Note: Descriptions are shown in the official language in which they were submitted.
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D-8512 C-3774
SELF STEERING RAILWAY TRUCK
Technical field
This invention relates to self steering
railway trucks of a type wherein the axles are allowed
limited freedom to seek substantially radial positions
in a curve. In preferred embodiments the invention
relates to powered railway trucks for locomotives and
the like, especially of the type wherein individual
traction motors are supported between the frame and
individual axles driven thereby.
Background
Various types of steering railway trucks have
been proposed wherein the angular position of the axles
and their associated wheels are allowed or forced to
adjust during curve negotiation to maintain more or
less radial positions with respect to the curve. The
purpose of such arrangements is, generally, to reduce
friction and wear of wheels and rails by minimizing
lateral creep forces. While most applications have
been proposed for non-powered railway car, trucks, some
locomotive applications have also been proposed.
Prior steering railway trucks have included
some having soft primary suspensions which allow
relatively free longitudinal and/or lateral motion of
the wheel and axle assemblies within established
limits. Some arrangements include inter-axle
connections that require related motions among axles of
the same truck. Some of the arrangements are such that
lateral wheel and axle motion gives rise to forced yaw
or steering, whereas other arrangements substantially
isolate these functions. Both powered and unpowered
~,~
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axles have been arranged for steering; however, forced
steering of powered axle vehicles relative to truck
turning motion in relation to the carbody is common.
Summary of the invention
The present invention provides an improved
arrangement for self steering railway trucks, and
particularly for powered railway trucks such as in
locomotives, in which equalized self steering of the
axles is provided through a linkage including connected
steering beams and traction rods. The mechanism is so
arranged as to separate the effects of steering and
lateral motions of the axles and is particularly
adapted for powered truck applications where it extends
around the sides and one end of the axle and fr~me
supported traction motors.
While particularly adapted to the requirements
of two axle motor powered road locomotive type railway
trucks, the invention is also capable of use in
unpowered trucks and in railway trucks having three or
more axles where the extreme end axles are
interconnected by linkage according to the invention.
In railway trucks according to the invention,
traction or connecting rods extend longitudinally from
journal boxes at the ends of each axle to a steering
beam extending transversely and pivotally mounted at
its center to the truck frame. The steering beams of
the opposite end axles are preferably interconnected by
a link or linkage to require equal and opposite
oscillating motions of the steering beams during like
steering motions of the axles. The steering beams and
traction rods are preferably mounted near axle height
to minimize the effect of traction forces on weight
distribution.
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The invention is applicable to various forms
of railway trucks including powered and unpowered,
having dual or other multiple axles, and with or
without bolsters. However, for a further understanding
of the features of the invention, reference will be had
to an application of the invention in a two axle
bolster type powered railway locomotive truck as
illustrated in the following description and drawings
in which:
Brief drawing description
Figure 1 is a side view of a two axle railway
locomotive truck in accordance with the invention as
installed under a locomotive carbody.
- Figure 2 is a top view of the truck from the
plan indicated by line 2-2 of Figure 1.
Figure 3 is a longitudinal cross-sectional
view through the central frame, linkage and bolster
portions from the plane indicated by the line 3-3 of
Figure 2.
Figure 4 is a transverse cross-sectional view
from the plane indicated by the line 4-4 of Figure 2.
Figure 5 is a diagrammatic view of the
interconnected axles and steering linkage showing their
operating positions on tangent track, and
Figure 6 is a diagrammatic view of the
interconnected axles and steering linkage showing their
operating positions on curved track.
Detailed description
In the drawings, numeral 10 generally
indicates a powered self steering railway truck of the
road locomotive type supporting one end of a locomotive
carbody 11 shown in Figures 1, 3 and 4 by phantom
lines. The truck 10 includes a unitary frame 12 which
may be fabricated, cast or otherwise manufactured. The
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frame 12 includes a pair of generally parallel,
laterally spaced, Iongitudinally extending side frames
14, 15 interconnected by a pair of transoms 16, 17,
longitudinally spaced equidistant from a central
transverse vertical plane 18. A central longitudinal
vertical plane 19, located equidistant from the side
frames 14, 15 intersects the transverse plane 18 in a
central vertical axis 20.
Adjacent their ends, the truck side frames 14,
15 include downwardly extending pedestals 22 for
receiving journal boxes 23 rotatably supported on the
ends of axles 24 carried by rail engaging wheels 26.
The wheels 26 are arranged in laterally spaced pairs
connected by a single axle 24 to form longitudinally
spaced wheel and axle assemblies. The journal boxes 23
are disposed in the pedestals between bearing surfaces
formed by pedestal liners 27 or other suitable pedestal
bearing surfaces. A small amount of longitudinal
clearance is provided to allow for limited longitudinal
motion of the journal boxes relative to the truck frame
for steering of the wheel and axle assemblies in a
manner to be subsequently described.
Lateral stops, not shown, are provided between
the journal boxes and the truck frame to limit lateral
motion of the wheel and axle assemblies to a
predetermined amount. The truck frame is supported on
the journal boxes by a relatively soft primary
suspension comprising coil springs 28 for which rubber
or other suitable alternative resilient suspension
means or devices could be substituted.
Centrally of the truck, a transverse bolster
30 is carried within a space bounded by the side frames
14, 15 and transoms 16, 17. The bolster is supported
upon the truck frame by a relatively stiff secondary
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suspension comprising, but not limited to, rubber
sandwich elements 31. Front and rear bearing plates 32
are provided between the bolster and transoms which
substantially limit movement of the bolster to lateral
and vertical motions relative to the truck frame and
transfer longitudinal traction and braking forces
between the bolster and truck frame. A center bearing
34 is provided at the center of the bolster for
pivotally connecting the truck with a downward
projection 35 of the carbody.
For powering the wheel and axle assemblies to
drive the locomotive, the truck is provided with a pair
of traction motors 36. Each motor has an outer end 37
supported by conventional bearing means on one of the
axles 24, and an inner end 38 carried from the adjacent
transoms 16, 17 by a depending link 39. The link is
flexibly or swivelly connected at its ends to allow a
limited amount of both longitudinal and lateral motion
between the inner end of the traction motor and the
adjacent transom member from which it is su~ported.
To provide for limited self-steering action of
the wheel and axle assemblies in accordance with the
invention, while transmitting traction and braking
forces between the wheel and axle assemblies and the
truck frame, the truck is provided with suitable
traction linkage. This linkage includes a pair of
lateral steering beams 40 pivotally connected at their
centers with the truck frame and each connected at
their ends with the journal boxes of one of the wheel
and axle assemblies by connecting rods, or traction
rods, 42. The traction rod connections are preferably
by means of rubber bushings, spherical connections or
other movable joints to permit relative vertical motion
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between the steering beams and their connected journal
hoxes.
The central pivotal mounting of the steering
beams 40 is provided by upper and lower support plates
43, 44 of a support structure carried below the
transoms 16, 17 of the truck frame and carrying pivot
pins 46, 47 on which the front and rear steering beams
40 are respectively pivotally carried. The pivot pins
46, 47 are vertically disposed along the central
longitudinal plane 19 of the truck and spaced
equidistant from the vertical central axis 20, just
inwardly of the transoms 16, 17.
The steering beams 40 are, in turn,
interconnected for substantially equal and opposite
pivotal motions. For this purpose, a link 48, connects
laterally offset forward and rearward extensions 50, 51
of the rear and front steering beams 40, respectively,
through pin and bushing connections 52, 53.
sraking action for the truck may be provided
for in any suitable manner. The illustrated embodiment
includes more or less conventional brake rigging,
including wheel engaging brake shoes 55 carried by
conventional frame supported brake rigging 56 actuated
by truck frame supported air brake cylinders 58. If
desired, vertical motions of the truck frame with
respect to the wheel and axle assemblies may be damped
in conventional manner by friction or hydraulic damping
devices 59 connected between the truck frame and one or
more of the axle carried journal boxes 23.
For the purposes of carrying out the
invention, the traction linkage comprising the steering
beams and connecting rods are preferably disposed near
axle height. The traction rods extend forward in the
parallel, generally hori20ntal orientation from the
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journal boxes at the ends of the axles toward the
central plane 18 of the truck. There they connect with
the steering beams to define a linkage passing
essentially around three sides of the traction motors,
so as to avoid extending through or otherwise impinging
upon the space provided for the traction motors and the
brake linkage adjacent the truck wheels. Also, if
desired, the wheel treads may be formed with a higher
than normal taper to encourage self-steering action,
although this is not necessarily a requirement of the
present design, which permits self-steering action to
occur even with the normal wheel tread taper
conventionally provided for locomotive trucks.
In operation, normal pivotal action of the
truck with respect to the railway carbody is provided
by the center bearing connection between the truck and
carbody. Such action could alternatively be provided
by bolsterless suspension means or other support means
known in the art. Also in known manner, the clearance
provided between the pedestals 22 and their associated
journal boxes 23 permits relative longitudinal motion
of the axles within the truck frame so as to allow
self-steering of the wheel and axle assemblies within
the truck frame. Such action is known in the art to
allow the axle members of conventionally or more highly
tapered wheel and axle assemblies, of the flanged rail
engaging type herein considered, to seek more or less
radial positions during curving action of a railway
vehicle.
Such self-steering action of the wheel and
axle assemblies is known to reduce friction and wear
between the wheels and rails and, in powered trucks,
has been found to provide more efficient application of
tractive effort and to reduce traction-limiting wheel
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slippage during curving action. ~owever, unrestrained
self-steering action of the axles may have the effect
of reducing stability of a railway truck in an
unacceptable degree. This is avoided in the present
instance by the interconnection, through the nearly
transverse link 48, of the steering beams 40, which
limits the pivotal motion of the steering beams to
substantially equal and opposite oscillating motion.
This, in turn, limits the turning motions of the
connected wheel and axle assemblies to like equal and
opposite oscillating motions so that self-steering
action is allowed, but only to the extent that the
turning motions of the axles are in equal and opposite
amounts, all within the limits provided by clearances
between the truck pedestals and journal boxes.
Traction and braking forces are also carried
from the wheel and axle assemblies to the truck frame
through the traction linkage consisting of the traction
links 42 and the steering beams 40. Thus, all traction
and braking loads are carried through the pivot pins
46, 47 to the truck frame and from the truck frame
through the bearing plates 32 to the bolster 30 where
they pass through the center bearing 34 to the carbody
1 1 .
Because of the parallel and longitudinal
orientation of the traction rods, the application of
traction and braking forces does not create any side
thrust forces on the wheel and axle assemblies. Also,
lateral motion of the axles relative to the truck
frame, allowed within desired limits to accommodate
track variations and other side thrust loads, do not
introduce any yaw, or steering, component of force into
the system, as is the case with diagonally
interconnected axles commonly providefl. Thus, with the
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present invention complete separation of yaw and
lateral motions of the truck axles is maintained.
While the invention has been disclosed by
reference to a particular embodiment chosen for
S purposes of illustration, it should be understood that
the self-steering and other features of the present
invention and the forms of trucks to which they are
applied could be modified without departing from the
spirit and scope of the novel concepts described.
Accordingly, it is intended that the invention not be
limited to the described embodiment, but that it have
the full scope permitted by the language of the
following claims.
