U.S. patent number 3,670,660 [Application Number 04/847,025] was granted by the patent office on 1972-06-20 for dampened railway car truck.
This patent grant is currently assigned to Midland-Ross Corporation. Invention is credited to Joseph Brown, Hans B. Weber.
United States Patent |
3,670,660 |
Weber , et al. |
June 20, 1972 |
DAMPENED RAILWAY CAR TRUCK
Abstract
A four-wheel, two-axle railway car truck having non-integral
side frames, a spring plank and a bolster, functioning both as a
swing motion truck and a roll control truck and having its side
frames journaled on the associated wheel and axle assemblies for
swinging movement of the side frames transversely of the truck. The
truck has a first stop means on the bolster for restricting the
lateral movement of the bolster relative to the side frames at a
level below the plane containing the longitudinal axes of the axles
and second stop means associated with the spring plank and side
frames for limiting the swinging movement of the side frames.
Inventors: |
Weber; Hans B. (Bedford,
OH), Brown; Joseph (Warrensville Heights, OH) |
Assignee: |
Midland-Ross Corporation
(Cleveland, OH)
|
Family
ID: |
25299579 |
Appl.
No.: |
04/847,025 |
Filed: |
August 4, 1969 |
Current U.S.
Class: |
105/171;
105/198.4; 105/208; 105/208.2; 105/193; 105/201; 105/222 |
Current CPC
Class: |
B61F
5/04 (20130101) |
Current International
Class: |
B61F
5/04 (20060101); B61F 5/02 (20060101); B61f
005/06 (); B61f 005/12 (); B61f 005/38 () |
Field of
Search: |
;105/182,185,186,187,188,189,192,193,197,197D,198,201,202,203,206,207,208,208.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: La Point; Arthur L.
Assistant Examiner: Beltran; Howard
Claims
We claim:
1. In a railway car truck comprising a pair of side frames rockably
journaled on associated wheel and axle assemblies for lateral
swinging movement under the action of laterally directed forces
applied to the truck, each frame comprising a tension member having
a base portion and a pair of vertical columns extending upwardly
from the base portion and spaced in the lengthwise direction of the
frame to define a bolster opening, a spring plank extending between
said frames with each end of said plank being received in said
opening of the adjacent frame, rocker means between each end of
said plank and said base portion of each frame for supporting said
plank for rocking movement in a direction laterally of said frames,
means interconnecting the ends of said plank and said frames to
interlock said frames to the plank, a bolster extending between
said frames and supported at its ends within the bolster opening of
the adjacent frame, spring means on said plank within each opening
for supporting said bolster end first stop means on said bolster
and plank adapted to engage upon a predetermined amount of lateral
swinging movement of said frames and transverse deflection of said
spring means to limit the lateral movement of said bolster relative
to said frames, said stop means engaging at a point below the plane
containing the axes of the axles and a friction shoe interposed
between and resiliently urged into engagement with a side of said
bolster and the opposing one of said columns for frictionally
resisting movement of said bolster; the improvement comprising:
second stop means associated with each end of the spring plank and
engageable with stop means on said base portion of the side frames
for limiting said predetermined amount of swinging movement of the
side frames in either direction from the central longitudinal
vertical plane of the side frame prior to the engagement of said
first stop means, said first and second stop means establishing a
non-linear, lateral force-travel curve comprising a first stage and
a second stage defining the resistance to lateral movement of said
bolster relative to said side frame.
2. The car truck as in claim 1 in which said second stop means
comprises engageable opposing surfaces on said rocker means and on
said base portion.
3. The car truck as in claim 1 in which each end of said plank is
formed with a pair of depending flanges disposed in close
overlapping relationship with the sides of said base portion to tie
said side frames to said plank.
4. The car truck as in claim 1 in which the lateral swinging
movement of said side frames and the transverse deflection of said
spring means act jointly prior to the engagement of said second
stop means and define said first stage of said curve wherein low
resistance to lateral movement of said bolster relative to said
side frames occurs.
5. The car truck as in claim 1 in which the transverse deflection
of said spring means after the engagement of said second stop means
and prior to the engagement of said first stop means defines said
second stage of said curve wherein high resistance to lateral
movement of said bolster relative to said side frames occurs.
6. The car truck as in claim 1 in which the swinging movement of
said side frames is limited by said second stop means to
approximately 3.degree. in either direction.
7. The car truck as in claim 1 wherein each frame has a compression
member and a tension member joined by said spaced vertical columns
and in which said base portion of said tension member defines the
bottom of said bolster opening and said spaced columns define the
opposite sides of said bolster opening; said rocker means
comprising an elongated plate section connected to said base
portion of said tension member between said columns centrally along
the longitudinal vertical plane of the side frame.
8. The car truck as in claim 7 in which said elongated plate
section has a trunnion member on each end of the plate for
pivotably supporting the plate, and said base portion of said
tension member has a pair of bearings spaced in the lengthwise
direction of the frame adapted to receive said trunnion members for
pivotal movement of the plate about a longitudinal axis disposed
within the vertical plane of the side frame.
9. The car truck as in claim 8 in which said base portion of said
tension member is U-shaped in cross section and said second stop
means comprises opposing surfaces on said U-shaped portion of said
tension member and said plate section.
10. The car truck as in claim 7 in which said plate section has an
upwardly facing surface of convex contour in the transverse
direction of the side frame for receiving in supporting rockable
relation said end of said spring plank.
11. The car truck as in claim 10 in which said second stop means
comprises opposing surfaces on said plate section and said spring
plank.
Description
BACKGROUND OF THE INVENTION
Two major problems confront railroads today in freight operations
where standard railway freight car trucks are in use. One of these
problems is lateral instability due to truck hunting at high speed.
High speed in this instance means a speed in excess of
approximately 55 miles per hour for A.A.R. approved commercial
railway freight car trucks. The other problem is car roll for high
capacity, high center of gravity railway cars.
Truck hunting causes the rolling wheels and axle assembly of a
standard railway freight car truck to move along a pair of rails in
a sinusoidal pattern. That is, the rolling wheels and axle assembly
first turn toward one rail and then toward the opposite rail as the
railway vehicle moves along the track. Thus, as the periodic motion
continues, it creates a sinusoidal wave pattern. In stable or
controlled truck hunting, the amplitude of this periodic lateral
motion is relatively small and wheel flange contact with the rails
is generally avoided. Truck hunting, however, becomes harmful at
high speeds when resonance occurs and when that resonance cannot be
controlled. That is, at high speeds the wave pattern of the wheel
and axle assembly can have the same frequency as the natural roll,
sway, and yaw frequencies of the car body. If the resultant lateral
disturbance of the car truck is large enough and in resonance with
the natural frequencies of the sprung car body, violent lateral
forces are created which act upon both the car trucks and car body
to sustain the resonance. Those lateral forces resulting from
uncontrolled hunting cause: (1) transverse sliding of the wheels on
the rails, (2) heavy lateral impacts between wheel flanges and
rails, (3) rail damage, (4) excessive wear to truck and car body
component parts, and (5) lading damage.
Just as uncontrolled truck hunting is critical at high speeds,
harmonic car roll is a critical problem at low speeds. With the
introduction of high capacity, high center of gravity cars a few
years ago, it was noted that as these cars moved over a section of
track having low, staggered rail joints, the cars rocked so
violently that they derailed. This derailment problem is generally
experienced with the above-mentioned cars which have a longitudinal
spacing between the car truck centers approximately equal to the
rail length, and either when the loaded cars are operated at a
running speed between 15 and 20 miles per hour or when empty cars
are operated at a running speed between 30 and 40 miles per hour
over a series of low rail joints. This combination results in
excessive car roll, causing wheel unloading and wheel lift, or
climb, especially on curved track.
Applicant has effectively minimized the car roll problem and
derailment tendencies of rocking, high capacity, high center of
gravity cars by using a "Roll Control" mechanism, which mechanism
is described in applicant's co-pending patent application Ser. No.
621,225, filed Mar. 7, 1967 now U.S. Pat. No. 3,461,814. Briefly,
incorporation of the "Roll Control" feature in a standard railway
freight car truck is accomplished by interconnecting the side
frames of the truck with a spring plank at the level of the load
support spring seats, and by providing lateral stops between the
spring plank and bolster at the level of the spring plank. As a
result, the point of application of the lateral forces is lowered
from the height of the conventional bolster gibs (which are
eliminated in the "Roll Control" truck) to the height of the bottom
portion of the bolster opening on the side frames. Accordingly, the
overturning moment of the truck caused by the lateral roll forces
which had previously tended to cause wheel unloading and wheel lift
is substantially reduced.
SUMMARY OF THE INVENTION
The invention as described hereinafter is a modification of the
"Roll Control" truck since it incorporates many of its essential
features. The improved railway car truck design is based upon the
swing motion principle which permits limited swinging movement of
the side frames on the adapters disposed within the pedestal jaws
of the side frames. Once the swinging motion of the side frames is
stopped, the truck functions as the "Roll Control" truck.
Applicant has modified his "Roll Control" truck by incorporating a
rocker seat between each side frame and the spring plank. The
rocker seat permits the side frames to swing in unison as
pendulums, or swing hangers, in either direction laterally of the
truck. Swinging of the side frames is stopped prior to the
engagement of the lateral stops provided between the bolster and
spring plank by contact between the side frame tension member
(formerly the load support spring seat) and the rocker seat. In
this manner, increased lateral motion of the bolster relative to
the side frame is obtained. Since lateral motion initially results
from partial transverse deflection of the load springs and from the
swinging of the side frames and subsequently solely by the
deflection of the load springs, the resulting lateral force-travel
curve characteristic defining the resistance to lateral motion of
the bolster relative to the side frames is non-linear. This
non-linear lateral characteristic is significant in the attainment
of improved high speed truck performance. It improves lateral ride;
minimizes lateral disturbances of the sprung car body due to truck
hunting; reduces the critical speed for hunting in combination with
car body roll, sway and yaw; acts as a resonance arrester; permits
controlled and safe ride qualities while passing through the
critical speed ranges; cushions lateral impact; reduces wear on
wheel flanges, truck and car component parts; reduces rail damage;
and minimizes lading damage.
It is therefore an important object of the invention to provide a
railway car truck having embodied therein a non-linear lateral
force-travel curve characteristic defining the resistance to
lateral movement of the bolster relative to the side frame.
It is a further object to provide a car truck for high center of
gravity freight car use of the type which incorporates a
replaceable rocker seat between the spring plank and side frame to
permit swinging of the side frames relative to journal axles.
Another object of this invention is to provide a mechanical
interference between the rocker seat and side frame to limit
lateral side frame swing.
Yet another object is to provide a railway car truck that is
effective in minimizing, (1) car roll and derailment of rocking
cars, without special additional anti-roll devices, and (2) lateral
disturbance of the sprung car body due to truck hunting.
DESCRIPTION OF THE DRAWINGS
In the drawings, with respect to which the invention is described
below:
FIG. 1 is a side elevation, partly in section, of a railway car
truck in accordance with the invention;
FIG. 1a is a vertical sectional view taken along line a--a of FIG.
1, looking in the direction of the arrows with the bearing assembly
removed.
FIG. 2 is a fragmentary plan view, partly in section, taken along
line 2--2 of FIG. 1;
FIG. 3 is an enlarged fragmentary side elevation, partly in
section, illustrating one end of a pivotally supported rocker
seat;
FIG. 4 is a fragmentary end view taken along line 4--4 of FIG.
3;
FIG. 5 is a fragmentary plan view taken along line 5--5 of FIG.
3;
FIG. 6 is a fragmentary end view, partially in section, taken along
line 6--6 of FIG. 1;
FIGS. 7 and 8 are views similar to FIG. 6, illustrating lateral
motion of the truck during the first and second stages of lateral
truck displacement;
FIGS. 9 and 10 are force-travel diagrams which show the
characteristic curves for empty and fully loaded cars for the
laterally displaced positions shown in FIGS. 7 and 8,
respectively;
FIG. 11 is a view similar to FIG. 6 illustrating another embodiment
of the invention;
FIG. 12 is similar to FIG. 11 and illustrates the position of the
bolster and side frame after full lateral truck displacement;
and
FIG. 13 is a partial side elevation view of an alternate friction
system for snubbing the vertical and lateral movements of the
bolster relative to the side frame.
DESCRIPTION OF THE EMBODIMENT
Referring to FIGS. 1 through 8 of the drawings, a snubbed railway
car truck is illustrated comprising a side frame 20 having a
tension member 21 and a compression member 22. The members merge as
at 23 and provide a pedestal jaw 24 for receiving in rockable
relation an adapter 25 and bearing assembly 26 of a journaled wheel
and axle assembly 27. A plate member 18 is interposed between jaw
24 and adapter 25. The top side of the adapter 25 is convexly
crowned as at 25a and is engaged by the convexly curved
undersurface 18a of member 18 to permit swinging movement of the
side frame relative to the adapter and the wheel and axle assembly.
Intermediate the lengthwise direction of the frame, there is
positioned a pair of spaced vertical columns 28--28. The columns
connect the tension and compression members to form and partially
define a bolster receiving opening 29. Opening 29 receives one end
of bolster 30 arranged with its longitudinal axis transverse to the
length of the frame. It will be understood that while only one side
frame has been shown in the drawings, there is a similar frame on
the other side of the car truck which cooperates with the bolster
and other parts of the truck in like manner.
Tension member 21 includes a U-shaped base portion 31 for partially
housing a rocker seat 32. The rocker seat comprises an elongated
plate section 33 and a depending inverted T-shaped strengthening
member 34. Each end of the rocker seat has a trunnion member 35 for
rockably supporting the rocker seat relative to the side frame.
Trunnion members 35--35 are pivotally supported in a pair of
longitudinally spaced-apart rocker bearings 36 which are disposed
beneath columns 28 and are coaxially aligned in base portion 31 of
tension member 21. Each rocker bearing 36 has a concave cylindrical
bearing surface 37 having a radius of curvature greater than that
of the associated trunnion member 35 pivotally received therein to
assure that rocking engagement occurs between the trunnion member
and bearing. Rocker seat 32 provides a top surface 38 for
supporting a channel shaped end of a spring plank 40 arranged with
its longitudinal axis transverse to the length of the frame. Plank
40 is interconnected to rocker seat 32 by upstanding bosses 41
formed on the seat and extending through openings in the plank to
interlock the two side frames together. A spring group 42 is
disposed between spring plank 40 and bolster 30 for resiliently
supporting the end of the bolster.
The bolster illustrated in FIGS. 1 and 2 is generally of box-shaped
construction at each end and comprises spaced vertical side walls
45--45, spaced top and bottom walls, 46 and 47, respectively, and a
vertical central wall 48 joining the top and bottom walls. A stop
lug 50 depends from the bottom wall of the bolster inwardly from
each of its ends and is in spaced relation with an upstanding
abutment 51 carried by spring plank 40 intermediate its ends. Lug
50 and abutment 51 are spaced apart a predetermined distance so as
to provide a clearance between opposing vertical surfaces thereon
preferably on the order of approximately five-eighths of an inch,
which clearance permits limited lateral movement of the bolster
transversely of the truck. It will be seen that the engagement
between each lug and abutment will occur at a level substantially
below the horizontal plane containing the rockable connection
defined by the adapter 25 and pedestal jaw 24, which connection may
be of the type disclosed in either U.S. Pat. Nos. 2,717,558 or
2,737,907. This form of a connection normally allows the side
frames of the truck to swing transversely of the truck.
For snubbing the sprung mass of the railway car truck, each end
portion of the bolster has at each side a pocket 55 opening towards
the adjacent column 28 for receiving a friction shoe 56. Each
pocket has an inclined rear wall 57 which slopes upwardly and
outwardly toward the adjacent column 28. Each friction shoe is in
wedging engagement between wall 57 and the opposing column 28. Each
shoe has a sloping surface 58 engaging surface 60 on wall 57 and a
vertical friction surface 59 engaging surface 61 on a wear plate 62
that is secured to the adjacent column. In operation the friction
shoe is urged upwardly and outwardly by a spring 63 disposed on
plank 40 into frictional engagement with surface 61 of the wear
plate to provide resistance to both vertical and lateral movements
of the bolster.
Referring to FIGS. 4 and 6 through 10, the operation of the railway
car truck will be explained. As mentioned hereinabove, the
structural arrangement of the truck parts permits the side frames
to swing laterally in unison. Swinging of the side frames in either
direction is stopped by contact between undersurface 65 of the
rocker plate section 33 and top surface 66 of one of the side walls
67--67 of base portion 31 of the tension member. The clearance
between these engaging surfaces permits approximately a 3 degree
side frame swing in either transverse direction of the side frame
from its neutral position as shown in FIG. 6. This swinging
movement results in approximately five-eighths inch lateral motion
of the bolster in either direction. An additional five-eighths inch
lateral motion of the bolster is obtained by the lateral deflection
of the load spring, as shown in FIG. 8. FIGS. 9 and 10 graphically
illustrate the resulting lateral load deflection characteristic for
each distinct stage of lateral movement of the bolster for both
empty and fully loaded cars. The empty and loaded car
characteristics shown are different because the resistance to
lateral motion, as in any swing hanger type railway car truck, is
dependent upon the load carried by the bolster. Thus the resistance
to lateral motion varies in proportion to the vertical load, and
any partial load will result in a curve proportionally located
between the curves for the empty and fully loaded car.
During the first stage of lateral movement, as illustrated in FIG.
7, the resistance against side frame swing is influenced basically
by three controlling factors (1) the swing hanger length; that is,
the vertical distance between the engaging portions of the pedestal
jaw 24-adapter 25 and the rocker bearing 36-trunnion 35, (2) the
normal forces of gravity acting upon the car body and side frames
20, and (3) the resistance to lateral distortion of the load spring
group 42. These controlling factors work together and in series to
provide the low resistance portions A and A' of the non-linear
curves shown in FIG. 9. After the swinging of the side frames has
been stopped by the engagement of rocker seat 32 with tension
member 21, the remaining lateral motion of the bolster is obtained
by the deflection of the load springs 42 as illustrated in FIG. 8,
resulting in the second stage or high resistance portions B and B'
of the non-linear curves shown in FIG. 10. In this manner the
non-linear lateral force-travel curve characteristic is obtained
and defines the low to high resistance to lateral movement of the
bolster relative to the side frame.
The first stage A and A' of the non-linear curves shown in FIG. 9
can be best explained in the following manner. Under the theory of
vibrations it is known that when a lateral load is applied to a
pendulum, the lateral displacement of the pendulum is in proportion
to the applied load. This characteristic is similar to that of a
spring in tension or compression since when a vertical load is
applied to a spring, its deflection is in proportion to the applied
load. Therefore, a theoretical spring rate for a spring can be
substituted for the lateral force-displacement characteristic of a
pendulum. That is, since the side frame functions as a swing hanger
or pendulum and moves in the same lateral direction as the
laterally distorted load springs 42, the lateral swinging movement
of the side frame has an effective spring rate. Further, a helical
spring has a lateral force-travel characteristic in addition to its
vertical force-travel characteristic. Therefore, the lateral
deflection of the load springs 42 and the lateral deflection of the
swing hanger can be considered as two springs acting in series. It
is well known that when two springs act in series, the resulting
spring rate K.sub.c is lower than that for either of the two
springs individually. Thus the low resistance portions A and A' of
the non-linear curves are basically governed by the formula K.sub.c
=(K.sub. 1.sup.. K.sub. 2)/(K.sub. 1 + K.sub. 2) : where K.sub. 1
in this instance is the effective spring rate of the swinging side
frame, K.sub. 2 is the lateral spring rate of the load springs 42,
and K.sub.c is the resulting spring rate that defines the
resistance to lateral movement of the bolster relative to the side
frame. After a predetermined amount of side frame swing, the
swinging is stopped and any remaining lateral travel of the bolster
relative to the side frame is working solely against the lateral
resistance of the load springs 42 which, as previously stated, have
a spring rate appreciably stiffer than the first stage.
Each stage of the non-linear lateral force-travel curve has the
following effect on the functioning of the present railway car
truck. If only the low force-travel characteristic of the first
stage was provided, as is known in the art, under large lateral
rail irregularities the total available amount of lateral travel
would be absorbed, thereby resulting in heavy lateral contact
between any bolster stops and side frame abutment stops provided,
such as bolster gibs or bolster safety stops. In addition, a
railway vehicle negotiating super-elevated curves would move
laterally the total available amount until contact is made between
whatever stops are provided between the bolster and side frame. The
vehicle would remain in this laterally displaced position until it
traverses the super-elevated curve; thus causing a poor lateral
ride.
Considering only the second stage or high resistance portion of the
curve, the lateral characteristic is substantially the same as that
obtained from the load springs in conventional trucks. This
conventional suspension system is not capable, due to its high
lateral resistance, of avoiding uncontrolled hunting or lateral
instability in the railway vehicle. As noted from FIGS. 9 and 10,
the total available built-in lateral motion in either lateral
direction is approximately 1 1/4 inches. As can be seen from the
curves, the low resistance or first stage has a lateral deflection
characteristic of approximately three-fourths of an inch. This 3/4
inch lateral capability is sufficient to absorb the normal lateral
disturbances caused by normal lateral rail irregularities plus
normal lateral amplitudes of the sinusoidal wave pattern produced
by the running wheels and axle assembly. These normal lateral
disturbances result in approximately 1/2 inch lateral travel, in
either direction, from the track centerline. Since these normal
lateral disturbances are within the 3/4 inch low resistance portion
of the curve, the forces transmitted into the car body are
substantially reduced. These reduced forces are easily damped by a
snubbing system, such as described hereinabove.
If the railway vehicle has to negotiate large lateral disturbances,
such as turn-outs and crossings, high lateral forces are
encountered. After the first stage of the non-linear curve absorbs
a portion of these lateral forces, the remaining lateral forces
resulting from the large lateral disturbance will be cushioned by
the high resistance portion of the stiffer second stage. This mode
of operation effectively reduces wheel flange contact between the
rail and wheel and minimizes wear on component parts of the truck
and car body.
Referring now to FIGS. 11 and 12, there is illustrated a modified
rocker connection between tension member 71 of a side frame 72 and
a spring plank 73. Briefly, a rocker bearing plate 74 having a
predetermined upwardly facing convex contour 75 in the transverse
direction of the side frame is secured to tension member 71. Plate
74 receives in supporting rockable relation one end of the spring
plank 73 having a horizontal bearing plate 76 attached to the plank
for engagement with plate 74. A pair of spaced flanges 77--77
extend downwardly from the underneath portion of the spring plank
to define a pair of surfaces 78--78 in flanking relation with
cooperating side frame surfaces 79--79. Flanges 77--77 are in close
spaced relationship to surfaces 79--79 to thereby interconnect the
plank with the side frame and prevent any longitudinal movement of
the plank relative to the side frame. Swinging of the side frame in
either direction is stopped by contact between the underneath
surface 81 of plate 76 with the predetermined sloping contour 75 of
plate 74. The wedge shaped clearance 83 defined between the
engaging portions of the two plates permits an approximate three
degree side frame swing in either transverse direction of the side
frame and results in approximately five-eighths of an inch lateral
movement of bolster 84 in either direction. If desired, surfaces
78--78 may be tapered downwardly and away from each other to
present a pair of sloping surfaces that define a wedge shaped
clearance between the sloping surfaces and the cooperating surfaces
79--79 of tension member 71. Accordingly, the swinging of the side
frame could then be stopped by the engagement of these cooperating
surfaces.
FIG. 13 illustrates an alternate friction system 90 well known in
the railway art and comprises the conventional friction shoe 91
housed in a pocket 92 of the side frame column 93. A spring 94
urges the friction shoe downwardly into frictional engagement with
a wear plate 95 secured to the bolster 96 to snub the vertical and
lateral movements of the bolster relative to the side frame.
Summarizing, the present railway car truck provides a moderate
total amount of lateral movement approximately equal to 11/4 inches
to either side of the railway track centerline. The truck further
combines: (1) the feature of a low resistance to normal lateral
movement of the bolster relative to the side frame for avoiding
uncontrolled hunting, with (2) the feature of a stiffer resistance
to any excessive lateral movement of the bolster for avoiding heavy
lateral contact between the bolster stops and associated parts of
the side frame.
* * * * *