EXTERNAL RUNFLATAPPARATUS
Inventors: Larry Stuck, Charles Tabone and Christopher enson
CROSS-REFERENCE TO RELATED APPLICATION
[0001 This application claims the benefit under 35 U.S.C. § 119(e) of the earlier
filing date of United States Provisional Patent Application No. 61/775,175 filed on March 8,
2013.
BACKGROUND
[0002] This application discloses an invention which is related, generally and in
various embodiments, to an external runflat apparatus. The external runflat apparatus may be
utilized in a guide wheel system of a monorail transport system.
[0003] Monorail systems are present throughout the world, and for certain
applications, provide an effective way of moving people from one location to another. In
general, an exemplary monorail system includes one or more monorail cars which ride on a
monorail track, and each monorail car has a corresponding monorail bogie system. The
monorail bogie system includes pneumatic drive wheel tires which operate to carry the load
associated with the monorail car and propel the monorail car in a given direction along the
monorail track, and pneumatic guide wheel tires which operate to guide the monorail car
along the monorail track and stabilize the monorail car with respect to any excessive
"sideways" movement.
[0004] In order to provide stability for the monorail car, the pneumatic guide wheel
tires are positioned against both the "left" side and the "right" side of the monorail track.
With this arrangement, as the monorail car begins to move to the "left" of the center of the
monorail track (e.g., as the monorail car is passing through a curved section of the monorail
track and centrifugal forces cause the "leftward" movement), the pneumatic guide wheel tires
positioned against the "right" side of the monorail track begin to exert more force against the
"right" side of the monorail track. The exertion of this force causes the pneumatic guide
wheel tires to compress or deflect, and the compression or deflection operates to counteract
the "leftward" movement of the monorail car and encourage the monorail car to move back
toward the center of the monorail track. An analogous sequence occurs if the monorail car
moves to the "right" of the center of the monorail track.
[0005] Although the above-described pneumatic guide wheel tire arrangement has
been employed to provide a certain level of stabilization to monorail cars, the overall
effectiveness of such stabilization efforts has been less than desired. For example, since tire
pressure can vary over time for a variety of reasons (e.g., temperature, leakage, etc.), if the
tire pressure of one or more of the pneumatic guide wheel tires fails below a normal
operational level, the stability provided by the affected pneumatic guide wheel tires will be
less than desired. Similarly, if external forces such as high winds cause more compression or
deflection than the normal operational compression or deflection of one or more of the
pneumatic guide wheel tires, the stability provided by the affected pneumatic guide wheel
tires will be less than desired.
[0006] To address such issues, "internal tire runflats" have been utilized with the
pneumatic guide wheel tires. These internal runflats are commonly composed of rubber or
composites, and are limited in their ability to precisely control the amount of pneumatic guide
wheel tire deflection, as the applied load must be transmitted through the compression of the
treads of the respective pneumatic guide wheel tires. Often these types of internal runflats are
designed with an outside diameter that can provide limited clearance between the internal
runflats and the fragile internal liners of the respective pneumatic guide wheel tires.
Incidental contact between an internal runflat and the internal liner of a corresponding
pneumatic guide wheel tire can occur, for example, from bumps at the expansion joints of the
monorail track. If a liner of a pneumatic guide wheel tire is damaged as a result of such
incidental contact, the warranty on the pneumatic guide wheel tire can be compromised.
Such incidental contact can also create a safety hazard, in that the pressurized air internal to a
given pneumatic guide wheel tire can breech the internal liner and escape into the belts of the
given pneumatic guide wheel tire, potentially causing a failure of the tire or an explosion.
Accordingly, although utilizing interna! runflats can be utilized to increase the stability
provided by the pneumatic guide wheel tires, the safety and stability provided thereby is still
less than desired.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Various embodiments of the invention are described herein in by way of
example in conjunction with the following figures, wherein like reference characters
designate the same or similar elements.
[0008] FIG. I illustrates various embodiments of an external runflat apparatus;
[0009] FIG. 2 illustrates an exploded view of the external runflat apparatus of FIG. 1;
[0010] FIG. 3 illustrates various embodiments of a tread member of the external
runflat apparatus of FIG. ;
[001 ] FIG. 4 illustrates various embodiments of a base member of the tread member
ofFIG. 3; and
[0012] FIG. 5 illustrates the external runflat apparatus of FIG. 1 utilized with a guide
wheel system of a monorail car according to various embodiments.
DETAILED DESCRIPTION
[0013] It is to be understood that at least some of the figures and descriptions of the
invention have been simplified to illustrate elements that are relevant for a clear
understanding of the invention, while eliminating, for purposes of clarity, other elements that
those of ordinary skill in the art will appreciate may also comprise a portion of the invention.
However, because such elements are well known in the art, and because they do not facilitate
a better understanding of the invention, a description of such elements is not provided herein.
[0014] FIG. 1 illustrates various embodiments of an external run flat apparatus 10.
The external runflat apparatus 10 may be utilized with, and form a part of, a guide wheel
system (See, e.g., FIG. 5) of a monorail transport system. The external runflat apparatus 10
includes a hub member 2 and one or more tread members 14 connected to the hub member
. The one or more tread members 4 may be connected to the hub member in any
suitable manner.
[0015] The hub member 1 is substantially circular-shaped, may be of any suitable
size and may be fabricated from any suitable material. For example, according to various
embodiments, the hub member 12 is fabricated from a metal, a plastic, or a composite
material. As shown in FIG. 1, according to various embodiments, the hub member 12 defines
a central opening 16, defines a plurality of openings 1 which are positioned radially outward
from the central opening 16 and are configured to receive studs (not shown) associated with
an guide wheel system, defines one or more openings 20 which are positioned radially
outward from the openings 18 and are configured to allow for access to a tire valve (not
shown) of an external guide wheel,
[0016] As shown more clearly in FIG. 2, according to various embodiments, the hub
member a so defines a plurality of openings 22 which are positioned radially outward
from the openings 20 and are configured to receive fasteners 24 which are utilized to connect
the one or more treads members 14 to the hub member . The fasteners 24 may be any
suitable type of fasteners, and may be fabricated from any suitable material. For example,
according to various embodiments, the fasteners 24 may be fabricated from a metal, a plastic,
or a composite material. According to various embodiments, the fasteners 24 are corrosion
resistant fasteners. According to various embodiments, the fasteners 24 may be secured in
place with corresponding nuts 26.
[001 7] FIG. 3 illustrates various embodiments of the one or more tread members 14.
For embodiments where the external runf!at apparatus 10 includes a plurality of tread
members 14, each tread member 14 is substantially arc-shaped, and collectively cooperate to
cover the outer circumference of the hub member . For embodiments where the external
runflat apparatus 10 includes a single tread member 14, the single tread member 4 is
substantially circular-shaped and covers the outer circumference of the hub member 12.
[001 8] Each of the one or more tread members 4 includes a base member 28 and a
covering 30 over the base member 28. The base member 28 will be described in more detail
hereinbelow with respect to FIG. 4. The covering 30 may be of any suitable "thickness",
may include any suitable material, and may be connected to the base member 28 in any
suitable manner. For example according to various embodiments, the covering 30 is at least
two millimeters thick, includes a material made from a thermoplastic (e.g., a nylon), a
thermoset (e.g., a polyurethane), a rubber, or a composite material, and is adhered or
mechanically fixed to the base member 28. According to various embodiments, the covering
30 is welded to the base member 28. According to other embodiments, the covering 30 is
vulcanized to the base member 30. As also shown in FIG. 3, and as described in more detail
hereinbelow, a plurality of bushings 32 may be connected to the tread member 14.
[0019] FIG. 4 illustrates various embodiments of the base member 28 of the one or
more tread members 14. The base member 28 may be fabricated from any suitable material.
For example, according to various embodiments, the base member 28 may be fabricated from
a metal, a plastic, a rubber, or a composite material. As shown in FIG. 4, according to
various embodiments, the base member 28 may include a plurality of perforations 34 through
the outermost/circumferential surface of the base member 28. The perforations 34 allow for
better adhesion of the covering 30 to the base member 28. For a given base member 28, the
perforations also operate to reduce the weight of the base member 28, and by extension, the
weight of the associated tread member 14. According to other embodiments, the base
member 28 is a solid base member 28 and does not include the plurality of perforations 34
shown in FIG. 4. The base member 28 may also include a plurality of ear members 36 which
extend radially inward from the outermost/circumferential surface of the base member 28,
and each ear member 34 may define an opening 38 therethrough. For a given tread member
1 , according to various embodiments, the opening 38 is configured to receive a
corresponding one of the bushings 32, and is coaxially aligned with a corresponding opening
22 of the hub member 1 if the given tread member 14 is connected to the hub member 12.
[0020] The bushings 32 may be fabricated from any suitable material. For example,
according to various embodiments, the bushings 32 are fabricated from a metal, a plastic, or a
composite material. Each bushing 32 defines an opening 40. For a given bushing 32, the
opening 40 is configured to receive one of the fasteners 24, and is coaxially aligned with a
corresponding opening 22 of the hub member 12 if the given bushing 32 is connected to the
base member 28 and the associated tread member 14 is connected to the hub member 12.
[0021] Fig. 5 illustrates the external runflat apparatus 1 utilized with a guide wheel
system 42 of a monorail car according to various embodiments. In general, each external
runflat apparatus 10 is utilized with a corresponding guide wheel tire 44 of the guide wheel
system 42. Therefore, it will be appreciated that a monorail car may utilize a plurality of
external runflat apparatuses 10. The external runflat apparatus 0 may be connected to the
guide wheel system 42 in any suitable manner. For example, according to various
embodiments, a given external runflat apparatus 0 may be connected to the same hub studs
that a corresponding guide wheel is connected to. For such embodiments (e.g., FIG. 5), the
hub studs pass through the openings 18 of the hub member 12 to connect the external runflat
apparatus 10 to the guide wheel system 42.
[0022] In operation, the external runflat apparatuses 10 improve the overall stability
and safety of monorail transport systems by controlling the deflection of the corresponding
guide wheel tires 44, More specifically, each external runflat apparatus 10 controls the upper
limit of its corresponding guide wheel tire 44 to maintain a safe level of monorail car
stability. This is true even in cases where the corresponding guide wheel tire 44 has failed
due to a loss of pressure.
[0023] When a corresponding guide wheel tire 44 reaches a certain deflection level,
the one or more tread members 14 come into contact with the monorail track and operate as a
"'harder stop" to absorb a portion of the applied guide wheel tire load, thereby limiting the
amount of deflection experienced by the corresponding guide wheel tire 44. The covering 30
of the one or more tread members 14 helps to absorb the shock resulting from the impact of
the tread member 1 colliding with the monorail track, and also provides a level of abrasion
resistance to protect the monorail track. According to various embodiments, an external
runflat apparatus 10 associated with a given monorail car can provide for continued mobility
of the monorail car up to a minimum of thirty miles with an applied load of 3,500 pounds.
[0024] According to various embodiments, the tensile modulus or other mechanical
properties of the covering 30 can be adjusted to different levels of impact resistance, shock
absorption, abrasion resistance and deflection(from applied load) to meet the meets of
different applications. Additionally, ultra violet (UV) additives and/or moisture resistant
additives can be incorporated into the covering 30 to protect the covering 30 against
deterioration caused by exposure to external elements.
[0025] Nothing in the above description is meant to limit the invention to any specific
materials, geometry, or orientation of elements. Many part/orientation substitutions are
contemplated within the scope of the invention and will be apparent to those skilled in the art.
The embodiments described herein were presented by way of example only and should not be
used to limit the scope of the invention.
[0026] Although the invention has been described in terms of particular embodiments
in this application, one of ordinary skill in the art, in light of the teachings herein, can
generate additional embodiments and modifications without departing from the spirit of, or
exceeding the scope of, the described invention. For example, although the external runflat
apparatus 10 has been described as having the one or more tread members 4 removeably
connected to the hub member 12 with fasteners 24, it will appreciated that other connectors,
or connection methods, may be utilized to connect the one or more tread member 4 to the
hub member 2 . For example, the one or more tread members may be bonded to the hub
member 2, welded to the hub member , or mechanically connected to the hub member 12
with a snap or other type of fastener. Accordingly, it is understood that the drawings and the
descriptions herein are proffered only to facilitate comprehension of the invention and should
not be construed to limit the scope thereof.
CLAIMS
What is claimed is:
1. An external runflat apparatus for a guide wheel system of a monorail transport
system, the external runflat apparatus comprising:
a hub member; and
a tread member connected to the hub member, wherein the tread member comprises:
a base member; and
a covering over the base member.
2. The external runflat apparatus of claim 1, wherein the hub member is
substantially circular and defines a central opening therethrough.
3. The external runflat apparatus of claim 2, wherein the hub member further
defines:
a first plurality of openings positioned radially outward from the central opening;
a second plurality of openings positioned radially outward from the first plurality of
openings; and
at least one opening positioned between the first and second pluralities of openings.
4. The external runflat apparatus of claim 1, wherein the tread member is
removeably connected to the hub member.
5. The external runflat apparatus of claim I, wherein the tread member is bonded
to the hub member.
6. The external runflat apparatus of claim 1, wherein the tread member is welded
to the hub member.
7. The external run flat apparatus of claim 1, wherein the tread member is
substantially circular-shaped.
8. The external runflat apparatus of claim 1, wherein the external runflat
apparatus comprises a plurality of tread members connected to the hub member, and wherein
at least one of the plurality of tread members is substantially arc-shaped.
9. The external runflat apparatus of claim , wherein the base member defines a
plurality of perforations therethrough.
10. The external runflat apparatus of claim , wherein the base member defines a
plurality of ear members.
11. The external runflat apparatus of claim 1 , wherein at least one of the plurality
of ear members defines an opening therethrough.
12. The external runflat apparatus of claim 1 , further comprising a bushing
connected to the tread member and coaxially aligned with the opening defined by the at least
one of the plurality of ear members.
3. The external runflat apparatus of claim 1, wherein the covering comprises a
thermoplastic material.
1 . The external runflat apparatus of claim 1, wherein the covering comprises a
thermoset material.
15. The external runflat apparatus of claim 1, wherein the covering comprises a
rubber material.
16. The external runflat apparatus of claim 1, wherein the covering comprises a
composite material.
17. The runflat apparatus of claim 1, wherein the covering includes an ultra violet
additive.
8. The runflat apparatus of claim 1, wherein the covering includes a moisture
resistant additive.
1 . The external runflat apparatus of claim 1, wherein the covering is adhered to
the base member.
20. The external runflat apparatus of claim 1, wherein the covering is
mechanically fixed to the base member.
2 1. The external runflat apparatus of claim 1, wherein the covering is welded to
the base member.
22. The external runflat apparatus of claim , wherein the covering is vulcanized
to the base member.