Background and overview
In 1990, JR East developed 251 series intercity DC electric multiple unit
(EMU) trains in order to improve the image of "Odoriko" intercity
services used on 185 series EMU built. 2 ten car sets consisting of 6 powered
vehicles and 4 trailer vehicles were delivered in 1980.
Car body
They have 2900mm wide body. Their body design incorporates a weatherproof steel sheet (Steel Plate Atmospheric) specified by Japanese national Railways' standard, and a stainless plate for their roof and floor. End vehicles and a 1st class intermediate vehicle feature bilevel construction, and the other vehicles feature high seating floor. Their end vehicles are not gangwayed. The front windscreen of end vehicles is extremely large with the driver's compartment being placed fairly low, allowing passengers a commanding view of the tracks ahead. Side horizontal band windows featuring wide curved glass are fitted excepting lowering bottom floor of the bilevel vehicles and a 1006mm wide single leaf plug door to realize airtight and omit the door case is fitted at the end of the class saro251, kuha251, and moha250 vehicles. The other vehicles are equipped with an 866mm wide back up plug door. Traditional destination rollsigns are fitted on the side of their body. End vehicles are equipped with an air conditioner, AU401, rated at 18000kcal/h on the floor, and air conditioner, AU402, rated at 18000kcal/h under the floor. A bilevel intermediate vehicle, class saro251, is equipped with two air conditioners, AU401, on the floor. The other vehicles are equipped with an air conditioner, AU403, rated at 32000kcal/h under their floor. Electric fans of air conditioner supply fresh air into the passenger room, instead of ventilators on the roof. their livery is azure blue with a white narrow band and gray skirting.
Bogies
Motored bogies are DT56A and trailer bogies are TR241A, featuring bolster-less
secondary air suspension, rolled rubber spring journal supporting system,
and the Z link traction device. They also employ the yaw dampers and anti-rolling
stabilizers to ensure smooth ride characteristics even at 120km/h. Motored
bogies employ single tread brake device and trailer bogies employ both
single disk brake device and single tread brake device.
Traction unit and ancillary equipments
Eight series-wound brushed DC traction motors, MT61, with a power output
of 120kW are controlled by the armature-resistance traction control system,
CS57, featuring field added excitation control. The gear ratio is 4.82
to realize operation for Ito and Izu Kyuko lines having graded mountain
routes at least 20‰, and maximum service speed at 120km/h. At the
armature voltage control stage, armature resistance control and series-parallel
control are applied. At the field weakening stage, field added excitation
system, HS54C, indirectly controls the electrical current of field by controlling
the electrical current of inductive shunt. Forced field control by HS54C
realizes regenerative braking from the high-speed range by using the field
weakening at 30%. At low-speed range, the voltage of regeneration keeps
by applying series-parallel control. So, the regenerative braking is available
until 30km/h. If the regenerative brake is not sufficient, additional brake
is provided by pneumatic friction brake. Their traction system introduced
the constant speed drive function over 60km/h.
The brake system is the rheostatic electric command pneumatic brake, employing pressure intensifying braking over 110km/h to shorten braking distance. Regenerative holding brake is available, which keep the travelling speed at the holding brake operation starting over 40km/h. Class moha251 vehicles are equipped with a crossed arm current pickup, PS27, having minimum footprint to maximize passenger salon. Class moha250-0 vehicles are equipped with a brush-less motor generator, DM106, with a power output of 190kVA for the auxiliary power supply and a motor driven air compressor, MH3094-C2000ML.
Accommodation
Each Two vehicles are designed as one room named "Green unit" providing high quality services, "Group unit" for families and small groups, and "Custom unit" for the others.
"Green unit" consists of two bilevel vehicles, class kuro250 and class saro251. Upper deck passenger room and observation room employ 2+1 abreast reclining seating with 1000mm seating pitch for observation room and 1300mm for the others. Lower deck of class kuro250 employs public open lounge and a kitchen providing light meal. Lower deck of class saro251 are equipped with three 4-seat compartments employing electric reclining seating.
"Group unit" consists of a bilevel vehicle and a high seating vehicle. The observation room of class kuha251 feature 2+2 abreast transverse seating with 810mm seating pitch. Upstairs passenger room of class kuha251 and saha251 are equipped with transverse seating bays with transparent partitions and 1790mm seating pitch. Lower deck of class kuha251 employs public child's play area and a nursing room.
"Custom unit" consists of class moha251 and moha250 vehicles. They have 2-2 abreast rotatable transverse seating with 1000mm seating pitch. Their luggage rack is the airplane overhead bin style.
An audio control unit for audio programme including FM broadcast and other music is provided for each seat. Class saro251 and moha251-100 vehicles are equipped with a refreshment counter. Class saro251 vehicles are equipped with a baggage shelf. All vehicles excepting class saro251 and kuha251 are equipped with a wester style toilet and a washroom. Class kuro250, moha251, moha250, and saha251 vehicles are also equipped with a flushing urinal. Class saha251 vehicles are equipped with a universal access toilet and a multi purpose room.
Operation
251 series EMU entered "Super view Odoriko" intercity revenue services linking Tokyo/Ikebukuro and Izukyu-Shimoda in April, 1990.
Additional delivery
JR East delivered additional 2 sets of 2nd batch's 251 series in 1992.
Modification and refurbishment
A refurbishment programme was commenced on 251 series from 2002. Their livery was changed into universe white with a light blue narrow band and emerald green skirting.
The accommodation of the observation room of class kuha251 was changed into 2-2 abreast reclining seating with 1000mm seating pitch. The accommodation of "Group unit" was changed into 2-2 abreast reclining seating with 1000mm seating pitch and eventually their seating capacity is decreased. Seating of "Custom unit" was also changed into reclining seating with same seating capacity as before refurbishment. As for "Green unit", their fabric of seating was only refurbished.
A second refurbishment programme of "Green unit" was commenced in 2006. All seating was replaced with new one and the seating pitch of observation room was increased to 1000mm.
Withdrawal
Although 251 series EMU had been used on "Super view Odoriko" intercity services, "Ohayo Liner Shinjuku" pay rapid services, and "Home Liner Odawara" pay rapid services, they were replaced with E261 series EMU and completely withdrawn in March, 2020. |
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