Background and overview
In 1965, Japanese National Railways developed 2nd generation AC electric
locomotive, ED76, for Kyushu region, due to the extension of electrified
lines in Kyushu. Although 1st generation AC electric locomotives, ED72
and ED73, for Kyushu employed mercury-arc rectifiers having low maintainability,
ED76 locos were developed, based on ED75 featuring solid-state silicon
rectifiers. There are some noticeable differences over class ED75 in having
a longer body to be fitted with a maintainability boiler for heating passenger
trains, and three-bogied (Bo2Bo) six axles to reduce axle load for adapting
lower class of track in Kyushu. Their mass is 87 tons and its axle load
is variable (from 14 tons to 16.8 tons). They have a total power output
of 1,900 kW (2,500 hp), adopting 4 JNR standard traction motors, MT52,
with a power output of 475kW.
ED76 0 locomotives were delivered for the start of electrified Kagoshima line between Kurume and Kumamoto in 1965.
Car body
No gangway door is fitted on the front of the body because they won't be
operated in pairs. Two headlights are mounted above the windscreens and
two tail-lights are fitted at the lower part of body ends. Ornamental stainless
stipes are fitted in front of the body. Two cab ventilation grilles are
fitted on each end of the body. A pair of diamond shaped current collectors,
PS100A, raised by compressed air are also fitted on the roof.
Bogies
Motored bogies having 2500mm wheel base are DT129C for the 1st end and
DT129D for the 2nd end, employing Jacquemin-linkage to realize lowering
virtual centre pivot. This bogie construction realizes to locate theoretical
force point on the top of the rail to enhance mechanical adhesion. A centre
trailer bogie is TR103A, employing rubber airbag secondary suspension to
absorb the change of their total mass depending on the quantity of the
fuel and the water used on the boiler for train-heating. TR103A is equipped
with no brake device and an axle-driven tachometer generator.
Traction unit and auxiliary equipments
ED76 locos adopt low voltage tap control. The tap control is that the tap
of the traction transformer, TM11B with a power output of 2350kVA, varies
the terminal voltage of the traction motors. The magnetic amplifier is
employed for continuous control of stepped voltage between the taps in
order to reduce the shock and wheel slipping and to enhance adhesion. The
magnetic amplifier realizes arc-less tap switching. Transformed alternate
current are converted to direct current to drive series-wound brushed DC
traction motors, MT52, by the traction rectifier, RS21A, and the traction
smoothing reactor. ED76 locos adopt the tap changers, LTC-3, placed on
the lower voltage transformer winding. The air-blast circuit-breaker is
CB101E, same as ED72. A maintainability boiler for heating passenger trains
is also SG3B, same as ED72.
Additional delivery
ED76 11 onward built for the start of electrified Nippo line between Kokura
and Kozaki in 1967 differ from earlier ED76-0s in employing centre trailer
bogie, TR103D, having brake device. TR103D realize variable axle load at
14.0, 15.0, 16.0 and tons. Motored end bogies were changed into DT129K
for the 1st end and DT129L for the 2snd end. CS36B and CS37B. The main
pneumatic reservoir pipe was added to haul 20 series sleeping coaches using
automatic electromagnetic command pneumatic brake later.
ED76 27 onward built for the additional capacity of freight services in
Kyushu in 1969 are equipped with the main pneumatic reservoir pipe at the
time when they were built. Taction motors are changed into MT52A. A boiler
for heating passenger trains of ED76 29 onward is changed into SG3B-S.
Current collectors of ED76 31 onward built for the start of electrified Kagoshima line between Kumamoto and Kagoshima in 1970 are changed into cross-arm type, PS102C. The circuit breaker of ED76 49 onward is changed from an air-blast circuit-breaker, CB101E into a vacuum circuit breaker, CB106.
ED76 55 onward built for the start of electrified Nippo line between Kozaki
and Minami-Miyazaki in 1974 differ from former ED76-0s in having a cab
ventilation grill and ornamental silver painted stipes on each end of the
body. Their tap changer is changed into LTC-3A.
Operations
ED76-0 locomotives were mainly used on the passenger train and the parcel
train using train heating at the first time. Then ED76-0s were gradually
used on the passenger services and freight services all over Kyushu by
the progress of electrification. They were also used on night trains, replacing
ED72 and ED73, because the 2nd sleeper coaches, 14 series and 24 series,
replacing 20 series.
At the splitting of JNR into the privatized JR companies, JR Kyushu and JR Freight received ED76 locomotives in 1987.
ED76-0 locomotives received by JR Kyushu were used on not only passenger
services of Nippo line including night trains. but they were withdrawn
by discontinuing sleeper services. Finally, they had been completely withdrawn
in 2012.
ED76-0 locomotives received by JR Freight have been used on freight services
all over electrified lines in Kyushu. JR Freight received some of surplus
ED76-0s owned by JR Kyushu. A steam boiler for train heating was removed
because of no use for freight services and air conditioner for the driver's
cabs and dead weight were fitted in place of a steam boiler.
Modification and refurbishment
The refurbishment programme commenced from 1995 involved replacing the
traction motors, MT52C, employing the roller bearing for the rotor shaft.
Superannuated ED76-0 locomotives are gradually replaced with EH500 locomotives.
Latest operation status
ED76-0 locomotives are now used of the freight services all over Kyushu. |
|
| Technical Data |
| Items |
Data |
| Supply
Voltage |
20,000VAC 60Hz |
| Service
speed |
115km/h |
| Max power |
1,900kW |
| Length |
17,400mm |
| Width |
2,800mm |
| Total
mass |
87.0t |
| Axles location |
B0-2-B0 |
| Bogie |
DT129C/ D, K/L (End), TR103A, D (Intermediate) |
| Current
collector |
PS100A, PS102C |
| Traction
motor |
MT52, MT52A |
| Tapped controller |
LTC-3 |
| Transformer |
TM11B (2330kVA) |
| Rectifier |
RS21A (2,400kW) |
| Steam Boiler |
SG3B-S |
| Designed
by |
Japanese National Railways |
|
|
