Background and overview
In 1966, Japanese National Railways (JNR) developed the Kiha45 series diesel multiple unit (DMU) trains for operation on non-electrified suburban lines. This series comprises:
- Kiha23: double-ended units for warm and cold regions
- Kiha24: double-ended units tailored for extremely cold climates
- Kiha45: single-ended units for warm and cold regions
- Kiha46: single-ended units designed for extreme cold
- Kiha53: double-ended units equipped with dual engines
These configurations allowed operational flexibility based on regional climate and route conditions.
Car body
Each vehicle features a steel body measuring 21,300 mm in length and 2,928
mm in width, with a bogie center spacing of 14,400 mm. The cab ends are
gangwayed, equipped with a gangway door and raised cab floor-300 mm above
standard-to protect against level-crossing collisions. Curved windscreens
enhance forward visibility, and a destination roll sign is mounted above
the cab door.
Lighting components include two sealed-beam headlights above the windscreen, and two taillights with pneumatic horns mounted below.
Passenger access differs by type:
- Kiha23, Kiha45, and Kiha53 vehicles are equipped with two 1,300 mm wide
double-leaf semi-automatic sliding doors. Adjacent to each door is a door
case window and a 470 mm wide vertically opposed sash window. Between the
doors, 1,080 mm wide double-hung windows are fitted; the upper sash slides
downward while the lower sash slides upward.
- Kiha24 and Kiha46 vehicles feature 1,000 mm wide single-leaf sliding
doors and double-paned windows for enhanced thermal insulation. These vehicles
also route exhaust pipes from the prime mover internally through the cab.
Water tanks are typically mounted beneath the floor, except for Kiha53 vehicles, where space constraints from dual prime movers necessitated installation across the aisle from the onboard toilet.
Door actuation units include TK106 for the Kiha23, Kiha45, and Kiha53 series, and TK105 for the Kiha24 and Kiha46. All variants are fitted with tight-lock automatic couplers using RD13 rubber draft gear.
The livery consists of a vermilion base with a wide beige stripe along the window line.
Bogies
The powered bogies are of type DT22C, while the trailers use TR51B. Both designs adopt a swing hanger structure, coil springs for bolster suspension, and a pedestal-type journal support system. The gear ratio for powered bogies is 2.976, and the brake rigging employs a single-tread configuration
Traction unit and ancillary equipments
Class Kiha53 vehicles are powered by two DMH17H diesel engines-four-cycle, inline eight-cylinder units each producing 180PS with a single-piece crankcase. All other units utilize a single DMH17H engine, horizontally mounted and secured using rubber vibration isolators.
Transmissions include:
- TC2A (Shinko Engineering): featuring a Lysholm-Smith torque converter
with a six-element, three-stage configuration and a single-plate dry clutch
- DF115A (Niigata Converter): sharing identical torque converter specs but utilizing a multi-plate wet clutch
The solenoid box location and oil cooler interface with the car body are standardized across both transmission types.
Compressed air is supplied by:
- Two C400 air compressors in the Kiha53 (each driven by a separate prime mover)
- One C600 air compressor in all other vehicles (driven by the single engine)
Braking is managed via a DA-type automatic air brake system.
Accommodation
Passenger saloons feature a combination of longitudinal bench seating near
the doors and transverse bays spaced at 1,400 mm pitch. Vestibules are
provided in Kiha24 and Kiha46 vehicles to improve thermal isolation. Lighting
is delivered via dual rows of fluorescent fixtures, and a water-based heating
system is installed. A traditional Japanese-style toilet is located at
the rear of the car.
Additional deliveries
From June 1967, vehicles were constructed with upgraded door operating mechanisms, TK106A, designed to simplify maintenance.
From October 1967, units produced for warm regions discontinued the use of protective snow shutters for pneumatic horns. Additionally, the Kiha 23-500 and Kiha 45-500 subseries were introduced for cold climate operation, incorporating engine covers to prevent snow intrusion.
In March 1969, the Kiha 45-600 series was developed, derived from the standard coach-baggage-RPO combination car Kiha 20-600. These cars featured a mixed interior layout with transverse seating bays at the rear and longitudinal bench seating at the front. Folding partitions positioned at the center of the passenger compartment and immediately in front of the front door allowed the temporary division of the interior into post office, baggage, and passenger sections.
Modifications
JR East
Prime Mover Replacement
In January 1988, JR East initiated test programs for a successor to the aging DMH17 engine. Following a train fire involving the Kiha 58 series, the full-scale prime mover replacement program was launched in September 1989. The DMF11HZ diesel engine manufactured by Komatsu Ltd., rated at 300PS, was selected. However, its output was limited to 250PS to accommodate the existing hydraulic transmission and propeller shaft systems, which were retained.
JR West
Air Conditioning Retrofit
Unit Kiha 23-520, operating on the Etsumi-North Line, received an air conditioning modification involving the installation of a roof-mounted self-powered unit (AU34), rated at 26,000 kcal/h.
JR West - Conductor-less Operation Conversion
To support one-man operation, vehicles were modified to include:
- A ticket vending machine adjacent to doorways
- An LED fare chart display and fare box behind the driver's cab
- Removal of transverse seating bays located directly behind the cab area
Operations
Initial deployment saw class Kiha23 and Kiha45 vehicles operating across the Boso region, Rikuu-East, Johana, Himi, and Yamaguchi lines. The Kiha 46 series was assigned to Hokkaido starting in 1966.
A total of 179 vehicles were constructed by 1969, serving both express services and local rural routes. In early service, they operated alongside Kiha10, Kiha20, and Kiha35 series units; in later years, with Kiha35 and Kiha47 series.
In East Japan, the units ran express services such as "Inawashiro" and operated local trains on the Boso lines as well as rural routes like Kitakami, Rikuu-East, Ishinomaki, Tadami, Echigo, and Yahiko lines. Upon electrification of the Boso lines, surplus vehicles were transferred to Mito Depot for use on the Suigun and Moka lines, and to Shikoku for rural operations. Similarly, vehicles displaced from Echigo and Yahiko depots were reassigned to Mito depot.
In West Japan, the series was used on the Himi, Johana, Takayama, Echigo-North, Kansai, and Wakayama lines, and across various Chugoku region lines, excluding the Masuda-east section of the San-in line.
In Shikoku, allocations were made to the Takamatsu, Tokushima, and Kochi Depots, including transfers from Chiba Depot. Most units in Shikoku were eventually concentrated in Tokushima Depot for operation on the Kotoku, Mugi, and Tokushima lines.
In Kyushu, the fleet participated in express operations such as the "Karakuni" services, as well as rural operations on the Houhi, Kyudai, Kitto, Hisatsu, and Yamano lines.
Post-Privatization Allocation and Withdrawals
At the time of Japanese National Railways' division into regional JR companies in 1987, the fleet was distributed as follows:
- JR Hokkaido: 15 vehicles
- JR East: 36 vehicles
- JR West: 84 vehicles
- JR Shikoku: 24 vehicles
- JR Kyushu: 17 vehicles
JR Hokkaido assigned its vehicles to Hakodate, Tomakomai, and Naebo Depots, but all units were retired by 1995.
JR East units used on the Suigun Line were scrapped by 1992; the remaining units operating on the Ishinomaki and Rikuu-East lines were withdrawn by 2000.
JR West units were distributed across the Takayama, Himi, Johana, Obama, Tsuyama, Inbi, Geibi, Kisuki, Yamaguchi, and San-in lines, but were fully decommissioned by 1991.
JR Shikoku used the fleet in the Tokushima region, with withdrawals completed by 1991.
JR Kyushu employed the vehicles on the Houhi, Kyudai, Hisatsu, and Kitto lines until their retirement in 1993. |
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