Background and overview
JR Hokkaido inserted the additional powered intermediate vehicles, class moha721-5100 and moha721-5200, and trailer intermediate vehicles, class saha721-4100 and saha721-4200, into surplus trailer end vehicles caused by 721-4100 series conversion to make them 6-car sets and to obtain surplus 721-0 series vehicles which replaced superannuated 711 series EMU. Modified 721-1000 series vehicles were reclassified into -5100 subseries. Four 6-car sets consisting of 2 powered vehicles and 4 trailer vehicles were delivered over the period from October 2003 until December.
Car body
The vehicle design has a 21200mm long and 2900mm wide body incorporating lightweight stainless-steel construction. The underseal is applied 3mm thicker than that of 721-0 series. Bodies are unpainted and have an olive-green waistline and headline bands running the length of each car below and above the windows. The cab end section constructed by whether proof steel is fitted with the gangway door and curved surface windscreens on the front. A classification rollsign is fitted above the gangway door. A pair of clusters of the head light and the taillight covered the glass to keep the visibility even if covered with snow are fitted above the windscreens. The additional headlights are also fitted under the windscreens. Anti-fall plates between vehicles are additionally introduced excepting the cab end. The cab end section is painted in silver, having the olive-green waistline band and around the windscreens are painted in black. Class saha721-5200 vehicles have a blue waistline band and red narrow band running the length of each car below the windows and vertical blue bands running outward of both ends of doors. Class saha721-5200, class kuha721-5100 and kuha721-5200 vehicles are equipped with three 1000mm wide single-leaf automatic stepped sliding doors and two fixed windows, a drop window, and a door case window incorporating polycarbonate plate are fitted between the sliding doors. On the other hand, the other vehicles are equipped with three 1000mm wide single-leaf automatic stepped sliding doors which can be operated manually by pushing the buttons fitted beside the door and two fixed windows and a drop window incorporating polycarbonate plate 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. Class kuha721-5100 and kuha721-5200 vehicles are equipped with an air conditioner, N-AU721A, rated at 23,000kcal/h on the centre of the roof. On the other hand, the other vehicles are equipped with an air conditioner, N-AU722, using R407C refrigerant@and rated at 30,000kcal/h on the centre of the roof and 1mm thick stainless cover plates between equipments fitted under their floor to reduce the waving for preventing snow and ice from sticking thereon.
Bogies
The motored bogies are N-DT721B, the trailer bogies applied for class kuha721-5100 and kuha721-5200 are N-TR721A, and trailer bogies applied for class saha721-5100 and saha721-5200 are N-TR721B. N-DT721B and N-TR721B employ the reinforced bogie frame and the low fitting position of the bolster suspension since the bolster suspension is interrupted by the doorstep. These bogies feature bolster-less secondary air suspension, axle arm type journal box supporting system, the single link traction gear, and the anti-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 5.19 to get high acceleration performance at the range of middle and high speed and the maximum service speed at 130km/h. Their bogies employ double tread brake riggings.
Traction unit and ancillary equipments
Class moha721-5100 and moha721-5200 vehicles are equipped with a traction system, N-CI721-2, which controls 4 AC induction 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 2-level Variable-frequency drive (VFD) employing IGBT. Class moha721-5100 and moha721-5200 vehicles are also equipped with a travelling wind self-cooling traction transformer, N-TM721A-AN, beneath the floor. Furthermore, trailer end vehicles, class kuha721-5200, and intermediate trailer vehicles, class saha721-4500, are equipped with a motor-driven air compressor, N-MH1785-C2000ML beneath the floor. Class kuha721-5200 vehicles are also equipped with an auxiliary power supply, N-APS721B, with a power output of 8kVA beneath the floor, and class saha721-5100 vehicles are N-APS721A with a power output of 4.25kVA. The brake system is the electric commanding brake with regenerative brake and holding brake, featuring brake control of trailer priority.
Accommodation
Class saha721-5200 vehicles having U seat accommodation have partition walls and automatic doors to separate the passenger rooms and the doorways and their accommodation consists of 2-2 abreast reclining seating with 1030mm seating pitch. Conductor's rooms are located at the front end of the body. An LED display for providing passenger information is fitted above the door between the doorway and the passenger room. Class kuha721-5100 and kuha721-5200 vehicles have partition walls and double-leaf sliding doors to separate the passenger rooms. Seating accommodation consists of 2-2 abreast switchable transverse seating with 910mm seating pitch at the centre and 1-1 abreast seating at the ends. The other standard class vehicles don't have the partition walls and automatic doors to separate the passenger rooms and the doorways, and their accommodation consists of the mixture of the longitudinal bench seating beside the sliding doors and 2-2 abreast switchable transverse seating with 910mm seating pitch between the longitudinal bench seating. The seating fabric of class kuha721-5100 and kuha721-5200 vehicles is coloured brown and that of the other standard class vehicles is coloured in dark gray. Straps are fitted above the longitudinal bench seating. Class kuha721-5200 vehicles are equipped with wheelchair space toward the front of the front passenger room, and a Japanese style toilet employing a chemical holding tank, and a water tank at the rear of the vehicle. On the other hand, class saha721-5100 vehicles are equipped with wheelchair space and a universal access toilet employing a chemical holding tank at the rear of the vehicle.
Car body
Class kuha721-5100 and kuha721-5200 vehicles converted from 721-1000 series are additionally fitted with 1mm thick stainless cover plates between equipments fitted under their floor to reduce the waving for preventing snow and ice from sticking thereon.
Operations
721-5100 series entered "Airport" rapid services in 2003. They are also used on the regional services on the Sapporo, Chitose, and Sassho lines. |
|
