shinkansen bogies
Technology
Technology Railway Technology Today 6 (Edited by Kanji Wako)Shinkansen Bogies Isao Okamoto In the previous issue we discussed some of the main features of bogies, and looked at bogie structure for various carriages,specific bogies for trains carrying commut-ers and other passengers over short dis-tances, tilting carriages using pendulum mechanisms, and steering bogies. Such trains run mainly on narrow-gauge track in Japan, at maximum speeds of 120 to130 km/h. This next article examines some of the characteristics of bogies re-quired for high-speed trains, particularly shinkansen that travel at maximum speeds over 200 km/h. I will also discuss the past and present development of shinkansen bogies, focusing particularly on their struc-ture.Technical Innovations The first scheduled shinkansen run was on 1 October 1964 but many prior tech-nical developments were necessary be-fore trains could travel at high speeds. The following summarizes some of the impor-tant advances made in bogie development in the 1950s.
?Incorporated springs and oil dampers
in bogie suspension, significantly reduc-
ing vibration
?Mounted traction motor on bogie frame
instead of using nose suspension sys-
tem and also used parallel Cardan drive
system (see JRTR 18, p. 58) to transmit
power to wheelset via flexible couplings
and gears, greatly reducing bogie
weight, in turn permitting faster speeds
on shinkansen and other electric trains
?Adopted press-welded structure for
bogie frames, reducing frame weight
considerably
?Introduced disk brakes, increasing brak-
ing power, in turn permitting faster
speeds
?Used air springs in carriage suspension
to improve ride comfort
These important technical innovations
raised bogie performance, lowered weight and reduced vibrations. As a result,
bogies could run at faster speeds, making
rapid shinkansen services possible.
Bogie Performance
Because shinkansen run at high speeds,
their bogies and carriages must not be
subjected to serious lateral vibrations,
called hunting. As a train runs faster, hunt-
ing can increase to such an extent that
the bogie vibrates severely side to side,
which creates passenger discomfort, dam-
ages the track, and can even derail the
train in extreme cases. To achieve oper-
ating speeds higher than 200 km/h, bogie
developers tried to solve the hunting prob-
lem through theoretical calculations and
trial runs using scale models and actual
carriages. These tests helped discover
effective ways to raise the speed at which
bogie hunting becomes a problem. Here,
I will summarize the steps used to solve
these problems and produce a new bogie
design for shinkansen.
Graded wheel tread gradient
The outer rim of the wheel in contact with
the rail is called the wheel tread (see JRTR
18, pp. 52 and 57). The wheel tread gen-
erally has a gradient to help the train
negotiate curves more easily, and to main-
tain the carriage in a central position on
straight track. If the main aim is to achieve
high speeds, the wheel tread gradient is
kept low. On the other hand, if the main
aim is to maintain high performance on
curves, the wheel tread has a higher
gradient. The wheel tread gradient for
shinkansen bogies takes into account both
the need for high speed and the need to
ensure that wheels do not continually run
on one side of the rail. The gradient used
to meet these conditions was 1:40 using
a conical wheel tread configuration.
However, circular wheel tread configura-
tions were developed for the shinkansen
in the mid 1980s, and recently almost all
bolsterless shinkansen bogies use this type
of wheel tread. The circular configura-
tion which is shaped like a large number
of arcs aligned next to each other, sup-
poses a wheel tread that has already been
subjected to wear. This configuration
reduces contact bearing forces between
the wheel tread and the running surface
of the rail. This means less wheel tread
wear, which in turn means better running
performance. The effective gradient of
shinkansen circular wheel treads is about
1:16, which meets demands for both
stability at high speeds and excellent run-
ning performance on curved track.
Axle box suspension ridigity
Important factors affecting bogie running
performance are: the structure of the axle
box suspension system supporting the
wheelset on the bogie frame; the struc-
ture of the axle bearings; and the rigidity
of the axle box suspension. In other
words, the axle box suspension system
must be constructed so that it prevents
play due to wear over many years of op-
eration. Moreover, the axle bearings must
be designed so that they prevent, as much
as possible, any play at all especially in
the axial direction. The rigidity of the axle
box suspension can be determined mainly
by theoretical calculations and tests us-
ing actual bogies. In the case of bogies
for older shinkansen, the rigidity required
of the axle box suspension depends on
the carriage type (Table 1).
Bogie rotational resistance
Previously, it was thought that bogie hunt-
ing could be prevented effectively by us-
ing friction to resist bogie rotation relative
to the car body. However, calculations
and test results showed that this bogie
hunting can be prevented more effectively
by using rotational moment obtained from
springs to resist bogie rotation. However,
such springs increase wheel lateral pres-
sure on curved track and make the bogie
structure more complex, so Series DT200
bogies use the frictional resistance ob-tained from side bearers that support the entire load of the car body.
Bogie Development
About 35 years have passed since the shinkansen began carrying passengers in 1964. Over the years, three types of bogies have been used on shinkansen carriages (Table 2). These are:?Series DT200 bogies used for many years after start of shinkansen ?Bolsterless bogies introduced in 1992 for new types of shinkansen ?Bolsterless bogies for Yamagata and Akita Shinkansen (running on both
shinkansen and conventional tracks
converted to standard gauge)
The following three sections describe the
development of these three bogie types
and their structure.
Development of Series DT200
bogies
When the shinkansen started operations,
it was the first train in the world to attain
operating speeds of more than 200 km/h.
Safety at such speeds can only be
achieved if the bogies perform properly,
so bogie designers and manufacturers
focused on the need to prevent the
wheelsets and bogies from hunting dan-
gerously, and the need to prevent failure
or other damage in important parts like
bogie frames, wheels, axles, axle bearings,
and springs. In mid-1962, before the
actual shinkansen cars were manufac-
tured, six test cars were built each using a
different type of driving bogie (DT9001
to DT9006) and axle box suspension types
(e.g., Minden, IS and Schlieren, etc.). Data
from trial runs on the Kamonomiya test
track (on part of the Tokaido Shinkansen
line) were used in the design and manu-
facture of Series DT200 bogies. For the
axle box suspension, the Series DT200
bogie combined the advantages of the
Minden system with an improved IS sys-
tem developed by the now defunct Japa-
nese National Railways (JNR). The bogies
that actually went into service were lighter
than the test models, and were easier to
manufacture and maintain (JRTR 18,
p. 56).
Spurred by the success of the Tokaido
Shinkansen, JNR built new shinkansen
lines to other parts of the country—first
the Sanyo Shinkansen, which began
operations to Hakata [Fukuoka] in 1975,
and next the Tohoku and Joetsu
shinkansen, which opened between
Omiya and Morioka, and between Omiya
and Niigata in 1982. Carriages also saw
changes. The pioneer Series 0 shinkansen
was improved with the introduction of the
Series 100 that began operations on the
Tokaido and Sanyo shinkansen in 1985,
and Series 200 on the Tohoku and Joetsu
shinkansen in 1982. The Series 100
shinkansen use DT202 driving bogies and
TR7000 trailing bogies. The Series 200
use DT201 driving bogies and TR7002
trailing bogies. Compared to the DT200
bogies for Series 0 shinkansen, the newer
bogies are lighter and easier to maintain.
The bogies for Series 200 trains on the
Tohoku and Joetsu shinkansen lines have
also been adapted to cope with the pre-
vailing cold snowy winter conditions.
Despite these improvements, the basic
structure of the new bogies for those new
series shinkansen carriages was the same
as that of the DT200 bogies used by the
Technology
Series 0. In other words, although they have undergone some modifications over about 30 years, shinkansen bogies con-tinue to use a design based on the DT200. During the same time frame, shinkansen operating speeds rose to 220 km/h on the Tokaido and Sanyo shinkansen in 1986, and then to 230 km/h on the latter line in 1989. The Tohoku Shinkansen saw an increase to 240 km/h in 1985, while speeds on part of the Joetsu Shinkansen rose to 275 km/h in 1990. Development of new shinkansen bolsterless bogies
The success of the shinkansen prompted European countries to develop their own high-speed trains in the 1980s. In 1988, the German ICE achieved 406.9 km/h, and then the French TGV posted a new world record of 515.3 km/h in 1990. These impressive advances spurred Japan to further effort. In addition, better expressways and improvements to domestic airports in Japan had resulted in faster road and air travel, posing another challenge for the railways. Shinkansen designers realized that they would have to come up with a new type of train capable of running at operating speeds of 270 to 300 km/h.
They knew that this target could only be met by development of a light, high-per-formance bogie. Over the years they had experimented with many test models, try-ing to develop a lighter shinkansen bogie that would permit higher speeds and greater ride comfort. But none of the test models were good enough to go into pro-duction. Realizing they would need a different approach, in about 1980, JNR designers began to develop a bolsterless bogie for shinkansen. Just before JNR was privatized in 1987, they built a number of trial bogies (DT9022 to DT9026) and then conducted experimental runs. How-ever, these test designs could not meet the required performance levels. As a result, after JNR was privatized and split into the seven JRs, the Railway T echnical Research
Institute (RTRI) was given the task. The
Institute chose the DT9023 trial bogie as
the basis for further development.
JR Central, one of the JR group, partici-
pated in new development trials by
mounting trial bogies on a Series 100
shinkansen and subjecting the train to
long-term experimental runs to test endur-
ance levels. The company was trying to
find a suitable bogie for the Series 300
shinkansen being developed at the time.
Their efforts paid off in 1992 when the
Nozomi Series 300 shinkansen entered
operation. Nozomi uses a bolsterless elec-
trically driven TDT203 driving bogie and
TTR7001 trailing bogie. It is smaller and
lighter than the DT200 bogie, and offers
far greater stability at high speed, more
dependable performance on curves, and
better ride comfort. As a result, it has been
adopted for all new shinkansen (Series
300 and later). For example, in 1997, JR
West adopted this bogie technology for
its Series 500 shinkansen that were de-
signed to reduce aerodynamic noise and
achieve a maximum operating speed of
300 km/h, thereby bringing Japan into the
age of rail travel at 270–300 km/h.
The three shinkansen operators (JR East,
JR Central, and JR West) realized that
higher shinkansen speeds create environ-
mental and other problems, including
noise, micro-pressure waves in tunnels,
ground vibration, and aerodynamic prob-
lems in tunnels when trains pass each
other at high speed. To resolve these prob-
lems and obtain data that could be used
to raise performance and ride comfort,
each company built a high-speed experi-
mental train (STAR21, 300X, and
WIN350) for running tests. The bogies
for these trains were based on the same
design principles as the above-mentioned
bolsterless bogie. During high-speed tests,
WIN350 ran at 350.4 km/h (August 1992),
STAR21 reached 425 km/h (December
1993), while 300X outran them both at
443 km/h (July 1996).
Development of bolsterless bogies
for Yamagata and Akita shinkansen
We have looked at two different types of
shinkansen bogies—the DT200 bogie for
the first and early shinkansen trains, and
the bolsterless bogie for more recent
shinkansen. A third type is a bogie for
trains running on shinkansen tracks with
through operations on conventional tracks
converted to shinkansen standard gauge.
Examples are the Yamagata Shinkansen
trains that began operations between
Fukushima and Yamagata in 1992, and
the Akita Shinkansen that began opera-
tions between Morioka and Akita in 1997.
These are the so-called mini-shinkansen
operated by JR East. For these trains,
the bogies have to be capable of stable
running at about 270 km/h on shinkansen
tracks, as well as be able to negotiate
sharp curves of approximately 400-m
radius on conventional tracks.
After the JNR privatization, RTRI obtained
funding from the national government to
develop a trial DT9027 bogie for experi-
ment. The result of this research was a
bogie with a shorter wheelbase of 2250
mm, the first time a shinkansen bogie had
varied from the 2500 mm wheelbase. The
Institute proposed giving the axle box sus-
pension system optimum rigidity and the
wheel tread optimum shape, to ensure an
ideal balance between stability at high
speeds and excellent running perfor-
mance on curved track. JR East manufac-
tured trial bogies (DT9028, DT9029,
DT9030) that also adopted hollow-bored
axles and a wheel diameter of 860 mm
for Series 400 trains to Yamagata. These
trial bogies were made lighter using tech-
niques obtained during development of
the shinkansen bolsterless bogie. For
example, they used an aluminium gear-
box, and three different axle suspension
systems. After many trials, the company
decided to base its bogie design on the
DT9030, which had a rubber/leaf spring
system for the axle box suspension sys-
tem. The new DT204 bogie was made
for Series 400 shinkansen. A trial run in 1991 on the Joetsu Shinkansen using bogies with the same smaller wheelbase of 2250 mm achieved 345 km/h. Structure of Series DT200 Bogies for First Shinkansen Trains and Some Subsequent Models
Figure 1 shows the composition of the DT200 bogie for shinkansen trains. The bogie has a bolster with air springs mounted on its upper surface. These air springs support the carriage body directly. As I will explain later, the bolster has been eliminated from recent shinkansen bogies in order to lighten the bogie and gain extra performance.
The main characteristics of the DT200 bogie are shown in Table 3. The main components of the DT200 bogie—the axle box suspension, bolster system, bogie frame, wheelset, and driving gear box are described briefly below.
Axle box suspension
After comparing results from tests of sev-eral types of axle box suspension systems mounted on trial shinkansen bogies, the IS type was chosen. The IS axle box sus-pension system had been developed pre-viously by JNR. A supporting plate (leaf spring) is attached to the front and rear of the axle box, with rubber bushings mounted on the front and rear ends of the supporting plates. The positioning of the rubber bushings ensures that the wheelset and axle box are suspended from the bogie frame in a relatively rigid manner longitudinally, yet in a relatively flexible manner laterally. Two advantages of this axle box suspension system are that the vertical movement of the axle springs is not obstructed, because vertical move-ment deflects the supporting plates and rubber bushings, and that the various parts have no play and are not subject to abra-sion or wear. However, one disadvantage is that the bogie must be made longer than
Axle box
Axle spring
Rubber bushing
Leaf spring
Brake
shoe
Brake
cylinder
Driving
gear box
Traction
motor
Bogie frame
Air spring
Bolster
Figure 1DT200 on Series 0 Shinkansen
(RTRI)
(Japan Overseas Rolling Stock Association)
Technology
ideal, because the supporting plates are arranged in series. This type of axle box suspension system was adopted for Series 0, 100, and 200 shinkansen.
Bolster system
The main components of the bolster sys-tem are: a bolster that supports the car-riage body, air springs, lateral dampers, side bearers, a bolster anchor that trans-mits tractive force between the bogie and the carriage body, and the centre pin. The centre pin allows the bogie to rotate rela-tive to the body on curved track, while the side bearers apply frictional resistance to prevent hunting. The bolster is made by pressing 9-mm thick steel plates and then welding these plates together into a box. The hollow part of the box serves as an auxiliary air chamber for the air springs. The experimental version of the bogie used a triple-folded bellow-type air spring, but the bogies installed on actual bodies have a special diaphragm self-sealing air spring. This type of air spring permits lateral rigidity, so designers could elimi-nate the swing bolster hanger found on conventional bogies at that time. The air spring is mounted as high as possible to control carbody rolling.
Bogie frame
The DT200 bogie frame consists of two side beams (left and right), a central cross beam, and end beams. The beams are formed by pressing 9-mm thick SS400 (rolled steel for ordinary structural pur-poses) steel plates, then welding them into box sections. These beams are then welded together to fabricate the bogie frame. The end beams were originally 6-mm thick, but this was later increased to 9 mm. Since 1976, SM400B steel plates have replaced the SS400 steel plates, which tend to contain layers of impuri-ties embedded during rolling. SM400B steel plates are very suitable for welding purposes.Wheelset and driving gear
Axles for the DT200 bogie are made of
S38C (carbon steel suitable for mechani-
cal structures) that has been heat-treated
by induction hardening. This process
changes only the surface into hard mar-
tensite, and at the same time generates
residual compressive stress at the axle
surface, raising the fatigue strength of the
material to extremely high levels. Induc-
tion-hardened axles are used for all
shinkansen bogies, to ensure greater
strength in mating parts that are prone to
fretting corrosion.
For safety, the bogie uses solid rolled
wheels. Designers were concerned about
wear and tear on the wheel tread over
daily long-distance travel, so they per-
formed tests on three different types of
candidate wheel materials. However, in
the end, they chose STY-80 that had al-
ready been used for many years.
The driving gear used a parallel Cardan
system. The basic technology of this sys-
tem was being put to practical use as early
as the Kodama limited express on the old
Tokaido main line. The designers were
concerned that the gears might not be able
to withstand the higher speeds and that
lubrication problems could develop, but
no problems were found in different tests
using prototypes.
Structure of Bolsterless Bogies
for New Shinkansen Trains
Bolsterless bogie development
As explained, the DT200 bogie was used
for many years on shinkansen, but a new
type was needed to meet the demands of
trains travelling at maximum speeds of
270 to 300 km/h. The required improve-
ments included:
?Greater stability at high speed
?Higher running performance on curves
?Less vibration and greater ride comfort
?Smaller size and lower weight to reduce
track wear and tear
Development of a bolsterless suspension
system began in earnest in about 1980.
After the JNR privatization, efforts focused
on the DT9023, a bogie type that JNR had
tested. It was realized that a number of
improvements would be required, includ-
ing:
?Reduce high-frequency chatter in car
floor immediately above bogie
?Reduce car vertical and rolling oscilla-
tions to improve ride comfort
?Achieve superior stability at high speeds
while ensuring excellent running per-
formance on curves
?Eliminate end beams on bogie frame
and reduce bogie size to reduce weight
of bogie between beams
?Reduce unsprung mass of bogie (e.g.,
mass of wheelset, axle box and gear sys-
tem)
When the improved trial bogie was tested
at RTRI, no stability problems were found
even at extremely high speeds of 450 to
500 km/h, and the bogie also proved
effective in reducing oscillations. Later
two endurance tests of the bogie on a
Series 100 shinkansen of JR Central each
covering about 300,000 km, validated
the result of the running test. By about
1990, it was clear that bolsterless bogies
were suitable for shinkansen and they are
now used for all Series 300 and later
shinkansen.
Structure of bolsterless
shinkansen bogie
Figure 2 shows the structure of a
bolsterless shinkansen bogie. Like its
DT200 predecessor, each bogie has two
air springs that support the carriage body
directly. However, unlike the older
bogies, these air springs are not supported
by a bolster. Instead, they are mounted
directly on the upper surface of the bogie
frame.
The main characteristics of this bolsterless
bogie are shown in Table 4.
Some important features of the compo-
nents of the bolsterless bogie for Series
300 shinkansen are described below.
cylindrical laminated rubber/wing-type spring system. In this system, the vertical load on the axle springs is borne mainly by coil springs that have linear deflection capabilities; the longitudinal and lateral loads are borne mainly by the cylindrical laminated rubber parts, which also sup-port and guide the axle box. Because the coil springs and cylindrical laminated rub-ber parts are arranged symmetrically (in a wing shape) at the front and rear of the axle box, the support and guidance of the axle box is smooth. Moreover, because the optimum degree of longitudinal and lateral support rigidity was given to the cylindrical laminated rubber parts, stabil-ity is achieved even at high speeds and running performance with reduced lateral pressure remains high on curves. The axle damper works in both directions and the increase in damping force reduces verti-cal vibrations in the bogie.
A number of axle box suspension systems are used to simplify the structure and per-mit easier maintenance. Some systems for bolsterless shinkansen bogies have an axle beam type of construction, while some others have a rubber/leaf spring type of construction.
Carriage body support system
The carriage body support system has no bolster so it is described as bolsterless.Instead, the body is supported directly by air springs, thereby permitting consider-able horizontal displacement. When the bogie rotates relative to the car body on curves, this relative angular displacement is absorbed through horizontal distortion of the air springs. Longitudinal forces between the car body and bogie are trans-mitted via the monolink or Z link, which is mounted at the virtual rotational centre of the bogie.
As explained above, side bearers are used on DT200 bogies to prevent hunting at high speeds. However, in the case of bolsterless bogies, rotation relative to the body is controlled by anti-yaw dampers
Figure 2Bolsterless Bogie on Series 300 and Later Shinkansen
Axle damper
Anti-yaw damper
Axle box Axle spring
Brake caliper
Gear box
Bogie frame
Air spring
Centre pin
Axle spring and axle box suspension
The axle spring and axle box suspension of the trial bogie included a conical lami-nated rubber structure. This would have
made construction easy, but it was unsuit-able for high-speed rolling stock, because the dynamic spring constant of the axle spring was too high. Therefore, the de-signers decided to use coil springs and a
(JORSA)
(RTRI)
Technology
mounted between the car body and bogie frame outside of and parallel to the side beams of the bogie frame. The damping force of the anti-yaw dampers and the ri-gidity of the rubber bushings at both ends of the damper both greatly improve the stability of bogies running at high speeds.
Bogie frame
The bogie frame is constructed in an ‘H ’shape. The two side beams (left and right)made of 8-mm thick rolled steel (SM490YA killed steel suitable for welded structures) are welded to a cross beam made of 9-mm or 12-mm thick seamless
steel pipe (STKM18B). The top of the side beams is made as flat as possible and the cross beam is made of seamless pipe to keep the bogie frame structure simple and to prevent welding defects. The cross beam is hollow, permitting creation of an auxiliary air chamber for the air springs.The DT200 bogie frame has end beams on which brake parts and other equipment are mounted. For the newer bogie frame,small caliper disk brakes were developed and mounted on the cross beam located across the bogie centre. This design elimi-nated the end beams. As a result, the bolsterless shinkansen bogie is about 80
cm shorter than the DT200 bogie, and it weighs about 3.3 tonnes less, although the wheelbase is the same (2500 mm).
Wheelset, driving gear, etc.
The wheels and axles of the bolsterless bogie are basically the same as those of the DT200 bogie but the wheel diameter was reduced from 910 mm to 860 mm,and a 60-mm straight hole was bored lon-gitudinally through the centre of the axle to reduce the unsprung mass as much as possible. Furthermore, at fabrication, the vector sum of the dynamic unbalanced mass in the wheelset is set below 5 kgf ?cm to ensure that when the wheels rotate at high speed, any centrifugal force created by unbalanced weight distribution will not cause high frequency vibration in the car-riage body, or ride discomfort.
The DT200 bogies use two types of axle bearings simultaneously: cylindrical roller bearings designed to bear radial loads,and ball bearings designed to bear thrust loads. More recent versions of the cylin-drical roller bearings have had a thrust collar, to bear thrust loads at the same time. When bolsterless shinkansen bo-gies were first produced, they used col-lared roller bearings, because it was thought this would minimize the lateral play of the roller bearings. The bolsterless axle box was also made smaller and lighter. However, it was later discovered that tapered roller bearings could actually reduce lateral play themselves, so tapered roller bearings are now used for bolsterless shinkansen bogies.
The axle box and gearbox of DT200bogies are made of cast steel, but on the bolsterless bogie they are made of aluminium alloy to reduce the bogie unsprung mass. There were fears that track ballast might fly up and damage this lighter material, but tests using flying stones proved these fears unfounded, per-mitting its introduction.
Future Possibilities for Shinkansen Bogies
Over more than three decades of shinkansen operations, no passenger lives have been lost because of a defective bogie. This excellent record is largely due to the extremely high reliability and stan-dards of the bogies ’ structure and mainte-nance.
To meet the demands of passengers today and in the future, Japan ’s shinkansen op-erators will have to make further improve-ments —for example, higher speeds, better running performance on curved track,greater ride comfort, less running noise,and better labour-saving maintenance methods. At the same time, every prior-ity must be placed on safety and reliabil-ity. The areas requiring further efforts are as follows:
?Research into bogie structure and manufacturing techniques to develop greater precision in components
?Considerable reduction in bogie weight between primary and secondary springs and unsprung mass by developing smaller lighter bogies
?Development of simpler bogie structure with fewer welded parts and greater re-liability of welded parts
?Improvements of semi-active and active suspension systems, and their more widespread use
?Development of pendulum tilt system for shinkansen
?More effective use of dampers, particu-larly anti-yaw dampers between cars ?Further study of aerodynamic causes of carriage vibration when high-speed trains pass in tunnels
I
Figure 4Bolsterless Bogie on Series E2 Shinkansen
Isao Okamoto
Mr Okamoto is General Manager of the Vehicle T echnology Development Division of the JR Railway T echnical Research Institute. He joined JNR in 1972 after obtaining a Masters degree in mechanical engineering from the graduate school of Waseda University. He worked in the Rolling Stock Design
Office of JNR before transferring to RTRI.
Kanji Wako
Mr Kanji Wako is Director in Charge of Research and Development at RTRI. He joined JNR in 1961 after graduating in engineering from T ohoku University. He is the supervising editor for this series on Railway Technology T oday.
(RTRI)
(JORSA)