fabricated from weather‑resistant steel plate. The exterior features unpainted bead‑stiffened stainless‑steel panels with olive‑green waistline and headline bands running the length of each car below and above the windows.
Each vehicle is equipped with six double‑leaf automatic sliding doors, each 1,300 mm wide and 1,850 mm high—50 mm higher than those on standard 205 series vehicles. Between the doors, the side panels feature drop windows measuring 600 mm in width. The “shut‑up” mode for the second doors from either end of the carbody was discontinued. The sliding doors are actuated by TK112 units employing pneumatic direct‑drive mechanisms mounted on the door headers.
Each car is fitted with a roof‑mounted AU722 air‑conditioning unit rated at 50,000 kcal/h and powered by 440 V AC, along with six roof‑mounted draught ventilators.
Bogies
The TR246E bogies feature bolsterless secondary air suspension and trailing‑arm link journal‑box supports. Traction force is transmitted via a single‑link draw gear. The side beams of the bogie frame are straight in shape, and the bogie transom incorporates seamless pipes to achieve a lightweight and simple construction. The distance between the two secondary suspensions is 200 mm narrower than on the earlier standard TR235 bogie, allowing the secondary suspension units to be mounted directly onto the side frames and thereby simplifying the bogie‑frame structure.
Each bogie combines a single‑disc brake device with single‑tread brake rigging to enhance overall braking performance.
Accommodation
The passenger saloon of the Class Saha 204‑100 is configured with fold‑down longitudinal seating, which can be locked in the stowed position during peak hours and folded down for passenger use during off‑peak periods. Hanging straps are installed throughout the passenger compartment in three parallel rows along the ceiling to support standing passengers. Stanchion poles are also placed at the centre of the saloon.
For thermal comfort, each vehicle is equipped with floor‑panel heating, as the limited seating leaves insufficient space for conventional under‑seat heaters. The air‑conditioning ductwork is installed above the ceiling to maintain a clean interior profile, with slit‑type vents providing evenly distributed airflow. Illumination is provided by fluorescent fixtures arranged in two parallel rows along the ceiling. Each vehicle is also equipped with a wheelchair‑accessible space located at the front end.
Modification
JR East
Pantograph replacement
The pantographs of Class Moha205 vehicles allocated to Kawagoe Depot were replaced with PS33C single‑arm pantographs. In addition, the pantographs of Class Moha205 vehicles allocated to Kamakura Depot began to be replaced with PS33E units in 2009.
JR West
Refurbishment Programme
JR West commenced a refurbishment programme for the aging 205‑0 series between 2012 and 2013. This programme included several modifications.
A guide pontoon was retrofitted to the outside of each corner post by welding to improve crash‑energy dissipation and to deflect a colliding vehicle in offset‑collision scenarios. Additional equipment included an LED destination display replacing the original rollsign, as well as two loudspeakers mounted on each side of the carbody to support passenger announcements. The windows on the side doors were replaced with laminated glass to eliminate the level difference between the glass and the interior panels.
Each car was retrofitted with an LED display installed above the header of each sliding door to provide passenger information. These locations also house door chimes for audible boarding notifications. Hanging straps were upgraded to larger looped handles—finished in green near priority‑seating areas and in orange elsewhere—to improve grip and visibility compared with earlier trains, and are fitted throughout the cabin. End vehicles are also equipped with a wheelchair‑accessible space located at the rear end.
Operations
JNR
Thirty‑four sets of 205‑0 series EMUs were assigned to the Yamanote Line and entered revenue service in 1985, replacing the aging 103‑0 series EMUs. JNR also delivered four seven‑car sets for deployment on commuter services on the Tokaido and Sanyo lines to provide additional capacity.
JR East
JR East continued to introduce 205‑0 series EMUs to the Yamanote Line and fully replaced the remaining 103‑0 series EMUs in 1988. In addition, 205‑0 series sets were delivered to completely displace the 103‑0 series operating on the Yokohama Line in 1989. The 205‑0 series also replaced selected 103‑0 series EMUs assigned to the Nambu, Chuo–Sobu, Saikyo, Keihin‑Tohoku, Keiyo, and Musashino lines.
Class Saha204‑0 vehicles were introduced to the Yamanote Line in 1991 to form eleven‑car sets, and Class Saha204‑100 vehicles were subsequently delivered to the Yokohama Line in 1994 to form eight‑car sets.
The 205‑0 series operating on the Keihin‑Tohoku Line were replaced by 209 series EMUs in 1996 and reassigned to the Chuo–Sobu Line. The 205‑0 series on the Chuo–Sobu Line were later replaced by E231‑0 series EMUs in 2001 and converted into the ‑1000 and ‑5000 subseries. Furthermore, the 205‑0 series operating on the Yamanote Line were displaced by E231‑500 series EMUs in 2004. Class Saha204‑0 six‑door intermediate trailer vehicles were relocated to the Saikyo Line, with selected vehicles reassigned to the Keiyo and Nambu lines, while the remainder were converted into the ‑1100, ‑1200, ‑3000, ‑3100, and ‑5000 subseries.
Subsequently, the 205‑0 series on the Keiyo Line were replaced by E233‑5000 series EMUs in 2011, those on the Yokohama Line by E233‑6000 series in 2014, those on the Nambu Line by E233‑8000 series in the same year, and those on the Saikyo Line by E233‑7000 series in 2016. All 205‑0 series EMUs owned by JR East were withdrawn and scrapped in 2016.
JR West
205‑0 series EMUs operating on the JR Kobe, JR Kyoto, and JR Takarazuka lines were replaced by 321 series EMUs in 2006 and transferred to the Hanwa Line after being reformed into six‑car or eight‑car sets. However, following the introduction of the 225‑5000 series to the Hanwa Line, the 205‑0 series were reassigned back to the JR Kobe, JR Kyoto, and JR Takarazuka lines in 2011 for use on peak‑hour commuter services.
Subsequently, the 205‑0 series—excluding Class Saha 205 trailer intermediate vehicles—were reformed into six‑car sets and relocated to the Hanwa Line for regional services alongside 103‑0 series EMUs. All Class Saha 205‑0 vehicles were scrapped in 2015. Later, the 225‑5100 series were delivered to the Hanwa Line to replace the remaining 103‑0 and 205 series EMUs operating on regional services. Eventually, the 205‑0 series were shortened to four‑car sets and reassigned to the Nara Line for regional operations, with surplus powered intermediate vehicles scrapped.
At present, the 205‑0 series operates on regional services on the Nara Line. |
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