Note: Descriptions are shown in the official language in which they were submitted.
1065190
While of broader applicability, for example in the field of
highway vehicles where use of certain features of the invention can retuce
lateral scrubbing of tires as well as lessening the width of the roadway
required for negotiating curves, this invention is especially useful in
railway vehicles and particularly rail~ay trucks having a plurality of
axles. Accordingly, and for exemplary purposes, the invention will be
illustrated and described with specific reference to railway rolling
stock.
The axles of the railway trucks now in normal use remain sub-
stantially prallel at all times tviewet in plan). A ~ost important
consequence of this is that the leading axle can not assume a position
radial to a curved track, and the flanges of the wheels strike the curved
rails at an angle, causing objectionable noise and excessive wear of both
flan~es and rails.
Much consideratio~ has been given to the avoidance of thisprobl~m notably the longstanding use of wheels the treads of which have
a conical profile. This expedien~ has assisted the vehisle truck to
negotiate very gradual curves.
. .
:
2. ~
- ~n~
llowcver, ~s economic factors h~ve le~ the railroads to
accept hi~her wheel loads and operating speeds, the rate
of wlleel an~ rail wear becomes a major problem. A second
serious limitation on performance and maintenance is the
result of cxcessive, and even violent, oscillation of the
trucks at high s~eed on straight tràck. In such "nosing",
or "hunting", of the truck the wheelsets bounce back and
forth between the rails. A~ove a critical speed hunting
will be initiated by any track irregularity. Once started,
~O the hunting action will often persist for miles with flange
impact, excessive roughness, wear and noise, even if the
speed be reduced substantially b~low the critical value.
In recent ef~orts to overcome this curving problem,
yaw fle~ibility has been introduced into the design of some
trucks, and arrangements have even been proposed which
allow wheel axles of a truck to swing and thus to become
positioned substantially radially of a curved track. I~ow-
ever~ such efforts have not met with any real success,
primarily because of lack of recognition of the importance
c of providing the required lateral restraint, as well as
yaw flexibility, between the two wheelsets of a truck, to
prevent high speed hunting.
For the purposes of this invention, yaw stiffness
can be defined as the restraint of angular motion of wheel-
sets in tlle steering direction, and more particularly to
the restraint of conjoint yawing of a coupled pair of wheel-
sets in a truc~. The ~'lateral" stiffness is defined as
the restrain~ of the motion of a wheelset in the direction
of i~s general axis of rotation, that is, across the line
~D of general motion of the vehicle. In the apparatus of the
inVeIltiOn, such lateral stifness also acts as restraint on
Sl90
differelltial yawing, of a coupled pair of wheelsets.
The above-mentioncd general problcms produce many
particular difficulties all of which contribute to excessive
cost of operation. For example, there is deterioration of
the rail, as well as widening of the gauge in curved track.
In straight track the hunting, or nosing, of the trucks
causes high dynamic loading of the trac~ fasteners, and of
the press fit of the wheels on the axles, with resultant
loosening and risk of failure. A corresponding increased
cost of maintenance of both trucks and cars also occurs.
As to trucks, mention may be made, by way of example, to
flange wear and high wear rates of the bolster and of the
surfaces of the side framing and its bearing adapters.
As to cars, there occurs excessive center plate
wear, as well as structural fatigue and heightened risk of
derailment resulting from excessive flange forces. The
effects on power requirements and operating costs, which
result from wear problems of the kinds mentioned above,
will be evident to one skilled in this art.
2D In brief, the lack of recognition of the part
played by yaw and lateral stiffness has led to: ~a)
flange contact in nearly all curves; (b)~ high flange
forces when flange contact occurs; and (c) excessive
difficulty with lateral oscillation at high speed. The
wear and cost problems which result from Eailure to pro-
vide proper values of yaw and lateral stiffness, and to
control such values, will now be understood.
SUM~ARY OF TIIE INVENTION
It is thc gcneral objective of my invcntioll to
overcome such problcms, and to this cnd I utilize an
~ nti5~
articulated truck having novelly positioned elastic restraint
~eans which makes it possible to achieve flange-free opera-
tion in gradual curves, low flange forces in sharp curves,
and good high speed stability.
I have further discovered that application of
certain principles of this invention to highway vehicles
not only reduces tire scrubbing and highway space require-
ments, as noted above, but also promotes good stability
at high speed.
According to one aspect of the invention, a rail-
way vehicle truck assembly comprises main truck framing,
first means movably associating said framing in load-bear-
ing rela~ion with the railway vehicle, a pair of subtrucks
each movably coupled to said main truck framing and each
carrying an axle-borne wheelset, each said subtruck having
a portion extending from its associated wheelset to a common
region substantially midway between the two axles, means
in said region resiliently coupling said subtrucks to one
another, independently of yaw-inducing connection with said
framing, for conjoint steering motions and consequent posi-
tioning of their axles radially of a curved track, and resil-
ient means interposed between spaced portions of at least
one subtruck and said main truck framing, said resilient
means being arranged to oppose departure of said subtrucks
from a position in which the wheelsets are parallel.
In accordance with another aspect of the inven-
tion, in a vehicle having at least one pair of axle-borne
wheelsets the axles of which are longitudinall~ spaced from
0
the center of the vehicle in generally parallel adjacency
and lie in a plane within which said axles may yaw, appara-
tus for mounting said wheelsets upon said vehicle including
mechanism for transmitting load from the vehicle to the
~wheelsets and providing for relative pivotal, yawing, move-
rnents of the axles in said plane, as the wheels roll on
a running surface, the apparatus for mounting the wheel-
sets comprises a pair of frame structures, each coupled
to an associated one of said axles in such manner that each
axle has a substantially fixed angularity with respect to
its frame structure in said plane, each frame structure
having a portion extending from its associated axle to a
common region substantially midway between said two axles;
means coupling said frame structures directly to one another
in said region, and independently of said load transmitting
mechanism, for relative yawing movement, and with predeter-
mined stiffness against motions in the general direction
of axle extension; a pair of side frame members each extend-
ing to and spanning a pair of adjacent end portions of the
two axles, said frame members being free for relative tilt-
ing movements in said plane; means forming connections coupl-
ing each end portion of each axle, and its frame structure,
to the adjacent side frame member, the connections coupl-
ing the ends of that axle which is more remote from the
~5 center of said vehicle, with the adjacent side frame mem-
bers, including means providing elastic restraint of pre-
determined stiffness against yawing movements of the latter
axle; and means coupling each side frame member to said
vehicle and including other elastic restraint means pro-
viding predetermined yaw stiffness between said frame mem-
bers and the vehicle.
a~
~J
3t)
In accordance with still another aspect of the
:invention, in a railway vehicle truck, having main framing
and a pair of axle-borne wheelsets each carried by a steer-
:ing arm which has spaced portions journalling its associated
wheelset, and which steering arms have means pivotally con-
necting them directly to one another, in a region substan-
tially midway between said two axles, and accommodating
positioning of the axles radially of a curved track, to
insure that steering moments are freely exchanged between
said wheelsets, means for minimizing wheel-flange-to-rail
contact, and for maximizing high speed stability, the means
connecting the steering arms comprises first elastomeric
means proportioned and disposed to provide each wheelset
with a predetermined value of yaw stiffness with respect
to the main framing; second elastomeric means proportioned
and disposed to provide a predetermined value of yaw stiff-
ness between the main framing and the vehicle body; and
third elastomeric means proportioned and disposed to resist
differential displacement of said steering arms while permit-
ting exchange of such steering moments between the wheelsetsand thereby permit each axle to assume a position radial
of a curved track, said third elastomeric means being located
in the region of said means pivotally connecting the steer-
ing arms to one another and reacting between said steering
arms.
With particular reference to railway trucks, the
truck is so constructed that: ~a) each a~le has its own,
frequently indivi~ual, value of yaw stiffness with respect
-5b--
f``~
51~0
to the truck framing; ~b) such lateral stiffness is pro-
vided as to ensure the exchangin~ of steering moments prop-
erly between the axles and also with the vehicle body; and
(c) the proper value of yaw stiffness is provided between
the truck and the vehicle.
An embodiment representative of the invention
has been tested at nearly eighty miles per hour, with vir-
tually no trace of instability. With another embodiment,
radial curving has been observed at less than 50 foot radius,
and flange-free operation is readily achieved with all em-
bodiments on curves of at least 4 degrees.
With more particularity, the yawing motion of
the axles is flexibly restrained by the provision of re-
straining means of predetermined value between the side
frames and the steering arms of a truck having a pair of
subtrucks coupled through steering arms rigidly supporting
the axles. Elastomeric means for this purpose is
-5c
~,~
provided between the axles and the adjacent side frames,
preferably in the region of the bearing means. ~uch means
may be provided at one or both axles o~ the truck. If pro-
vided at both axles, it may have either more or less re-
straint at one axle, as compared with the restraint at theother, depending upon the requirements of the particular
truck design.
Elastomeric restraining means is provided in the
region of the coupling between the arms to damp lateral
axle motions, which results in so-called "differential"
yawing of a coupled pair of subtrucks.
~ tow bar arrangement is used to take care of
longitudinal forces between the car body and the flexibly
mounted wheelsets. This arrangement has several advantages,
discussed hereinafter, one of which is to prevent exces-
sive deflections, in the elastomeric pads which mount the
steering arms to the side frames and the side frames to
the car body.
A special sliding bearing surface is provided
between the truck side frames and the car body, further
to limit the flange forces in very sharp curves.
Brake improvements are provided and when used
in conjunction with articulated trucks of the kind herein
disclosed, the contact of the brake shoes with the wheel
flanges is virtually eli~inatea. With prior arrangements,
such contact has resulted in substantial wear and in uneven
braking.
--6--
~q
l Q ~ O
BRI}~F DESCRI~'TION O~ THF. DRI~WINGS
Several embodiments representative of my inven-
tion are illustrated.
In the drawings:
Pigure 1 is a schematic showing of a first
embodiment of the invention, and illustrating a railway
vehicle having truck means which includes a pair of
wheelsets coupled and damped in accordance with principles
of the invention;
Figure 2 shows schematically, and in basic terms,
the response of such a truck to a curve;
Figure 3 shows a plot of the reaction of the
flange force between the truck side frames and the vehicle,
using modified restraining means and under conditions of
ve-ry sharp curving, the reaction being plotted against
the angle of track curvature;
Figure 4 is a force diagram analyzing the response
o a truck generally similar to that shown in Figure 1, and
including in addition a stee~ing link or tow bar;
Figure S is a plan view of a railway truck con-
structed in accordance with the invention, and embodying
principles illustrated schematically in Figures 1 and 4;
Figure 6 is a side elevational ~iew of the apparatus
shown in Figure 5;
: Figure 7 is a plan view of the railway truc~ of
~Figures 5 and 6 with certain upper parts omitted, in order
more clearly to show the steering arms, their central
connection, and features of brake rigging;
1~51~
I`i~ure S is a side elevational view of the a~paratus
sl~own in l:i~urc 7;
Fi~ure 8a is a force polygon illustrating th~ function-
ing of the brakes;
Figure 9 is a cross-sectional view taken on the line
9-9 of Figure 6;
Figure 10 is an enlarged cross-sectional view of the
journal box structure taken on the line 10-10 of Figure 6;
Fi~ure 11 is an enlarged sectional view of the central
,o connection of the steering arms taken on the line 11-11 of
Figure 7;
Figure 12 is a cross section taken on the line lZ-12
of Figure 11;
Figure 13 is a plan view illustrating a modified form
of railway truck embodying the invention which uses side frame
and bolster castings similar to those used in conventional
freight car trucks;
Figure 14 is a side elevational view of the apparatus
of Figure 13;
r
~ igure 15 is an enlarged sectional plan view of the
central connection device of the steering arms of the truck
of Figures 13 and 14;
Figure 16 is a plan view of another modified form of
truck, similar to Figure 5, but having inboard ~earings;
Figure 17 is a fragmentary plan viel~ of a modification
illustrating latcral stops for the side frames of a truck of
the general kind shown in Figures 5-10; and
S~
~ igure 18 is a fra~mentary cnd view of the
apl~aratus o~ ~igure 17.
D~SCRIPTION OF REPRESEINTATIVE EMBODIM~NTS
The steering features of a first embodiment for a
four wheel railroad car truck are illustrated somewhat
schematically in Figures 1 and 2. The embodiment for use
under the trailin~ en~ of a highway vehicle would be vir-
tually identical, but, for simplicity, railroad truck ter-
minology is used in the description.
The essential parameters are as follows:
.
The yaw (longitudinal) stiffness between the
"inside" axle "B" and the truck side frames "T" is very
high, i.e. a pinned connection.
The yaw stiffness between the "end" axle "A" and
the truck side frames "T" is ka.
.
The yaw stiffness between the truck side frames
"T" and the vehicle is k .
The side frames "T" are essentially independent
being free to align themselves over the bearings ~not
. ~O illustrated) of axles "A" and "B", even when there is sub-
. stantial deflection in the longitudinal direction of the
resilient member ka.
.
Lateral forces between the two axles are exchanged
at point "P", located in the mid-region between a.pair of
: subtrucks, or steering arms, A' and B'. This interconnec-
tion has a lateral stiffness of kl and may also make a
contribution to the yaw stiffness bctween the two axlcs.
This connection provides for balancin~ of stccrin~ momcnts
~ 9 . . .
bct~een tlle two a~le5 ~ as w~ll as providing the lateral
stiffll~s~s .
The basic response of such a truck to a curve is
shown in Figure 2. The elastic restraints ka and ke haYe
been deflected by lateral forces "F". The forces "F" can
arise either from flange contact or from steering moments
caused by creep forces between the wheels and the rails.
Experimentally it has been observed that for relatively low
values of ka and ke, the axles will tend to assume a radial
D position in curvcs for a large range of variation of the
ratio ~. I have further discovered that for higher values,
the proper value for this ratio must be chosen as a function
of the truck wheelbase "w" and the distance s from axle "B"
to the vehicle center. Thus a means is provided to have the
high value for yaw stiffness needed for high speed stability
while simultaneously providing radial positioning of the
axles in sharp curves. The basic mathematical relation-
ships which assure radial positioning of the axles are as
follows:
For the axles to be in a radial position, their
.20
angular displacement will be proportioned to their distance
from the center of the car body;
~A ~ ~B = c x w and ~B = c x s , where c ~ the curvature
per foot of length along the curve.
This gives the following ratio between the angles and the
distances.
~A ~ ~B = w
The angles are also dependen~ on the yaw stiffness.
~A - ~B ~ ~ x w!2 and ~B = F x w
ka x d ke X-
10 .
Si~
Substituting, we find tllat thc relationship between theyaw stiffnesses and the ~istance should be;
ke ~ ka x 2w , or ka - s
S ke 2w
Given the proportionality ka = s it is a
simple matter to translate the values for elastic restraint
into suitable components. In the desi~n and testing of one
of the truck embodiments described below, the value for ka
was selected to obtain stability against hunting up to a
car speed of one hundred miles per hour. With this com-
/D ponent established, use of the pro~ortionality consideredabove readily yields the values to be embodied in the
other elastomeric restraints, which are disposed between
the car body and side frame ~ke~.
In the case of rail vehicles where there is only
a small clearance between the wheel flanges and the rail,
the above ratio should be closely maintained. The action
of the orces arising from the sel steering moments of
the wheelsets will correct for some error, and the curving
behavior will be superior to a conventional truck, even
if it is not perfect.
In the case of highway vehicles, when a low value
of ka is chosen, the rear bogie will tend to follow the
front end o~ the vehicle rather precisely in a curve. As
ka is increased, the trailing end of the vehicle will track
inside ~he front end. If ka is made very stiff, the bogie
will approach, but always be superior to, the tracking
characteristics of a conventional bogie. As will be under-
stood, given ka~ ke can be calculated.
ln~s~
l~']lilc thc cmbo~iment shown in Figures 1 and 2
~ill provi~e thc ~csired major improvement in curving
bellavior and high spee~ stability on all ordinary railroad
curves, there is also a need to limit the flange force "F"
which occurs when operating ocCasionally on very sharp
curves. This is most easily done by making ke a non-linear
elastic reStraint as shown in Figure 3.
This restraint is comprised of a steep linear
center section where ke ~ ka x 2w and end sections where
o the value is much less. This will limit the reaction
force "R" between the truck sideframes and the vehicle,
which will in turn limit the flangb force "F".
For certain applications such as rail rapid transit
vehicles where there is a need to obtain the lowest possible
flangwear and operating noise on sharp curves, and at the
same time obtain good high speed stability, it will be
found desirable to add the feature shown in Figure 4. The
addition of steering link, or tow bar, "L" provides a means
to keep the yaw stiffness high on straight track without
contributing significantly to the flange force in curves.
The presence of the restraints kt make it possible to
choose low values for ~a and ke without sacrificing yaw
stif~ness between the vehicle and the running-gear and
within the running-gear.
The following parameters are dealt with in con-
sideration of Figure 4:
s = distance from vehicle center to closest axle;
w - truck wheelbase, axle-to-axle;
b = center line of subtruck (steering arm) associated with
3D axle B;
a = center line of subtruck (steering arm) associate~ with
axle A;
.
12l .
51~
c - center linc of truck fr~ling;
O = ccnter (pivot point) of truck framing,
P = point of interconncction of the subtrucks;
L = tow bar (steering link). In Figure 4 it is shown
offset from the vehicle centerline better to show kt;
M ~ the point of interconnection between the tow bar and
subtruck a;
x = the distance between the truck center O and the inter-
connection at M;~ kt = the lateral flexibility which limits the ability of
the steering link to keep the lateral position of M
the same as the lateral position of P;
[When certain prototype trucks were operated in the
Figure 4 configuration, kt was the lateral stiffness
of pads used to provide ka between the side frames
and the subtrucks.]
y = the distance between the connection of the steering
link to the truck framing at ~I, and the point of
connection of the link to the vellicle; and
2~ f = the distance between the truck centerline and point M
at the distance x from the truck center. This dimen-
sion is used in deriving the computation of the proper
dimension for x. r
The optimum values for x and kt must be found by
experiment. However, it can be shown that x should be
larger than a specific mi~imum at which the axles would
assume a radial position if the restrain~s kt were infini-
tely rigid. This minimum ~alue can be calculated using
the equation xn~in = ~2 . This valuc is based on
4 (s + w~
30 the fact that thc anglc bctween "h;' ~ L to axlc B, Figs.
1 and 2) and the vehiclc centeT line,and the angle bctwecn
13.
1065190
"a" ~ L to axle A, Figs. 1 and 2,) and the vehicle center^
line arc proportional to the.distanccs from the center of
tlle vellicle (w and s + w). The latcral distance "f" in
Figure 4 can be calculated two ways, i.e.:
(1) f = - ( 2s + w ) x and;
t2) f r t w - x ) w where r is the track
curvature.
Equating these two expressions;
2sx ~ wx ~ ( w - x ) w
o Solving for x gives; -x 4 (w ~-w)-; -
The optimum value for kt will depend primarilyon the total value for yaw stiffness required for h'igh
speed stability, the percentage of that valuc supplied by
ka and ke~ and the percentage of that value contributed by
the rotational stiffness of the connection at P. The
value kt can be chosen to make up the ~emainder required.
There is also the ques,tion o~ choosing a proper
value for y. This should in general be chosen as long as
practical, if it is desired to minimize coupling between
20 the lateral motion of the vehicle with respect to the
running-gear and ~he steering motions of the axles. However
the length y has been made as short as two thirds w with
success in prototypes,.there being-some indication in test-
ing that a certain amount of coupling between lateral motion
of the car,body, with respect to the tTuck, and the steer-
ing action of the truck helps to stabilize lateral motions
of the car body.
The principles disclosed above can be used dircctly
~ 14.
~?~Sl~
to dcsigll running-gcar haYing an evcn number of ~xles by
grouping thc1n in pairs. These principles have also been
used to desigJI a three-axle bogie.
The principles considered above have been applied
in the design of a number of s~ecific trucks, particularly
railway freight trucks. By way of example, three such
embodiments arc shown. One appears in ~igures 5 to 12,
another in Figures 13 to lS, and the third in Figure 16.
Detail modifications are shown in Figures 17 and-18.
~ Yith detailed reference, initially, to Figures
7 and 8, from which part~ have been omitted more clearly
to show the manner in which each of two axles 10 and 11
is rigidly supported by its subframe (termed a "steering
arm" in the following description), it will be seen that
each axle is carried by its steering arm, 12 and 13, respect-
ively, ~nd that each axle has a substantially fixed
angularity with respect to its steering arm, in the general
plane of the pair of axles. The steering arms are gen-
erally C-shaped, as ~iewed in plan, (c.f. the steering arms
A' and B' o~ Figures 1 and 2), and each has a portion
extending from its associated axle to a common region
(12a, 13a) substantially midw~y between the two axles.
Means bearing the general designation 14, to which more
detailed refcrence is made below, couples the steering arms
12 and 13 with freedom for relative pivotal movement and
with predetermîned stiffness against lateral motion in the
general direction of axle extension. In this embodiment
the stiffness against lateral motion, in the direction of
axle extension and in the plane of the axles.(it corres-
ponds ~o the rcsilient means Kl sllown diagrammatically at
P in Fi~ure 1), takes ~hc form of a tubular block 15 of any
1'3~
suitable elastomeric material, e. g. rubber. It is suit-
ably bonded to a ferrule, or bushing 16 (see particularly
Figures 11 and 12), which is provided as an extension of
steering arm 13, and to a bolt 17 which couples the steer-
ing arms, as is evident. This block or pad 15, throughwhich the steering moments are exchanged, has considerable
lateral stiffness. The resilience is sufficient so that
each axle is free to assume a position radial of a curved
track, and sufficient to allow a slight parallel yaw motion
of the axles. This acts to prevent flange contact on straight
track when there are lateral loads such as strong cross winds.
Turning now to the manner in which each axle is
carried by its associated arm, it is seen that each steer-
ing arm carries, at each ~f its free ends, journal box struc-
ture 18 integral with the arm (see for example arm 12 inFigures 17 and 18). The box shape can readily be seen from
the figures and opens downwardly to receive bearing adaptor
structure 19, of known type, which locates the bear cartridge
20. Both ends of both axles 10 and 11 are mounted in this
fashion, which does not require more detailed description
herein. Retaining bolts 21 prevent the bearing 20 from
falling out of the adapter 19 when the car truck is lifted
by the truck framing.
Each journal box 18 has spaced flanges 22,22 which
have portions extending upwardly and laterally of the journal
box. These flanges serve as retaining means for the car
side frames, and also for novel pads interposed between the
journal boxes and the side frames, as will presently be des-
cribed. However, before proceeding with
-16-
~n~ o
that dcscription, and still witll reference to Figures 7 and
8, it will be noted that each steering arm 12 and 13 carries
a novel bra~e and bra~e beam assembly. These assemblies are
designated, generally, at 23 ~Figure 8) and each includes
a braced brakc beam 24, extending transversely between the
wheels (e.g. the wheels 25,25 ca-rried by axle 10), and each
end of each beam carries a brake shoe 26 which is aligned
with and disposed for contact with the confronting tread of
the wheel. The mounting of the brake assemblies is charac-
teristic of this invention - in which each axle is fixed as
against swinging movements with respect to its associated
steering arm - and has significant advantages considered
later in this descriptinn. For present purposes it is
sufficient to point out that the brake beams 24 are pre
vented from moving laterally toward and away from the
~langes 25a of the wheels, and for this purpose the opposite
end portions of the beams are carried by rod-like hangers
27, ~ach of which extends through and is secured in a sloped
pad 28 provided in corner portions of each steering arm 12
and 13 (see particularly Figure 8).
In particular accordance with my invention, and
with reference to ~igures S and 6, reference is now made
to tlie manner in which the truck side frames 29,29 are
carried by the steering armsj being supported upon elas-
tomeric means which flexibly restrains conjoint yawing
mo~ions of the coupled pair of wheelsets, that is provides
restraint of the steering motions of the axles with respect
to each other, and thus opposes departure of the subtrucks
(the steerin~ arnls and thcir a~lcs) from a pOSitiOJl in
which the wheelsets are parallel~ As will now be under-
s~ood from Figures 2 and 3, described above, this restrain-
ing means (ka in those figures) may be provided only at
t~
thc cnds of that axle w}lich is n-ore.remote from the ccnter
of the vehicle. Ilowevcr, it is frequently ~esirable to
provide SUCll restraint at the en~s of each axle. Accord-
ingly, Figures 5 and 8 show restraint at each axle; it can
be of different value at each, depending upon tlle part-
icular truck design.
As shown in Figures S to 8, the restraining means
takes the form of elastomeric pads 30, preferably of rubber,
supported upon the journal box, between the flanges 22, and
interposed between the upwardly presented, flat, surface
18a of each journal box 18 and the confronting lower sur-
face 31 (Figure 10) of the I-beam structure which comprises
the outboard end portions 32 of each side frame 29. As
indicated in Figures 7 and 8, and as shown to best advan-
tage in Figure 10, the pads 30 are sandwiched between thin
stecl plates .~.0~, 30a, the upper of which carries a dowel
33 and the lower of which is provided with a pair of dowels
34. The upper and lower dowels are received within suit-
able apertures provided, respectively, within the surface
~o 31 of side frame end portion 32, and the confronting sur-
face 18a of journal box 18. The purpose of the dowels is
to locate the elastomeric pads 30 with respect to the jour-
nal box, and to position the side frame with respect to
the pad 30. The side frame is thus supported upon the pads
and between the flanges 22.
~ As shown in Figure 6, each side frame 29 has a
~ center porti~n which is lower (when viewed in si~e eleva-
; tion) ~han its end portions 32. This center portion includes
part of .a web 35 having a tvp, laterally extending, flange
36 wllich is narrower at its outer extremities (Figure 5)
which overlie the journal box 18, and provides the bcaIing
18.
l Q~ S~
surface 31 ~igure 10). The flange 36 reaches its maximum
width in a flat central section 37 which c~mprises a seat
for supporting an elastomeric spring member 38. This member
has the form, prior to imposition of the load, of a rubber
sphere. Member 38, although not so shown in the drawings,
may if desired be sandwiched between steel wear p~ates.
Desirably, and as shown, means is provided for locating the
member 38 with respect to the seat 37 of the side frame,
and with respect to the overlying car bolster 39 (Figures
6 and 9), which, with sill ~0, spans the width of the car
and is secured thereto. The car is illustrated fragmentarily
at 41, in Figure 6. This locating means, as shown in Figures
5, 6 and 9, may ~onveniently take the form of lugs 42 integral
with the support surface 37 and the confronting lower surface
of car bolster 39. A bearing pad 43, which may be of poly-
tetrafluoroethylene, available on the market under the trade-
mark "Telfon", is interposed between the upper surface of
car bolster 30 and the overl~ing car sill structure 40 (Figures
6 and 9)~ This forms a sliding bearing surface, which operates
to place a limit on flange forces which might otherwise become
excessive in very sharp curves.
As will be understood, the resilience of the elasto-
meric shpere-like members 39 provides the restraint identified
as ke in the description with reference to Figures 1 and
. 25 2. As stated, its value is determined in accordance with
the proportionality ka = s In one embodiment of the invention
:~ ke ~w
: which yielded good results, sphere-like springs marketed
by Lord Corporation, of Erie, Pennsylvania, and identified
by part number J-13597-1, were found suitable for applicant's
special purposes described above.
-19-
l~;Si9V
Thc truc~.shown in ~-igures 5 - 8 can be made to
function as does the truck of ~igures 1 and 2 by either
omitting pads 30' at axle ll,`or ~y ma~ing these pa~s
substantially stiffer than pads 30 at axle 10. The bene-
fit acllieved by doing this is that the steering effect
of a lin~age L, such as shown in Figure 4, is obtained
merely by the pro~ler distribution of the stiffness of pads
at the axles.
A support, or cross-tie, 44 extends between ~he
o webs 35 of the side frames 29, in the central portion of
the latter (Figures 5 and 6), and has its ends fastened
to the side frame web as shown at 45 in Figure 9. The
cross-tie is a relatively thin plate with its height ex-
tending vertically, and its centçr portion has an aperture
46 through which passes the means 14 which couples the
mid-portions o~ the two steering arms 12 and 13. It is
important for the purposes of the invention that there be
freedom for limited tilting of one side frame with respect
to the other, in the general plane containing the axles
~O 10 and 11. (See also the ~lexible side frames T of the
apparatus shown schematically in Figures 2 and 3.) In the
present embodiment this freedom is ensurcd by limiting
the thickness of the cross-tie 44 to a value such as to
permit the required flexibility between side rames.
A p~ir of strut-like dampers 47,47 interconnect
~he side frames and the.car bolster 39. I~hile these dam-
pers have been omitted from Figures S and 6, in the inter-
est of clarity of illus~ration, they show to good advan-
tage in Figure 9. Their purpose is to damp vertical and
~o horizontal excursion of the car body and, importantly, they
are inclined in~ardly and upwardly to minimize the efcct
~ 20.
o~ vertical track surface irregularities on lateral motion
of the car body.
It has been found very advantageous to have a
tow bar which interconnects one steering arm with the body
of the car or other vehicle. The tow bar comprises the
steering link L, in the diagrammatic representations of
Figure 4, and it appears at 48 in Figures 5, 6 and 9. Its
disposition and point of securement to the car body are
unique as has already been explained with reference to Fig-
ure 4.
As best shown in Figures 5 and 9, the tow bar
48 has an arcuately formed portion 49 intermediate its ends
and this portion 49 is journaled within and cooperates with
spaced, confronting arcuate flanges 50,50, carried by the
central part of the upper edges of the tie-bar 44. This
cooperation provides for swinging movements of the tow bar
about the center of its said arcuately formed portion 49
and permits the side frame assembly to serve as a point
of reaction for torque forces imposed by the connection
of the ends of the tow bar to one of the steering arms and
to the car body. As illustrated in Figures 5 and 6, the
left end of the tow bar overlies the steering arm 12, which
should be understood as being associated with that axle
(10) which is the more remote from the center of the car
body. This end is connected to steering arm 12 by pivot
-21-
~s
~ 30
mechanism represented by the pin 51. The opposite end of
the tow bar extends in the direction of the center of the
car body, and its pin 52 is rotatably carried by a tow bar
trunnion 53 secured to a portion 41a (Figure 6) of the car
sill structure 40, at a point lying
-21a-
~,. ,,~
-` ` lQf~5190
along the longitudinal cen~er line of the car (Figure 5).
rhe sill structure extends across the car, being, at its
outboard ends, relatively narrow in the direction of car
]Length, as appears at 40 in Figure 6, and widening and ex-
t:ending downwardly toward the car center. Figure 6 includes
a fragmentary showing of this widened and downwardly extended
sill portion, at 41a, where steering arm pin 52 is connected,
as stated above. Certain portions of this known type of
sill structure are omitted from the showing in Figure 6
in order to avoid confusion of lines in the drawing.
As described above with reference to Figure 5,
the point of securement of the tow bar 48 to the more remote
steering arm 12 is at a point 51 whose location is a func-
tion of the truck assembly's wheelbase w, and the distance
s between the two truck assemblies, under a car body. The
minimum value of the distance x, from the truck center 49
to the point 51, should satisfy the expression
xmin = w2 . The primary function of the tow bar is
4 (s + w)
to take care of longitudinal forces between the car body
and the resiliently mounted wheelsets. Such forces arise,
for example, from braking and coupling impacts. In conven-
tional trucks, e.g. freight car trucks now in common use,
where no tow bar is present, these forces associated with
braking and coupling are passed through the bolster and
side frames. These forces, particularly the forces caused
by coupling impacts, would, if not properly dissipated,
cause unacceptable deflections and wear in the elastomeric
pads 30 which mount the steering arms to the side frames,
and the side frames to the car body.
-2~-
.~ ,
190
Reference is now had to a modified form of railway
truck embodying the invention, and illustrated in Figures
13 through 15. In this somewhat simpler apparatus a cross
bo].ster is embodied in the truck, and imposes the weigh~
of the car upon the side frames. Additionally this truck
bolster is flexibly associated with the two side frames and
serves as the only interconnection between the two.
-22a-
~ '3~
In tcrlns of l)asic structure ~or supl~orting the
axlc-borllc ~ cclscts, and for ~roviding rcsilicnt damping
at thc axlc end portions, and also between the truc~ and
the car body, the apparatus is in many respects similar
to the embodimcnts already described. Accordingly, like
parts bear like designations, with the subscript b. Thus,
axles lOb and 11_ are, respectively, carried by generally
~-shaped steering arms 12b and 13b, and each steering arm,
as was the case in the preceding embodiment, has a portion
~o extending from its associated axle, with respect to which
it has a substantially fixed angularity, to a common region
substantially midway between the two axles. Means 14b
couples the steering arms with freedom for relative pivotal
movement, and with predetermined substantial stiffness
against lateral motion in the general direction of axle
extension. In this embodiment, the coupling means 14_
(see Figure 15) comprises a pair of studs 55 and 56, each
of which extends from an associated one of the steering
arms toward the zone of coupling. The stud 55, carried by
arm 12b, is recessed as shown at 57, while stud 56 has a
reduced, hollow end portion 58 which extends within the
recess. Blastomeric material 59, preferably rubber, is
interposed between extension 58 and the interior t~àll de-
fining the recess 57, and is bonded to the adjoining sur-
faces. A bolt 60 serves to retain the parts in assembly.
Again, as was the case with the preceding embodiment, the
coupling 14b,through which the steering moments are ex-
changed, has considerable lateral stiffness and an angular
~lexibility suficient so that each axle is free to assume
a ~osi~ion radial of a curvcd track and free to adjust to
track surface irregularities.
As shown in the cross-sectional portions of Figurc
23.
51~()
13, which is taken as indicated by the line 13-13 applied
to Figure 14, it will be seen that each steerinq arm has
journal box structure 61, at each end thereof, and in this
case flanging, shown at 62, projects from the journal box
structure in the direction of the length of the truck.
The journal box has an upper substantially flat surface
63 upon which is seated an elastomeric pad 64. These pads
may be sandwiched in steel and, if desired, mounted upon
the surface 63 in the manner already described with respect
to Figures 5 - 8. The axles lOb and llb are supported by
structure which is of the character already described with
respect to the earlier embodiment, and which fits within
the downwardly facing pedestal opening provided by jaws
68. In practice, means (now shown) would be provided to -
retain the axle and the bearing adapter structure within
the pedestal opening. Brakes have also not been illustrated,
since in this embodiment, they would either be conventional
or be of the kind already described with respect to Figures
5, 6 and 9.
In accordance with various embodiments of my inven-
tion, the truck side frames 65,65 are carried upon the bear-
ing portions of steering arms and, importantly, are sup-
ported upon the pads 64, as appears to good advantage in
Figure 14. Such pads have been shown at each end of each
; 2~ axle, although it will now be understood that they may be
. used at the ends of one axle only, or that pads providing
':
-~4-
'
,:
clifferent degrees of flexible restraint may be used with
each axle. These pads, as will now be understood, restrain
t:he steering motions of the axles with respect to each other
and oppose departure of the subtrucks, which are comprised
of the wheelsets and steering arms, from a position in which
the wheelsets are parallel. Each side frame comprises a
-24a-
vertically extending web portion 66 having horizon~al flanging 67
(Figure 13) extending laterally from each side of the web. The
f]anging tapers from a substantial width in the central region,
between the two steering arms, to a relatively narrow width where
the arm overlies the pads 64. Each side frame has a pedestal
opening between pedestal jaws 68 tFigure 14~ which straddles the
journal box assembly and is restrained thereon by cooperation with
the interior surfaces 69 of flanges 62, in the manner shown in
Figure 13. Each side frame 65 is provided with a generally rec- -
tangular aperture 70 tFigure 14), the upper portion of which
accommodates th~ end portions 72 of a truck bolster 71, and
provides a seating surface for the springs 73 (in this case six
are provided), which react between the side frame 65, at 74 as
shown in Figure 14, and the undersurface of the projecting end
72 of the truck bolster 71.
The bolster extends laterally of the width of the
truck and provides articulated connection means between the
two side framas. In this instance no tie-bar i5 used. The
bolster ends, since they pass freely through upper portions
of the side frame apertures 70, flexibly interconnect the
side frames with the freedom for relative tilting movements
which is characteristic Qf this invention. In a center
par~ of the bolster, overlying the means 14b which couples
the steering arms, there is a bowl-type receiver 75, for
the car body center plate which, as will be understood by
those skilled in this art, is fastened to the car"; center
sill, which is not illustrated,
To provide the resilient restraint identified
as ke, in the description with reference to Pigures 1 and
2, that is the res*raint between the truck and the car body,
25.
a pair of cl;lstorncric pads 76,76 are carried, at spaced por-
tions of thc uppcr surface of truck bolster 71, being held
there in any desire~ manner, and are coo~era~le with the
car bolster (llOt shown) which forms part of the sill struc-
ture. The function of these ~ads will be understood with-
out further description. It should also be understood that
a less suitable, but in some cases adequate, yaw restraint
of the truck bolster can be provided by a conventional cen-
ter plate and side bearing arrangement.
In Pigure 16, there is illustrated another mod-
ified embodiment of the in~ention which, in this case, need
be shown in plan view only. This embodim,e~t adapts the
principles of the invention to truck ap~aratus in which the
side frames and bearings lie inboard of the wheels 25c;
rather than outboard thereof. This apparatus has a number
of advantages, ;.e. the wheelsets are lighter, the axles
are shorter, the bending moments in the axles are less
and the steering arms and the associated'mechanism may be
of lighter construction, since they are smaller. The axles
are shown at lOc and llc, and the steering arms at 12c and
13c. Coupling means between the steering arms is shown at
14c and may, in this embodiment, take su~stantially the
form shown and described in detail ~ith reference to Pigure
15. A relatively flexible tie-bar 44c interconnects the
two side ~rames 77,77. The construction and function of
this tie-bar and of the central arcuate, seat structure 78
which it supports, is similar to the construction and oper-
ation of the corresponding parts already described with
respect to the embodiment of Fi~ures S and 6. Each
steering arm has journal box structure 79, and each jour-
nal box structure suplorts an elastomeric pad 80 OT 80' .
- 26.
.
` - 10~
Thcse pa~s, ~hich cooperate with the journal box and with
cJId portions of tllc sidc fralllc structure 77 in the manner
shown in ~i~urcs 13 and 14, serYe the s~me purpose as is
served by the pads 30 and 30' of the embodiment of Fi~ures
5, 6 and 9, and by thc pads 64 of the embodiment of Figures
13 and 14. This purpose is, of course, consistent with
the principlcs shown schematically in Figures 1 and 2, and
embodied in that structure by resilient restraint ka~ A
truck bolster 71c is supported upon resilient members 38c,
c and the upper surface of the bolster carries a pair of
spaced bearing pads 43c, 43c which are disposed for contact
with the car body. Tl~ese pads serve the purpose of pads
43, in Figure 9.
In the embodiment of Figure 16 a tow bar is also
utilized. This bar (48c) is mounted for rotation about a
region intermediate its ends, as described with reference
to Figure 5, and has pivot structure shown at 51c and 52c
for cooperation, respectively, with the steering arm 12c
and the car body, in the manner described with reference to
~v Figures 4, 5 and 6. Brakes shown at 23c are carried by
the side frames.
Figures 17 and 18 show alternative structure which
is useful to provide some input to the steering action from
lateral forces while limiting side-frame-to-steering-arm
movement. This apparatus, which is shown as applied to
journal box and side frame apparatus of the kind appearing
in Figures 5 and 6, is particularly useful where there is
no tow bar to provide coupling between the motion of the
car bo~y Wit]l respect to the trucX and stccrin~ motion of
3~ the truck, as described with reference to Figures 5 and 6.
In this embo-liment, journal box structure 18d carries
27.
- lnt~ o
flanging ~ ct~e~n t~rl~ich is rccciYe~ an elastomcric ~ad
30d and a side fra~e apparatus 32d, all as sho-~n and des-
cribed ~itll rcfcrcnce to Figures S an~ 6. Sr~lall stops 81
are eacll carried by one of the flanges ~ and they are so
positioned that the lateral forces bctween the side frame
and the steering arm are transferred primarily through the
stops rather than through the pads 30d. The eccentricity
of these lateral stops tthey are disposed eccentrically
with respect to the center line of the axle, when viewed
~o in plan) introduces a desirable steering action caused
by lateral force. The direction of the steering action
is chosen for stability to cause the wheelsets to turn in
that direction which tends to keep them centered under
the car body.
Finally, further reference should be made to the
unique braking apparatus characteristic of the invcntion
and to the advantages which are achieved thereby. In
prior brake apparatus commonly used in the railroad art,
the brake beam is supported by an extension member which
20 rides in a slot in the truck frame. This system has
several substantial drawbacks. . The friction created at
the slot interferes with prccise control of the force be-
tween the wheel tread and the brake shoe, and the radial
distance between the friction face of the shoe and its
point of support in the slot, results in an overturning
moment on the brake shoe which, in turn, causes large
variations in the unit pressure between the shoe and the
wheel tread, along tl-e length of the shoe face. ~nother
problem with conventional brake rigging is tl-e large
latcral clearance between the bra~e beams and the car
truck side frames. ~iit}l conventional trucks this clear-
ancc is required to prevent high lateral forces which
28.
ln~s~o
woul~ occur if the ~istortion of thc truck fra~ing in
curves is limitcd by contact betwcen the brake shoes and
thc wheel flangcs. The a~ove problems can combine to
produce stuck brakes~ overheated wheels, wcaring contact
of the brake shoes with the wheel flanges, and even de-
railment due to wheel failure.
In the brakin~ arrangement shown in Pigures 7,
8 and 8a, these disadvantages are oYercome, primarily
because the association of the brake beams with the steer-
~ ing arms makes it possible virtually to eliminate unevenwear at the shoe and com~letely to prevent any contact
between the shoes and the wheel flanges. Since the brake
beams 24 are carried by hangers 27 which are supported in
pad structures 28, formed integrally with the steering arms,
and because of the fixed angular relationship between the
wheelsets an~ the steering arms, the brake pads 26 always
remain properly centered with respect to the wheel treads.
Figure 8 shows how the proper choice of geometr-
ical relationships can.be used to provide two different
~o values for the braking force B on the leading and trail-
ing wheelsets. This compensates for the transfer of
weight from the trailing to ;the leading wheelset during
braking. Thus, providing this compensation reduces the
risk of wheel sliding. The braking effcct on the lead
wheelset BL is made larger than the braking effect on
tha trailing wheelset, BT, by choosing a center line for
the hanger structure 27 which is incline~ with respect to
a line t, which is tangent to the wheel surface at the
center of the brake shoe face. Referring to the two
3c force ~olygons which comprise ~i~urc 8a, it can ~c sccn
that the e~fect of thc mcntione~ anglc is to crcate an
2~.
.
O
anglc ~CtWCCII thc vectors l~L and BL, and the vectors RT
and BT. The prcscnce of thcse angles causes the normal
force NL , between the S]IOC and the lead wheel, to be
'Larger than the force ~T between the shoe and the trailing
wlleel. It is necessary to have the same ratio between
the normal forces N and the braking force~ ~, for both
wheelsets, and the ratio is established by the coefficient
of friction chosen for the bra~e shoe material an~ the
steel face of the wheel.
The total force applied to the brakes is shown in
the drawings by arrows appearing on the brake beam linkage
in Figures 7 and 8. As shown by the force polygon, the
braking force applied to the beam linkage at the leading,
or right hand, wheelset is F2, while the force applied to
the linkage at the trailing wheelset, is represented in
the polygon as the equal and opposite Fl. Since two brake
shoes are actuated by each beam assembly, the arrow show-
ing brake actuator force for the leading wheelset is.labeled
2F2 ~ while the brake actuator force is labeled on the
trailing wheelset as amounting to 2Fl. As will be under-
stood, this force can be supplied by any convenient con-
ventional means (not shown), adap~ed to apply the force
in the direction o~ the arrows shown on the center strut
of the brake beam structure.
As indicated ab~ve, this apparatus substantially
reduces brake shoe wear and results in much safer bra~ing.
In summary, the apparatus shown in the several
ermbodirllents of the invention base~, as it is, on recog-
nition of the important part played by control of yaw and
lateral stiffness, virtually eliminates flange contact
. 30.
0
in curves and greatly reduces flange forces when contact
does occur. In addition, excellent high speed stability
is achieved, with resultant minimization of wear and cost
problems. As will now be understood, these advantages are
achieved by providing restraining means between the side
frames and the steering arms of a truck, to restrain yaw-
ing motion of the axles, by having the steering arms coupled
through further restraining means, and by providing suit-
able restraining means between the side frames, or their
associated bolster, and the body of the vehicle. Use of
equal restraint between the side frames and the steering
arms at each side, e.g. the four pads 30 in the embodiment
of Figures 5 and 6, has the advantage of minimizing parts
inventory and simplifying assembly and maintenance. Use
of unequal restraint, which in some instances can be done
by eliminating restraining pads at one axle, can further
improve the radial steering action desired during curving.
Limiting the side frame car body forces, as for
example by the use of the tow bar, is highly advantageous
for reasons which will now be understood, while the use
of eccentric lateral stops between the steering arms and
the side frames can, in certain instances, provide a stabil-
izing benefit similar to that achieved by the tow bar steer-
ing linkage.
~ Q ~cj~ ~ o
Various aspects of the invention have been analyzed
mathematically, and illustrated schematically, as well as
being shown and described with reference to several struc-
tural embodiments. While the emphasis herein has been on
the use of elastomeric restraints, similar advantages can
be achieved
-31a-
ln~
by the use of rcsilicnt steel springs. The use of elas-
t:omcric rcstraints, llo~evcr, llas the a~vantage of
simultancously providing side-franle-to-car-body elas-
l:icity, whilc also pr~viding both vertical and lateral
l-lexibility in tlle suspcnsion.
In general, however, it will be understood that
the use of steel restraints, or of such other structural
modifications as properly come within the terms of the
appended claims, are within the scope of this invention.
3~.
.
