U.S. patent application number 12/234594 was filed with the patent office on 2010-03-25 for integrated locking control and status indicator for manually operated railway switch stand.
Invention is credited to Gary Click, Brent Duffner, Kenneth Ouelette, Bradley Smith.
Application Number | 20100072326 12/234594 |
Document ID | / |
Family ID | 42036642 |
Filed Date | 2010-03-25 |
United States Patent
Application |
20100072326 |
Kind Code |
A1 |
Click; Gary ; et
al. |
March 25, 2010 |
INTEGRATED LOCKING CONTROL AND STATUS INDICATOR FOR MANUALLY
OPERATED RAILWAY SWITCH STAND
Abstract
The invention relates to a device to be integrated with to a
manual switch stand, particularly for use in dark territory. The
device secures the spindle of the switch stand against rotation,
thereby preventing authorized throwing of the switches. The device
also contains sensors that will clearly indicate to an external
observer both the position of the switch points and the locked or
unlocked status of the switch stand. A particular sequence of steps
must be taken before an operator will be able to unlock the switch
stand and throw the switch, and further steps are required before
he can secure the switch stand and remove his key. The switch stand
must therefore be left in a locked state, and it continuously
indicates the status of the switch stand to a remote monitor.
Inventors: |
Click; Gary; (Birmingham,
AL) ; Duffner; Brent; (Pinson, AL) ; Smith;
Bradley; (Pell City, AL) ; Ouelette; Kenneth;
(St. Albert, CA) |
Correspondence
Address: |
MAHAMEDI PARADICE KREISMAN LLP
550 Winchester Boulevard, Suite 605
SAN JOSE
CA
95128
US
|
Family ID: |
42036642 |
Appl. No.: |
12/234594 |
Filed: |
September 19, 2008 |
Current U.S.
Class: |
246/393 |
Current CPC
Class: |
B61L 5/10 20130101; B61L
5/02 20130101 |
Class at
Publication: |
246/393 |
International
Class: |
B61L 5/00 20060101
B61L005/00 |
Claims
1. A rail switch stand comprising: an elongated spindle mounted for
rotation about a vertical axis and wherein rotation of said spindle
is adapted to cause actuation of a throw rod; a lever for manually
actuating rotation of said spindle, the plane of motion of said
lever being spatially offset from said axis; a plate lying
substantially in a horizontal plane and being coupled to an
intermediate portion of said spindle for co-axial rotation
therewith, said plate comprising at least one engagement surface
for engaging a locking bar, wherein engagement of said locking bar
in said at least one engagement surface locks said spindle against
rotation; and a lock sensor for sensing when said locking bar is
engaged in said engagement surface.
2. The rail switch stand of claim 1 further comprising an enclosure
mounted about said intermediate portion of said spindle, said plate
being disposed in said enclosure.
3. The rail switch stand of claim 1 wherein said at least one
engagement surface comprises a notch in said plate.
4. The rail switch stand of claim 1 wherein said plate further
comprises a second engagement surface, said at least one engagement
surface corresponding to a first position of said throw rod and
said second engagement surface corresponding to a second position
of said throw rod.
5. The rail switch stand of claim 4 wherein each of said engagement
surfaces comprises a notch.
6. The rail switch stand of claim 4 wherein said at least one
engagement surface and said second engagement surface are disposed
about said plate at 90 degrees of angular separation.
7. The rail switch stand of claim 1 further comprising a switch
position sensor for sensing the rotational position of said plate,
said rotational position corresponding to the position of said
throw rod.
8. The rail switch stand of claim 7 further comprising an enclosure
mounted about said intermediate portion of said spindle, said
plate, said lock sensor and said switch position sensor all being
disposed in said enclosure.
9. The rail switch stand of claim 8 wherein said switch position
sensor comprises two contacts corresponding to two angularly
displaced other contacts on said plate.
10. The rail switch stand of claim 7 wherein said switch position
sensor comprises two contacts corresponding to two angularly
displaced other contacts on said plate.
11. The rail switch stand of claim 1 further comprising a
retractable stop member for retaining said locking bar in a first
position corresponding to engagement with said engagement surface
when a key is in a locking state.
12. The switch stand of claim 11 further comprising retention means
to retain said key within said switch stand when said key is in a
non-locking state.
13. The rail switch stand of claim 1 wherein said locking bar is
vertically elongated and is displaceable into and out of engagement
with said engagement surface by lateral movement.
14. The rail switch stand of claim 13 wherein said lateral movement
of said locking bar is actuated by movement of a handle member.
15. The rail switch stand of claim 1, further comprising: a second
engagement surface disposed about said plate at 90 degrees of
angular separation from said first engagement surface; a switch
position sensor for sensing the rotational position of said plate,
said rotational position corresponding to the position of said
throw rod; said switch position sensor comprising two contacts
corresponding to two angularly displaced other contacts on said
plate.
16. An integrated lock control and status indication device for a
manually operated railway switch stand, comprising: a plate; a
locking member engageable with at least one engagement surface in
said plate to prevent rotation of said plate; a handle member to
control engagement and disengagement of said locking member with
said at least one engagement surface; a lock means to maintain said
locking member in engagement with said engagement surface until a
matching key has been inserted; and a first sensor to sense the
engagement and disengagement status of said locking member.
17. The device of claim 16, wherein said at least one engagement
surface corresponds to a rail switch position of normal or reverse,
and said locking member prevents rotation of said plate only if the
rail switch is fully in a normal or reverse position.
18. The device of claim 17, wherein said handle member can move
into a locked position only when said locking member is engaged
with said at least one engagement surface.
19. The device of claim 17, wherein said lock means retains said
key unless said locking member is engaged in said at least one
engagement surface.
20. The device of claim 16, wherein said engagement or
disengagement status is communicated to an external notification
device.
21. The device of claim 16, further comprising a second sensor to
sense the position of said plate and to provide an indication of a
rail switch position of normal or reverse.
22. The device of claim 21 wherein said indication of a rail switch
position is communicated to an external notification device.
23. A manually operated rail switch stand comprising: a throw
handle rotatably connected to a spindle, by which switch points may
be controlled; a plate through which said spindle passes, such that
said plate and said spindle rotate in a coordinated manner; a
locking member that may engage at least one engagement surface in
said plate to prevent rotation of said plate and said spindle; a
handle member to manually control engagement and disengagement of
said locking member with said at least one engagement surface; a
lock means that maintains said locking member in engagement with
said plate until a matching key has been inserted; and a first
sensor to monitor engagement and disengagement status of said
locking member.
24. The switch stand of claim 23, further comprising a second
sensor to monitor the position of said plate and to provide an
indication of a position of said switch points.
25. The switch stand of claim 23, wherein said engagement or
disengagement status is communicated to an external notification
device.
26. The switch stand of claim 24 wherein said indication of a rail
switch position is communicated to an external notification
device.
27. A method of operating a rail switch stand, comprising the
sequential steps of: inserting a key to move a retractable stop
member out of abutment with a locking member; turning a handle
member to disengage said locking member from a first engagement
surface on a plate; actuating a lever to rotate a spindle on which
said plate is coaxially mounted, thereby rotating said plate and
wherein rotation of said spindle causes rotation of a throw rod
operatively connected to said lever; and sensing when said locking
member is disengaged from said first engagement surface through a
first sensor means in operative communication with said locking
member and thereby determining a status of said switch stand.
28. The method of claim 27 comprising the further step of signaling
said status to an external notification device.
29. The method of claim 27 comprising the further step of sensing a
position of said throw rod through a second sensor means in
operative communication with said plate.
30. The method of claim 29 comprising the further step of signaling
the position of said throw rod to an external notification
device.
31. A method of securing a rail switch stand, comprising the
sequential steps of: moving a lever operatively connected to a
throw rod and to an elongated spindle, such that said throw rod is
in a reverse or normal position; actuating a handle member to
engage a locking member with an engagement surface on a plate
mounted on an intermediate portion of said spindle; sensing that
said locking member is engaged with said first engagement surface
with a sensor means; applying a retractable stop member to a
lateral portion of said locking member; and removing a key from a
lock means controlling said retractable stop member.
32. The method of claim 29 comprising the further step of locking
said lever in place, when said throw rod is in said normal or
reverse position.
33. The method of claim 31 comprising the further step of signaling
that said locking member is engaged with said first engagement
surface to an external notification device.
34. The method of claim 27 comprising the further step of sensing a
position of said throw rod through a second sensor means in
operative communication with said plate.
35. The method of claim 29 comprising the further step of signaling
the position of said throw rod to an external notification device.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a mechanism to provide a definite
indication of the position of the switch controlled by a switch
stand and to secure the stand against unauthorized switching, and
is particularly applicable for stands used in dark territory.
BACKGROUND OF THE INVENTION
[0002] A railroad switch includes moveable switch points (sometimes
called blades) that direct the wheels onto the appropriate track.
The switch points are driven from a first position, to direct the
train onto one track, to a second position, to direct the train
onto another track, by a power operated switch machine, or by a
manually operated switch stand. The points are locked in one
position until required to be switched back to the other position.
Rail terminology commonly refers to the switch point position for
the track most frequently used as the "normal" position, and the
position for the track less frequently used as the "reverse"
position.
[0003] A power operated switch machine is typically used in areas
of high rail traffic or in other areas where the expense of a
centrally controlled signal system can be justified. The switch
machine monitors whether the switch points have been locked and, if
so, in what position they are locked, and notifies the signal
system of this status. The signal system uses this information to
regulate approaching trains and to ensure safe operation given the
status of the switch points.
[0004] At locations where the cost of a power operated switch
machine is uneconomical, a manual switch stand may be used to
control the operation of the switch points. The manual switch stand
is operated by a railway employee standing adjacent to the track.
To prevent tampering, most manual switch stands located outside of
classification yards are locked with a padlock. To operate the
switch stand, the employee must unlock the padlock, disengage the
locking mechanism holding the switch points, and lift or rotate the
hand throw lever to move the points to the new position. The
locking mechanism must then be engaged and the employee must
visually confirm that the points are held in the intended position
before allowing a train to pass over the switch. Before leaving the
switch, the employee must leave the switch points locked in a
specified position, and reattach and relock the padlock. Safe
operation of this type of system is ensured only if all employees
are familiar with, and follow, a detailed set of rules in order to
secure the switch stand.
[0005] However, a single human error can result in a manual switch
stand being left unattended in an incorrect position. If the switch
stand is left unlocked, vandals may tamper with the hand throw
lever, leaving the switch points in an unexpected position, or in a
position in which the points are not locked in either of the
expected positions. Numerous train accidents have been documented
as a result of employee failure to properly secure a manual switch
stand. U.S. Pat. No. 5,642,870 to Sargis describes a switch stand
having a locking device to clamp a throw lever within a cradle, but
no means to secure that locking device against unauthorized
operation.
[0006] The simplest way to lock a manually operated switch stand is
to immobilize the throw lever. A switch stand system including a
padlock to secure the hand throw lever is shown in U.S. Pat. No.
6,164,601 to Scheer and McCord. U.S. Pat. No. 383,965 to Manning
shows a spring-biased bolt extending into a recess in a throw
lever, securing the lever until a key is inserted to retract the
bolt. U.S. Pat. No. 1,092,259 to Ham shows an integral key-based
lock to secure the throw lever. U.S. Pat. No. 379,708 to Manning
shows a lock-case on the throw lever which slides to secure the
lever within a guide on the switch stand. A series of patents
issued to Torpey (U.S. Pat. Nos. 952,022; 949,098; 900,131; and
868,305) show a locking bolt in a casing integrated into the switch
stand housing, which engages notches provided in the hub of the
throw lever, immobilizing the hub and lever until the bolt is
raised.
[0007] A switch stand may also be secured by locking other parts of
the switch stand. A system including multiple padlocks to secure
various parts of the switch stand is shown in U.S. Pat. No.
7,267,304 to Scheer. Generally, padlock-based security systems rely
heavily on the competence and attention of the operator, as
discussed above.
[0008] In most situations, if a key is to be used to lock and
unlock the switch stand, it is preferable that the locking
mechanism physically retain the key in the lock until the points
are confirmed to be fully locked in the normal or reverse position,
and the stand is secured against further movement. This prevents a
switch operator from leaving a switch open without also leaving his
key behind, and also should prevent a key from being lost during
switch operation. Further, if a key is left behind, it may be
traced to a particular operator. U.S. Pat. No. 525,678 to Dedel
describes a specialized key that is retained within a lock once the
lock is opened to release the throw lever, and further includes a
belt worn by the operator, to which the key is attached, rendering
it very difficult to leave a switch open accidentally.
[0009] In addition to properly securing the switch points
controlled by a manual switch stand, it is important to monitor the
position of the switch points and to clearly communicate that
information to an oncoming train before it passes over the switch.
If the switch point status can be visually displayed to an oncoming
train, this allows the train to stop for an incorrectly positioned
switch. Status display may be done through a flag-based system,
such as that shown in U.S. Pat. No. 7,267,304 to Scheer, which
shows a multi-coloured flag-based system, wherein the colour of the
flag displayed to a train operator indicates the position of the
switch. U.S. Pat. No. 2,740,041 to Marcum describes a status
indicator which uses appropriately colored lights to indicate the
switch position. U.S. Pat. No. 5,470,035 to Sagis shows an
electrical switch stand having lights to indicate switch
position.
[0010] In order to monitor the position of the associated switch
points, several systems have been used. U.S. Pat. No. 5,348,257 to
Ocampo shows a detection system located near the stock rail, along
with a heating element to prevent adverse weather conditions from
affecting the efficiency of the detector. U.S. Pat. No. 2,740,041
to Marcum describes a status indicator having electrical contacts
located between the rails in the switch, which respond to movements
of the rod connecting the points to illuminate appropriately
colored signal lights. U.S. Pat. No. 6,427,949 to Hager et al.
describes a point detection system based on a linear variable
differential transformer. Many other systems use proximity sensors.
For example, U.S. Pat. No. 6,149,106 to McQuistian describes a
point position indicator having proximity sensors located on the
stock rails at a switch. In U.S. Pat. No. 5,806,809 to Danner,
proximity sensors are located near the switch points, with other
proximity sensors being located within the switch machine to
monitor the position of various lock rods and lock bars. U.S. Pat.
Nos. 6,186,448 to Wydotis et al., 6,688,559 to Brushwood and
6,296,208 to Franke all incorporate proximity sensors near a
sleeved point detection bar.
[0011] A common monitoring system is a switch circuit controller,
such as that shown in U.S. Pat. No. 5,598,992 to Chew. This type of
controller is typically mounted to the railroad ties and is
connected to the operating rod or to one or more switch rods. Any
movement of a rod causes a crank arm associated with the controller
to rotate, in turn rotating a cam shaft, and causing the
appropriate electrical contacts to be made within the controller
housing. However, a switch circuit controller must be regularly
adjusted to compensate for lost motion between the cams of the cam
shaft, the crank arm and the operating rod, as well as to ensure
that all internal movable contacts are properly aligned. This is
time-consuming, expensive and can be difficult to do correctly.
U.S. Pat. No. 6,484,974 to Franke discloses a switch machine
controller using Namur sensors to detect point positions. U.S. Pat.
No. 6,062,514 to McQuistian also discloses a switch circuit
controller based on proximity sensors.
[0012] It is therefore an object of the invention to provide a
locking mechanism and a point position indicator that overcomes the
foregoing deficiencies.
[0013] In particular, it is an object of the invention to provide a
simple means to secure a switch stand and to obtain constant
indications of the status of the switch stand and of the associated
switch.
[0014] It is a further object of the invention to provide a device
which will secure a switch and will provide constant indications of
the status of the switch, without the need for ongoing adjustment
of the internal components of the device.
[0015] These and other objects of the invention will be appreciated
by reference to the summary of the invention and to the detailed
description of the preferred embodiment that follow.
SUMMARY OF THE INVENTION
[0016] Generally speaking, the invention employs two main
mechanisms: an integrated locking system and an arrangement of
sensors that can continuously notify an external monitor or
monitoring device as to the status of the switch points.
[0017] The integrated lock system is designed to require the
operator to insert a key before throwing the switch point lock
handle. The lock handle must be physically disengaged (unlocked)
before the switch points can be moved, but the handle cannot be
disengaged until the key is turned. Further, once the key is
inserted properly it is retained within the device and can only be
removed once the locking handle has been returned to an engaged
(locked) position, presumably after the switch points have been
moved to the desired position.
[0018] To ensure proper and safe operation of the switch, the
locking handle cannot be engaged unless the switch points are
either in the "normal" position or the "reverse" position. The
locking handle will not lock (and the key therefore cannot be
removed) if the switch points are at any position between normal
and reverse. The operator cannot leave the switch points unlocked
in a mid-throw position without leaving the key behind.
[0019] Sensors are used to continuously monitor the location and
status of the switch stand, whether it is unlocked, locked in the
normal position, or locked in the reverse position. An external
device or monitor receives information obtained from these sensors
and broadcasts the status of the switch points so that approaching
trains can be handled accordingly.
[0020] The locking control and status indicator prevents human
error from compromising the safety of manually operated railway
switches. It requires employees operating a switch stand to leave
the stand in a locked state, and it continuously indicates the
status of the switch stand (unlocked, locked in normal, or locked
in reverse) through an external notification device to a remote
monitor.
[0021] In one aspect, the invention comprises a rail switch stand
comprising an elongated spindle mounted for rotation about a
vertical axis, wherein rotation of the spindle is adapted to cause
actuation of a throw rod; a lever for manually actuating rotation
of the spindle, the plane of motion of the lever being spatially
offset from the axis; a plate lying substantially in a horizontal
plane and being coupled to an intermediate portion of the spindle
for co-axial rotation therewith, the plate comprising at least one
engagement surface for engaging a locking bar, wherein engagement
of the locking bar in the engagement surface locks the spindle
against rotation; and a lock sensor for sensing when the locking
bar is engaged in the engagement surface. The engagement surface
may be a notch in the plate. The locking bar may be vertically
elongated and displaceable into and out of engagement with the
engagement surface by lateral movement, which may be effected by
movement of a handle member.
[0022] In a further aspect, the invention comprises an enclosure
mounted about an intermediate portion of the spindle, and the plate
is disposed in the enclosure.
[0023] In yet a further aspect, the rail switch stand of the
invention may comprise a second engagement surface, each of the
engagement surfaces corresponding to first and second positions of
the throw rod. The engagement surfaces may be disposed about the
plate at 90 degrees of angular separation.
[0024] In another aspect, the invention comprises a rail switch
stand having a switch position sensor for sensing a rotational
position of the plate, the rotational position corresponding to the
position of the throw rod. In a more particular aspect, the switch
position sensor may comprise two contacts corresponding to two
angularly displaced other contacts on the plate.
[0025] In yet another aspect, the invention comprises a retractable
stop member for retaining the locking bar in a first position
corresponding to engagement with the engagement surface when a key
is in a locking state.
[0026] In another aspect, the invention comprises a switch stand
having retention means to retain a key within the switch stand when
the key is in a non-locking state.
[0027] In a more particular aspect, the invention comprises a rail
switch stand having a second engagement surface disposed about the
plate at 90 degrees of angular separation from a first engagement
surface; and a switch position sensor for sensing the rotational
position of the plate, the rotational position corresponding to the
position of the throw rod; the switch position sensor comprising
two contacts corresponding to two angularly displaced other
contacts on the plate.
[0028] In another aspect, the invention comprises an integrated
lock control and status indication device for a manually operated
railway switch stand, comprising a plate; a locking member
engageable with at least one engagement surface in the plate to
prevent rotation of the plate; a handle member to control
engagement and disengagement of the locking member with the at
least one engagement surface; a lock means to maintain the locking
member in engagement with the engagement surface until a matching
key has been inserted; and a first sensor to sense the engagement
and disengagement status of the locking member. In a further
aspect, the engagement surface corresponds to a rail switch
position of normal or reverse, and the locking member prevents
rotation of the plate only if the rail switch is fully in a normal
or reverse position. In yet a further aspect, the handle member can
move into a locked position only when the locking member is engaged
with the engagement surface, and the lock means may retain the key
unless the locking member is engaged in the engagement surface.
[0029] In another aspect of the invention, the engagement or
disengagement status of the switch and the switch stand may be
communicated to an external notification device.
[0030] In another aspect of the invention, the device may comprise
a second sensor to sense the position of the plate and to provide
an indication of a rail switch position of normal or reverse. The
indication of a rail switch position may be communicated to an
external notification device.
[0031] In yet another aspect, the invention comprises a manually
operated railway switch stand comprising a throw handle rotatably
connected to a spindle, by which switch points may be controlled;
an plate through which the spindle passes, such that the plate and
the spindle rotate in a coordinated manner; a locking member that
may engage at least one engagement surface in the plate to prevent
rotation of the plate and the spindle; a handle member to manually
control engagement and disengagement of the locking member with the
at least one engagement surface; a lock means that maintains the
locking member in engagement with the plate until a matching key
has been inserted; and a first sensor to monitor engagement and
disengagement status of the locking member. The invention may
further comprise a second sensor to monitor the position of the
plate and to provide an indication of a position of the switch
points.
[0032] The engagement or disengagement status and/or the indication
of a rail switch position may be communicated to an external
notification device.
[0033] In another aspect, the invention comprises a method of
operating a rail switch stand, comprising the sequential steps of
inserting a key to move a retractable stop member out of abutment
with a locking member; turning a handle member to disengage said
locking member from a first engagement surface on a plate;
actuating a lever to rotate a spindle on which said plate is
coaxially mounted, thereby rotating said plate and wherein rotation
of said spindle causes rotation of a throw rod operatively
connected to said lever; and sensing when said locking member is
disengaged from said first engagement surface through a first
sensor means in operative communication with said locking member
and thereby determining a status of said switch stand. The status
sensed may be signaled to an external notification device. The
method may include the further step of sensing a position of said
throw rod through a second sensor means in operative communication
with said plate. The position sensed may also be signaled to an
external notification device.
[0034] In another aspect, the invention comprises a method of
securing a rail switch stand, comprising the sequential steps of
moving a lever operatively connected to a throw rod and to an
elongated spindle, such that said throw rod is in a reverse or
normal position; actuating a handle member to engage a locking
member with an engagement surface on a plate mounted on an
intermediate portion of said spindle; sensing that said locking
member is engaged with said first engagement surface with a sensor
means; applying a retractable stop member to a lateral portion of
said locking member; and removing a key from a lock means
controlling said retractable stop member. The method may comprise
the further step of locking said lever in place, when said throw
rod is in said normal or reverse position. A signal that said
locking member is engaged with said first engagement surface may be
sent to an external notification device. The method may comprise
the further step of sensing a position of said throw rod through a
second sensor means in operative communication with said plate. The
position of said throw rod may also be signaled to an external
notification device.
[0035] The foregoing was intended as a broad summary only and of
only some of the aspects of the invention. It was not intended to
define the limits or requirements of the invention. Other aspects
of the invention will be appreciated by reference to the detailed
description of the preferred embodiment and to the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] The preferred embodiment of the invention will be described
by reference to the drawings in which:
[0037] FIG. 1 is a perspective view of a switch stand incorporating
the locking control and status indicator of the invention;
[0038] FIG. 2 is a top perspective view of the switch stand of FIG.
1, with the top cover of the locking control and status indicator
of the invention removed; and
[0039] FIG. 3 is a sectional view of the locking control and status
indicator of the invention, taken along line 3-3 of FIG. 2;
[0040] FIG. 4 is an enlarged sectional view of the locking control
and status indicator of the invention, taken along line 4-4 of FIG.
2.
DETAILED DESCRIPTION OF THE INVENTION
[0041] Referring to FIG. 1, the switch stand 10 is preferably a
manual stand comprising a base 12 supporting a lever or throw
handle 14 which moves between normal and reverse positions and may
be secured in those positions by foot latches 16. FIG. 1
illustrates the throw handle 14 having a yoke 17 to interact with
the foot latch 16, but it will be understood that any throw handle
14 of suitable configuration may be used, and in particular that
the throw handle 14 need not have any yoke 17, but if a yoke is
present, it may be of any suitable configuration. In addition, a
secondary locking method, such as a padlock (not shown) may be used
to secure the throw handle 14 to one of the foot latches 16, as is
known in the art. The actuation of the throw handle 14 causes a
vertical, elongated spindle 18 to rotate, moving the appropriate
rods, such as throw rods, and throwing the associated switch points
(not shown). Rotation of the spindle 18 also moves the mounted flag
or target 22 to an appropriate position to visually indicate the
position of the switch points.
[0042] Switch stand 10 is further fitted with an extended support
24 terminating in an enclosure 26 designed to house the locking
control and status indicating apparatus. As best shown in FIGS. 2
and 3, the spindle 18 passes through the enclosure 26 and is fitted
within a plate, such as index plate 28, inside the enclosure 26.
The spindle 18 is preferably fitted within index plate 28 such that
rotation of the spindle 18 causes index plate 28 to rotate in a
coordinated, preferably essentially co-axial, manner. Index plate
28 comprises one or more engagement surfaces, which may be of any
appropriate configuration, such as notches 30, and preferably
comprises two notches, one corresponding to a normal switch
position, and the other corresponding to a reverse switch
position.
[0043] A locking member, such as lock bar 32, is positioned to
engage the index plate 28, and may be spring biased to remain
engaged with the index plate 28, or to force the lock bar 32 out of
engagement with the index plate 28. When the lock bar 32 engages
either of two notches 30, the index plate 28 cannot rotate. This
also prevents the spindle 18 from rotating, and therefore prevents
the throw handle 14 from being rotated, preventing the throw rod
from being actuated and the switch points from being thrown.
[0044] Lock bar 32 is moved in and out of engagement with the index
plate 28 by operation of a handle member, such as lock handle 34
(see FIG. 1), which protrudes from the enclosure 26. Lock handle 34
(see FIG. 1) is coupled to the lock bar 32 by any suitable means,
such as a screw or bolt. As an additional safety feature, one or
more shear bolts 36 may be used to couple the two assemblies. Shear
bolt 36 is designed to fail if excessive force is applied to the
lock handle 34, as might be done in an attempt to defeat the
locking mechanism of the switch stand 10. Lock handle 34 is
preferably made readily visible in order to allow an operator to
easily determine the position of the lock. For example, the lock
handle 34 may be somewhat large, or it may be painted a highly
visible or luminous colour. In addition, the lock handle 34
preferably has at least two distinct positions, such as vertical
and horizontal, so that an operator can easily visually verify
whether it is locked or unlocked.
[0045] As best seen in FIG. 4, a lock mechanism, such as lock core
38, is preferably located near the lock handle 34, and may be
operated by a regular mechanical key or an electronic key (not
shown). Lock core 38 is preferably located under an overhang 40 of
the enclosure 26, or under some other type of protective hood, in
order to protect it from the elements and from tampering. The lock
core 38 preferably retains an inserted key, by mechanical or
electrical retention, as appropriate, at all times when the switch
stand 10 is unlocked or when the switch points are in a mid-throw
position. The lock core 38 preferably is in a locked state by
default, such as by spring-bias means or magnetic means, such that
the key can only be inserted or removed when the lock core 38 is
locked. When the lock core 38 is in a locked state, a retractable
stop member, such as lock core cam 42, abuts the lock bar 32,
pressing it into the notch 30 and preventing it from moving out of
contact with the index plate 28 unless lock core 38 is opened. This
prevents unauthorized tampering with the switch points, and also
prevents an operator from accidentally leaving the switch unlocked,
unless he also leaves his key behind.
[0046] Enclosure 26 further houses one or more sensors, which sense
and provide information regarding the status of the switch and
switch stand. In the preferred embodiment, a lock sensor, which may
be a lock bar switch 44 (FIG. 2), is in contact with the lock bar
32 via one or more contacts 46, which provides an indication of
whether the lock bar 32 is engaged or disengaged with the notch 30
in the index plate 28. If the lock bar 32 is not engaged with one
of the notches 30, the contact 46 on the lock bar switch 44 will
open, indicating that the switch is unlocked.
[0047] A second sensor, such as directional switch 48 which
determines the switch position, is also located in the enclosure
26, in order to monitor the position of the index plate 28 as it
rotates between the normal and reverse positions. The rotational
position of the index plate 28 corresponds to the position of the
railroad switch. Preferably, the directional switch 48 comprises at
least two contacts 50, 52 (FIG. 3), one of which is closed only
when the railroad switch is in the normal position and the other of
which is closed only when the railroad switch is in the reverse
position. The pair of contacts provides two distinct signals, each
of which can be correlated to a specific switch position. The
contacts 50, 52 may be actuated by any suitable engagement with the
index plate 28, such as fitting into notches in the circumference
of the index plate 28 or by coming into contact with teeth or other
specifically selected contact areas on the index plate 28. The
signals produced by each of the lock bar switch 44 and the
directional switch 48 are preferably provided to a remote monitor
by an external notification system 54. The external notification
system may be of any type known in the art, including but not
limited to, fixed wayside signals; analogue radio broadcasts to the
crew on an oncoming train, which may be triggered by DTMF, or
automatically as the train crosses sensors along the track; digital
radio broadcasts to special devices in an oncoming train; and
analogue or digital messages to a remote rail traffic control
office.
[0048] Because of the self-contained nature of the locking control
and status indicator, and the relatively simple binary nature of
the signals received from the lock bar switch 44 and the
directional switch 48, the invention is simple to operate and
maintain. In particular, the invention is not subject to serious
impact or vibrations from passing trains or otherwise during
operation, and therefore does not require continuous adjustment
throughout the lifetime of the device.
[0049] The enclosure 26 can also be designed to accommodate
additional equipment to enhance the functionality of the switch
stand 10. For example, a remote locking mechanism may be used in
addition to the lock core cam 42, to further secure the lock bar
32. The remote locking mechanism, which may comprise a second lock
bolt or any other means to immobilize the lock bar 32, would
preferably normally be engaged, preventing any manual actuation of
the switch stand 10. Upon receiving a command from a remote or
local source, the remote locking mechanism would disengage from the
lock bar 32, allowing the switch stand 10 to be operated as
described above. Upon completion of the switching operation, the
remote locking mechanism would return to its normal default locked
condition.
[0050] The enclosure 26 may also be fitted with miniature
communication equipment to allow two-way communications with the
switch stand 10. These communications may take any suitable form,
such as conventional radio frequencies currently used by railways,
commercial cellular phone systems or private satellite
communications.
[0051] A Global Positioning System receiver may also be
incorporated into the enclosure 26. This device would allow the
switch stand 10 to distinguish its unique position in an area where
several similarly fitted switch stands are operating.
Operation
[0052] In operation, the switch stand 10 is initially locked and
aligned to position the railway switch points to allow travel along
a selected railroad route, in either the reverse or normal
direction. An operator would insert his electronic or mechanical
key into the lock core 38, releasing the lock core cam 42 from its
abutment with the lock bar 32, thereby unlocking the switch stand
10. A mechanical key would likely release the lock core cam 42 by
rotating the key, while an electronic key could be rotated, or may
send a signal to the lock core cam 42, instructing it to release.
At this stage, the lock bar switch 44 is open, indicating that the
switch stand 10 is unlocked. Because the index plate is still in
contact with one of the contacts 50, 52 in the directional switch
48, the directional switch 48 will indicate that the switch is in
the appropriate position, either reverse or normal. The external
notification system 54 will consider these two readings in
combination and will indicate that the turnout is unsafe for
transit at track speed.
[0053] The key is preferably retained by the lock core 38, such as
by mechanical, electrical magnetic or any other suitable means, and
cannot be removed until the switch stand 10 is relocked.
[0054] The operator actuates the lock handle 34, which in turn
frees the lock bar 32 from the notch 30 in the index plate 28. This
allows the index plate 28 to rotate freely. Upon pressing the foot
latch 16, the operator can move the throw handle 14 from its
current position to the opposite position, e.g. clockwise, in FIG.
1. The spindle 18 rotates, moving the switch points and causing the
index plate 28 to rotate. As the index plate 28 rotates, it breaks
contact with the contact in the directional switch 48, causing the
directional switch 48 to indicate that the switch points are out of
position, i.e. not in the reverse or normal position. The lock bar
switch 44 is still open, indicating that the switch is unlocked.
When these two readings are combined, the external notification
system 54 will indicate that the turnout is unsafe for transit at
track speed.
[0055] If a secondary locking mechanism, such as a padlock on the
foot latch 16, is used, the operator would typically unlock and
remove the padlock at any point prior to depressing the foot latch
16.
[0056] As the rotation of the throw handle 14 is completed, it will
engage the opposite foot latch 16, and the index plate 28 will
complete its rotation, allowing the notch 30 to engage with lock
bar 32. The index plate 28 will also close the appropriate contact
50 or 52 in the directional switch 48. The external notification
system 54 will therefore signal that the switch is in the normal or
reverse position, and that the switch is still unlocked, rendering
the switch unsafe for transit at track speed.
[0057] The operator then returns the lock handle 34 to its original
position, engaging the lock bar 32 with notch 30. The operator can
then rotate his key to the original insertion position, if
necessary, re-engaging the lock core cam 42 with the lock bar 32,
and forcing the lock bar 32 to remain within the notch 30. The lock
bar 32 then completes the circuit with the contacts 46 of the lock
bar switch 44, so the lock bar switch 44 can indicate that the
switch is locked. The external notification system 54 can therefore
signal the remote monitor that the switch is in the normal or
reverse position and that the switch is locked, so that it is safe
for transit. These indications reassure the operator and the remote
monitor that the switch is in a proper position and is secure
against tampering or operator negligence.
[0058] If a secondary locking mechanism, such as a padlock on the
foot latch 16, is used, the operator would preferably reattach and
lock the padlock on to the foot latch 16 holding the throw handle
14. The switch is then further secured against tampering.
[0059] It will be appreciated by those skilled in the art that
other variations to the preferred embodiment described herein may
be practised without departing from the scope of the invention,
such scope being properly defined by the following claims.
* * * * *