Note: Descriptions are shown in the official language in which they were submitted.
TRANSPORTATION SYSTEM
FIELD OF THE INVENTION
[0001] The present invention is a transportation system.
BACKGROUND OF THE INVENTION
[0002] In the conventional configuration of railroad equipment (i.e.,
steel treads engaging
standard rails), the gradient is limited by the ability of a prime mover
(i.e., a locomotive) to push
or pull the load-carrying cars. The weight of the locomotive enhances
traction, but as the gradient
increases, the tractive effort available to move payload decreases. As is well
known in the art,
increasing the gradient will ultimately reach a point where the locomotive is
unable to move the
loaded cars up grade.
[0003] Steel wheel treads on standard rails offer maximum operating
efficiency, due to
minimum rolling resistance. The shape of the standard rail has been optimized
for use with steel
wheel treads.
[0004] One conventional solution has been to use softer treads, to
increase the gradient
that the loaded cars can be moved over. Because of the increase in friction,
there are some
disadvantages, e.g., increased costs due to increased wear on the softer
wheels, and decreased
overall efficiency. In any event, even with softer wheel treads, there is a
significant reduction in
load haulage capacity as the steepness of the track increases.
[0005] The constraints to which conventional railroad equipment are
subject tend to have
significant consequences, i.e., they may result in significant costs. For
example, a tunnel boring
machine engages ground at a front end thereof to produce muck (broken ground)
that is removed
from the back end of the tunnel boring machine by any suitable method. As is
well known in the
art, the muck may be loaded at a back end of the tunnel boring machine into
muck cars, typically,
relatively small-capacity rail-mounted cars. The muck cars are included in a
muck train.
[0006] In this arrangement, the maximum grade at which the muck train can
operate may
limit the grade of the tunnel that is excavated by the tunnel boring machine.
This constrains the
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tunnel design, and in certain contexts (e.g., when constructing penstocks at a
hydroelectric power
plant), such constraints may result in significantly greater expense overall.
SUMMARY OF THE INVENTION
[0007] There is a need for a transportation system that overcomes or
mitigates one or
more of the defects or disadvantages of the prior art. Such defects or
disadvantages are not
necessarily included in those listed above.
[0008] In its broad aspect, the transportation system includes one or
more transportation
assemblies. Each transportation assembly includes a body and two or more sets
of first wheels
mounted to the body and respectively having first wheel treads configured for
engaging a pair of
first rails spaced apart by a first distance, the first rails being positioned
at one or more first grades,
and at least two sets of second wheels mounted to the body and respectively
having second
wheel treads configured for engaging a pair of second rails spaced apart by a
second distance
that is larger than the first distance. The second rails are positioned at one
or more second grades
that are steeper than the first grade.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention will be better understood with reference to the
attached drawings, in
which:
[0010] Fig. 1A is an embodiment of a transportation system of the
invention including an
embodiment of a transportation assembly of the invention and an embodiment of
a rail assembly
of the invention;
[0011] Fig. 1B is a schematic illustration of another embodiment of the
rail assembly of
the invention, on which the transportation assembly of Fig. 1A is
positionable, drawn at a smaller
scale;
[0012] Fig. 1C is a portion of the rail assembly of Fig. 1B, drawn at a
larger scale;
[0013] Fig. 1D is another portion of the rail assembly of Fig. 1B;
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[0014] Fig. 1E is an isometric view of an embodiment of a car included in
the
transportation assembly of the invention;
[0015] Fig. 2A is an isometric view of embodiments of sets of first and
second wheels
positioned on first rails of the rail assembly, drawn at a larger scale;
[0016] Fig. 2B is an isometric view of the wheelsets of Fig. 2A prior to
engagement of the
second wheels with transition portions of second rails of the rail assembly;
[0017] Fig. 2C is an isometric view of the wheelsets of Figs. 2A and 2B
in which the
second wheels are positioned on the transition portions;
[0018] Fig. 2D is an isometric view of the wheelsets of Figs. 2A-2C
positioned on straight
portions of the second rails;
[0019] Fig. 3A is a side view of the wheelsets of Figs. 2A-2D positioned
on the first rails;
[0020] Fig. 3B is a side view of the wheelsets of Figs. 2A-2D prior to
engagement of the
second wheels with transition portions of second rails of the rail assembly;
[0021] Fig. 3C is a side view of the wheelsets of Figs. 2A-2D in which
the second wheels
are positioned on the transition portions;
[0022] Fig. 3D is a side view of the wheelsets of Figs. 2A-2D in which
the second wheels
are engaged with the straight portions;
[0023] Fig. 4A is a front view of the wheelsets of Figs. 2A-2D in which
the first wheels are
engaged with the first rails;
[0024] Fig. 4B is a front view of the wheelsets of Figs. 2A-2D in which
the first wheels are
engaged with the first rails, and the wheelsets are in the transition zone;
[0025] Fig. 4C is a front view of the wheel sets of Figs. 2A-2D in which
the second wheels
are engaged with the transition portions of the second rails, and the
wheelsets are in the transition
zone;
[0026] Fig. 4D is a front view of the wheel sets of Figs. 2A-2D in which
the second wheels
are engaged with the straight portions of the second rails;
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[0027] Fig. 5A is a side view of an embodiment of the transportation
assembly that
includes an embodiment of an arrestor module, drawn at a larger scale;
[0028] Fig. 5B is a cross-section of the arrestor module of Fig. 5A,
taken along section C-
C;
[0029] Fig. 5C is a cross-section of a portion of the arrestor module of
Figs. 5A and 5B
showing brake shoes of the arrestor module in a disengaged condition, drawn at
a larger scale;
[0030] Fig. 5D is the cross-section of Fig. 5C in which the brake shoes
are shown in an
engaged condition;
[0031] Fig. 6A is a front view of the wheelset of Figs. 2A-2D, drawn at a
smaller scale;
and
[0032] Fig. 6B is a side view of the wheelset of Fig. 6A.
DETAILED DESCRIPTION
[0033] In the attached drawings, like reference numerals designate
corresponding
elements throughout. Reference is made to Figs. 1A-4D and 6A-6B to describe an
embodiment
of a transportation system 20 of the invention. In one embodiment, the
transportation system 20
preferably includes one or more transportation assemblies 22 (Fig. 1A). It is
preferred that each
of the transportation assemblies 22 includes a body 24 and two or more sets 26
of first wheels 28
mounted to the body 24 and configured for engaging a pair of first rails 30
spaced apart by a first
distance "D1". As will be described, the first rails 30 preferably are
positioned at at least one first
grade "G1". Preferably, the transportation assembly 22 also includes two or
more sets 32 of
second wheels 34 mounted to the body 24 and respectively comprising second
wheel treads 36
(Fig. 2A) configured for engaging a pair of second rails 38 spaced apart by a
second distance
"D2" that is larger than the first distance "D111. As will also be discussed
further below, it is preferred
that the second rails 38 are positioned at at least one second grade "G2" that
is steeper than the
first grade "G1".
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[0034] As will be described, in one embodiment, each of the
transportation assemblies 22
preferably includes a motor "M", so that the load in the transportation
assembly 22 improves the
traction thereof.
[0035] The first and second rails 30, 38 are included in an embodiment of
a rail assembly
39 of the invention. As will be described, the first rails 30 preferably are
conventional. As
illustrated in Fig. 1B, in one embodiment, the rail assembly 39 preferably
includes a lower set of
first rails (located at a lower elevation) and an upper set of first rails
(located at a higher elevation),
identified in Figs. 1B-1D by reference characters 30A, 30B for clarity of
illustration. Those skilled
in the art would appreciate that the arrangement schematically illustrated in
Fig. 1B may be used
where the transportation assembly 22 (not shown in Figs. 1B-1D) is used to
move material from
a lower level (i.e., at which the first rails 30A are located) to an upper
level (i.e., at which the
second rails are located), and vice versa.
[0036] Those skilled in the art would also appreciate that, depending on
the
circumstances, the rail assembly 39 may, alternatively, include only the first
rails 30A and the
second rails 38, or the first rails 30B and the second rails 38.
[0037] As can be seen, e.g., in Fig. 1B, the first grade "Gl" is
relatively flat. Those skilled
in the art would be aware that, in general, the first grade "Gl" may vary
between 0% and
approximately 10% or more. The second grade "G2" preferably is much steeper
than the
maximum of the first grade "Gi". It is believed that the second grade "G2" may
be up to
approximately 30% or more and may be safely climbed by the transportation
assembly 22 of the
invention.
[0038] It will be understood that the transportation assembly 22 may move
up the first and
second grades "Gl" and "G2" in the direction indicated by arrow "A", in Fig.
1B and may move
downwardly on the first and second grades "G1" and "G2" in the direction
indicated by arrow "B"
in Fig. 1B.
[0039] It will also be understood that the transportation system 20
preferably includes the
transportation assembly 22 and the rail assembly 39. The rail assembly 39
preferably includes
the first rails 30, and the second rails 38.
[0040] It is preferred that the first rails 30 are conventional steel
rails, and the second rails
38 are not, as will be described.
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[0041] As can be seen in Figs. 1C and 1D, the first rails 30 and the
second rails 38
preferably overlap laterally in a transition zone "Z". For clarity of
illustration, the transition zone
"Z" is shown in Figs. 1C and 1D as including transition sub-zones "ii" and
"Z2".
[0042] It has been found that, for a smooth transition of the
transportation assembly 22
from the first rails 30 to the second rails 38, a part "C" of the second rails
38 in the transition sub-
zone "Z2" preferably is located at substantially the same grade as the first
rails 30, i.e., at grade
"Gi". For clarity of illustration, a line "J" that is parallel to grade "Gi"
is included in Fig. 1C.
[0043] In Figs. 1C and 1D, the vertical distance between a top running
surface "Si" of the
first rails 30 and a top running surface "S2" of the portion of the second
rails 38 that is in the
transition sub-zone "Z2" is identified by the reference character "Hi" for
convenience. It will be
understood that the distance "Hi" is exaggerated in Figs. 1C and 1D for
clarity of illustration.
[0044] In one embodiment, a portion "K" of the first rails 30 that is
located in the transition
region "Z" gradually diverges downwardly from the grade "Gi". It has been
found that this
downward trajectory provides for a more smooth transition of the
transportation assembly 22 from
the first rails 30 to the second rails 38, when the transportation assembly 22
is travelling in the
direction indicated by arrow "A". For clarity of illustration, the vertical
distance between the top
surface of the first rail 30 at the end of the portion "K" and the surface
"S2" proximal to the second
rail 38 is identified by reference character "H2" in Figs. 1C and 1D.
[0045] It has also been found that the grade "G2" preferably is
determined in order to
permit the transportation assembly 22 to be substantially aligned, grade-wise,
for the change in
gradient, i.e., from "Gi" to "G2", and from "G2" to "Gi". Depending on the
circumstances, "G2" may
include more than one grade, which may be based on one or more radii.
[0046] As can be seen in Figs. 4B and 4C, in one embodiment the second
rails 38
preferably are positioned further apart from each other than are the first
rails 30, i.e., "D2" is larger
than "Di". Those skilled in the art would appreciate that, in an alternative
embodiment, the second
rails 38 may be positioned more closely to each other than the first rails 30,
i.e., distance "D2"
may alternatively be less than distance "Di". As illustrated in Figs. 2A-2D,
the first rails 30 and
the second rails 38 overlap laterally only in the transition zone "Z" (Fig.
1B) in which the grade at
which the transportation assembly 22 is positioned changes from the first
grade "Gi" to the second
grade "G2", and vice versa, depending on the transportation assembly's
direction of travel.
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[0047] It will also be understood that, for convenience, only one of the
first rails and only
one of the second rails will be described in detail, as the other rail in each
case is substantially
the same.
[0048] The second rails 38 preferably include portions 40 thereof that
are positioned at
the second grade "G2". As noted above, the second grade "G2" may include a
number of grades.
For instance, as can be seen in Figs. 1C and 1D, it is preferred that the part
"C" of the second
rails 38 is a relatively small part of the portion 40 of the second
(augmented) rail. The upper, or
running, surfaces "S1" and "S2" of the first rails 30 and of the portions 40
of the second rail
respectively define the first and second grades "G1" and "G2".
[0049] As can be seen in Figs. 1C, 1D, and 2A, in one embodiment, the
second rails 38
preferably include transition portions 42 thereof that are formed to enable
the transportation
assembly 22 to move relatively smoothly between the first rails 30 and the
portions 40 of the
second rails 38. Those skilled in the art would appreciate that the transition
portions 42 may have
any suitable configuration. For example, as illustrated in Fig. 1B, in one
embodiment, the
transition portion 42 has an upper surface 44 thereof that is substantially
straight.
[0050] The transition portion 42 extends between a first end 46, at which
the upper surface
44 is proximal to the running surface "S1" of the first rail 30, and a second
end 48, at which the
upper surface 44 is proximal to the running surface "S2" of the second rail 38
(Fig. 2B). As
illustrated in Fig. 1B, it is believed that the transition portion 42 may be
relatively short.
[0051] As can be seen in Figs. 50 and 5D, in one embodiment, the second
rail 38
preferably includes a web portion 70 that supports an inner upper flange 72
and an outer upper
flange 74. In Figs. 2A-2D, it can also be seen that, in the transition portion
42 of the second rail
38, the inner upper flange 72 has been removed. As will be described, this is
believed to facilitate
the movement of the transportation assembly 22 between the first rail 30 and
the straight portion
40 of the second rail 38.
[0052] Also, part of the outer upper flange 74 is removed, to provide a
chamfered portion
75 of the outer upper flange 74, to facilitate movement of the unit up the
inclined surface 42.
[0053] It can be seen in Fig. 1C that the downwardly-bent portion "K" of
the first rail 30
causes the second wheels 34 to engage the inclined surfaces 42 as the
transportation assembly
22 moves in the direction indicated by arrow "A".
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[0054] Preferably, in the transition zone "Z", the sets 32 of the second
wheels 34 engage
the second rails 38 and the sets 26 of the first wheels 28 engage the first
rails 30 (Figs. 2A-3D),
although not necessarily simultaneously. As will be described, in the
transition zone "Z", the
engagement of the first wheels 28 with the first rails 30 and the engagement
of the second wheels
34 with the second rails 38 may be sequential. If the engagement is
sequential, then the order in
which the wheels engage the respective rails depends on the direction in which
the assembly 22
is moving.
[0055] As can be seen in Fig. 3A, the first wheel 28 preferably includes
a first wheel tread
50 that engages the upper surface "Si" of the first rail 30.
[0056] The manner in which the first wheel treads 50 of the first wheels
28 initially engage
the upper surface "Si" of the first rail 30 before the second wheel treads 36
of the second wheels
34 engage the surface 44 of the transition portion 42 can be seen in Figs. 3A
and 3B, in which
the first and second wheels 28, 34 are moving in the direction indicated by
arrow "A".
[0057] In Fig. 3B, the first and second wheels 30, 34 are entering the
transition zone "Z".
At that point, the first wheel treads 50 of the first wheels 28 are still
engaging, and supported by,
the upper surface "Si" of the first rails 30.
[0058] As can be seen in Figs. 3B and 3C, the upper surface 44 of the
transition portion
42 may define a substantially straight incline, ending at the upper surface
"S2" of the straight
portion 40 of the second rail 38.
[0059] Preferably, the transition portion 42 is formed so that the second
wheel tread
surface 36 engages the upper surface 44 near the second end 48 of the
transition portion 42. At
that point, illustrated in Fig. 3C, the first wheel tread surface 46 may still
be engaged with the
upper surface "Si" of the first rail 30.
[0060] As can also be seen in Figs. 3C and 3D, forward movement of the
transportation
assembly 22 (i.e., in the direction indicated by arrow "A" in Figs. 3C and 3D)
causes the entire
transportation assembly 22 to be raised due to the engagement of the second
wheel tread surface
36 with the upper surface 44 at the upper end 48 of the transition portion 42,
and with the upper
surface "S2". Due to such engagement, the first wheel tread 50 is raised above
the first surface
"Si" by a vertical distance "V" (Fig. 3D).
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..
[0061] As noted above, in one embodiment, the first rail 30
preferably includes the portion
"K" thereof, which is generally convex, relative to the second rail 38, and
which is also positioned
below the second rail 38. When the transportation assembly 22 is moving in the
direction
indicated by arrow "A", the first wheels 28 follow the first rails 30 until
the first wheels 28 are lifted
upwardly, off the first rails 30, due to the engagement of the second wheels
34 with the inclined
surfaces 42 of the second rails 38.
[0062] Similarly, when the transportation assembly 22 is
travelling in the direction
indicated by arrow "B", the first wheels 28 engage the portion "K" of the
first rail 30 when the
second wheels 34 have travelled sufficiently far along the portion 42 to cause
the first wheels 28
to engage the portion "K".
[0063] As can be seen, e.g., in Figs. 4A, 6A, and 6B, in one
embodiment, it is preferred
that pairs of the first wheels 28 and pairs of the second wheels 34 are
respectively positioned
coaxially in a wheelset 52. It will be understood that the transportation
assembly 22 may include
one or more drive modules 54, to which one or more muck car modules 56 may be
attached (Fig.
1A). Each of the modules 54, 56 preferably includes at least two of the
wheelsets 52.
[0064] As will be described below, in one embodiment, the muck
car modules 56 may
include motors respectively, and the drive modules may not be needed.
[0065] An axis "X" about which each of the first and second
wheels 28, 34 rotates is
schematically illustrated in Figs. 4B, 4C, and 6A.
[0066] From the foregoing, it can be seen that the
transportation assembly 22 may be
hauling a payload uphill, and/or downhill. These are discussed separately.
Down Grade Haulage
[0067] In this scenario, an empty train moves up grade, and
payload is moved downgrade.
[0068] The drive is sized to manage the empty train's tractive
effort needs up the grade.
[0069] The system can support haulage on standard rail on
gradients up to 10%,
extending gradeability to 30% on augmented rail (the second rails 38).
[0070] The system can be battery powered with the regeneration
available in controlling
the loaded train downgrade offsetting the energy required to move the empty
train up grade.
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[0071] In one embodiment, a compound wheel with a size reduction between
the standard
rail wheel (larger) and augmented rail wheel (smaller), both fixed to a common
axle, preferably
provides increased tractive effort. Halving the wheel diameter on the
augmented rail would double
the train's gradeability between the standard rail and augmented rail
sections.
[0072] In applications where the gradient differential between the
standard rail and
augmented rail sections exceeds a factor of 2.5, a gear reduction preferably
is added between
the rail wheel and the softer augmented tire to balance the loading on the
drive.
[0073] A transportation assembly 122 that includes at least one main
gearbox 180 and at
least one planetary gearbox 182 is illustrated in Fig. 1E. The transportation
assembly 122
preferably also includes at least one motor "M" (Fig. 1E). As can be seen in
Fig. 1E, in one
embodiment, the first wheels 128 preferably are mounted to an axle 184 and
driven through the
main gearbox 180, and the second wheels 134 preferably are mounted to rotate
about other, non-
co-axial axes. The second wheels 134 preferably are driven through the
planetary gearbox 182.
It will be understood that the motor "M" transmits power to the axle 184 via
the main gearbox 180,
and the rotating axle 184 in turn transmits power to the second wheels 134 via
the planetary
gearbox 182. It will be understood that the transportation assembly 122 has a
larger capacity
(e.g., larger than the transportation assembly that is illustrated in Fig.
1A), and the transportation
assembly 122 is for use in an up-grade haulage system, in which the
transportation assemblies
122 are loaded when hauling up grade.
[0074] As will be described, tractive effort in the loaded condition can
be augmented with
mechanical axle braking with an arrestor module added to the system to
positively secure the
train on the augmented rail.
[0075] Those skilled in the art would appreciate that the transportation
assembly 22 is
required to have the capacity to back up grade when fully loaded, but such
performance only
needs to be marginal, as this is an emergency condition and it is acceptable
that the drive can
only sustain loaded up grade performance for a minimum amount of time.
Up Grade Haulage
[0076] In this scenario, a loaded train is moved up grade.
[0077] System supports haulage on standard rail up to a 10% grade
extended to 30% on
augmented rail (second rails 38).
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,
..
[0078] The drive is sized to manage the loaded train's tractive
effort needs up the grade.
[0079] The power source preferably is via a trolley feed, or
diesel-electric, as the
regeneration available in controlling the empty train down grade is minimal
compared to the
energy requirements to move the loaded train upgrade.
[0080] As will be described, an arrestor module is added to the
system to positively secure
the train when an augmented track system is utilized.
[0081] In these circumstances, a gear reduction between the
softer tire 34 and rail wheel
28 (Fig. 1E) is required to allow a common drive to effectively service both
applications.
[0082] Utilizing a planetary bogie configuration with a second
softer tire located at each
rail wheel provides a compact assembly with an increased load capacity per
axle for larger
capacity haulages (Fig. 1E).
[0083] As the speed differential between the two rail systems
increases, it may be
necessary to introduce a clutch (not shown), which allows the rail wheels to
free-wheel during the
train's operation on the augmented section 38. The free-wheeling reduces wheel
face wear and
smoothens the transition between the two trackage systems.
[0084] Completely supporting the load being carried with driven
wheels proportionately
increases the available traction as the load on the wheels increases. Grade
capability
(gradeability) is not impacted by fluctuations in the gross weight of the
transportation assembly,
unlike a conventional train configuration.
[0085] In use, when the transportation assembly 22 is travelling
in the direction indicated
by arrow "A", when one of the wheelsets 52 first enters the transition zone
"Z", the first wheel
treads 50 of the first wheels 24 are engaging the surfaces "Si" of the first
rails 30. As the wheelset
52 progresses further into the transition zone "Z", the second wheel treads 36
engage the surfaces
"S2" of the second rails 38. After this occurs, the entire wheelset 52 is
lifted upwardly due to the
grade of the upper surface 44 of the transition portion 42.
[0086] When the wheelset 52 progresses past the second end 48 of
the transition portion
42, the second wheel treads 36 are engaging the surfaces "S2" of the second
rails 38.
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..
[0087] In another embodiment, the second wheel treads 36
preferably include a high-
friction material, e.g., rubber. This material is advantageous because, due to
its use, the second
wheels 34 are unlikely to slip on the second surface "S2" of the second rails
38. Because the
second rails 38, the surfaces "S2" of which are intended to be engaged by the
second wheel
treads 36, are generally located at relatively steep grades, including the
high-friction material on
the second wheel treads 36 has the advantage of enhancing the ability of the
transportation
assembly 22 to travel on the steeply inclined second rails 38.
[0088] Those skilled in the art would appreciate that the high-
friction material has the
disadvantage that it is more susceptible to wear than the steel of the first
wheel treads 50.
[0089] Due to the relative steepness of the second grade "G2" at
which the second rails
38 are positioned, in one embodiment, it is preferred that one or more
arrestor modules 60 are
attached to the transportation assembly 22 (Fig. 5A). It will be understood
that the arrestor module
60 provides an emergency brake function. Those skilled in the art would
appreciate that the first
and second wheels would also be braked during operation by braking systems
(not shown) that
are controlled by an operator.
[0090] It will also be understood that the straight portion 40
of the second rail 38 of Fig.
5A is illustrated at a substantially flat grade solely to simplify the
drawing. Those skilled in the art
would appreciate that the straight portion 40 may be positioned at any
suitable grade "G211
.
[0091] Preferably, the arrestor module 60 includes an arrestor
module body 61 and one
or more sets of brake shoes 64 (Fig 5B) mounted to the arrestor module body
61. As will be
described, the brake shoes 64 preferably are movable between a disengaged
condition (Fig. 5C),
in which the brake shoes 64 are disengaged with the second rails 38, and an
engaged condition
(Fig. 5D), in which the brake shoes 64 are engaged with the second rails 38,
to hold the
transportation assembly 22 stationary relative to the second rails 38.
[0092] It is also preferred that the arrestor module 60 includes
idler wheels 65 (Figs. 5B-
5D) that are mounted to the arrestor module body 61, to support the arrestor
module body 61
when the brake shoes 64 are disengaged from the second rails 38. The idler
wheels 65 also
guide the arrestor module 60 up or down the transition portion 42. The idler
wheels 65 thread
onto the second or first rails (as the case may be) at speed.
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[0093] It is also preferred that the arrestor module 60 additionally
includes an actuator
(not shown) operatively connected with the brake shoes 64, for controlling
engagement of the
brake shoes 64 with the second rails 38.
[0094] As can be seen in Fig. 5A, the arrestor module body 61 preferably
is connected
with the body 24 of the transportation assembly 22. It is preferred that the
arrestor module body
61 is connected with the body 24 of the transportation assembly 22 by a
linkage (not shown) that
holds the arrestor body module 61 relatively rigidly relative to the body 24
front to back. However,
subject to the foregoing, it is also preferred that the arrestor module body
61 be somewhat
movable vertically relative to the body 24, and also that some side-to-side
movement of the
arrestor module body 61 relative to the body 24. Such side-to-side movement
may be needed,
e.g., to enable the transportation assembly 22 and the arrestor module 60 to
negotiate curves in
the railway.
[0095] In one embodiment, the brake shoes in the arrestor module 60
preferably includes
one or more upper brake shoes 64u, and one or more lower brake shoes 64L
(Figs. 5C, 5D). In
Fig. 5C, the upper and lower brake shoes 64, 64L are shown as being disengaged
from upper
and lower surfaces 66, 68 of the flange 70 of the second rail 38 (Fig. 5C). In
Fig. 5D, the upper
and lower brake shoes 64u, 64L are illustrated in the engaged condition. It
will be understood that
the upper and lower brake shoes 64u, 64L remain disengaged from the surfaces
66, 68
respectively until the brake shoe 64u is moved to its engaged condition.
[0096] To engage the inner upper flange 72, the brake shoe 64u is moved
downwardly by
a suitable means (e.g., preferably a suitable spring) (not shown) upon
actuation, i.e., it is moved
in the direction indicated by arrow "E' in Fig. 5D. Preferably, upon
engagement of the upper
brake shoe 64u with the upper surface 66 of the flange 70, the spring
continues to urge the upper
brake shoe 64u downwardly, to press the upper brake shoe 64u against the upper
surface 66 with
force.
[0097] It is also preferred that the shoes 64u, 64L are released by a
suitable mechanism
(e.g., hydraulic, pneumatic, electric) (not shown). The brake subassembly is
biased to
engagement of the brake shoes with the flange 70, i.e., upon a power failure
or an emergency
stop button being depressed, the brake shoes are urged against the upper
flange by the springs.
[0098] The downward movement of the upper brake shoe 64u, and its
engagement with
the inner upper flange 72, causes upward movement of the arrestor module body
61 and the idler
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wheel 65, so that the idler wheel 65 is disengaged from the outer upper flange
74 when the upper
brake shoe 64u engages the inner upper flange 72. The direction of such upward
movement is
indicated by arrow "F" in Fig. 5D, i.e., the upward movement of the arrestor
module body 61 is in
a direction opposite to the downward direction indicated by arrow "E".
[0099] In use, when the transportation assembly 22 moves from the first
rails 30 into the
transition zone "Z", the brake shoes 64 are not required to be positioned
above and below the
upper inner flange 70 because, as noted above, the upper inner flange 70 has
been removed
from the transition portion 42 of the second rails 38. Instead, the upper and
lower brake shoes
64u, 641 are positioned above and below the brake shoes 64 respectively at the
commencement
of the straight portion 40 of the second rails 38.
[0100] As noted above, the arrestor module 60 is intended to provide an
emergency
braking function, i.e., to prevent the transportation assembly 22 from moving
downwardly on the
straight portion 40 of the second rails 38 in an uncontrolled way, e.g., in
abnormal circumstances
that would compromise otherwise workable traction on the gradient.
[0101] Those skilled in the art would appreciate that the invention may
be used in a
number of applications other than tunnelling, e.g., surface mining, and also
underground mining.
[0102] It will also be appreciated by those skilled in the art that the
invention can take
many forms, and that such forms are within the scope of the invention as
claimed. The scope of
the claims should not be limited by the preferred embodiments set forth in the
examples, but
should be given the broadest interpretation consistent with the description as
a whole.
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