Background and overview
In 2015, JR Kyushu introduced the 305 series DC commuter electric multiple
unit (EMU) trains to replace the aging 103-1500 series EMUs, which had
been assigned to interrunning services on the Fukuoka City Subway Kuko
Line and were frequently malfunctioning. Six six-car sets, each comprising
four powered cars and two trailer cars, were built and allocated to the
Karatsu Depot.
Car body
The carbody of the 305 series measures 19,500 mm in length and 2,800 mm
in width, with a bogie centre distance of 13,800 mm. It features a double-skinned
aluminum alloy construction. The floor height is set at 1,125 mm to lower
the vehicle's centre of gravity and eliminate the level difference between
platform and floor, thereby improving accessibility. The exterior livery
consists of white urethane paint.
The cab ends are constructed from steel to protect the driver from obstacles at level crossings. An emergency gangway door is positioned to the left of the cab, and the cab ends are covered with tempered glass. Each corner post is chamfered at approximately 45 degrees to deflect colliding vehicles away from the cab in the event of a non-head-on collision.
A full-colour LED destination indicator is mounted behind the upper portion
of the driver's side windscreen. Exterior lighting includes two halogen
headlights positioned below the windscreens, two externally mounted LED
fog lamps, and two rectangular taillights located below.
Each car is equipped with four 1,300 mm-wide double-leaf automatic sliding doors, actuated by electric rack-and-pinion mechanisms with attenuated closing force mounted on the door headers. Flashing alarm lamps are installed above the headers to indicate door operation status. The side panels are fitted with a fixed window measuring 1,840 mm in width between the doors, and a fixed window measuring 650 mm at the end of the carbody. All windows employ UV-cut, heat-absorbent double-glazing glass to enhance noise and thermal insulation and prevent condensation.
Roof-mounted air conditioning units (AU410K), rated at 50,000 kcal/h, are installed on each car. Roof-mounted electric fans are provided to exhaust indoor air. Additional equipment includes a full-colour LED destination display mounted on each side of the carbody.
Bogies
The powered bogies are designated as type DT408K, while the trailer bogies are classified as type TR408K. Both types feature a bolster-less design with secondary air suspension, a trailing arm–type journal box support system, and a single-link draw gear. They also incorporate a bow-shaped frame and smaller-diameter wheels (810 mm), which lower the bolster suspension height, contributing to a reduced floor level and improved vehicle stability.
Power transmission is achieved through Twin Disc (TD) flexible joints incorporating deflecting plates made of carbon-fiber-reinforced plastic (CFRP). The gear ratio is set at 6.5 to optimize acceleration performance across medium- and high-speed ranges.
Both powered and trailer bogies are equipped with single-tread brake rigging.
Traction system and ancillary equipment
Each powered car is equipped with four MT403K permanent magnet synchronous motors, each rated at 150 kW. These motors are controlled via the PC406K variable-frequency drive system, which is installed on Class Moha305 vehicles and governs both cars in a fixed married-pair configuration with Class Moha304. The system implements axle-based control and incorporates a two-level inverter utilizing insulated gate bipolar transistors (IGBTs).
To ensure braking reliability under conditions where regenerative braking
may be ineffective—such as on single-track sections with low power demand—the
305 series employs an electrically commanded braking system that combines
regenerative and rheostatic braking. The PC406K system includes a braking
chopper unit to facilitate smooth transition to rheostatic braking when
regeneration is not feasible.
Current collection is achieved via two PS402K single-arm pantographs mounted
on the roofs of Class Moha305 vehicles.
Auxiliary systems are installed on Class Moha304 vehicles, which are fitted with SC409K auxiliary power supply units delivering an output of 150 kVA, also employing IGBT technology. These vehicles are additionally equipped with motor-driven scroll-type air compressors (type MH3096K-SC1600K), which supply compressed air for braking and door operation.
End cars are equipped with an onboard ATO system for automatic train operation, as well as ATC-9 and ATS-SK onboard signaling systems mounted beneath the floor.
Accommodation
Passenger accommodation consists of longitudinal bench seating, with stanchions dividing the seats into three- or four-person sections, each providing 440 mm of width per occupant. This layout increases overall capacity and helps alleviate overcrowding. The seat and backrest are made of fire-resistant wood and fitted with fabric-covered cushions. Two seats at each end of the saloon are equipped with headrests.
A 17-inch LCD display is mounted on the headers of the sliding doors, showing destination and stop information accompanied by a door chime. Straps are installed throughout the carbody for standing passengers. For illumination, the saloon is equipped with two rows of ceiling-mounted LED light fixtures.
At the rear end of the saloon, accessible spaces are provided for passengers using wheelchairs or strollers. A universal access toilet employing a vacuum toilet system is installed at the rear end of Class Kuha305 trailer cars.
The driver’s cab is full-sized and equipped with a one-handle master controller operated by the left hand.
Modifications
In 2018, an additional 17-inch LCD display began to be installed adjacent to the existing destination and stop information display on the door headers, enabling the provision of video advertisements.
Operations
The 305 series entered revenue service in February 2015. Currently, 305 series EMUs are assigned to the Chikuhi Line between Meinohama and Nishi-Karatsu, including interrunning services on the Fukuoka City Subway Kuko Line. |
|
| Technical Data |
| Items |
Data |
| Supply Voltage |
1500 V DC |
| Service
speed, etc. |
Acceleration: 3.5 km/h/s Deceleration: 3.5 km/h/s Service speed: 110 km/h |
| Length |
19,500 mm |
| Width |
2,800 mm |
| Height |
4,050mm |
| Bogie |
DT408K (motored) TR408K (trailer) |
| Collector |
PS402K (single-arm) |
| Traction
motor |
MT403K (150 kW) |
| Gear ratio |
6.50 |
| Traction system |
2 level Variable Frequency Drive (IGBT): PC406K |
| Air conditioner |
AU410K (50,000 kcal/h×1) |
| Designed
by |
JR Kyushu |
|
|
