Japan Railway & Transport Review No. 1 (pp.31–35)
Photo: STAR21 passing Omiya Station on Tohoku Shinkansen
|E351 Series Pendulum EMU and a short history of tilting trains in Japan|
The East Japan Railway Company (JR
East) took first delivery of the E351 Series
of pendulum EMUs in September 1993.
This is the first time JR East has introduced
pendulum trains. JR Central and JR
West inherited the 381 Series of EMU
Natural Pendulum Trainsets from JNR.
JR Shikoku and JR Hokkaido have already
developed and are operating pendulum
trains; JR Kyushu has recently ordered
new EMU pendulum trains.
Photo: E351 Series Pendulum E.M.U.
1. Development of Pendulum Trains In Japan
1.1 381 series EMU (JNR) The first generation of Japanese pendulum trains were introduced in 1973 between Nagoya and Nagano making JNR one of the first railways in the world to use pendulum trains. This 381 Series of limited expresses uses a natural pendulum system with cylindrical surfaces under the car body supported by rollers on bogies. The centre of curvature of the cylindrical surface is 2.3 m above the rail. The maximum tilt is 5 degrees compensating for lateral acceleration of 0.1G. The centre of gravity of the car body was lowered using an aluminium-alloy lightweight body to provide sufficient tilting moment as a result of centrifugal force. This tilt mechanism is very simple and reliable, but sometimes the inertia of the car body delays the tilting motion when negotiating transient curves which degrades comfort. JR Central and JR West are now using 277 cars of these 381 Series EMUs.
1.2 2000 Series DMU (JR Shikoku) and KIHA 281
Series DMU (JR Hokkaido)
After the 1987 restructuring of JNR, JR
Shikoku and the JR Technical Research
Institute developed the 2000 Series
DMUs with actively-controlled body tilting
in 1988. The tilt mechanism is similar
to the 381 Series but pneumatic cylinders
between the car body and bogies
control the tilt angle. When the train
negotiates a curve, these cylinders are
actuated by commands determined by
the train speed and track geometry
memorized in an onboard controller to
compensate for the lateral acceleration.
The memory is collated with the actual
position of the train on the track using
the ATS (Automatic Train Stop System)
induction coils on the track. The control
system issues the tilt command slightly
before the curve to compensate for the
tilt delay and improve the ride comfort.
Curves with a radius of 400 m can be negotiated
at 100 km/h or 25 km/h faster
than ordinary trains.
1.3 8000 Series EMU (JR Shikoku) JR Shikoku developed the 8000 Series pendulum EMU in 1992; it is similar to the 2000 Series DMU but the pantographs are mounted on sliding circular arches across the roof and connected to bogie frames by wires so the relative position on the overhead wire does not change despite the tilt. The running performance is similar to the 2000 Series.
1.4 E351 Series EMU (JR East) This pendulum EMU series is the successor to the 8000 Series but, for higher reliability, the pantographs are fixed on top of the tall suspension frames attached directly on the bogie frames without tilting. The running performance is expected to be better than the 2000 Series and the tilting system and bogies are now under adjustment.
Photo: 381 Series Pendulum EMU
2. Outline of E351 Series
This series has been developed to replace
the old 183 Series. It is being used as the
Azusa limited express on the Chuo line
with 18 trains in each direction per day.
One trainset is composed of up to 12 cars
but can be split into 4- and 8-car sets depending
on the number of passengers; the
gangways between carsets are coupled automatically. A maximum of 713 passengers
can be carried including 50 in the Green
Car, an increase of 26% over the earlier 9-
car Azusa. The maximum speed is 130 km/
h or 10 km/h faster and the curve speed is
also higher. Larger windows give passengers
a better view of the passing countryside,
and the muted interior colour scheme
suits businessmen better.
Photo: Pantograph on suspension frame
Mr. Yamada graduated in 1969 from Waseda University's Post-Graduate School with a Master's degree in Mechanical Engineering. He worked for JNR from 1969 to 1987 and as Deputy Director of JR East Paris Office from 1987 to 1990. He is presently General Manager of the Rolling Stock Division of JR East.