Background and overview
Commuter transportation was increasing in Sapporo area and getting overcrowded
by 4% every year. 711 series suburban AC electric multiple unit trains
used on commuter services in Sapporo area chronically caused approximately
5-minute delay because of their poor acceleration performance and fewer
doorways, compared to 721 series EMU. Furthermore, 711 series EMU was getting
superannuated. Hence, JR Hokkaido developed the next generation commuter
electric multiple unit, 731 series. Four 3-car sets consisting of a powered
vehicle and 2 trailer vehicles were delivered in 1996.
Car body
They have a 2812mm wide body with slanted upper part of the body, incorporating light weight stainless steel construction and same cross-section shape as that of kiha201-0 series DMU incorporating pneumatic tilt system. Bodies are unpainted and have a light green and red waistline band running the length of each car below the windows. The floor level is 50mm lower than 721 series EMU to shorten boarding and alighting time. Gangwayed cab ends constructed by steel feature higher mounted driver's cab and shock absorbing construction for the protection against obstacles at the level crossing, and the automatic gangway connection device to ease rush-up operation. A destination rollsign is fitted above the gangway door and clusters of a headlight employing shield-beam light bulb and a taillight employing LED are fitted at the left and right sides of the rollsign. Additional clusters consisting of headlights employing a shielded-beam light bulb and a high intensity discharge (HID) lamp are also fitted on each side of the gangway door. They are equipped with three 1200mm wide single-leaf automatic stepped sliding doors which can be operated manually by pushing the buttons fitted beside the door and two fixed windows having 945mm height and 2000mm width are fitted between the sliding doors. The door operating equipment is TK103A fitted above the door header of the sliding doors. A roller-binding destination screen is fitted on each side of the body and the louver of the snow separator employing the cyclone to remove airborne snow from intake for cooling the traction motor is also fitted on each side of the powered vehicles. An air conditioner, N-AU731, rated at 30,000kcal/h is fitted on the centre of the roof.
Bogies
Motored bogies are N-DT731, trailer bogies of end vehicles and trailer
bogies are N-TR731 featuring bolster-less secondary air suspension, trailing
arm link journal box supporting system, and the single link traction device.
The wheel diameter is reduced to 810mm to lower their floor level. These
bogies feature yaw dampers to ensure smooth ride characteristics even at
130km/h. Twin Disc (TD) flexible joint employing deflecting plates made
of carbon-fiber reinforced plastic (CFRP) is applied for power transmission
device. The gear ratio is 4.895 to get high acceleration performance and
the maximum service speed at 130km/h. Both motored and trailered bogies
employ the double tread brake device with high adhesive alloy cast iron
shoes.
Traction unit and ancillary equipments
Powered intermediate vehicles, class moha731-100, are equipped with a traction system, N-CI731, which controls 4 AC traction motors, N-MT731, with a power output of 230kW on truck basis. This traction system consists of a 3-level PWM converter employing Insulated Bipolar Transistor (IGBT) and a 3-level Variable-frequency drive (VFD) employing IGBT to keep "Guideline of counter measures taken by users against higher harmonics received at high voltages or extremely high voltages" provided by Ministry of International Trade and Industry. Class moha731 vehicles are also equipped with a traction transformer, N-TM731, and an auxiliary air compressor under the floor, a cross-arm type current pickup, N-PS721B, and a vacuum circuit breaker, N-CB721 on the roof. Class kuha731-200 vehicles are equipped with an auxiliary power supply, N-APS 731A with a power output of 4.21kVA, and an air compressor, MH1785-C2000ML. 731 series employ the electric commanding brake with regenerative brake, featuring multimode brake skid re-adhesion control. 731 series also adopt the traction control system to work in multiple with kiha201 series DMU.
Accommodation
Passenger accommodation consists of longitudinal bench seating throughout, with an individual seat width of 455 mm per person and two stanchions to divide seating into three sections. Flip-down auxiliary seating is provided next to the doorway at both ends of the vehicle to increase standing capacity and to ease boarding and alighting during peak hours. Since they don't have the vestibule areas used on the earlier 721 series trains, they are equipped with air curtains mounted above the doorway, and electric blow heaters located beside the doorway to reduce the penetration of outside cold air into the heated passengers' cabin. Roller blinds are gotten rid of. Class kuha731-100 vehicles are equipped with a Japanese style toilet, and class kuha731-200 vehicles are equipped with a wheelchair space.
Additional delivery
Ten 3-car sets were additionally delivered in 1998, and five in 1999. Vehicles built in 2005 differ from former 731 series EMU in employing the side windows outside framed with polycarbonate reinforcement for the protection against the breakdown of the windowpane, anti-fall plates between vehicles excepting the cab end. A universal access toilet and a wheelchair space were introduced to class kuha731-100 and this change caused the doors and side windows arrangement change having a narrower side window at the rear of the vehicle than former end vehicles and the rear door moved toward the front. The current pickup was changed into the single-arm type current pickup, N-PS785.
Modification and refurbishment
Side windows outside began to be additionally framed with polycarbonate reinforcement for the protection against the breakdown of the windowpane in 2002. A gangway door window located at the front of the cab was additionally fitted with a defroster to clear condensation, and thaw snow from the window. Furthermore, the current pickup was replaced with the single-arm type current pickup, N-PS785.
The refurbishment programme commenced on 731 series EMU in 2016. The traction system was replaced with N-CI731B. The automatic gangway connection device was removed, and lightweight gangway connection was employed. Anti-fall plates between vehicles are additionally introduced excepting the cab end.
Operations
731 series EMU entered the revenue services on the Hakodate and Chitose
lines in December 1996. They also entered the Sassho line local services
in 2012. They are now used on the regional services in Sapporo area. |
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