Note: Descriptions are shown in the official language in which they were submitted.
CA 02619334 2008-01-30
SWIVEL JOINT FOR LIGHTING FIXTURE
BACKGROUND OF THE INVENTION
The present invention relates to lighting fixtures for industrial
applications,
and more particularly to a lighting fixture which is easily and safely
accessed for
servicing and repairs.
In industrial applications such as mining, processing plants or refineries,
there
are typically long runs of piping or conveyors from one building structure to
another.
Often there are elevated catwalks along these long runs for maintenance
purposes.
Lighting fixtures are typically mounted on the catwalks to provide
illumination in
dark areas and at night.
Typical methods for servicing or replacing components of such lighting
fixtures involve use of a ladder to access the lighting fixture head, which is
often
supported more than eight to ten feet above the catwalk. Obviously, a danger
exists
for the maintenance worker precariously climbing a ladder supported on a
catwalk
high above the ground.
One known method for providing access to the light fixture head without use
of a ladder is by incorporating a light fixture pole with a means to permit a
top portion
of the pole to pivot downward. For example, U.S. Patent No. 6,957,832 to
Pannekoek
discloses a light fixture pole having an interconnect joint disposed at a
forty-five
degree angle to permit a top portion of the pole to pivot with respect to the
bottom
portion, thereby allowing a maintenance worker to access the lighting fixture
head.
However, one problem with the disclosed pivot joint is that its geometry
causes the lighting fixture head to be pivoted laterally beyond the catwalk,
thereby
requiring a maintenance worker to reach outwardly over the rail of the catwalk
to
access the head. Again, a danger exists for the maintenance worker, who needs
to
reach over the catwalk rail to access the light fixture head,
Another drawback with conventional lighting fixtures is the number of tools
typically required to service or replace components of the fixture. For
example,
removal of the fixture head from the mounting pole of a conventional lighting
fixture
CA 02619334 2008-01-30
may require one or more differently sized wrenches and screwdrivers to loosen
and
remove fixture hardware, which gives rise to another problem relating to loose
hardware. Thus, a maintenance worker would typically need to carry a large
tool
chest or satchel along the catwalk in order to perform such tasks, and must
also be
careful not to drop or lose the hardware necessary to mount the lighting
fixture head
to the pole.
Still another consideration with lighting applications in industrial
environments such as mining, processing plants or refineries is the
requirement in
certain hazardous installations that the lighting fixtures not produce any
electrical arcs
or sparks. In particular, disconnecting a live plug connection of a light
fixture for
servicing or repair, for example, could result in an electrical arc or spark,
which must
be prevented in a hazardous atmosphere for safety reasons.
One approach for addressing this safety issue is to terminate power at the
source before disconnecting any lighting fixture wiring or plug connections.
The
drawback here is that a number of fixtures will typically be turned off at the
same
time during servicing of a single fixture, resulting in large areas of the
facility not
illuminated.
Another solution is to provide individual fixtures with on/off switches that
must be manually actuated before servicing the fixture. This adds to the cost
of the
fixture itself, as well as the cost of installation. There also remains the
possibility that
the maintenance worker inadvertently fails to activate the switch before
making any
electrical disconnections.
Accordingly, it would be desirable to provide a lighting fixture for mounting
on a catwalk that is safely and easily accessible by a maintenance worker
standing on
the catwalk. It would be further desirable to provide a lighting fixture that
can be
serviced and repaired without the need for tools and with minimal risk of
losing
lighting fixture mounting hardware. It is still further desirable to provide a
safe
lighting fixture that will automatically electrically disconnect upon
initiation of
servicing or repair.
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CA 02619334 2008-01-30
SUMMARY OF THE INVENTION
The present invention is a lighting fixture having an improved swivel joint,
also referred to as a coupling knuckle. The lighting fixture generally
includes an
upper conduit having a longitudinal axis, a fixture head disposed at an upper
end of
the upper conduit, an upper swivel joint member attached to a lower end of the
upper
conduit opposite the fixture head, a lower swivel joint member rotatably
coupled to
the upper swivel joint member about a plane of rotation, and a lower conduit
attached
to the lower swivel joint member, wherein the plane of rotation is disposed at
an angle
of between zero degrees (0 ) and thirty degrees (30 ) with respect to the
longitudinal
axis of the upper conduit.
In a preferred embodiment, the lower conduit also has a longitudinal axis,
wherein the longitudinal axis of the lower conduit is parallel to, but
laterally offset
from, the longitudinal axis of the upper conduit. The upper and lower swivel
joint
members also preferably include joint surfaces that make sliding rotational
contact
with each other, wherein the joint surfaces define the plane of rotation.
The upper and lower swivel joint members are preferably in the form of
hemispherical cups defining an internal wiring chamber therebetween. Each of
the
upper and lower hemispherical cups preferably includes a dome shaped wall
terminating at a circumferential flange, wherein the circumferential flanges
of the
cups are coupled together to prevent lateral movement therebetween.
In a preferred embodiment, the light fixture further includes a locking bolt
centrally coupling the upper swivel joint member to the lower swivel joint
member.
The locking bolt defines a centerline of rotation between the upper and lower
swivel
joint members and is adapted to be selectively tightened to lock the upper
swivel joint
member to the lower swivel joint member, thereby preventing rotation
therebetween.
In this regard, each of the upper and lower swivel joint members preferably
includes
an internal sleeve for receiving the locking bolt. The sleeve of the upper
swivel joint
member makes annular contact with the sleeve of the lower swivel joint member
to
prevent over tightening of the locking bolt.
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CA 02619334 2008-01-30
One of the upper and lower swivel joint members preferably includes a stop
block fixed thereto and the other of the upper and lower swivel joint members
preferably includes a mechanical stop disposed thereon, wherein the stop block
makes
contact with the mechanical stop upon rotation of the upper swivel joint
member to
prevent further rotation.
An index pin can also be provided to prevent rotation. Thus, each of the upper
and lower swivel joint members can include at least one index pin aperture
disposed
adjacent a circumferential edge thereof, wherein the aperture of the upper
swivel joint
member aligns with the aperture of the lower swivel joint member when the
swivel
joint members are rotated to a desired degree. Insertion of the index pin in
the aligned
apertures will prevent rotation of the upper swivel joint member with respect
to the
lower swivel joint member.
The present invention further involves a lighting fixture swivel joint for
pivoting an upper conduit having a fixture head disposed at an upper end
thereof
downward with respect to a lower conduit. The swivel joint generally includes
an
upper swivel joint member and a lower swivel joint member rotatably coupled to
the
upper swivel joint member about a plane of rotation. The upper swivel joint
member
includes an upper conduit receptacle defined by a longitudinal axis and being
adapted
to receive a lower end of the upper conduit, whereby the upper conduit is
coaxially
aligned with the longitudinal axis. The plane of rotation is disposed at an
angle of
between zero degrees (0 ) and thirty degrees (30 ) with respect to the
longitudinal axis
of the upper conduit receptacle of the upper swivel joint member.
The lower swivel joint member preferably includes a lower conduit receptacle
defined by a longitudinal axis. The lower conduit receptacle is adapted to
receive an
upper end of the lower conduit, whereby the lower conduit is coaxially aligned
with
the lower conduit receptacle longitudinal axis. The upper conduit receptacle
longitudinal axis is parallel to, but laterally offset from, the lower conduit
receptacle
longitudinal axis.
The present invention further involves a method for gaining access to a
fixture
head disposed at an upper end of an upper conduit of a lighting fixture. The
method
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CA 02619334 2008-01-30
generally includes the step of rotating an upper swivel joint member attached
to a
lower end of the upper conduit about a plane of rotation with respect to a
lower swivel
joint member rotatably coupled to the upper swivel joint member, wherein the
plane
of rotation is disposed at an angle of between zero degrees (00) and thirty
(30 ) with
respect to a longitudinal axis of the upper conduit.
The method according to the present invention further preferably includes the
step of loosening a locking bolt to permit the rotation. The locking bolt
centrally
couples the upper swivel joint member to the lower swivel joint member and
defines a
centerline of rotation between the upper and lower swivel joint members.
A preferred form of the lighting fixture, as well as other embodiments,
objects,
features and advantages of this invention, will be apparent from the following
detailed
description of illustrative embodiments thereof, which is to be read in
conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side view of the lighting fixture formed in accordance with the
present invention.
Figure 2 is a perspective view of the pivot joint for the lighting fixture of
the
present invention.
Figure 3 is a cross-sectional view of the pivot joint shown in Figure 2.
Figure 4 is a side view of the lighting fixture of the present invention
showing
a top portion of the fixture being pivoted downward for servicing.
Figure 5 is a top perspective view of the lighting fixture shown in Figure 3.
Figure 6 is a top perspective view of the stanchion arm of the lighting
fixture
of the present invention showing the lighting fixture removed therefrom.
Figure 7 is a bottom perspective view of the stanchion arm shown in Figure 5.
Figure 8 is a top view of the stanchion arm shown in Figure 5 with its top
cover removed showing the hub of the fixture head being inserted therein.
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Figure 9 is a top view of the stanchion arm shown in Figure 5 with its top
cover removed showing the hub of the fixture head being rotated therein.
Figure 10 is a top view of the stanchion arm shown in Figure 5 with its top
cover removed showing the hub of the fixture head engaging a guard lever.
Figure 11 is a top view of the stanchion arm shown in Figure 5 with its top
cover removed showing a pin inserted through the arm and the hub and actuating
an
electrical switch.
Figure 12 is a top view of the stanchion arm shown in Figure 5 with its top
cover removed showing an alternative embodiment of the guard lever and the
contact
member.
Figure 13 is a partial cross-sectional view of the stanchion arm and hub
assembly shown in Figure 12.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
Referring first to Figure 1, the lighting fixture 10 of the present invention
generally includes a lower conduit 12, an upper conduit 14, a pivot joint 16,
a
stanchion arm 18, a fixture head 20, a rail mounting hardware 22 and ajunction
box
24. The lighting fixture 10 of the present invention is ideally adapted for
mounting to
a handrail 26 of a catwalk structure 28. Thus, the rail mounting hardware 22
generally includes conventional brackets, angles and bolts for securely
attaching the
lower conduit 12 to the rail 26. However, the invention is not limited to
handrail
mounting and other mounting configurations for other lighting applications are
within
the scope of the present invention.
The lower and upper conduits or tubes 12 and 14 are preferably tubular
members made from stainless steel pipe or other durable and weather resistant
material. Electrical wiring (not shown) run within the conduits 12, 14 from
the
junction box 24 to the fixture head 20. Additional wiring conduits (not shown)
will
generally connect junction boxes 26 of adjacent fixtures 10 mounted along the
catwalk.
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CA 02619334 2008-01-30
In order to access the fixture head 20, for service or repair, the upper
conduit
14 pivots downwardly about the pivot joint 16 toward the lower conduit 12.
This is
accomplished by a unique design of the pivot joint 16, which enables the
fixture head
20 to be brought down toward a maintenance worker standing on the catwalk 28.
Turning to Figures 2 and 3, the pivot joint 16, also referred to as a swivel
joint
or a hinging knuckle, includes a lower swivel joint member 30 and an upper
swivel
joint member 31, which make sliding rotational contact along a plane of
rotation 32,
sometimes referred to as a swivel plane. The lower and upper swivel joint
members
30, 31 are preferably in the form of cast hemispherical cups, which define a
wiring
chamber 33 therebetween. Each bowl-shaped cup 30, 31 includes an outer dome
wall
34, 35 which terminates at a flange 36, 37. In a preferred embodiment, one
flange is
nested within the other flange so as to prevent excess lateral movement
between the
cups. For example, as shown in Figures 2 and 3, the flange 37 of the upper cup
31 is
preferably provided with a lip 37a disposed radially outward from the
perimeter of the
lower cup flange 36 so as to retain the lower cup flange therein. Thus, as
will be
discussed in further detail below, when the locking bolt 46 is loosened
slightly, the
lower and upper cups 30, 31 will remain engaged to some extent.
The flange 36 of the lower cup 30 has a machined joint surface 38, which
mates in a sliding relationship with a machined joint surface 39 provided on
the flange
37 of the upper cup 31. The machined joint surfaces 38 and 39 of the lower and
upper
cups 30 and 31 define the swivel plane 32 of the pivot joint 16.
The lower cup 30 further includes a lower conduit receptacle 40 adapted to
securely receive an upper end of the lower conduit 12. The lower conduit
receptacle
40 is provided on the outer surface of the dome wall 34 and forms a well 42
defined
by an axis 44. The inner surface of the well 42 can be internally threaded to
engage
an external thread of the upper end of the lower conduit 12, or can be adapted
for
welding to the lower conduit, or provided with other means to attach the lower
conduit therein.
The plane defined by the machined joint surface 38 of the lower cup 30 is
disposed at a zero (0) to thirty (30) degree angle with respect to the axis 44
of the
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CA 02619334 2008-01-30
lower conduit receptacle well 42. In a preferred embodiment, the angle between
the
plane defined by the machined joint surface 38 of the lower cup 30 and the
axis 44 of
the lower conduit receptacle wel142 is about fifteen (15) degrees.
Similarly, the upper cup 31 further includes an upper conduit receptacle 41
adapted to securely receive a lower end of the upper conduit 14. The upper
conduit
receptacle 41 is provided on the outer surface of the dome wall 35 and forms a
well
43 defined by an axis 45. Again, the inner surface of the well 41 can be
internally
threaded to engage an external thread of the lower end of the upper conduit
14, or can
be adapted for welding to the upper conduit, or provided with other means to
attach
the upper conduit therein.
The plane defined by the machined joint surface 39 of the upper cup 31 is
disposed at a zero (0) to thirty (30) degree angle with respect to the axis 45
of the
upper conduit receptacle well 43. In a preferred embodiment, the angle between
the
plane defined by the machined joint surface 39 of the upper cup 31 and the
axis 45 of
the lower conduit receptacle well 43 is about fifteen (15) degrees.
The lower and upper cups 30, 31 are preferably held together by a single
locking bolt 46, which passes through the interior wiring chamber 33 formed by
the
cups. In this regard, each cup 30, 31 is preferably formed with an internal
cast-in
sleeve 48, 49 defining a passageway 50 through which the bolt extends. The
bolt 46
includes a head 52, which is retained within a similarly shaped recess 53 of
the lower
cup 30 surrounding the passageway 50, to prevent rotation of the head. Thus,
in the
case of a hexagonal bolt 46, as shown in Figures 2 and 3, the lower cup 30
would
have a hexagonal recess 53 formed in the annular region surrounding the
passageway
50. The bolt 46 has a threaded end 54 opposite the head, and a washer 56 and a
nut
58 are preferably provided on the threaded end 54 to provide a compressive
force
against an annular region of the upper cup 31 surrounding the passageway 50.
An
annular face 60 of the lower cup inner sleeve 48 contacts an annular face 61
of the
upper cup inner sleeve 49 to prevent over-tightening of the bolt 46.
The inner wiring chamber 33 defined by the lower and upper cups 30, 31
provides a water-tight passageway for electrical wiring (not shown) passing
from the
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CA 02619334 2008-01-30
lower conduit 12 to the upper conduit 14. To enhance the water-tight
construction,
one or both of the mating surfaces 38, 39 of the lower and upper cups 30, 31
is formed
with a circumferential groove 62, in which an o-ring 64 can be seated, as
shown in
Figure 3. One or more additional locking bolt o-rings 66 can also be provided
to seal
the interface between the locking bolt ends and the lower and/or upper cups
30, 31.
The wiring within the wiring chamber 33 is further protected by the internal
cast-in
sleeves 48, 49 of the lower and upper cups 30, 31.
Upon assembly, the axes 44, 45 of the lower and upper receptacles 40, 41 will
typically be oriented in a vertical direction, whereby the lower and upper
conduits 12,
14 will extend vertically parallel with each other. Moreover, the axes 44, 45
of the
lower and upper receptacles 40, 41 are not co-axial or co-linear with each
other, but
instead are laterally offset from each other.
In operation, the nut 58 of the locking bolt 46 is loosened to permit the
lower
and upper cups 30, 31 to slide against each other along their respective
mating
surfaces 38, 39, 60, 61. The sliding contact between the cups 30, 31 acts as a
brake to
prevent the upper conduit 14 from pivoting too rapidly. In this regard, use of
a single
locking bolt 46 allows better control of contact pressure during servicing.
By orienting the swivel plane 32 at a zero to thirty degree angle with respect
to
vertical (ninety to sixty degrees with respect to horizontal), and more
preferably at a
fifteen degree angle with respect to vertical (seventy-five degrees with
respect to
horizontal), the upper conduit 14 can be pivoted to a position that enables
safe and
easy access to the fixture head 20 to a maintenance worker standing on the
catwalk
28, as shown in Figures 3 and 4. In other words, the "rotation plane" 32
between the
two cups 30, 31 is nearly parallel to the extending tubes. As compared to
prior art
swivel joints having a forty-five (45) degree rotation plane with respect to
the
longitudinal axis of the extending conduits 12, 14, the present design
provides the
ability to pivot the two extending tubes back upon themselves to reverse
course nearly
one hundred eighty (180) degrees.
The importance of this feature is shown in Figures 4 and 5. In particular, in
the case of conventional swivel joints having a forty-five (45) degree
rotation plane,
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CA 02619334 2008-01-30
the upper extension 14 would, when swung or rotated for access from the
catwalk 28,
extend well into the catwalk and maybe even beyond it over the rail or into
other
structures. This is not the case with the present design since the near
vertical rotation
plane 32 between the lower and upper cups 30, 31 allows the two extending
tubes 12,
14 to be rotated back on themselves so that they are nearly parallel to each
other. This
means that a technician can now easily access the fixture head 20 from the
catwalk 28
since the upper end of the upper conduit 14 no longer extends out from the
knuckle 16
to any significant degree. Thus, the technician does not have to lean over the
railing
26 of the catwalk 28 to access the fixture head 20. Furthermore, as shown in
Figures
4 and 5, the rotated fixture head 20 does not obstruct the catwalk 28 as would
be the
case with prior knuckle designs.
To provide positive positioning upon pivoting, the swivel joint 16 can further
be provided with a stop block 68, mechanical stops 70 and/or an indexing pin
72.
More particularly, a durable rubber stop block 68 can be fastened to the
flange 37 of
the upper cup 31 and one or more mechanical stops 70 can be provided on the
flange
36 of the lower cup 30. (Of course, this arrangement can be reversed.) The
mechanical stops 70 can be integrally cast stops 70a, or they can take the
form of
bolts 70b, or some other form of fasteners, removably attached to the lower
cup 30.
The stop block 68 and the mechanical stop 70 can be radially spaced ninety
degrees
(90 ), one hundred eighty degrees (180 ), or any other desired angle, with
respect to
each other. Moreover, removable stops 70b can be provided to lock the lower
and
upper cups 30, 31 in a vertical orientation, as shown in Figure 2. When the
removable
stops 70b are removed, as the upper cup 31 is rotated about the locking bolt
46 with
respect to the lower cup 30, the stop block 68 will make contact with the
mechanical
stop 70a at the desired angle and will prevent further rotation. For
additional safety,
an indexing pin 72 can be inserted through aligned holes formed in the lower
and
upper cup flanges 36, 37 to temporarily lock the cups with respect to each
other.
Turning now to Figure 6, the fixture head 20 of the present invention
generally
includes a hub 74, a mount 75, a ballast tank 76 and a refractor or lens 78.
As will be
discussed in further detail below, the hub 74 is specially designed for unique
engagement with the stanchion arm 18. The hub 74 is attached to the mount 75
with
CA 02619334 2008-01-30
conventional screws or bolts, for example, and the mount 75, in turn, is
releasably
attached to the ballast tank 76. The ballast tank 76 and the refractor 78 can
be of
conventional design, and will generally contain a source of illumination, such
as a
lamp, ballast components and a wiring harness 80 for connection with a fixture
wiring
harness 82 of the stanchion arm 18. A latch mechanism 84 is preferably
provided
between the mount 75 and the ballast tank 76 so that the ballast tank can be
detached
from the mount. The latch mechanism 84 is preferably designed for universal
latching with any number of conventional ballast tanks 76.
With additional reference to Figure 13, the hub 74 includes a base 86, a
circular boss 88 extending upwardly from the center of a top surface thereof
and a
finger 90 extending radially outward from the boss. The base 86 and the boss
88 have
a central opening 92 formed therein for passage of the ballast tank wiring
harness 80
therethrough. The finger 90 is spaced above the top surface of the base 86 so
as to
leave a gap 94 therebetween. The finger 90 also includes an upright portion 96
extending perpendicularly upward from the finger in an axial direction away
from the
base 86. The upright portion 96 includes an aperture 98 for receiving a
locking pin
100 of the stanchion arm 18, as will be discussed in further detail below.
The hub 74 preferably further includes at least one counter finger 91
extending
radially outward from the circular boss. The counter finger 91 is disposed at
the same
height with respect to the base plate 86 so as to define a similar gap
therebetween as
described above. As will be discussed in further detail below, the counter
finger 91
provides additional rigidity to the fixture head 20 when mounted to the
stanchion arm
18.
Referring additionally to Figures 7-11, the stanchion arm 18 generally
includes a housing 102 and a cover 104 removably attached to the housing. The
housing 102 defines a compartment 106 for containing the internal parts of the
stanchion arm 18. The housing 102 further includes an upper conduit receptacle
108
adapted to receive the upper end of the upper conduit 14 for mounting thereto.
The
upper conduit receptacle 108 can be internally threaded to mate with an
external
thread provided on the upper end of the upper conduit 14, and can also include
one or
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CA 02619334 2008-01-30
more set screw apertures 110 for receiving one or more set screws to lock the
stanchion arm 18 to the upper conduit 14.
The housing 102 further includes a locking pin aperture 112 sized to receive
the fixture head locking pin 100. A rim or other bearing element is preferably
provided around the aperture 112 to add strength. The locking pin 100 is
preferably
tethered to the housing 102 to prevent loss of the pin when not inserted in
the aperture
112.
The housing 102 further includes a key-hole shaped entry 114 sized to receive
the circular boss 88 and finger 90 of the fixture head hub 74. The entry 114
further
preferably includes a notch 116 sized to receive the counter finger 91 of the
hub 74.
The entry 114 is simply a cut-out portion in the bottom 118 of the housing 102
that
will allow insertion of the top of the circular boss 88, the finger 90 and the
counter
finger 91 of the hub 74 into the housing. The thickness of the housing bottom
118
surrounding the entry 114 must be less than the gap 94 between the hub finger
90 and
the hub base plate 86 to allow insertion and rotation of the hub finger 90
within the
housing 102, as will be discussed in further detail below.
Contained within the housing 102 are a guard mechanism 120 and a switch
mechanism 122. The guard mechanism 120 includes a hat member 124 mounted to
the bottom 118 of the housing 102 at least partly over the entry 114. The hat
member
124 is spaced above the housing bottom 118 a sufficient distance to allow full
insertion and rotation of the hub finger 90 within the housing. The guard
mechanism
120 further includes a guard lever 126 pivotally attached to the hat member
124 about
a pivot point 128. The guard lever 26 must also be spaced above the housing
bottom
118 a sufficient distance to allow full insertion and rotation of the hub
finger 90
within the housing. The guard lever 126 includes a blocking face 130 opposite
the
pivot point 128, which, when the guard lever is in a home position, blocks the
locking
pin aperture 112 of the housing.
The guard lever 126 can be maintained in its home position by any suitable
means. In one embodiment, the guard lever 126 is spring biased into its home
position by one or more helical springs 132 provided between the hat member
124
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CA 02619334 2008-01-30
and the guard lever adjacent the pivot point, as shown in Figure 8. Such
spring
biasing will return the guard lever 126 to its home position when no longer
urged out
of the way, whereby the blocking face 130 will again block the locking pin
aperture
112.
However, in a preferred embodiment, as shown in Figure 13, the spring can be
eliminated by providing the guard lever with a tab 133 angularly spaced from
the
blocking face 130, which engages the hub finger 90 when the hub 74 is rotated
in a
reverse direction upon removal of the hub from the stanchion arm housing 102.
Specifically, when removing the fixture head 20 from the stanchion arm 18, the
hub
74 is rotated so that the hub finger 90 moves away from the locking pin
aperture 112
into alignment with the key-hole entry 114 of the stanchion arm housing 102.
As the
finger 90 moves away from the locking pin aperture 112, it contacts the tab
133 of the
guard lever 126, which causes the guard lever to rotate about its pivot point
128. This
rotation returns the guard lever 126 to its home position, whereby the
blocking face
130 takes up residence at the locking pin aperture 112 to block entry of the
locking
pin 100.
The switch mechanism 122 generally includes a limit switch 134 and an
actuating arm 136 pivotally connected to the limit switch. The limit switch
134 can
be an off-the-shelf variety, but is preferably rated for a high number of
cycles in harsh
environments and preferably includes hermitically sealed contacts to isolate
the
connections from the environment. Wires 137 coming from the upper conduit 14
are
fed through the upper conduit receptacle 108 and are connected to one pole of
the
switch 134 and the wiring harness 82 coming from the fixture head 20 is
connected to
the opposite pole of the switch. The actuating arm 136 is attached to the
mechanical
portion of the limit switch 134 so that pivoting of the arm will activate the
switch to
provide a current path between the wiring 137 of the upper conduit 14 and the
wiring
harness 82.
The actuating arm 136 preferably includes a contact member 138 pivotally
attached to the housing. The contact member 138 includes a locking pin contact
face
140 disposed at the locking pin aperture 112 of the housing behind the
blocking face
130 of the lever guard 126, when the lever guard is in its home position. In
other
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CA 02619334 2008-01-30
words, the locking pin 100 cannot make contact with the contact face 140 of
the
contact member 126 when the contact member is in its home position. Mechanical
cooperation between the contact member 138 and the actuating arm 136 can be
achieved, for example, via a cam roller 142 provided on the actuating arm and
which
is engaged with a roller surface 144 provided on the contact member.
In one embodiment, as shown in Figures 8-11, the contact member 138 is
pivotally connected to the bottom 118 of the housing 102 at one end, with the
opposite end of the contact member having the contact face 140 and the roller
surface
144 being disposed therebetween. In an alternative embodiment, as shown in
Figures
12 and 13, the contact member 138a is pivotally attached to the hat member 124
at
one end, with the opposite end of the contact member having the roller surface
144
and the contact face 140 being disposed therebetween. In any event, pivoting
of the
contact member 138 about its pivot point causes the actuating arm 136 to pivot
with
respect to the limit switch 134, thereby changing the state of the switch.
Here too, the contact member 138, 138a and/or the actuating arm 136 are
preferably spring biased into a home position, wherein the switch 134 is open
and
whereby the electrical current is interrupted to the fixture head. When the
contact
face 140 of the contact member 138, 138a is pushed back by the locking pin
100, as
will be described in further detail below, the actuating arm 136 is pivoted
thereby
closing the switch to provide a current path to the fixture head 20.
In use, installation of the fixture head 20 can be carried out as follows.
First,
with the tethered locking pin 100 removed and the limit switch 134 open, the
wiring
harness 80 of the fixture head 20 is electrically and mechanically coupled to
the
wiring harness 82 of the stanchion arm 18, as shown in Figure 6. This is
accomplished safely and without the risk of arcing since the limit switch 134
is in its
home open state prior to installation of the fixture head 20 in the stanchion
arm.
As shown in Figure 8, the hub 74 of the fixture head 20 is brought up to the
stanchion arm 18 and the boss 88, the finger 90 and the counter finger 91 are
inserted
through the entry 118 of the bottom 118 of the stanchion arm housing 102. The
hub
74 is then rotated, as indicated by arrow 146 of Figure 9, until the hub
finger 90
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CA 02619334 2008-01-30
engages the lever guard 126. As the hub 74 is rotated, the bottom 118 of the
housing
102 surrounding the entry 114 is captured in the gap 94 formed between the hub
base
plate 86 and the bottom of the finger 90. The counter finger 91 of the hub 74
also
retains a portion of the bottom 118 of the housing 102 to securely couple the
hub to
the stanchion arm 18.
The hub 74 is rotated further so that the upright portion 96 of the hub finger
90
pushes the blocking face 130 of the lever guard 126 away from its blocking
position
behind the locking pin aperture 112 of the housing 102, as shown in Figure 10.
As
described above, the blocking face 130 will normally prevent insertion of the
pin 100
through the housing aperture 112 when the lever guard 126 is in its home
position.
With the blocking face 130 of the lever guard thus pivoted out of position,
the
locking pin aperture 98 of the finger upright portion 96 can be brought into
alignment
with the locking pin aperture 112 of the housing 102. Once the apertures 98,
112 are
aligned, the locking pin 100 can be inserted through the housing 102 into the
upright
portion 96 of the finger 90, as shown in Figures, 11-13. As the pin 100 is
inserted
through the aperture 98 of the finger upright portion 96, it will push the
contact face
140 of the contact member 138, 138a in the direction of arrow 147, as shown in
Figure 11, causing the contact member to pivot about its pivot point. Pivoting
of the
contact member 138, 138a will in turn urge the actuating arm 136 out of its
home
position in the direction of arrow 149, thereby closing the switch 134 to
provide
current to the fixture head 20. Thus, power is automatically provided to the
fixture
head 20 upon locking the hub 74 to the stanchion arm 18 with the locking pin
100.
The upper conduit 14 is then swiveled back to its upright vertical position by
pivoting the upper cup 31 with respect to the lower cup 30 of the swivel
joint. Once
the upper conduit 14 is in position, the swivel joint indexing pin 72 can be
inserted
and the nut 58 securing the locking bolt 46 can be tightened, as described
above, to
complete the installation.
Removal of a fixture head 20 can be accomplished essentially in reverse.
With the swivel joint indexing pin 72 removed and the nut 58 of the locking
bolt 46
loosened, the upper cup 31 of the joint 16 is rotated with respect to the
lower cup 30
CA 02619334 2008-01-30
to pivot the upper conduit 14 downward to provide access to the fixture head
20. The
locking pin 100 is then removed from the housing 102, thereby releasing the
contact
member 138, 138a and actuating arm 136 and returning the limit switch 134 to
its
open state. Thus, electricity is automatically terminated to the fixture head
20 upon
removal of the locking pin 100.
The fixture head hub 74 can then be rotated in a direction opposite to the
arrow 146 of Figure 9 until the finger 90 of the hub aligns with its
corresponding
portion of the housing entry 114. The hub 74 can then be lowered away from the
stanchion arm 18 and the wiring harness 80 of the fixture head 20 can be
safely
disconnected from the wiring harness 82 of the stanchion arm 18.
As a result of the present invention, a lighting fixture has been provided
that
permits safe and easy servicing. The lighting fixture, which, when assembled,
is
typically about ten (10) feet high, is accessed by tilting an upper mounting
pole
downward with respect to a lower mounting pole. A unique swivel joint, or
knuckle,
located in the middle of the fixture between the mounting poles permits such
tilting.
Another feature of the present invention is the locking/switching mechanism
incorporated between the fixture head and the stanchion arm that automatically
disconnects the power to the individual fixture during servicing. Conversely,
power
can be activated only when the fixture head is installed and secured to the
stanchion
arm.
Although the illustrative embodiments of the present invention have been
described herein with reference to the accompanying drawings, it is to be
understood
that the invention is not limited to those precise embodiments, and that
various other
changes and modifications may be effected therein by one skilled in the art
without
departing from the scope or spirit of the invention.
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