Background and overview
In 1991, selected 115‑series cars were reallocated to the Aboshi Depot to introduce three‑door‑equipped stock for special rapid and rapid services on the JR Kobe and JR Kyoto Lines.
To compensate for this reallocation, a number of 117‑series powered intermediate cars were selected and converted to permit multiple‑unit operation with 115‑series trailer end cars.
These converted vehicles were reclassified as the 115‑3500 series in 1992.
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, 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.
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.
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.
Roof‑mounted AU75B air‑conditioning units, each rated at 42,000 kcal/h, are installed on every car and are flanked by forced‑ventilation units, eliminating the need for separate roof ventilators.
A destination rollsign housing is provided on each side, including provisions for the future installation of side destination indicators.
Bogies
The bogies, designated DT32H, employ diaphragm‑type air springs for the secondary suspension, with the upper surface of each air spring slanted laterally. A pedestal‑type journal box support configuration is adopted. Unlike conventional 115‑series bogies, the secondary air‑spring assemblies are mounted on the bogie frame itself, rather than being attached directly to the carbody.
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 while maintaining a lower motored‑to‑trailer car ratio.
The braking system utilizes single‑truck brake rigging with a single‑action brake cylinder.
Traction unit and ancillary equipments
The 115-3500 series is equipped with eight MT54D series-wound brushed DC traction motors, each rated at 120 kW. These motors are controlled by the CS43A motor-driven camshaft control system and the MR136 forced-draught traction resistor, both installed on Class Moha115-3500 powered intermediate cars. The system employs armature-resistance control to regulate acceleration and power output, and provides holding-braking and reverse-notching capability.
Class Moha114-3500 intermediate cars are fitted with an MH135-DM92 motor-generator unit rated at 160 kVA and an MH113B-C2000M motor-driven air compressor, both mounted beneath the floor. These units supply electrical power for onboard auxiliary systems and compressed air for braking and door operation.
Current collection is provided by a PS16J lozenge-type pantograph mounted on the roof of Class Moha115-3500 cars.
Inter-car electrical connectors differ between the 115 series and 117 series: the 115 series employs three KE58 jumper couplers, while the 117 series uses a KE96. To address this incompatibility, special jumper connectors are utilized to permit multiple-unit operation between the converted 3500-series motor cars and existing 115-series trailer end cars.
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 115-3500 series is arranged with a hybrid seating configuration. Between the doors, four-seater longitudinal bench seating is provided adjacent to the doorways, while the centre of the saloon is fitted with four rows of 2+2 flip-over transverse seating with a pitch of 910 mm. At each end of the saloon, three additional rows of flip-over transverse seating are installed. Overhead luggage racks are constructed using pipe-frame structures.
The air-conditioning ductwork is installed above the ceiling, maintaining a clean interior profile and concealing the equipment from view. Slit-type vents are used to provide evenly distributed airflow throughout the saloon.
Cabin lighting is provided by two rows of covered fluorescent light fixtures, which replaced the original 254 V AC fixtures with new units powered by 100 V AC.
Modification and refurbishment
Life extension programme N30
Between August 2004 and May 2009, JR West implemented Life Extension Programme N30 on twenty-four 115-3500 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
- Installation of hanging straps throughout the passenger compartment
- Sealing of traction‑motor inspection holes
- Upgrading of end doors to incorporate self‑closing mechanisms
Operations
In 1992, JR West allocated a number of 115-3500-series intermediate cars to the Okayama Depot to compensate for the transfer of 115-1000-series intermediate cars—originally assigned to four-car formations—to rapid services on the JR Kobe, JR Kyoto, and Biwako Lines. The 115-3500 series subsequently entered local services on the Sanyō, Akō, and Hakubi Lines. However, these vehicles were later displaced by surplus 115-1000-series intermediate cars, themselves released following the introduction of 227-series EMUs to the Hiroshima area between April 2015 and June 2016. All 115-3500-series vehicles allocated to the Okayama Depot were eventually withdrawn and scrapped.
Separately, another group of 115-3500-series intermediate cars was assigned to the Shimonoseki Depot in 1992 to replace 115-0-series intermediate cars operating with 115-3000-series end cars. These units entered both local and rapid services in the Hiroshima region. Following the implementation of Life Extension Programme N30 on the 115-3000 series, the fleet received a new exterior livery and was subsequently repainted into a yellow monochromatic scheme in 2012, coinciding with the discontinuation of rapid services.
Nevertheless, the 115-3500 series began to be withdrawn from local services east of Iwakuni in 2016, following the introduction of the 227 series 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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