Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to rotating warning
lamps and specifically to improvements in their
application in heavy-duty construction and industrial
machinery.
Backqround of the Invention
Devices used to warn approaching motoxists
of a hazardous condition are generally constructed in
a manner to facilitate the rendering of visual signals -
over a complete field of 360 degrees. Consequently,
such devices generally comprise a plurality of sealed
beam lamps rotating about a vertical axis.
The utilization of such devices on heavy
equipment, such as snow plows, road graders and the
like, has generally resulted in severe problems due
to reductions to normal life-expectancy. Experimen-
tation has determined that these abnormally premature
failures are caused by the mechanical exaggeration
of electrical erosion at current carrying bearing or
journal points. Normal applications of such devices
.
use the rotating shaft of the device to carry current
to the sealed beam bulbs. This results in an appre-
ciable degree of arcing activity between the shaft
and the journal bushings. In the presence of severe
vibration loads, the constant motion serves to ~ ~
:~;' ~ ':
~' ;' ,
.~ : ' .
...,, . . . . . ~ . . : . , :
. - . : ,,: :, . , ....... :., . . ~ : .: .... . .
. . .
~ -
10831~
- significantly ampllfy the arcin~ factor, giving rise to
a spark-erosion conditionO As the shaft rotates about
its axis, circumferentially encompassed by the journal
bushing, the effect of normal friction is grossly in- !
creased by the combined factors of increased shaft and
journal temperatures and the erosion generated particles
from the generally soft journal bushing. The direct
result is the formation of an abrasive lapping compound
which rapidly deteriorates the basic dimensional accu-
racies of fit initially established. As the clearance ¦-
between the components increases, the arcing increases ¦
in severity and the -Eactors causing failure are aggravated.
Therefore, the invention is directed to a rotating
warning lamp wherein the lamp current does not pass through
the shaft-journal interconnection an*, preferably, the motor 1 ~
current also does not pass throuyh the shaft-journal inter- ~ ;
i . .
connection.
S~MMARY OF THE INVENTION ~ -
In accordance with one aspect of this invention I -
there is provided in a rotating lamp,
a base,
a motor including a housing and a wlnding,
means for mounting said motor on said base '!
such that said housing is electrically isolated from
said base,
a shaft extending u~wardly from said motor
a plurality of bulbs,
.
means for mounting said bulbs on said shaft,
said shaft being hollow,
electrically conductive means extending
~hrough said shaft and rotatable therewith,
r~ ~
.... ~ .
.. ~ ' ' ' : ~ ,- . : .
. .
1083108
means for electrically insulating said shaft~
from said electrically conductive means,
means for providing an electrical connec~ion
from said electrically conductive means to said bulbs,
means for providing an electrical connection .
from a source to said electrically conductive means,
means for providing a grounding from said .
bulbs to said housing,
means for providing an electrical connection I ~.
rom a source to said motor.
In accordance with another aspect of this inven- : .
tion there is provided in a ro~ating lamp,
a base,
a motor including a housing and a winding,
means for mounting said motor on said base. .
such that said housing is electrically isolated from
said base,
.
. a shaft extending upwardly from said motor~ .
: a plurality of bulbs,
means for mounting said bulbs on said shaft,
said shaft being hollow, ¦~
a rod bf electrically conductive material
extending ~hrough said shaft and rotatable therewith,
,~ ,
i~ ,
~ 083~
means for electrically insulating said shaft
from said rod,
means for providing an electrical connection
from said rod to said bulbs, ~ :
means for providing an electrical connection
rom a source to said rod, ~:
means for providing a grounding from said :
bulbs ~o said housing,
.. means *or pxoviding an electrical connection ~ ;
*rom a source to said motorO
.
Description of the Drawinqs ¦~
, ' ' '~ ' .
~igO 1 is a perspective view of a rotating
warning lamp embodying the invention.
Fig. 2 is a vertical sectional view thereof. ~ .
Fig. 3 is a ragmentary sectional viewO
Fig. 4 is a wiring diagram of the lamp. i :
.
'' . . ~
i,. :.
t~:
,
- . ' -:
~ .
-3a- ; :
.. ~. ' '
. .
' -
( ~ , , ,. : ,
'' ' ' ' ~ , ', ' ;
.
~L~133~
Description
Referring to the drawings, the rotating
warning lamp 11 comprises a base having a transverse
top wall 12a, an electric motor assembly 30 mounted
securely to the underside of the top wall 12a, and
a rotatable vertical shaft 13 extending upwardly
from the gear box section 14 of the motor assemhly
30. A plurality of sealed beam lamps 15 are mounted
on the shaft 13 by an upper bracket 16b and a lower
bracket 16a. The assembly of lamps 15 and brackets
16a, 16b is maintained in position on the shaft 13
by a retaining ring 19 at the bottom which snaps
into a groove in shaft 13 and a nut 18 at the top
(Figs. 2 and 3).
Shaft 13 is hollow and has a through-bore
13a. An insulating tube 20 surrounds an electrically-
conductive rod 21 which passes through shaft 13. The
rod 21 is electrically connected to the sealed beam
lamps through wires 37, 38 made to positive contacts
37a, 38a of the sealed beams 15. A nut 27a is threaded
on rod 21 to retain the end of wire 37 against insulating
washer 27b and complete the circuit to rod 21. The lower
end of the rod 21 has an annular contact 22 held in place
by a nut 27. Contact 22 passes through a clearance hole
in plate 26 and is electrical~y isolated from the shaft
. ' ,' '
, , . .. . . . . : .. . ... .. .. . .
~L~83~
13 by the shouldered insulating bushing 17. Plate 26
is rigidly mounted onto the electric motor assembly 30
by bolts 25. It is electrically insulated therefrom by
insulating wash~ers 28, 29 which encircle bolts 25. srush
assembly 23 which is mounted on plate 26 includes a brush
24 yieldingly urged against contact 22 (Fig. 2). A
terminal 35 is connected to the brush assembly 23 and
a lead 35a provides a circuit between the supply system,
noted as a battery, and the sealed beam lamps 15. The
10 gear box 14 includes shaft journals 60a, 60b. Shaft 13
is mounted through ~ournals 60a, 60b. Gear 14a in gear
box 14, part of motor assembly 30, is mounted on shaft
13. The motor assembly 30 and gear box 14 are mounted
on top wall 12a of the base 12 by bolts 51 which pass
.. . :. .
through electrically insulating washers 52, 52a. Washers
52, 52a insulate top wall 12a, which is electrically
connected to circuit ground, from motor assembly 30
including gear box 14 and shaft journals 60a, 60b.
A contact member 45 spaced from top wall 12a
20 is held in place on shaft 13 by a set screw 47 and a -
brush assembly 43 on wall 12a yieldingly urges a brush
44 against contact member 45 to provide eléctrical ; ;
continuity between the shaft 13 and the-top wall 12a.
The brush assembly 43 is fastened to the top wall 12a
by suitable means, such as on,e or more tubular rivets
62 and the brush lead 61 is clamped therebetween.
~83~8
As shown in Fig. 2, the sealed beam contacts
14b and 14c are interconnected by a wire 38b and a wire
38c extends from contact 14b therefrom to lower support
bracket 16a. The lower support bracket 16a is, in turn,
electrically connected through shaft 13 to contact 45.
The lamp circuit current passes between the shaft 13
and top wall 12a only by means of the brush assembly 43.
Thus, the shaft-journal interconnection is electrically
inert. The source of power such as a battery is connected `
to the motor 31 of motor assembly 30 by a lead 64. A
ground lead 63 from the motor extends to base 12a. ;
The circuit thus formed is shown in Fig. 4
with corresponding contact points identified in Fig. 2.
Current from the battery is supplied to point Bl at j -;
brush 24, to point B2 (annular contact 22), then to
point B3 (rod 21) to points B4, B5, B6 (wire 37 and
bulbs L1, L2), points A5, A4 (contacts 14c, 14b),
point A3 (bracket 16a), point A2 (annular contact 45),
point Al (brush 44) to point A7 (housing 12a) which
is grounded. Current is supplied to the winding of
motor 31 from contact B7, through the winding of the
motor to ground via the contact A6. If four bulbs
are used instead of two, added contacts Bg, Blo and ; -
Alo, A11 are provided for supplying current to bulbs
L3, L4.
.' ~'','''"."' .
, .~ . ... . . . .
', , ', ' ', , ' . ': ' ' ' , ' ' ' ',
33~
Although, in accordance with the invention,
the lamp current is preferably prevented from passing
through the journals by electrically insulating the
motor housing from the grounded base, in the light
of the disclosure, it will be apparent to persons
skilled in the art that satisfactory results can be
achieved by making the motor housing, journals or ~:
hollow shaft of non-conductive material; it being
understood that if the shaft is made of non-conductive
material, a circuit must be completed through other
means such as wires. :;:
.
