Background and overview
In 1982, Japanese National Railways (JNR) developed the 115‑3000 series suburban DC electric multiple unit (EMU) trains to replace the aging 153 series EMUs used on regional services in the Hiroshima and Shimonoseki areas, and to increase the number of train sets available for frequent local operations.
The design combines the lightweight, high‑rigidity carbody structure of the 117 series with the standard 115‑series running gear, and was engineered to allow multiple‑unit operation with 111‑series motor cars.
The fleet consists of six four‑car sets, each comprising two powered cars and two trailer cars, and thirty trailer end cars designed for operation in formations with 111‑series powered cars.
All units were delivered to the Shimonoseki Depot between September and October 1982.
Car body
The cars feature wide steel bodies measuring 19,500 mm in length and 2,900 mm in width, with a bogie centre distance of 13,800 mm. To reduce overall weight, lightweight shaped steel sections and press‑formed beams are employed. The body skin is fabricated from 1.6 mm cold‑rolled steel plates, the wainscot panel from 1.6 mm stainless‑steel plates for improved corrosion resistance, and the roof from 1.2 mm hot‑rolled steel plates. The floor structure consists of lightweight resin‑coated composite panels, providing enhanced flame retardancy and dimensional stability.
The cab end is gangway‑equipped and incorporates a gangway door. The front structure consists of 4.5 mm‑thick front panels and curved windscreens, while the driver’s cab is elevated 300 mm above floor level to improve forward visibility and provide additional protection against obstacles at level crossings. Lighting equipment comprises sealed‑beam headlights mounted on either side of the gangway door and a tail lamp positioned below, with a destination rollsign installed above the gangway door.
Each car is equipped with two double‑leaf automatic sliding doors, each 1,300 mm wide. The side panels are fitted with pre‑assembled double‑hung windows designed to reduce drafts. Between the doors, four pairs of double‑hung windows (715 mm wide) and two door‑pocket windows (713 mm wide) are provided. At each end of the carbody, a pair of double‑hung windows and a 713 mm door‑pocket window are installed. On Class Kuha115‑3000/‑3100 cars, a 713 mm door‑pocket window is fitted immediately behind the rearward‑extended cab on the driver’s side, while a narrower 512 mm double‑hung window and a 713 mm door‑pocket window are provided on the assistant driver’s side. The upper sashes slide upward, while the lower sashes slide downward. Door operation is controlled by TK8A units mounted on the door headers, which also permit manual operation. The introduction of a door‑actuator switchover valve reduces the operating effort required for manual control.
The roof configuration varies by train set. Cars assigned to four‑car sets are fitted with a roof‑mounted AU75G air‑conditioning unit rated at 42,000 kcal/h. Class Moha114‑3000 cars are equipped with four roof‑mounted draught ventilators, while other variants feature six. A destination rollsign is mounted on each side.
In contrast, trailer end cars intended for operation with 111‑series powered cars are equipped with seven roof‑mounted draught ventilators and a roof opening covered by a plate, allowing for future installation of an air‑conditioning unit at the centre of the roof. A destination rollsign housing is provided on each side, including provisions for the future installation of side destination indicators.
The exterior livery is cream with a blue waistline band below the side windows.
Bogies
The powered bogies are designated DT21B, while the trailer bogies are classified as TR62A. Both bogie types employ coil springs for the bolster suspension and adopt a pedestal‑type journal box support configuration.
A parallel cardan drive system with a hollow shaft is used for the power transmission mechanism.
The gear ratio is 4.82, providing high acceleration performance across medium‑ to high‑speed ranges.
The braking system differs by bogie type:
powered bogies are equipped with double‑tread brake rigging, while trailer bogies employ disc brake rigging.
Traction unit and ancillary equipments
The 115‑3000 series is equipped with eight MT54D series‑wound brushed DC traction motors, each rated at 120 kW. These motors are controlled by the CS15F‑G2 motor‑driven camshaft control system and the insulation‑enhanced MR52D forced‑draught traction resistor, both installed on Class Moha115‑3000 powered intermediate cars. The system employs armature‑resistance control to regulate acceleration and power output, and provides holding‑braking and reverse‑notching capability.
Class Moha114‑3000 intermediate cars are fitted with a DM106 brushless motor‑generator unit rated at 190 kVA and an MH113B‑C2000M motor‑driven air compressor, both mounted beneath the floor. Class Moha115‑3000 cars are equipped with a 500 VA backup power‑inverter unit. To permit operation in formations with 111‑series powered cars, Class Kuha115‑3000 cars are additionally fitted with an MH80A‑C1000 motor‑driven air compressor. These units supply electrical power for onboard auxiliary systems and compressed air for braking and door operation.
Current collection is provided by two PS16 lozenge‑type pantographs mounted on the roof of Class Moha114‑3000 cars.
The forward pantograph serves as the primary unit, while the rear pantograph is retained as a backup.
Inter‑car electrical connections are made using two KE58 multicore jumper couplers for control circuits and a KE5 jumper coupler for three‑phase AC supply.
The braking system consists of an electromagnetic straight‑air brake supplemented by rheostatic braking, providing effective deceleration performance while reducing mechanical wear.
Accommodation
The interior of the 115‑3000 series consists of a mixture of longitudinal bench seating located adjacent to the doorways and at each end of the saloon, and flip‑over transverse seating with a pitch of 910 mm. Overhead luggage racks are constructed using pipe‑frame structures.
A trapezoidal air‑conditioning duct is installed beneath the ceiling and fitted with rectangular vents. Non‑air‑conditioned cars are equipped with seven electric fans mounted beneath the duct to enhance air circulation within the saloon. Interior lighting is provided by two rows of ceiling‑mounted fluorescent light fixtures, each rated at 40 W.
Class Kuha115‑3000 B‑end cars are equipped with a Japanese‑style toilet constructed from fibre‑reinforced plastic and located at the rear of the car, while Class Kuha115‑3100 A‑end cars are not fitted with a toilet.
Additional delivery
In 1983, six pairs of powered intermediate cars were additionally delivered
to replace the aging 111‑series powered intermediate cars operating in
formations with the end cars of the 115‑3000 series. These additional units
enabled the complete standardization of running gear within the 115‑3000‑series
formations and eliminated the reliance on 111‑series motor cars for mixed‑formation
operation.
Modification and refurbishment
Japanese National Railways
Air conditioner retrofitting
From 1983, non‑air‑conditioned 115‑3000 series cars were progressively retrofitted with AU75G air‑conditioning units, standardizing the fleet with the equipment adopted on the original air‑conditioned cars.
JR West
Life extension programme N30
Between August 2004 and November 2008, JR West implemented Life Extension
Programme N30 on sixty‑eight 115‑3000 series cars as a cost‑reduction alternative
to the Refurbishment Programme N40 applied to the 115‑2000 series.
Car body modifications
- Replacement of damaged body panels with weather‑resistant steel
- Bonding of windshields and door‑pocket windows to the carbody
- Introduction of manual door operation via push‑button controls adjacent to each door
- Removal of roof ventilators
- Retention of original side‑window construction, rain gutters, and door‑operating units
Accommodation modifications
- Installation of hanging straps throughout the passenger compartment
- Sealing of traction‑motor inspection holes
- Upgrading of end doors to incorporate self‑closing mechanisms
Operations
The 115‑3000 series was delivered to the Shimonoseki Depot and entered local services on the Sanyō and Kure Lines in the Hiroshima region. In 1983, the 111‑series intermediate cars that had been operating in formations with 115‑3000‑series end cars were progressively displaced—some replaced by the newly delivered 115‑3000‑series intermediate cars, and the remainder by air‑conditioned 115‑0‑series intermediate cars.
Following the privatization of JNR in 1987, the fleet received the Hiroshima Rapid Service livery and was transferred to the Hiroshima Depot to operate rapid services linking central Hiroshima with the new Hiroshima Airport, which opened in 1993. During this period, the 115‑0‑series intermediate cars still operating with 115‑3000‑series end cars were replaced by Class Moha 115/114‑3500 vehicles. The fleet was subsequently reassigned to the Shimonoseki Depot again in 2003.
JR West then commenced Life Extension Programme N30 on the 115‑3000 series, accompanied by a new exterior livery. From 2012, the fleet was repainted into a yellow monochromatic scheme, coinciding with the discontinuation of rapid services. Nevertheless, the 115‑3000 series began to be withdrawn from local services east of Iwakuni in 2016, following the introduction of the 227 series EMUs for Hiroshima‑area local services from 2014.
The remaining units are now assigned to rural services on the Sanyō Line between Iwakuni and Shimonoseki. |
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