Note: Descriptions are shown in the official language in which they were submitted.
CA 02356487 2001-08-31
TITLE OF INVENTION
ASSIST ROD AND BASKET ASSEMBLY
TECHNICAL FIELD OF THE INVENTION
This invention relates to assist rod and basket assemblies for throwing
railway
switch points.
BACKGROUND OF THE INVENTION
Railway switches generally include a switch machine mounted on the outside of
the rails adjacent the turnout points. The switch machine actuates a throw rod
that is
connected to a switch rod extending between the switch points.
A lost motion device, commonly referred to as a basket, may be provided
between
the throw rod and the switch rods to take up some of the motion of the throw
rod before
transmitting it to the switch rods. The basket enables a signal maintainer to
adjust both
the initial position and the throw of the switch rod to account for differing
design
applications of the rods and the total linkage length of the rod and to
compensate for
differing design locations of the switch machine in relation to the switch
point.
In order to ensure coordinated movement between the point and heel ends of the
movable rails, assist rods are used with longer switch points. For convenience
the point
and heel ends of the assembly are referred to as the front and rear ends
respectively. The
assist rods act to transfer force from the front end switch rods to those at
the rear end.
Operating or throw rods extend from the switch rods to the assist rod. The
assist rod
extends along the outside of the running rail, but on the side of the tracks
opposite to the
switch machine. This is done to accommodate the clearance requirements between
switch
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CA 02356487 2001-08-31
accessories and the rail (to allow for tamping and protection from dragging
equipment on
passing trains). Juxtaposing the switch machine and the assist rod would
require
unusually long ties to maintain the necessary clearance.
S In a typical arrangement, the throw rod is connected to the switch rods by
means of
a basket. The switch rods are in turn connected to the switch point (rails).
The switch
rods are also connected to a connector rod that extends under the running rail
to a crank
stand located on the outside of the running rail. The crank stand includes a
lever, one end
of which is connected to the connector rod and the other end of which is
connected to an
elongated assist rod running parallel to the running rail. The lever is
mounted on a hinge
on the crank stand such that when the connector rod causes one end of the
lever to rotate
about the hinge, the other end causes axial displacement of the assist rod.
The assist rod
is attached at its rear end to a similar lever and crank stand assembly that
is in turn
connected to a connector rod. The rear end connector rod is connected to a
basket which
1 S transfers movement of the connector rod to the rear end switch rods.
It has also been proposed to used a torsional assist rod mounted on the side
of the
track that is distal from the switch machine. The assist rod is connected by a
pin to the
end of the switch rod or to the end of a connector rod. Displacement of the
front end
switch rod causes the assist rod to rotate. By a similar arrangement at the
rear end,
rotation of the assist rod throws a connector rod connected to the rear end
switch rod. It
is also known to locate torsional assist rods between the rails.
One disadvantage of prior art assist rod assemblies is that the basket is
located
between the rails to allow for tamping on the outside of the rails. However,
the location
of the baskets between the rails results in limited accessibility due to hot
air ducts used for
snow removal that are frequently mounted between the rails over the top of the
basket. In
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CA 02356487 2001-08-31
addition, the signal maintainer must place himself in the direct path of
oncoming rail
traffic to service or adjust the device.
In addition, the switch ties must accommodate both a switch machine (on one
end)
S and an assist rod and its associated linkage components (on the other end).
As a result,
relatively long ties (typically 14 feet long) are needed. In the case of
crowded rail yards,
the loss of space resulting from adjacent switches becomes critical.
It is an object of the present invention to provide an improved assist rod
assembly
that overcomes the foregoing deficiencies.
SUMMARY OF THE INVENTION
The invention provides an assist rod and basket assembly. The summary herein
provides a general overview of the preferred embodiment and is not intended to
define
essential features of any aspect of the invention.
The front and rear baskets of the invention play a dual role. They both take
up lost
motion and they actuate the assist rod.
The front basket includes an upwardly extending head portion adapted to link
to a
torsional assist rod and to rotate the assist rod when the basket undergoes
lateral
movement (transverse to the running rails) as a result of the switch being
thrown. An
elongated hinge connection allows the basket to be restricted to substantially
lateral
displacement while causing rotation of link arms attached to the assist rod.
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CA 02356487 2004-09-23
The head of the basket comprises a bore for receiving a pin for rotation in
the bore.
A pair'of link arms extend from the ends of the pin. The link arnos engage the
assist rod or
an assist rod assembly to cause it to rotate when the basket undergoes lateral
movement
transverse to the assist rod. The assist rod or a portion of the assist rod
assembly is
separately mounted for rotation in a sleeve on a support clip. The basket
comprises an
internal structure similar to prior art structures. A threaded connector rod
slidably extends
through the basket. Movement of the basket in relation to the connector rod is
limited by
nuts threaded onto the rod at each end of the basket. Adjustment of the nuts
serves to adjust
the amount of lost motion to be taken up by the basket before actuating the
connector rod by
abutment of the basket with the nuts.
The rear basket comprises two link arms, one end of which arms engage the
assist
rod. The other ends are rotatably mounted on pins extending from opposed sides
of a slide
block sandwiched between the ends of the link arms. A connector rod is
slidably
received in the slide block. Nuts are disposed on the connector rod at each
side of the slide
block so as to enable adjustment of the amount of flee motion that the basket
will be
allowed to undergo before actuating displacement of the connector rod by
abutment of the
basket to the nuts.
The baskets are at least partially housed in hollow ties which also house
rodding
associated with the switch. This avoids interference of the baskets with
tamping, even
when the baskets are located on the outside of the running rail.
The invention allows for a more compact switch assembly in which the baskets
and
~e assist rod may be located, in the preferred embodiment, on the same side of
the rails as
the switch machine. This is turn allows for the use of shorter ties. The
invention also has
the advantage of comprising a smaller number of components than the assist rod
assemblies
of the prior art.
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CA 02356487 2004-09-23
In one aspect the invention is a railroad switch assembly comprising point and
heel
end switch rods (or switch rod assemblies) housed in hollow ties, and a front
basket that is
at least partially housed in the point end hollow tie and that is connected to
the assist rod to
directly actuate movement of the assist rod when the basket is displaced.
In another aspect, the front basket is located between the switch machine and
the
running rail adjacent the switch machine.
Lateral displacement of the front basket causes rotation of the assist rod.
The front basket is operatively connected to the assist rod by at least one
torsion arm
extending between the assist rod and the front basket.
In another aspect, the invention is a railroad switch assembly comprising a
switch
machine, a throw rod actuatxd by the switch machine, a front basket for
adjusting the throw
applied by the throw rod to a point end switch rod or switch rod assembly, and
wherein the
front basket directly actuates rotation of a torsional assist rod or rod
assembly. In more
specific aspects of the invention; displacement of the front basket is
substantially lateral, the
point end switch rod assembly is housed in a hollow tie, and the front basket
is at least
partially housed in the hollow tie.
In another aspect, the invention is a railroad switch assembly comprising a
switch
machine, a throw rod actuated by the switch machine, and a front basket
located between
the switch machine and a running rail proximal to the switch machine.
Other aspects of the invention relate to the structure of the front and rear
baskets and
basket assemblies as disclosed herein.
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CA 02356487 2001-08-31
These and further aspects of the invention will be appreciated by reference to
the
detailed description of the preferred embodiment and are defined by the claims
that
follow.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a layout drawing (plan view) of a prior art switch and associated
assist rod
assembly;
Fig. 2 is a longitudinal cross-section of a prior art basket assembly;
Fig. 3 is a layout drawing (plan view) of the assist rod assembly according to
the
1 S preferred embodiment of the invention;
Fig. 4 is a side elevation of the front end basket assembly taken along line 4-
4 of
Fig. 3;
Fig. 5 is a side elevation of the rear end basket assembly taken along line S-
5 of
Fig. 3;
Fig. 6 is an end view of the front basket assembly according to the preferred
embodiment but not including the assist rod;
Fig. 7 is a plan view of the front basket assembly without the assist rod;
Fig. 8 is a cross-section of the front basket assembly;
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CA 02356487 2001-08-31
Fig. 9 is a plan view of the front basket and assist rod assembly;
Fig. 10 is a side elevation of the rear basket;
Fig. 11 is an end view of the rear basket and assist rod assembly; and,
Fig. 12 is a plan view of the rear basket and assist rod assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
OF THE INVENTION
Fig. 1 illustrates a fairly typical prior art switch layout in which the
assist rod and
basket assembly is shown. The switch is used to throw the switch point (rails
12, 14).
A switch machine 16 is mounted on the outside of the rails on a switch stand
plate
attached to the ends of elongated ties 18. Switch machine 16 actuates a throw
rod 20 that
is connected to a pair of switch rods 22, 24 connected end to end and
extending between
the points 26, 28 of the switch point rails.
A front basket 30 is disposed between the throw rod 20 and the switch rods 22,
24.
As is known, the basket 30 is adapted to slide a predetermined amount along
the throw
rod 20 before the basket will engage so as to actuate movement of the switch
rods. As
will be appreciated by reference to Fig. 2, the predetermined amount may be
adjusted in
the field by displacing basket nuts 31, 33 that are engaged on a threaded
portion of the
throw rod 20.
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CA 02356487 2001-08-31
The switch may also include ancillary rodding that may include a detector rod,
a
lock rod and the like, none of which is illustrated in Fig. 1.
In order to ensure coordinated movement between the front (point) and rear
(heel)
ends of the switch point, assist rods 34 extend along the outside of the
running rail 36 on
the side of the tracks opposite to the switch machine 16. One or more
connector rods 38
extend parallel to the switch rods and under the running rail 36. One end of
connector
rod 38 is attached to switch rod 24 while the other end is connected to a one
arm 40 of a
lever 42 that is hinged to a crank stand 44 located on the outside of the
running rail 36.
Second and third arms 46, 47 of the lever are hinged to elongated assist rod
34
running parallel to the running rail 36. When the connector rod 38 causes arm
40 of the
lever to rotate about the hinge, the other arms 46, 47 cause axial
displacement of the assist
rods 34. The assist rods 34 are hinged at their rear end to arms 50, 51 of a
similar lever
52. Arm 54 of lever 52 is in turn hinged to a connector rod 56. Connector rod
56 is
connected to a rear basket 58 which transfers movement of the connector rod to
the rear
end switch rods. Rear basket 58 is also a lost motion basket and is attached
to rear switch
rods 60, 62 that are in turn attached to the heel end of the switch point
rails 12, 14.
Additional passive connector rods 64, 65, 66 may be provided intermediate the
front and rear end rods in order to coordinate the movement of the opposed
movable rails.
A typical basket assembly according to the prior art is shown in Fig. 2.
Housing
72 includes a passageway so as to accommodate a threaded throw rod 74
therethrough.
Conical nuts 78, 80 are disposed on the threaded rod such that the extended
portions 82,
83 of the nuts extend into the housing 72 and provide a bearing surface for
axial
displacement of the housing. The housing 72 includes a neck portion 73 located
medially
of the housing. Neck 73 is of such a diameter to allow passage of the throw
rod 74 but
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CA 02356487 2001-08-31
not of the extended portions 82 of the nuts. The length of the portions 82 is
greater than
the depth of the opposed recesses 75, 77 of the housing. As a result, relative
movement
between the nut and the housing is limited by abutment of the nut against the
neck 73. It
will be appreciated that movement between one of the nuts and the housing may
therefore
S take place before the nut will abut the neck of the housing and force the
housing to
displace.
Referring now to Fig. 3, the preferred embodiment of the invention finds
application where the front and rear switch rods 84 and 86 are housed within
hollow ties
88, 90. A "hollow tie" as referred to herein and in the art refers to a
substantially three
sided channel with an open upper end and having the approximate width and
depth of a
railroad tie. Such hollow ties are typically made of metal. Additional
rodding, such as a
lock rod 92, a detector rod 94 and a rod 96 for use in conjunction with the
lock rod and
the detector rod, will typically also be housed within a hollow tie.
Referring to Fig 4, a switch rod assembly 84 comprises switch rod 85 which is
connected to another rod 98, herein referred to as a "connector basket rod",
which is also
housed within hollow tie 88. Although the switch rod assembly of the preferred
embodiment includes a switch rod and a connector basket rod, it will be
appreciated that
the switch rod assembly may consist of a single switch rod.
Connector basket rod 98 is attached to front basket 100 through which extends
throw rod 102. Throw rod 102 is attached to the throw bar of the switch
machine 104.
Front basket 100 is illustrated in detail in Figs. 6, 7 and 8. Housing 106
includes a
passageway enabling the passage therethrough of throw rod 102. The portion of
throw
rod 102 in the vicinity of basket 100 is threaded to receive elongated
"conical" nuts 108,
110. Connector basket rod 98 is attached to the housing by bolts 112, 114.
Movement of
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CA 02356487 2004-09-23
the basket 100 in relation to the throw rod 102 is limited by the position of
the nuts 108, 110
threaded onto the throw rod at each end of the basket. Adjustment of the
position of the
nuts serves to adjust the amount of lost motion to be taken up by the basket
before actuating
the throw rod by abutment of the neck 105 of the basket with the ends of the
nuts.
The basket housing 106 includes an upwardly extending head 116 including a
bore
118 for receiving a pin 120. Pin 120 extends out of each side of the bore 118
to
accommodate the mounting of link arms 122; 124 (not shown in Fig. 8 but seen
in Fig. 4).
The opposite end of the link arms 122, 124 are rigidly associated with an
assist rod 126.
Link arms 122, 124 are in effect torsion arms for actuating rotation of the
assist rod 126. In
the preferred embodiment, link arms 122, 124 are rigidly connected to a
transfer rod 127
which is in turn connected end to end with assist rod 126. In some
embodiments, transfer
rod 127 can be dispensed with in favour of an assist rod that extends to
connect directly to
the link arms 122, 124.
Assist rod 126 extends parallel to the rails but between the switch machine
104 and
the proximal fixed rail 107. The assist rod 126 is preferably cylindrical
along its length but
it will be appreciated that it need not necessarily be so. Appropriate
adapters may be used
between the link arms and the assist rod to cause the assist rod to rotate in
the event a non-
cylindrical assist rod is used Referring to Fig. 9, the transfer rod 127 is
supported for
rotation within support clips 166, 168 located adjacent each side of the front
basket 100.
Link arms 122 and 124 are provided with an elongated slot 125 (partially
visible in Fig. 4)
through which pin 120 is engaged.
It will be appreciated that when the basket undergoes lateral movement
(transverse to
the fixed rails) as a result of the switch being thrown, the link arms 122,
124 will cause the
transfer rod 127 (and therefore the assist rod 126) fo rotate. The elongated
slot 125
CA 02356487 2001-08-31
accommodates the fact that, in the preferred embodiment, the pin will be
translated in a
straight horizontal direction while the link arms will rotate about the pin
(the other end of
the link arms not being free to displace vertically).
S At the heel end of the switch, the rear basket 130 comprises two link arms
132,
134. An end of each of the link arms is rigidly associated with the assist rod
126,
preferably by connection to a transfer rod 129 rigidly connected to the end of
the assist
rod 126. The assist rod 126 is supported for rotation in support clips 136,
138 adjacent
each side of the rear basket. The ends of link arms 132, 134 that are opposite
to the assist
rod include bores 140 to receive two pins 142, 144 extending from opposite
sides of the
slide block 146. The slide block 146 is sandwiched between the link arms 132,
134 and a
threaded connector rod 148 is slidably received in the slide block 146. Nuts
150, 152 are
threaded on the connector rod at each side of the slide block 146 so as to
enable
adjustment of the amount of free motion that the basket 130 will undergo
before actuating
displacement of the connector rod 148 by abutment of the slide block 146 with
the nuts
1 S0, 152. The rear basket 130 is located on the outside of fixed rail 106.
At its distal end, connector rod 148 is hinged to the end of rear switch rod
86 as at
154 in Fig. 5. The connector rod 148 is housed within hollow tie 90. Rear
basket 130 is
partially housed within the hollow tie 90. Because link arms 132, 143 are both
hinged
about a single axis (e.g. they do not include the elongated slot found on the
link arms of
the front basket), the ends of the link arms which are distal from the assist
rod undergo
some displacement in the vertical plane when the assist rod is rotated. The
hinged
connection between the connector rod 148 and the rear switch rod 86 allows the
basket
end of the connector rod to displace in the vertical plane to accommodate such
displacement of the basket.
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CA 02356487 2001-08-31
In the preferred embodiment, the assist rod 126 is actually comprised of two
rod
segments 156, 158 that are operatively connected by means of a rotary drive
connector
bar 160. In this disclosure and in the claims, it will be understood that the
reference to an
assist rod includes any composite assist rod assembly wherein rotation of the
assembly at
the front (point) end causes the assembly to rotate at the rear (heel) end.
Similarly any
reference to a connection between part of the front or rear basket and the
assist rod
includes a connection to an intermediate element (such as the transfer rod of
the preferred
embodiment) which is in turn connected to an elongated assist rod.
Other variations to the preferred embodiment described herein may be practised
without nonetheless departing from the scope of the invention.
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