Note: Descriptions are shown in the official language in which they were submitted.
2000748
St red Axles for R~ilro~d (and other) Vehicle~ p~ge 1
.
This invention relates to the carried in bearing housings 4 and
steering of railroad vehicle axles 5. Link 6 connects irame 1, at
into radial alignment with curved 75 pivot 8, to bearin8 houein84 at
track. In particular it enables true pivot 10, and link 7 connect8
radial alignment to be achieved by irame 1, at pivot 9, to bearin8
all axles oi a truck which has a hous1n85 at ptvot 11. Wheel~et 3
rigid i'rame, even though one of is carried in bearing housings 12
the axle6 is iixed to the irame oi' 80 and 13 which are both ~txed to
the truck and not adapted ior yaw ~rame 1.
motions relative to it. The i'orced-
steering vereion oi the device Links 6 and 7 may also serve the
could similarly be used to align purpose oi carrying the vehicle
the axles oi highway trailers.85 load irom the truck irame to the
bearing housing, thus eliminating
In trucks having riBid irames the the need ior other load bearing
irame typically spans between the devices such as sliders, shear
housings oi the axle bearings and pads or springs between the ~rame
thus takes up an orientation 90 and wheelset 2. Thts ts illustrated
parallel to the chord joining the in iigure 5.two axle centres. In such a
situation, if true radtal alignment The device as shown in iigures 4
of the axles is to be attained, each and 5 may be used as a seli-
must be capable oi taking up a95 steering truck (i.e. one that will
yaw angle relative to the truck generate radial alignment oi the
irame (except, oi course, ior the wheelsets rrom the seli-centring ~-
centre axb oi a three axle truck, eifect oi their conicity) and can
which only needs lateral ireedom be made stable at practical -
in order to be properly aligned). 100 operating speeds by provision Ol' -
This situation is illustrated in suiiicient constraint at the pivots ~ -~
Figure 1. 8 and 9. The constratnt may take -~-
the iorm oi dampers, iriction, -~ -
The truck structure might be torsional spring stiiI'ness or a - ~::
simplified if one axle could be 105 combination oi all oi' these. Figure
iixed to the truck irame and only 6 shows a construction ior the - -~
the second axle moved in relation pivot, using elastomeric elements, - - --
to it to accomplish the steering. In which combines torsional elastic
order for this to be achieved, the and damping constraint. Item 14 is
movabb axle must move laterally 110the upper element, which also
relative to the truck irame, at the carries the vertical load, item 15 `-
same time as rotating in yaw. This is the lower one, the two elements
is illustrated in Figure 2. form the pivot 8. -
A mechanism which can create the 115There is a limit to the track -
required yaw rotation when curvature upon which the truck oi
displaced laterally is the four-bar figures 4 or 5 will operate ~--
chain shown diagrammatically in satisiactorily. Once the track ~-
Figure 3. In such a device, when curve radius becomes sui~iciently
one leg moves laterally, relative to 120 small that the wheelset conicitr is
the opposite one, it must also yaw insuIlicient to generate the - -
relative to it. The amount of yaw required rolling radius difierence
rotation will depend upon the between inner and outer wheels
inclination oi the other two bars the seli-steering eiiect is
in the chain relative to each 125 eliminated, and may even be - -
other. Ii those two bars are reversed. In this situation radial -
parallel to one another there will alignment is not achieved, or even
be no rotation; as the angle approximated. Similarly, if the
between them increases the amount internal, stabilizing, constraints
OI yaw rotation increases. In 130 overcome the available adhesion at ~ -
Figure 3 the 601id lines show an the wheel treads, seli-steering is
initial position and the dashed again ineiiective.
lines show a displaced position.
This mechanism may be used to In these circumstances it becomes
achieve the objective oi providing 135 advisable to include a iorced
iull radial steering oi all axles steering mechanism connected to
while allowing one axle to be fixed the carbody and relatin~ the
to a rigid truck irame. interaxle angle to the
truck/carbody swivel angle. It i8 ::
Figure 4 shows an embodiment of 140 well known that such a device can
the invention applied to a two-axle also increase the vehicle stability
truck. Item 1 is the truck frame, and improve curving. It also
item 2 is one wheelset and item 3 eliminates the need for constraints
the other wheelset. Wheelset 2 is at the pivots 8 and 9. Figure 7
Z000748
SL ~ed Axles for R~ilro~d (~nd other) Vehicles p~e 2
show6 a mechanism, consisting of Extensions 23 and 24 are
another four-bar chain, connected connected together by link 25. By
between the truck frame and the 75 this simple expedient the yaw
carbody, to provide the required motions ot the two outer axles are
forcing input. In this device the con~trained to always be equal
truck frame 1 and the carbody 16 and oppo~ite, thus preventing in-
are connected by two non-parallel phase motion~ while no con~traint
links 17 and 18. 80 18 imposed upon their out-of-phase
~or steering) motion~.
An alternate forced steering
mechanism is shown in figure 8. In The device of figure 10 may al~o
this case the wheelset 2 is forced be accomplished u~ing other
to move laterally relative to the 85 arrangements, as will be obvious
truck frame 1, by the action of to those skilled in the art. In
the carbody swivel motion, particular the link 26 may be
through lever 19 which is pivotted replaced by a hydraulic system,
to frame 1 at 20, connected to which may prove more convenient.
bearing housing 4 by link 21 and 90 Figure 11 shows such a system in
connected to the carbody 16 by which a hydraulic actustor 26 i~
link 22. connected between the e~ttendon
of one link and the truck frame, ~ -
Figures 7 and 8 show two possible hydraulic actuator 27 is connected
steering mechanisms, other 95 between the extension oi the
steering mechanisms which can second link and the truck frame .. 1
also relate the carbody/truck and the two actuators are
swivel angle to the relative connected hydraulically through
position oi wheel6et 2 and truck pipe 28. When hydraulic nuid i8
frame 1 are well-known to those 100 forced out of actuator 26 by the --~
skilled in the art. motion of the axle at one end it
must be forced into actuator 27,
Figure 9 shows the invention thus making the second a~le
applied to a three-axle truck. In perform opposite motions to the - --~
this case the centre axle is fixed 105 first. If the axles attempted similar . ~
to the frame of the truck and motions to each other the ;` ~ -
each of the outer axles is hydraulic iluid would be subjected
connected to the frame by non- to pressure or vacuum and would
parallel links which create the thus resist the motion. - -
steering motions in response to 110 --
`~ the axle lateral displacements, ~ -
~ ~40 relative to the truck frame, caused
; ~ by the track curvature. This -- embodiment of the invention may
be made stable at practical 115
operating speeds by the provision - -
of constraint at the pivots 6uch as
wa~ described for the two axle
version. It may also be provided
with steering linkages such as are 120
shown in figures 7 and 8 to
50 improve the curving and stability.
In the case of the three-axle
truck, however, another mechanism
may be resorted to, which does 125
not require that connections be
55 made to the car body.
The only mode of freedom not
properly constrained in the truck 130
as shown in figure 9, if the pivots
60 are allowed to be freely moving
without constraint, is one in which
the two outer axles yaw in-phase
with one another and the centre 135
axle and truck irame yaw together
65 and out-of-phase with the other
two. This construction could lead
to unstable oscillations in thi~
mode under certain circumstances. 140
This may be avoided by the device
70 shown in iigure 10. In this iigure
link6 6 and 8 are shown with - ~
exten6ions 23 and 24 respectively. - ~
