Background and overview
In 1994, JR East developed the 701-1000 series suburban AC electric multiple unit (EMU) trains, incorporating several improvements over earlier models, to replace locomotive hauled trains operating in the Morioka region and the 715-1000 series EMUs used in the Sendai region.
The fleet consists of two-car and four-car sets. A total of fifteen two car sets were delivered to the Morioka Depot, and two four car sets were delivered to the Sendai Depot, all in 1994.
Car body
The carbody of the 701-1000 series measures 19,500 mm in length and 2,870 mm in width, with a bogie centre distance of 13,800 mm. The structure is primarily composed of stainless steel, except for the bolster beams, the end sections of the centre sill, and selected cross beams, which are fabricated from weather resistant steel plate (Steel Plate Atmospheric).
The body employs Kawasaki’s two-sheet spot-welded stainless-steel structure, in which a pressed inner stainless-steel sheet is spot-welded to an outer sheet. This double skin construction provides the required rigidity without the use of bead embossing. The exterior consists of unpainted flat stainless steel panels.
Cars allocated to the Morioka Depot are accented by a blue-violet waistline band, with light and dark violet bands applied below the windscreens. In contrast, cars assigned to the Sendai Depot feature a green waistline band with a narrow red accent band, and green bands applied below the windscreens.
The cab end is gangway-equipped, incorporating a gangway door and a low profile driver’s cab. Flat windscreens are adopted to reduce manufacturing costs. Lighting equipment consists of two sealed beam headlights mounted above the gangway door and two taillights positioned below the windscreens. A destination rollsign is mounted above the co-driver’s-side windscreen.
Each car is fitted with three 1,300 mm-wide double-leaf automatic stepped sliding doors on each side. Door operation is controlled by TK113C units employing pneumatic direct-drive mechanisms mounted above the door headers. Manual operation is enabled via push-button controls located adjacent to each door.
Between the doors, the side panels are fitted with a horizontal band of four windows, including two double hung side windows with a height of 960 mm, while fixed windows are installed at each end of the carbody. All windows employ heat absorbent glass, eliminating the need for blinds.
Traditional roller-blind destination indicators and external loudspeakers—used for platform-side passenger announcements—are installed on each side of the carbody.
A roof mounted AU710A air-conditioning unit, rated at 38,000 kcal/h, is installed at the centre of the roof. No roof ventilators are provided.
End cars are equipped with an automatic jumper coupler to facilitate rapid turn-back operations.
Bogies
The powered bogies are designated DT61A, while the trailer bogies are classified as TR246A, the same types used on the 701-0 series. Both bogie types employ bolsterless secondary air suspension and trailing arm link journal box supports. Traction force is transmitted via a single-link draw gear.
Both bogie types incorporate a bow-shaped frame design, adopted to lower the bolster-suspension height and thereby contribute to a reduced floor level. The distance between the two secondary suspension units is 200 mm narrower than on the earlier standard TR235 bogie, allowing the secondary suspension assemblies to be mounted directly onto the side frames, thereby simplifying the bogie frame construction.
Power transmission utilizes Twin Disc (TD) flexible couplings with carbon-fiber-reinforced plastic (CFRP) deflecting plates, with a gear ratio of 7.07.
The braking configuration differs between bogie types: powered bogies are equipped with single-tread brake rigging, while trailer bogies combine single-disc brake units with single-tread brake rigging.
Traction unit and ancillary equipments
Class Kumoha701-1000 cars are equipped with the CI1 traction system, which
controls four MT65 three phase AC asynchronous traction motors on a per-bogie
basis, each rated at 125 kW. The traction system comprises a thyristor/diode
hybrid-bridge traction rectifier and a three-level variable-frequency drive
(VFD) utilizing power transistors.
Class Kumoha701-1000 cars are also fitted with an SC49 auxiliary power supply unit (10 kVA) and a TM26 traction transformer, both mounted beneath the floor. The transformer employs a shell-type core with forced-oil cooling, and provides a primary voltage of 20 kV, with secondary and tertiary outputs of 825 V and 388 V, respectively. A PS105 lozenge-shaped pantograph, featuring a reduced folding height, and an MR102 braking resistor are mounted on the roof.
Class Kuha700-1000 end cars are equipped with an MH1112-C1600MF motor-driven air compressor mounted beneath the floor.
The braking system is an electrically commanded brake with rheostatic braking.
Accommodation
Passenger accommodation features longitudinal bench-type bucket seating throughout. Each bench is fitted with end partition panels to reduce cold-air intrusion. The air-conditioning ductwork is installed above the ceiling, maintaining a clean interior profile, with slit type vents providing evenly distributed airflow.
The cab is a left-side compartment-type design, optimized for conductor less operation. Two-car sets are equipped with ticket vending machines located near the doorways, as well as fare chart displays and fare boxes positioned behind the driver’s cab. Four-car sets are not equipped with these devices. A 1,200 mm-wide double-leaf sliding door is fitted at the gangway to facilitate movement between cars during conductor-less operation.
Class Kuha700-1000 trailer end cars are equipped with a western-style toilet incorporating a chemical holding tank. A wheelchair space is provided across the aisle from the toilet.
Additional delivery
JR East delivered five two-car sets to the Sendai Depot between January and February 1995, followed by six two-car sets between September and October 1995. A further twelve two-car sets were delivered to the Aomori Depot between December 1995 and March 1996.
Modification
A refurbishment programme for the 701-1000 series commenced in 2011. The original CI1 traction system was replaced with the CI19A traction unit, comprising a three-level PWM converter employing Insulated Gate Bipolar Transistors (IGBTs) and a two-level variable-frequency drive (VFD), also employing IGBTs. This system controls four MT65 AC asynchronous traction motors on a per-bogie basis. In the event of a failure in one of the two traction circuits, the failed circuit can be isolated, providing enhanced redundancy.
The roof-mounted braking resistor unit was removed, as regenerative braking became available with the introduction of the new traction system. The traction transformers were upgraded to TM32A units, which incorporate measures to reduce harmonic-current heating. The auxiliary power supply was replaced with the SC93 unit, featuring IGBT technology.
The destination rollsigns fitted on the front and bodyside were replaced
with LED destination displays. The pantographs of selected cars were upgraded
to the PS106 single-arm pantograph.
Operations and transfer
The 701-1000 series entered revenue service on the Tōhoku Line between Shiraishi and Morioka in December 1994. They were subsequently deployed on rural services of the Tōhoku Line between Kuroiso and Aomori, as well as on the Senseki Line.
With the opening of the Tōhoku Shinkansen extension between Morioka and Hachinohe in 2002, four two-car sets were transferred to the Iwate Galaxy Railway (IGR) and one two-car set to the Aoimori Railway. Following the further extension of the Tōhoku Shinkansen between Hachinohe and Shin-Aomori in 2010, an additional seven two-car sets were transferred to the Aoimori Railway.
The 701-1000 series units remaining under JR East are currently operated
on rural services of the Tōhoku Line between Shin Shirakawa and Morioka.. |
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