Background and overview
Although Hokuriku line was electrified at 20kV 60Hz AC, the section of
Itoigawa and eastward was planned to be electrified at 1500V DC, connecting
with DC electrified Shinetsu line. Japanese National Railways had a plan
that Uetsu line connecting Niitsu and Akita would be electrified at 20kV
50Hz AC. After the Sea of Japan coastal route would be electrified completely,
the new locomotive type, which could be used on the inter running passenger
and freight services thorough 1500V DC, 20kV 50Hz AC, and 20kV 60Hz AC
electrified lines, were desired. So, JNR developed EF81 1 pre-production
type of multi-voltage AC/DC electric locomotive for the start of electrified
Hokuriku line between Itoigawa and Naoetsu, 1968.
EF81 locomotives were designed based on EF65 standard DC electric locomotives,
employing light-weight extra-high voltage equipments and bogies in order
to add the transformer and the rectifier for the alternative current. EF81
was a six-axle, three-bogied (BoBoBo) electric locomotive and had a total
power output of 2,550 kW (3,420 hp) on DC and 2,350kW (3,180 hp) on AC,
adopting 6 standard traction motors, MT52A, with a power output of 425kW.
Its mass was 100.8 tons and its axle load was 16.8 tons.
A pre-production locomotive, EF81 1, was allocated at Toyama depot in December,
1968, and underwent extensive test running on Hokuriku.
Car body
They have 18,600mm long and 2,900 mm wide body in order to fit additional
extra-high voltage electric equipments. No gangway door is fitted on the
front of the body because they won't be operated in pairs. Tow headlights
are mounted above the windshields and two tail-lights are fitted at the
lower part of body ends. The disconnecting switch, circuit breaker, and
main fuse are fitted inside their body in order to protect them against
salt damage and heavy snow. Covered traction resistors are fitted over
the roof for space saving. A pair of cross-arm type current collectors,
PS22, are also fitted on the roof.
Bogies
Bogies having 2600mm wheel base are DT138 for outer and DT139 for centre, featuring bolster-less construction and the cylindrical rubber bush journal supporting system.
Traction unit and auxiliary equipments
Traction motors are controlled by a traction system, CS36, featuring camshaft
contactor vernier control for acceleration and deceleration, and a camshaft
contactor field control system, CS37, for anti-slip control and axle load
compensating. Slight brake and automatic notch back controls are applied
while wheels slipping. Newly developed traction transformer is TM17, and
newly developed traction rectifier is RS36 including inverter function.
The electrical power for train-heating is supplied from the traction rectifier,
RS36 on the DC electrified line and from the third wiring of the traction
transformer, TM17, to discontinue the electrical heating power supply.
The train heating indicator lights are located next to the cab doors. EF81
adopts the nose suspended drive.
Mass-Production vehicles
The mass-production type of EF81 began to be delivered in 1969. They differ
from a pre-production locomotive, EF81 1, in having some improvements.
A camshaft contactor vernier control traction system was changed into CS36A,
a camshaft contactor field control traction system was changed into CS37A,
and a traction rectifier was changed into RS36A. As EF81 1 had a problem
of sharp torque fluctuation while wheels slipping, mass-production locomotives
adopted to automatic notch hold control. A cover of traction resistors
was changed because of increased capacity of resistors.
Improvement
EF81 39 onward built for the start of electrified Uetsu line between Niitsu and Akita in 1972 differ from earlier EF81-0s in employing CS36B and CS37B. Cab ventilation grilles are fitted on the front were discontinued and an electric fan was fitted one the ceiling of the cab.
EF81 75 onward built for additional capacity of the Sea of Japan coastal
route in 1973 differ from previous batches in employing CS36C and CS37C.
EF81 137 onward built for replacement of superannuated EF15 locomotives
used in Niigata region in 1983 differ from some improvements. They were
built with sun-visor plates above the windscreens. Their traction motors
were changed into MT52B, featuring larger rotor shaft. Traction systems
were changed into CS37D and CS38D. The material for their bogie frame was
changed from general structural rolled steel into welding structural rolled
steel.
Operations
EF81-0 locomotives were allocated at Toyama depot and Nagaoka depot to
haul passenger and freight services of the Sea of Japan coastal route.
EF81-0 locomotives allocated at Nagaoka depot were relocated and additional
EF81-0s delivered to Sakata depot in order to be used on the passenger
and freight services of the Sea of Japan coastal route for the start of
electrified Uetsu line. In 1973, EF81-0 locomotives were also delivered
to Tabata depot for freight services of Tohoku line and "Blue Train"
coaches of Joban line. EF81-0 locomotives built for the additional capacity
of freight services in Niigata region were delivered to Higashi-Niigata
depot.
In 1986, EF81 locomotives which JR East and JR West would receive were
relocated to Nagaoka depot and Tsuruga depot for the preparation the splitting
of JNR into privatized JR companies. They were received by JR East and
JR West on 1 April, 1987. Some EF81 locomotives were relocated to Moji
depot to replace superannuated EF30 locomotives and remodeled to -400 subclass.
EF81-0 locomotives received by JR East and JR West were used on not only
passenger services but freight services. The couplers of some EF81-0 locomotives
belonging to JR East were converted to the dual coupler in order to haul
the electric multiple unit trains. The couplers of some EF81-0 locomotives
used on the "Twilight Express" sleeper services were converted
to tightlock couplers with pneumatic connecters. EF81-0 locomotives owned
by JR East were replaced with EF510-500 locomotives and transferred to
JR Freight. Some EF81-0 locomotives owned by JR West were withdrawn by
discontinuing sleeper services.
Latest operation status
All EF81-0 locomotives owned by JR Freight were classified into -600 subclass
to identify the difference of maximum service speed against EF81-0 owned
by JR East and JR West. Now EF81-0 locomotives are owned by JR East and
JR West for the use on distribute trains. |
|
| Technical Data |
| Items |
Data |
| Supply
Voltage |
1,500VDC,
20,000V 50/60Hz AC |
| Service
speed |
115km/h |
| Max power |
2,550kW (DC), 2,370kW (AC) |
| Length |
18,600mm |
| Width |
2,900mm |
| Total
mass |
100.8t |
| Axle arrangements |
B0-B0-B0 |
| Bogie |
DT138
(End), DT139 (Intermediate) |
| Current pickup |
PS22 |
| Traction
motor |
MT52A |
| Rheostatic vernier control system |
CS36, CS36A,
CS36B, CS36C |
| Field control system |
CS37, CS37A |
| Transformer |
TM17 |
| Rectifier |
RS36, RS36A |
| Designed
by |
Japanese National Railways |
|
|
