Background and overview
Although the 203 series EMUs equipped with chopper-controlled traction systems had already been introduced for inter-running services between the Joban Line and the Chiyoda Line of the Teito Rapid Transit Authority, Japanese National Railways (JNR) developed the 103-1500 series DC commuter EMUs in 1982 for inter-running operations between the Chikuhi Line (JNR) and Line 1 of the Fukuoka City Transportation Bureau.
This decision was driven by operational constraints: the long station intervals on the Chikuhi Line and the low passenger demand in the Chikuzen-Maebaru area reduced the effectiveness of regenerative braking systems typically employed with chopper control.
Between 1982 and 1983, a total of nine six-car trainsets were delivered. Each set consisted of four motored cars and two trailer cars.
Car body
The vehicles feature narrow steel carbodies measuring 19,500 mm in length and 2,800 mm in width. To reduce overall weight, lightweight shaped steel and press-formed beams are employed. Weather-resistant steel plates (Steel Plate Atmospheric) are used for the side walls and roof panels, with continuous welding and a polyurethane waterproof coating applied to the roof to enhance corrosion resistance.
The cab end is gangwayed, incorporating an emergency gangway door and a driver's cab elevated 300 mm above the floor level. This raised position improves forward visibility and offers additional protection against obstacles at level crossings. Flat windshields are adopted to reduce manufacturing costs, and ivory-coloured FRP panels are fitted around the windshield perimeter.
Exterior lighting consists of two sealed-beam headlights on either side of the gangway and two taillights positioned below. A destination rollsign is installed above the gangway door, and an operation number indicator is located behind the assistant driver's windshield.
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 pre-fabricated double-hung windows measuring 920 mm in width. Additional double-hung windows are provided at each end of the carbody. The upper sash slides downward, while the lower sash slides upward, with the lower sash opening height limited to 150 mm. Door operation is controlled by TK4J units installed beneath the bench seats.
Each car is fitted with a roof-mounted AU75G air conditioner rated at 42,000?kcal/h. Class Moha103-1500 vehicles are equipped with four roof-mounted draught ventilators, while other variants feature six. A destination rollsign is also mounted on each side of the carbody.
The exterior livery of the 103-1500 series features a light blue base colour accented by an ivory waistline band located beneath the side windows.
Bogies
The powered bogies are designated DT33, fitted with 910 mm diameter wheels and a wheelbase of 2,300 mm. The trailer bogies are type TR201, equipped with 860 mm diameter wheels and a 2,100 mm wheelbase. Both bogie types utilize coil springs as bolster springs and feature pedestal-type journal supports.
A parallel cardan drive system with hollow shaft is employed for power transmission. The gear ratio is set at 6.53, enabling high acceleration performance while allowing for a reduced ratio of motored to trailer cars.
The braking system on powered bogies uses single-truck brake rigging with a single-action brake cylinder, whereas trailer bogies are equipped with disc brake rigging.
Traction unit and ancillary equipments
The 103-1500 series EMU is equipped with eight MT55A series-wound brushed DC traction motors, each rated at 110 kW. These motors are controlled via the CS20D-G3 motor-driven camshaft control system, which employs armature resistance control to regulate acceleration and power output. A naturally ventilated traction resistor unit (MR87A) is used to reduce noise, particularly in tunnel sections.
Class Moha102-1500 vehicles are fitted with a motor-generator unit (MH128D-DM85D) rated at 110 kVA, repurposed from retired 153 series EMUs, along with a motor-driven air compressor (MH113B-C2000M). Both units are mounted beneath the floor and supply electrical power for onboard systems and compressed air for braking and door operation.
Current collection is provided by a PS21 lozenge-type pantograph mounted on the roof of class Moha103-1500 vehicles. Class kuha103-1500 vehicles are equipped with an onboard ATC signaling system installed beneath the floor.
The braking system consists of an electromagnetic straight air brake, supplemented by rheostatic braking. This configuration ensures effective deceleration while minimizing mechanical wear.
Accommodation
The passenger saloon of the 103-1500 series EMU is configured with fully longitudinal seating, designed to maximize capacity and facilitate smooth passenger flow during boarding and alighting. Each bench is equipped with end partition panels to define individual seating areas. The air conditioning ductwork is installed above the ceiling to maintain a clean interior profile, with slit-type vents providing distributed airflow. Illumination is provided by fluorescent fixtures arranged in two parallel rows along the ceiling.
Modifications
Class Kumoha103-1500
To adapt the original six-car formations for three-car operations on the Chikuhi Line between Chikuzen-Maebaru and Nishi-Karatsu, JR Kyushu converted selected class Moha103-1500 motored intermediate cars into motored-end cars in 1989 and 1995. These modified vehicles were reclassified as class Kumoha103-1500. The conversion involved the construction of a new cab-end structure and the installation of automatic coupling and uncoupling equipment. Unlike existing trailer-end cars, they are not equipped with onboard ATC signaling units.
Class Kumoha102-1500
In parallel, JR Kyushu converted selected class Moha102-1500 motored intermediate cars into motored end cars in 1989 and 1995. These units were reclassified as class Kumoha102-1500. The conversion similarly included a newly built cab-end and automatic coupling/uncoupling equipment. These cars also lack onboard ATC signaling units, distinguishing them from conventional trailer-end vehicles.
Toilet Retrofitting
Beginning in 2002, odd-numbered class Kuha103-1500 and Kumoha103-1500 cars underwent modifications to install universal-access toilets. These facilities employ a vacuum toilet system and are located at the rear end of the carbody.
Operations
The 103-1500 series EMU trains commenced inter-running operations between the JNR Chikuhi Line and Line 1 of the Fukuoka City Transportation Bureau in 1983, coinciding with the electrification of the Chikuhi Line between Meinohama and Karatsu, and the Karatsu Line between Karatsu and Nishi-Karatsu. In response to low passenger demand, 3-car formations began operating between Chikuzen-Maebaru and Nishi-Karatsu in 1989.
Their operations on the Fukuoka City Subway Line 1 were gradually reduced following the introduction of the 303 series EMUs in 2000. Due to frequent failures with the aging 103-1500 series fleet, the 305 series EMUs were introduced in 2015, leading to the complete withdrawal of the 103-1500 series from subway service.
As of now, the 103-1500 series trains are assigned to local services on the Chikuhi Line between Chikuzen-Maebaru and Nishi-Karatsu. |
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