Note: Descriptions are shown in the official language in which they were submitted.
CA 02409490 2002-11-08
WO Ol/855Z1 PCT/EPOl/05330
Undercarriage of a rail vehicle with radially
adjustable wheelsets
The invention relates to an undercarriage of a rail
vehicle with radially adjustable wheelsets in
accordance with the preeharacterizing clause of claim
1. The undercarriage proposed can be used, in
particular, on freight car trucks.
In many cases, conventional freight car trucks have the
disadvantage of guiding the wheelseta in a
longitudinally rigid manner as seen in the direction of
travel, which is hard on the track and noisy. The link-
suepenaion truck, which is also known for freight cars,
does have longitudinally flexible, radially adjustable
wheelsets but squealing noises occur owing to the
friction in the suspension linkages. The cutting of the
wheel flange into the rail causes Loud squealing and
screeching noises. At the same time, there is a
relatively large amount of wear between the wheel and
the rail despite the radial adjustment effected.
Moreover, the link-suspension truck is relatively
costly owing to the complex suspension.
The underlying object of the invention is to specify an
improved undercarriage with radially adjustable
wheelseta which is capable of being used, in
particular, for Lreight car trucks.
According to the invention, this object is achieved by
the features characterized in claim 1 in conjunction
with the features of the precharacterizing clause.
The advantages that can be achieved with the invention
arc, in particular, that the proposed undercarriage of
a rail vehicle with radially adjustable wheelsets has a
relatively low weight, allows quiet operation and
imposes less stress on the track and furthermore can be
produced at relatively~low cost. The low weight is
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achieved, in particular, through the compact,
functionally integrated construction. Quiet operation
is achieved through the virtually optimum radial
position that is produced. Moreover, the compact .
5 construction minimizes the sound-reflecting surfaces
and the surfaces that are excited into vibration.
Further details, features and advantages of the
invention will emerge from the following description of
10 a number of exemplary embodiments, from the subclaims
and from the schematic drawing, in which:
Fig. 1 shows a partial side view of an undercarriage or
truck of a rail vehicle with radially adjustable
15 wheelsets according to the invention,
Fig. 2 shows a section along the line II-II in fig. 1
of a primary suspension of an undercarriage according
to the invention,
Fig. 3 shows a section of a wheelset along the line
III-III in fig. 1,
Fig. 4 shows a partial plan view of the wheel~sets in
25 fig. 1, concealed components being illustrated in
broken lines, and
Fig. 5 shows a side view of a twin-axle truck according
to the invention.
Fig. 1 illustrates a aide view of a portion of the
proposed undercarriage of a rail vehicle with radially
adjustable wheelsets. It shows a rtulning wheel 1 oI an
undercarriage of a rail vehicle, the axle 2 of which is
35 supported at both ends in a known manner by means of
ax7.e bearings integrated into axle-bearing housings 3.
The rail is denoted by reference numeral 4.
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The primary suspension of a running wheel 1 is provided
by two coil springs 5, 6 arranged on both sides of the
axle-bearing housing 3. The coil springs 5, 6 axe
supported at the bottom by way of a seat 7 that
projects on both sides of the axle-bearing housing 3. 1~'~~,~
The upper ends of the coil springs 5 and 6 engage is
friction wedges 8 and 9, respectively, and press
against these friction wedges, the sloping top sides of
which are supported by inclined planes 10 and 11 of a
seat 12 of the undercarriage frame or truck frame. The
side faces of the friction wedges 8 and 9, which face
the axle-bearing housing 3, are provided with friction
plates 13 and 14.
Fig. 2 illustrates a section through this primary
suspension. It shows the seat 12 of the undercarriage
frame or truck frame of the rail vehicle, said seat
surrounding the friotion wedge 9, and the coil spring 6
clamped between the seat 7 of the axle-bearing housing
and the seat 12.
Fig. 3 illustrates a section through a wheelset of the
rail vehicle. It shows the running wheel 1 with the
axle 2, the axle bearing .15, the axle-bearing housing
3, the seat 7 of the axle-bearing housing and the seat
12 of the undercarriage frame or truck frame. The
lateral mobility between the wheelset and the frame of
the truck is limited by a stop 16 of the undercarriage
frame or truck frame relative to the axle-bearing
housing.
Fig. 4 illustrates a plan view of a portion of a
wheeleet of the rail vehicle. It shows the wheel 1 with
the axle 2, the axle bearing 15 with the axle-bearing
housing 3, the two coil springs 5, 6, the seat 7 of the
axle-bearing housing and the two friction plates 13,
14.
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Fig. 5 illustrates a side view of a truck 17 with two
wheelsets of the rail vehicle. The truck frame is
advantageously embodied as a toreionally flexible H
frame without a buffer beam. In contrast, conventional
5 solutions have a buffer beam. The truck 17 has two
wheelsets 18, 19, double thrust bearing housings 20, 21
being used to suppoxt the axles, rather than the closed
axle-bearing housings shown in figures 1 to 4.
10 To support the primary suspension at the bottom, each
double thrust bearing housing 20, 21 has two separate
seats 22, 23 for the coil springs. Lower bearing shells
Z4, which can be removed in a simple manner, form the
lower housing portion of a double thrust bearing
15 housing or axle-bearing 3~s.ousing. This alternative
solution with downwardly open double thrust bearing
housings 20, 21 advantageously allows simple, rapid and
economical exchange of the wheelsets without removing
the axle-bearing housing and the suspension. The lower
20 bearing shell is mounted on the right-hand wheelset of
the truck according to fig. 5. The exemplary embodiment
shown in fig. 5 can, of course, also be embodied with
axle-bearing housings that enclose the axle bearing (as
described with reference to figs 1 to 4).
25
As is already apparent from the above explanations, the
primary suspension of the undercarriage of the rail
vehicle comprises the coil Sprlllg9 5, 6, which are
arranged on both sides of the axle bearing 15 or axle-
30 bearing housing 3, 20, 21 and optionally comprise a
one-piece or a two-piece spring. Where a one-piece
spring is used, the coil springs preferably have a
progressive spring characteristic (TKS
[trapezoidal/circular cross-section coil) spring).
35 Where a two-piece spring is used, each coil spring has
an inner and an outer spring, which are preferably
provided concentrically with one another.
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The friction wedges 8, 9 are supported on the upper
side of the springs and are pressed against the axle-
bearing housings 3, 20, 21 on both sides by way of the
inclined planes 7.0, 11 of the seat 12 and the vertical 'a:
5 force. 'this produces a contact force on the axle
bearing 15 required for vertical friction damping. The
frictional damping results from the contact force,
which is dependent on the spring loading and the
friction coefficient between the friction plates 13, 14
10 and the axle-bearing housing 3, 20, 21. The frictional
damping is thus increased proportionally to the desired
extent in accordance with the rail vehicle's payload.
The commercially available friction pairs comprising a
15 friction plate 13, 14/axle-bearing housing 3, 20, 21
combination are chosen in such a way that no noise is
produced during the movements that occur.
Transverse suspension is accomplished by means of the
20 flexi-coil effect of the coil springs S. 6. The
movement in the transverse direction, i.e. transversely
to the direction of travel, takes place between the
axle-bearing housing 3, 20 , 21 arid the friction wedges
e, 9, which are located in the seat 12. The friction
25 wedges e, 9 in turn are guided in the transverse
direction relative to the undercarriage frame or truck
frame of the rail vehicle. when the maximum permissible
transverse movement has been reached, the stop action
takes place between the truck frame and the axle-
30 bearing housing 3, 20, 21. Like the vertical movement,
the transverse movement is likewiee damped by means of
the vertical friction plate 13, 14 of the friction
wedge e, 9 relative to the axle-bearing housing 3, 20,
21. Here too, the friction damping takes place to the
35 predetermined and desired extent as a function of the
payload.
The requirements as to radial adjustability are met by
means of the geometrical relationships between the
CA 02409490 2002-11-08
center of the wheelset, the height of the foot of the
spring and the height of contact of the friction wedge
8, 9 in conjunction with the mobility of the friction
wedge e, 9 in the longitudinal direction. The tapered
5 wheel profile produces turning forces that act at the
wheel contact point and are referred to as Tx forces.
These Tx forces act in opposite directions on a
wheelset 18, 19 and tend to adjust the wheelset
radially.
The radial adjustability of the wheelset 1A, 19 is
achieved in two stages. In the first stage, in which
the Tx forces are smaller than the occurring frictional
force, there is a turning movement due to the distance
15 between the axle bearing center and the height of the
friction wedge. Owing to the moment about the
transverse axis produced by the distance, the axle-
bearing housing 3, 20, 21 performs a pendulum motion
about the point of support oI the friction wedge A, 9
20 relative to the axle-bearing housing 3, 20, 21. This
pendulum motion, which takes place above the axle
center of the wheelset 18, 19, causes a longitudinal
movement in the plane of the center of rotation of the
wheelset . This enables small steering movements of the
25 wheelset 18, 19 to be achieved in the first stage.
In the second stage, in which the Tx forces are greater
than the occurring frictional force, there is a
displacement of the friction wedges 8, 9 relative to
30 the undercarriage frame or truck frame of the rail
vehicle and hence a larger steering movement of the
wheelset 18, 19. Owing to the radial adjustment of the
wheelset 18, 19 now effected, the Tx forces fall, and
the steering movement returns to the mechanism of the
35 first stage, in which only small corrections of the
steering movement are effected. The movement performed
by means of the second stage results in a new,
virtually force-free state of equilibrium on a bend.
This is the prerequisite for the desired low wear
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through the radial adjustment of the wheels of the rail
vehicle.
Compared with conventional radially adjustable
wheelsets on rail vehicles, Where the Tx forces act
continuously against the resistance of the primary
spring stiffness (cx stiffness) during the entire
cornering process, there is advantageously a new,
virtually force-free state of equilibrium with the
design solution according to the invention.
The complete construction of the device according to
the invention is obtained from the arrangement of just
one coil spring unit next to the axles or axle bearings
for each running wheel. As a result, a relatively short
lever arm of the spring forces is advantageously
obtained at their upper and lower supports relative to
the axle 2 and, in particular, to the support of the
truck frame on the car body:
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List of reference numerals
1 Running wheel
2 Axle
3 Axle-bearing housing
4 Rail
5 Coil spring
6 Coil spring
7 Seat of the axle-bearing housing
l0 8 Friction wedge
9 Friction wedge
Inclined plane
11 Inclined plane
12 Seat of the truck frame
13 Friction plate
14 Friction plate
15 Axle bearing
16 Stop
17 Truck
I8 Wheelset
19 Wheelset
20 Double thrust bearing housing
21 Double thrust bearing housing
22 Seat
23 Seat
24 Lower bearing shell
