Fluid self-steering railway vehicle truck

Leading and trailing wheel set assemblies of a railway vehicle truck are independently steered while traversing a curve by employing the lateral and longitudinal forces generated thereby to reposition rub plates which contact associated wheel set assembly journal boxes.

BACKGROUND OF THE INVENTION 
This invention relates generally to railway vehicles and in particular to 
the improved steering of railway vehicles around curves. 
In a conventional railway vehicle truck or "bogie", wheel set assemblies 
are restrained longitudinally and laterally by contact with rub plates on 
the truck frame to travel in nearly the same direction as the frame. On 
straight track the directional restraint of the wheel set assemblies is 
acceptable. However, on curving track it would be desirable for the 
leading wheel set assembly to angle in the direction of the curve, and the 
trailing wheel set assembly to angle opposite to the leading wheel set 
assembly. In this manner the truck would be "steered" around a curve. 
These angular differences between preferred and actual wheel set angles are 
sufficient to develop lateral creep forces at the wheels which are limited 
only by wheel-rail friction. Such friction not only results in high levels 
of wear on both rail and wheels, but it is also a significant contributing 
factor to derailment by tipping the rail over. Reduction of these lateral 
forces is the primary object of this invention. 
Although this problem is not confined to a particular type of railway 
vehicle, it is however, particularly severe with large, 3-axle locomotive 
trucks since the difference between the preferred angle of travel of the 
leading and trailing wheel set assemblies is proportional to the truck 
length. The problem is further aggravated in that the tractive force of a 
locomotive exerted on an associated wheel set pushes it against the truck 
frame, thereby further restraining the wheel set direction of travel to 
that of the frame. Furthermore, the wheel-rail friction of a locomotive is 
relatively large due in part of its characteristically heavy wheel 
loadings, and the resultant combination of this, together with the 
above-described strong lateral forces developed by the locomotive wheel 
set angular differences in a curve, can generate an increase in 
detrimental friction related effects such as noted hereinabove. 
Accordingly, a certain amount of wheel set assembly angling is desirable 
while traversing curves to improve railway vehicle truck performance. 
However, a degradation of truck performance can result from insufficiently 
restrained wheel set assemblies as exemplified by the phenomena of truck 
hunting defined herein as an oscillatory motion consisting of combined 
yawing and lateral displacement of the truck. Accordingly, it is another 
object of the present invention to avoid this type of performance 
degradation in a self-steered railway vehicle truck. 
Prior self-steering truck designs as exemplified by U.S. Pat. No. 4,136,620 
to Scheffel et al and U.S. Pat. No. 4,164,188 to Hallam et al have 
typically employed mechanically interconnected wheel sets. Such designs 
require a substantial amount of undercarriage space and are not easily 
adaptable to existing truck designs. Accordingly, it is still another 
object of the present invention to provide a new and improved 
self-steering railway vehicle truck which can be relatively easily 
employed in existing truck designs or retrofitted into existing trucks. 
Copending patent application Ser. No. 389,726 filed June 18, 1982 of the 
present inventor and assigned to the assignee hereof discloses a new and 
improved self-steering railway vehicle truck. In that disclosed invention 
four fluid-filled lines are typically extended along a truck frame between 
the leading and trailing wheel set assemblies such that the steerage of 
these wheel set assemblies is interdependent. In certain applications it 
may be beneficial to allow truck wheel set assemblies to be steered 
independently, which accordingly is another object of the present 
invention. Moreover, it is still another object of the present invention 
to further minimize the usage of undercarriage space while simultaneously 
avoiding possible wear and damage to extended fluid-filled lines by 
enabling a reduction in the required length of the lines. Furthermore, the 
present invention employs lateral forces to steer a truck which are not 
employed in the above-noted application. 
SUMMARY OF THE INVENTION 
The above and other objects and advantages are achieved in a self-steering 
railway vehicle truck in which wheel set assemblies are independently 
angled while traversing a curve such that the leading assembly is angled 
in the direction of the curve and the trailing assembly is angled opposite 
thereto through the employment of means for repositioning the journal 
boxes associated with a particular wheel set assembly. The repositioning 
means include a plurality of means for transmitting longitudinal and 
lateral forces exerted on load bearing surfaces of a wheel set assembly 
journal box when entering or leaving a curve, and conduits which 
interconnect preselected force transmitting means into sets whereby the 
force exerted on a first journal box load bearing surface is effectively 
transmitted to a second load bearing surface of the set for repositioning 
the journal boxes of an associated wheel set assembly. In a preferred 
embodiment a flow restricting device is included in the interconnecting 
conduits to selectively dampen the transmission of relatively short-lived 
forces such as those associated with the phenomena of truck hunting.

DETAILED DESCRIPTION OF THE INVENTION 
As illustrated in FIG. 1, a self-steered railway vehicle truck includes a 
rigid truck frame 1 in which multiple wheel set assemblies are operatively 
positioned. The truck herein described is adapted for use in a large 
locomotive, and accordingly employs three wheel set assemblies driven by 
traction motors 2 including leading, middle and trailing wheel set 
assemblies denoted as 3, 4 and 5, respectively for the direction of travel 
indicated. However, it will be appreciated that the present invention is 
not limited in practice to this embodiment and may be employed in 
conjunction with railway vehicle trucks of various constructions. 
As best depicted in FIG. 4, each wheel set assembly includes an axle 6 and 
a pair of flanged wheels 7 non-rotatably mounted on the axle 6. The wheels 
7 have a wheel tread conicity as depicted for a new wheel at 8 in FIG. 3. 
Each wheel set assembly also includes journal boxes 9 mounted adjacent the 
ends of the axle 6. The journal boxes are of a type well known in the 
prior art and include bearings mounted about a section of the axle 6 which 
provides a means of rotation of the axle relative to the journal box. The 
bearing may comprise any structure which allows rotation of the axle in 
the journal box. The type conventionally used in typical railway vehicle 
trucks is a tapered roller bearing, of the type manufactured by the Timken 
Company under the designation of Class GG. Such bearings are well known in 
the art have been available prior to Feb. 28, 1980. If the invention is 
used as a retrofit of an existing railway vehicle truck, the bearing would 
be of the type previously used in the retrofitted truck. 
The wheel set assemblies are operatively positioned in the truck frame by 
contact between journal box load bearing surfaces and juxtaposed rub 
plates carried by pedestal sections 10 of the frame 1. More specifically, 
and as best appreciated from FIGS. 2 and 5, the journal boxes 9 are 
equipped with longitudinal load bearing surfaces 11 and lateral load 
bearing surfaces 12. Conventionally the load bearing surfaces 11 and 12 
are positioned adjacent fixed rub plates 13 with a small clearance 
therebetween as depicted in FIG. 4 for the middle wheel set assembly 4. 
The rub plates 13 are bolted to the sides of corresponding frame pedestal 
sections 10. Rub plate spacers 14 are bolted into recessed portions of the 
pedestal sections 10. According to the embodiment of the present invention 
herein illustrated the rub plates juxtaposed the journal box load bearing 
surfaces of the leading and trailing wheel set assemblies 3 and 5, 
respectively, are not fixed, but are movable relative thereto. 
In particular, and as can best be appreciated from FIG. 2, means are 
provided for independently repositioning the leading and trailing wheel 
set assemblies, which means includes a number of force transmitting means 
positioned in frame pedestal sections 10 adjacent corresponding journal 
boxes 9. In the embodiment herein illustrated each force transmitting 
means comprises a rub plate 15 affixed to an oil filled bellows 16 and 
engageably positioned with respect to a juxtaposed journal box 
longitudinal load bearing surface 11 or lateral load bearing surface 12. 
The force transmitting means as depicted also includes an adapter plate 17 
which is suitably affixed to the bellows 16 and attached to a portion of a 
truck frame pedestal section 10. The adapter plates 17 associated with 
force transmitting means adjacent longitudinal load bearing surfaces 11 
can be advantageously formed to fit in that portion of the pedestal 
section 10 otherwise occupied by the rub plate spacers 13. Bellows 16 are 
a type well known in the prior art, and may comprise, for example, the 
bellows manufactured by Firestone Industrial Rubber Products Company under 
the name Airstroke. Such bellows are advertised and illustrated in the 
1970 Sweet's Product Design file, which is incorporated herein by 
reference. Of course, it is understood that alternative force transmitting 
means can be employed such as a hydraulic cylinder having a rub plate 
integral therewith. The hydraulic cylinder used would be of a conventional 
type well known in the prior art. 
Preselected force transmitting means adjacent individual wheel set 
assemblies are interconnected by conduits 18 which are attached in flow 
communication with the force transmitting means by suitable connectors 19 
to thereby form force transmitting sets. In particular, as depicted in 
FIG. 4 the force transmitting means associated with the leading wheel set 
assembly 3 are interconnected into 3 sets. The first set includes the 
force transmitting means 20, 21 and 22 on a first set side of the truck 
and adjacent the journal box lateral load bearing surfaces 12 and the 
longitudinal load bearing surface 11 positioned forward of the axle 6, 
respectively. The second set includes similarly positioned force 
transmitting means 23, 24 and 25 on the opposite side of the truck. The 
third set includes force transmitting means 26 and 27 adjacent the journal 
box longitudinal load bearing surfaces 11 positioned aft of the axle 6 of 
the leading wheel set assembly 3. 
Although the present invention may be employed to steer a single wheel set 
assembly of a truck, additional advantage may be had by employing the 
present invention on both a leading and a trailing wheel set assembly to 
thereby further decrease the lateral creep forces generated in traversing 
a curve as noted above. Accordingly, in the preferred embodiment herein 
depicted, force transmitting means associated with the trailing wheel set 
assembly 5 are also interconnected into 3 sets. As illustrated in FIG. 4, 
these 3 interconnected sets are configured somewhat similar to those of 
the leading wheel set assembly 3 but in a reversed order, thereby allowing 
for wheel set steering in either direction of truck travel. Thus, the 
first interconnected set associated with the trailing wheel set assembly 5 
includes force transmitting means 28, 29 and 30; the second set includes 
means 31, 32 and 33; and the third set includes means 34 and 35. 
In a preferred embodiment of this invention flow restricting devices 36 are 
included in the interconnecting conduits 18 and are of a suitable size so 
as to effectively dampen out forces transmitted of a relatively brief 
duration such as those associated with truck hunting. Since the time 
required for a locomotive to transverse a curve is of the order of 5 
seconds while hunting motions may have a period of about 1/4 seconds, a 
suitable flow restricting device might dampen forces of less than 1 second 
without degrading the beneficial self-steering aspects of the present 
invention. Flow restricting devices 36 are of a type well known in the 
prior art, and may comprise, for example, a conventional fluid controlling 
valve. When the valve is partially open, the amount of fluid flowing 
through the valve during a time period of five seconds, such duration 
being generally equal to the time required to transverse a curve, is 
significant. However, the amount of fluid flowing through the valve during 
periods lasting less than one second, such as the duration of forces 
associated with truck hunting, is insignificant. The valve size and 
opening should be such that the amount of fluid required to accomplish the 
steering function can flow through the valve in a time period of five 
seconds, but the amount of fluid required to initiate the steering 
function cannot flow through the valve in a time period of less than one 
second. Typical fluid controlling valves are manufactured by such 
companies as NuPro Company and Whitey Company, and are advertised in the 
1979 catalog of the Whitey Company which is incorporated herein by 
reference. Of course, it is understood that actual flow restricting device 
selection will involve consideration of design criteria surrounding a 
specific application such as the mass, inertia, and fluid volume of the 
particular wheel set used, as well as the mass of the rail vehicle on the 
truck. 
The truck frame itself is horizontally positioned by springs 37 located 
intermediate the frame 1 and the journal box 9. A bolster (not shown) to 
which a railway vehicle body is connected typically rests above the truck 
frame 1 on bolster mounts 38. 
In operation, the wheel set assemblies are typically oriented to travel in 
the direction of the longitudinal axis of the truck. Upon traversing the 
buildup of a curve in rails 39 the wheels in the leading wheel set 
assembly 3 attempt to continue traveling in the direction of the 
longitudinal axis of the truck. As a result, the outside wheel 40 tends to 
ride up on the rail 39 to a portion of the wheel tread having a greater 
radius due to the conicity of the wheel tread as depicted at 8 in FIG. 3. 
Simultaneously, the inside wheel 41 begins to travel on a portion of the 
wheel having a reduced radius. As a result, the tangential velocity of the 
wheels changes, with the outside wheel 40 having a greater tangential 
velocity than that of inside wheel 41. Due to this change in tangential 
velocity an increased longitudinal force is generated against the force 
transmitting means 25 by contact between the corresponding journal box 
longitudinal load bearing surface 11 and the rub plate 15. Similarly, the 
longitudinal force against the force transmitting means 27 is decreased. 
Through a corresponding mechanism longitudinal forces on force 
transmitting means 22 and 26 are decreased and increased, respectively, 
resulting from the decreased tangential velocity of the inside wheel 41. 
As the truck enters a curve the flange on the outside wheel 40 will contact 
or "scrub" the rail resulting in a lateral force on the wheel set assembly 
3. This lateral force is resisted by contact between the journal box 
lateral load bearing surfaces 12 adjacent the force transmitting means 20 
and 21. Thus, the force exerted upon the means 20 and 21 is increased, 
while the force on means 23 and 24 are correspondingly decreased. 
These forces on a first force transmitting means which result from wheel 
tangential velocity variations or flange-rail contact in the buildup of a 
curve are transmitted to an associated force transmitting means of a force 
transmitting set. Accordingly, as depicted in FIGS. 4 and 5, the increased 
longitudinal force against force transmitting means 25 forces oil out of 
the corresponding bellows 16 and through the conduit 18 to the bellows 
associated with the force transmitting means 23 and 24. Upon receipt of 
the transmitted oil the bellows associated with the force transmitting 
means 23 and 24 expand, thus forcing the rub plates 15 affixed thereto to 
be repositioned outward. Through a similar mechanism the rub plates of 
force transmitting means 22 and 26 are repositioned aft, the rub plate of 
force transmitting means 27 is repositioned forward, and the rub plates of 
the force transmitting means 20 and 21 are repositioned inward. This 
repositioning of the rub plates also effects a corresponding repositioning 
of the adjacent journal boxes in contact with the rub plates through the 
longitudinal and lateral load bearing surfaces 11 and 12 respectively. In 
this manner, the leading wheel set assembly 3 is rotated about a vertical 
axis to a direction corresponding to the curvature of the rails 39. This 
can be appreciated from FIG. 5 in which the leading wheel set assembly 3 
is in operative position angled into a left curve, with the bellows of 
force transmitting means 22, 23, 24 and 27 inflated, and of means 20, 21, 
25 and 26 deflated. A similar mechanism upon leaving the curve will cause 
the wheel set assembly to be repositioned to approximately their original 
positions relative to the truck longitudinal axis. 
Of course, upon entering the buildup of a curve a similar mechanism will 
cause force transmitting means 28, 29, 33 and 35 to deflate, and the 
bellows of force transmitting means 30, 31, 32 and 34 to inflate whereby 
the trailing wheel set assembly 5 will be rotated in a direction opposite 
to that of the leading wheel set assembly 3. 
Accordingly, lateral wheel forces are reduced through the practice of the 
present invention. Similarly, unwanted wheel oscillations such as that 
associated with truck hunting can be significantly reduced through the 
practice of the present invention when a suitably selected flow 
restricting device is included therein. Additionally, it will be 
appreciated that the present invention can be employed with relatively 
minor modifications in existing railway vehicle trucks. Finally, the 
present invention enables the independent self-steering of truck wheel set 
assemblies with little usage of undercarriage space or of exposed and 
extended fluid filled lines. 
The above described embodiment of this invention is intended to be 
exemplitive only and not limiting and it will be appreciated from the 
foregoing by those skilled in the art that many substitutions, alterations 
and changes may be made to the disclosed structure without departing from 
the spirit or scope of the invention.