U.S. patent number 3,597,560 [Application Number 04/843,613] was granted by the patent office on 1971-08-03 for electric switch with releasable screw-threaded spring charging means.
This patent grant is currently assigned to Empire Switchboard Co. Inc.. Invention is credited to Alexander R. Norden.
United States Patent |
3,597,560 |
Norden |
August 3, 1971 |
ELECTRIC SWITCH WITH RELEASABLE SCREW-THREADED SPRING CHARGING
MEANS
Abstract
A normally manually operable electric switch is provided with
stored energy mechanism which can be remotely controlled to open
the switch without interfering with the direct manual operation to
open or close the switch. The stored energy mechanism consists of a
threaded rod portion and releasable screw-threaded means engaging
said rod portion and allowing a spring to be compressed; upon
release of the releasable screw-threaded means, the spring
discharges. The stored energy mechanism is manually operable to
render it potentially operable to open the switch automatically by
remote control and provision is made to render said mechanism
inoperable when said remote control is not desired.
Inventors: |
Norden; Alexander R. (New York,
NY) |
Assignee: |
Empire Switchboard Co. Inc.
(Brooklyn, NY)
|
Family
ID: |
25290524 |
Appl.
No.: |
04/843,613 |
Filed: |
July 22, 1969 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
599904 |
Dec 7, 1966 |
3496319 |
Feb 17, 1970 |
|
|
Current U.S.
Class: |
200/400; 185/39;
200/405; 74/424.78 |
Current CPC
Class: |
H01H
3/30 (20130101); H01H 3/58 (20130101); Y10T
74/19735 (20150115); H01H 2003/3089 (20130101) |
Current International
Class: |
H01H
3/54 (20060101); H01H 3/58 (20060101); H01H
3/00 (20060101); H01H 3/30 (20060101); H01h
003/30 (); H01h 021/40 (); H01h 003/40 () |
Field of
Search: |
;200/153.23 ;337/8,7
;335/171,173,23 ;185/37,39 ;74/59,89.15,127,509 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schaefer; Robert K.
Assistant Examiner: Vanderhye; Robert A.
Parent Case Text
This is a continuation-in-part of my Application Ser. No. 599,904
filed Dec. 7, 1966, now U.S. Pat. No. 3,496,319, issued Feb. 17,
1970.
Claims
What I claim is:
1. An electric switch comprising, a stationary contact member, a
companion movable contact member, a fuse associated with one of
said contact members, mechanism coupled to said movable contact
member for opening and closing the switch manually operable means
for normally actuating said mechanism to open and close the switch
releasably coupled to said mechanism and means operable
independently of said manually operable means to actuate said
mechanism to open said switch after it is closed by actuation of
said mechanism by said manually operable means said independently
operable means comprising rotary screw-threaded means, spring means
which is stressed by rotation induced longitudinal movement of said
screw-threaded means in one direction coupled to said mechanism for
rendering it potentially operable to actuate said switch opening
mechanism, said spring means being coupled to said screw-threaded
means for biasing said screw-threaded means for longitudinal
movement in a direction opposite to said one direction, and means
coupled to said screw-threaded means for releasably preventing
nonrotary longitudinal movement of the screw-threaded means in said
opposite direction and permitting said longitudinal movement of
said screw-threaded means in said opposite direction by said spring
means for actuation of said switch opening mechanism.
2. An electric switch comprising switch closing mechanism and
switch opening mechanism, means to actuate said switch opening
mechanism comprising rotary screw-threaded means, spring means
which is stressed by rotation-induced longitudinal movement of said
screw-threaded means in one direction coupled to said mechanism for
rendering it potentially operable to actuate said switch opening
mechanism, said spring means being coupled to said screw-threaded
means for biasing said screw-threaded means for longitudinal
movement in a direction opposite to said one direction, and means
coupled to said screw-threaded means for releasably preventing
nonrotary longitudinal movement of the screw-threaded means in said
opposite direction and permitting said longitudinal movement of
said screw-threaded means in said opposite direction by said spring
means for actuation of said switch opening mechanism.
3. An electric switch according to claim 2, wherein said
screw-threaded means comprises a screw-threaded rod, the companion
confronting sides of rib-defining grooves of the threads defining
an obtuse angle therebetween, a split nut coupled to said threaded
rod and releasable therefrom to permit said nonrotary longitudinal
movement of said rod.
4. An electric switch according to claim 1 wherein said
screw-threaded means comprises a screw-threaded rod, the companion
confronting sides of rib-defining grooves of the threads defining
an obtuse angle therebetween, a split nut coupled to said threaded
rod and releasable therefrom to permit said nonrotary longitudinal
movement of said rod.
5. An electric switch according to claim 3, wherein said split nut
comprises two parts, a pivot on which said parts are pivotally
mounted for engagement with and disengagement from said rod, and
means for moving said parts of the nut into and out of engagement
with said rod.
6. An electric switch according to claim 5 wherein the means for
moving said parts of the nut into engagement with said rod
comprising manually movable means releasably coupled to said parts
of the nut and movable to a projected position and to a retracted
position.
7. An electric switch according to claim 5 wherein the means for
moving said parts of the nut into engagement with said rod
comprises camming means releasably coupled to one of said parts of
the nut and comprising a manually operable means for actuating said
camming means.
8. An electric switch according to claim 5, wherein the means for
moving the split nut out of engagement with said rod comprises said
stressed spring acting on said rod when said movable means which is
releasably coupled to the nut is moved to a retracted position.
9. Stored energy mechanism comprising, longitudinally movable screw
means, spring means stressed by rotation-induced longitudinal
movement of said screw means in one direction, said spring means
being coupled to said screw means for biasing said screw means for
longitudinal movement in a direction opposite to said one
direction, and releasable means coupled to said screw means for
releasably preventing nonrotary longitudinal movement of the screw
means in said opposite direction and permitting said longitudinal
movement of said screw means in said opposite direction by said
spring means.
10. Stored energy mechanism according to claim 9, wherein said
screw-threaded means comprises a screw-threaded rod and said
releasable means comprising a split nut having separable parts
disengageable from said rod to permit said longitudinal movement of
said rod.
11. Stored energy mechanism according to claim 10 wherein the
companion confronting sides of rib-defining grooves of the threads
of said rod define an obtuse angle therebetween.
Description
BACKGROUND OF THE INVENTION
This invention relates to a high current quick make and quick break
switch which is normally manually operable to effect rapid closing
and rapid opening of the switch. In the invention described in the
above identified application, an arc chute is provided for each of
a plurality of lines which are connected by main and auxiliary
contacts and there is an interlock between the movable companion
main and auxiliary contacts which prevents engagement of the main
movable contact with the companion stationary contact if the
companion arc chute is not in place, said interlock being released
to permit closing of the companion main contacts if the arc chute
is in place.
OBJECTS OF THE INVENTION
One object is to provide a simple and rugged stored energy
mechanism to effect rapid opening movement of the switch without
requiring operation of the normal manually operable handle.
Another important object is to provide a mechanism as above stated
and which will not interfere with the operation of the normal
switch actuating mechanism and will not affect the normal
electrical and mechanical functions of the switch.
Another object is to provide a normally manually operable switch
with a stored energy mechanism which can be conditioned to open the
switch by either remote or manual control without actuation of the
normally manually operable handle.
These and other objects, features and advantages of the invention
will become apparent from the following description considered in
connection with the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an embodiment of this invention,
showing the switch in its open position, and with one arc chute
removed for the purpose of illustration;
FIG. 2 is a right side detail view of the contact assemblies,
showing the contacts in their fully open disposition;
FIG. 3 is a left side detail view of the contact assemblies,
showing the auxiliary arcing contacts in closed disposition and the
main contacts still open, all with the left half of the arc chute
removed for the purpose of illustration;
FIG. 4 is a left side detail view of the contact assemblies in
their fully closed positions, with the left half of the arc chute
removed for the purpose of illustration;
FIG. 5 is a front detail view of the switch operating
mechanism;
FIG. 6 is a front detail view of the switch operating mechanism in
the switch closed position;
FIG. 7 is a cross-sectional view of FIG. 6 taken along the plane
FIG. 6-6;
FIG. 8. is a view taken on the line 8-8 of FIG. 1;
FIG. 9 is a view taken on the line 9-9 of FIG. 8;
FIG. 10 is a view taken on the line 10-10 of FIG. 9;
FIG. 11 is a view taken on the line 11-11 of FIG. 10; and
FIG. 12 is a view taken on the line 12-12 of FIG. 8.
DETAILED DESCRIPTION OF THE INVENTION
The switch which is shown in FIG. 1 is supported on a frame
provided by two rear upstanding angles 12 and 14, a front plate 16,
and two sideplates 18 and 20. An upper dielectric back panel 33 is
mounted to and between the angles 12 and 14, as by a plurality of
bolts and nuts 24. A lower dielectric back panel 26 is mounted to
and between the angles 12 and 14, as by a plurality of bolts and
nuts 28.
Three lines or phases are here shown as being simultaneously
switched. Each phase includes: A line terminal 30, which is secured
to and between two angles 32, 32, as by nuts and bolts 34, and
which angles are secured to the upper dielectric panel 22, as by a
plurality of nuts and bolts 36. An upper fuse terminal 38, which is
secured to and between two angles 40, 40, as by a plurality of nuts
and bolts 42, and which angles are secured to the upper dielectric
panel 22, as by a plurality of nuts and bolts 44. A lower fuse and
load terminal 46, which is secured to and between two angles 48,
48, as by a plurality of nuts and bolts 50, and which angles are
secured to the lower dielectric panel 26, as by a plurality of nuts
and bolts 52. A fuse 54 has an upper terminal 56 which is secured
to the upper fuse terminal 38, as by a plurality of nuts and bolts
58, and a lower terminal 60 which is secured to the lower fuse
terminal 46, as by a plurality of nuts and bolts 62. The various
angles 32, 40 and 48 each have a plurality of fins 64 formed
thereon for rapid heat radiation.
As best seen in FIGS. 2, 3, and 4, a main moving contact 66
comprises a pair of bars 68 which are pivotally mounted to and
astride the upper fuse terminal by a lower cross-shaft 70. The pair
of bars 68 is also provided with an upper cross-shaft 72 and a
cross-rod 74. The right end of the lower cross-shaft 70 is integral
with a crank 76, exterior to the right bar, having a short arm 78
and a long arm 80. The distal end of the long arm 80 terminates in
a right angle 82 which is secured, as by a plurality of nuts and
bolts 84, to a dielectric crossbar 86. The left end of the lower
cross-shaft 70 is threaded into a nut 88, exterior to the left bar,
which is fixed to the left bar, as by a machine screw 89. The right
end of the upper cross-shaft 72 is integral with a crank 90,
exterior to the right bar, having a short arm 92. The left end of
the cross-shaft is threaded into a nut 94, exterior to the left
bar, which is fixed to the left bar, as by a machine screw 95. The
distal ends of the short arms 78 and 92 are interconnected by a
connecting rod 96. Downward movement of the connecting rod, and
associated rotation of the cranks 76 and 90 and their respective
cross-shafts 70 and 72 draws the pair of bars closer to each
other.
In the main contact open position, shown in FIG. 2, the connecting
rod 96 is in its upper position. In the intermediate position,
shown in FIG. 3, the bars 68 are swung upwardly about the lower
cross-shaft 70. The lower corner 98 of the terminal 30 is cut away
to clear the bars in the intermediate position. The connecting rod
remains in its upper position. In the fully closed position, shown
in FIG. 4, the bars 68 are swung upwardly further to overlap the
terminal 30. A notch 100 is cut into the terminal 30 to receive the
upper cross-shaft 72. The connecting rod is in its lower position,
and the bars 68 are clamped onto the terminal 30 and a terminal
38.
A relatively movable, auxiliary arcing contact assembly 102 is
carried by each main moving contact 66. A fixed, auxiliary arcing
contact assembly 104 is secured to each line terminal 30. The
assembly 104 includes a pair of spring blades 106 which are
respectively secured to each side of the terminal 30, as by a
plurality of nuts and bolts 108. The distal ends of the blades each
have a reflex bend 110 therein to form a female contact. The
assembly 102 has an outline which approximates a question mark. The
upper end 112, which serves as the male contact, is advantageously
made of a solid bar. The lower end 114 is bifurcated, and is
advantageously made of a pair of bars secured to the upper end, as
by a plurality of nuts and bolts 116. The lower end 114 is
pivotally mounted between the bars 68 by the cross-rod 74 passing
through a journal 118 mounted through the bars. A second dielectric
crossbar 120 is secured to each of the pair of bars 68, as by a
plurality of machine screws 122. A compression spring 124 is
mounted on one leg of a U-shaped guide 126. The reflexed end of the
guide and the lower end of the spring are disposed in a blind bore
130 in the crossbar 120. The upper end of the spring is disposed in
a notch 132 out into both bars 114, while the upper ends of the
guide pass beyond the notch between the pair of bars 114. The
spring is thus captured.
A pair of latches 134 are respectively mounted to the upper ends of
the bars 68. Each latch 134 is pivoted to the bar 68, as by a
machine screw 136. An elongated hole 138 is cut into the latch to
pass the shank of a machine screw 140, while the head of the screw
140 precludes lateral movement of the latch. The upper portion 142
of the latch is bent over to form a camming surface. A hairpin
spring 144 is disposed with its reflex portion under the head of
the screw 136, and its legs between the cam 142 and the screw 140,
to bias the latch upwardly. A cross-pin 146 is secured through the
upper part of the lower end portion 114 of the movable arcing
contact assembly 102. A hook 148 is formed into each latch 134 and
this hook is normally biased upwardly by the spring 144 when the
switch is in its open position to engage behind the cross-pin 146.
When the latch is so engaged, the main contact bars 68 cannot swing
upwardly without similar movement of the movable arcing contact
assembly 102. The compression spring 124 biases the moving
auxiliary arcing contact 114 into abutment with the shaft 72 of the
crank 90.
An arc chute assembly 150 is secured to each line terminal 30. A
U-shaped bracket 152 is secured to the edge of the terminal 30, as
by a plurality of machine screws 154. A pair of chute halves 156
are secured to the bracket, as by a plurality of machine screws
158, and to each other, as by a plurality of nuts and bolts 160.
The pair of chute halves together form a hollow enclosure in which
the making and breaking of the auxiliary arcing contact is
performed. The halves have mutually abutting surfaces at portions
162, 164, 166 and 168. The female contact 104 projects into the
enclosure between the portions 166 and 168. The male contact 102 is
movable into this enclosure between the portions 164 and 168. A
plurality of grooves are formed into the inner walls of the chute
halves to support a plurality of V-notched arc extinguishing plates
170. The portion 168 projects downwardly and serves as a cam which
rides against the camming surface 142 of the latch 134 when the
moving contacts 66 and 102 are swung upwardly from the open
position of FIG. 2 to the intermediate position of FIG. 3. The male
contact 102 passes into the enclosure, between the bifurcations of
the V-notched plates 170 above the portion 168 into the female
contact 110 until it abuts the edge of the terminal 30. Normally,
each portion 168 will cam its respective latch 134 downwardly
releasing the movable main contact assembly 66 for movement
independently of the auxiliary arcing contact assembly 102.
However, should any one of the arc chute halves 156 be missing from
any of the terminals 30, then none of the contact assemblies 66
will move beyond the intermediate position of FIG. 3, since all of
the main contacts are secured to the second dielectric crossbar
120.
Any arcing between the auxiliary arcing contacts 104 and 102 as
they make or break will be blocked by the respective portions 168
of the arc chute from the main contact assembly 66. Any ionized gas
will be drawn up between the plates 170 and will be blown out the
top of the arc chute between the projections 162 and 164. On break
motion particularly, when the arcing contacts first separate, the
portion 168 ensures that the lowest potential path for the arc is
between the arcing contacts, rather than between one arcing contact
and the and the other main contact.
The first and second dielectric crossbars 86 and 120 are
interconnected by a pair of toggle assemblies 172. Each toggle
assembly includes a cam 174 which is pivotally mounted at its lower
end, as by a capped machine screw 176, to the crossbar 86, and
which has a notch 178 at its upper end. An arm 180 is pivotally
mounted at its upper end, as by a capped machine screw 182, to the
crossbar 120, and is pivotally mounted at its lower end, as by a
spooled rod 184, to the middle of the cam 174. A tension spring 186
is secured to and between the screws 182 and 176, and around the
spooled rod 184. In the locked position of the toggle assemblies
shown in FIGS. 2 and 3, the notch 178 of the cam sits on the cap of
the screw 182. A pair of striker assemblies 188 are secured to the
upper dielectric back panel 22 in line with the respective toggle
assemblies. Each striker assembly includes a bolt 190 secured to
the panel 22 and a cap 192. When the moving main contact assembly
66 moves from the intermediate position of FIG. 3 to the closed
position of FIG. 4, the cap 192 of the striker assembly abuts the
edge of the cam 174, moving the pivot 184 over center against the
bias of the spring 186, breaking the toggle, and permitting the
crossbar 86 to move upwardly towards the crossbar 120. Upward
movement of the crossbar 86 swings the crank arm 80 upwardly and
the connecting arm 96 downwardly; rotating both cranks 76 and 90 to
clamp the bars 68 tightly against the terminal 30 and the terminal
38.
Quick make and break operation of the switch is provided by an
operator assembly 200. The operator assembly includes a shaft 202
which is journaled through the front plate 16 to an intermediate
plate 204 and which plate is secured to the sideplate 18, as by
nuts and bolts 206.
In accordance with the present invention, when the switch is
provided with stored energy remote control mechanism for the
opening operation of the switch, as hereinafter described, there is
a releasable connection 209 between operating handle 208 and shaft
202. For this purpose shaft 202 extends forwardly of front plate 16
and has a rotary bearing in member 211 secured to said plate,
handle 208 being releasably connectable to shaft 202 by engagement
of the pin 213, fixed to shaft 202, in the slot 215 of handle 208
in opposition to the compression spring 217 which normally holds
handle 208 in retracted position against the stop 219 on the
forward end of shaft 202, which extends in a slot 219a in handle
208. When operating handle 208 is out of operating engagement with
shaft 202 it pivots on said shaft into engagement with the stop 221
on front plate 16. It will be understood that slot 219a is wide
enough to permit turning of shaft 202 for opening of the switch
under remote control without rotation of the handle 208.
A charging spring assembly couples rotation of the shaft 202 to
movement of the dielectric crossbar 86. The charging spring
assembly includes a bracket 212 which is secured at one end to the
crossbar 86, as by a plurality of nuts and bolts 214, and at its
other end is adapted to interlock with a hook 216 on the end of a
detent 218. The bracket is pivotally secured to a clevis 220, as by
a pin 222. The clevis is integral with a cap 224 and a stud 226.
The cap is secured to the top of a tube 228, as by a pin 230
through the stud and the tube. The bottom of the tube 228 rests on
a shoulder 232 of a spool 234 and is secured thereto, as by two
pins 236. A cup shaped washer 238 also sits on the shoulder 232. A
helical compression spring 240 is disposed on the tube 228 and is
captured between the plate 224 and the washer 238. A rod 242 is
disposed through a longitudinal bore 244 in the spool. The lower
end of the rod is threaded and is secured to a convoluted washer
246 by a washer 248 and a nut 250. A helical compression spring 252
is disposed on the rod 242 and is captured between the top of the
spool 234 and a washer 254 and a cross-pin 256 through the top of
the rod. A cup 258, having a longitudinal bore 260 which clears the
spool and a shoulder 262 which engages the washer 238, is supported
on the convoluted washer 246. Two crank arms 264 and 266 are
secured to the shaft 202, as by welding, and are pivotally secured
to the cup 258, as by pins 268 and 270 respectively.
The detent 218 is pivotally mounted to the front plate 16, as by a
nut and bolt 272, and is limited in its swing by a pin 274 fixed to
said detent and projecting through a relatively larger hole 276 in
the front plate. An arm 278 is pivotally secured at one end to the
detent 218, as by a nut and bolt 280, and at its other end to one
end of an arm 282 by a roller, a stud and a C spring 284. The other
end of the arm 282 is pivotally secured to the front plate 16, as
by a nut and bolt 288. A tension spring 290 is connected to and
between the arm 282 and the front plate 16 to bias the detent 218
towards the bracket 212. A right angle 292 is secured to the arm
266, as by a plurality of machine screws 294 and has a foot portion
296 which is disposed under the roller 284.
When the switch is in its normal open position, the end of the
bracket 212 is under the hook 216 of the detent 218. Upward
rotation of the handle 208, towards the closed position, swings the
brackets 266 and 264 upwardly and slides the cup 258, the washer
262, the spring 240, the clevis 220 and the bracket 212 upwardly to
abut the bracket against the hook 216. Further rotation of the
handle compresses the spring 240 against the clevis, and when the
spring is fully compressed providing a direct drive, until the foot
portion 296 engages the roller 284 to swing the detent 218 away
from the bracket 216, thereby releasing the bracket from the hook.
The now released compressed spring fires the bracket 212, the
dielectric crossbar 86, the toggled locked thereto dielectric
crossbar 120, the main moving contact assemblies 66 and the
auxiliary arcing moving contact assemblies 102 upwardly. On normal
operation, sequentially, the auxiliary male contact 112 will mate
with the auxiliary female contact 110, the arc chute portion 168
will strike open the latches 134, the main contact bars 68 will
overlap the terminal 30, the striker 192 will break the toggle 172,
and the dielectric bar 86 will rotate the cranks 76 and 90 to clamp
the bars 68 on the terminal 30 and the terminal 38.
If one or more of the arc chute halves 56 is missing, the
respective latch 134 will not be opened and the switch will halt in
the intermediate open position of FIG. 3.
If a short circuit condition should exist at the instant of closing
of the arcing contacts 112 and 110, the flow of current creates
electrodynamic forces having a direction which opposes the closing
force of the spring 240 and the momentum of the high inertial mass
of the moving contacts.
In the case of a relatively less severe short circuit, these
electrodynamic forces are insufficient to prevent the normal
closing sequence of the switch. The moving arcing contacts 112 will
be driven into engagement with the respective stationary arcing
contacts 110 by the respective latches 134 engaged with their
respective cross-pins 146. Subsequently, the latches will be
disengaged from the cross-pins by the respective camming portions
168 of the arc chutes and the main moving contacts will close onto
the main stationary contacts. In due course, depending on the
current and the fuse ratings, the fuses will blow.
In the case of a very severe short circuit, these electrodynamic
forces will equal or exceed the closing force of the spring 240 and
the momentum of the high inertia mass of the moving contacts. Under
such conditions, the fuses will blow within one-half cycle, while
more than one-half cycle will be required to either drive the
moving arcing contacts in their closing direction from the
commencement of mating with the stationary arcing contacts to the
point of disengagement of the latches 136 from their respective
cross-pins, or to arrest and reverse the direction of movement of
the high inertia mass of the moving contacts driven by the spring
240. Therefore, within this one-half cycle the fuses will blow; and
the light springs 124 will be compressed and the moving contacts
will be arrested by the cross-pins pushing against the latch hooks
148 so that the latches 136 will not reach the camming portions 168
and will not be disengaged from their respective cross-pins, and
the main moving contacts will not mate with the main stationary
contacts. Should the electrodynamic forces exceed the driving
force, and the moving contacts be thrown back, such forces will be
shock-absorbed and cushioned by the compression of the spring 240,
and will not be directly transmitted to the handle.
When the switch is in its normal closed position, downward rotation
of the handle 208 towards the open position, swings the brackets
266 and 264 downwardly and slides the cup 258, the convoluted
washer 246, and the rod 242 downwardly, compressing the inner
spring 252, when the spring 252 is fully compressed, the handle 208
is in direct drive with the clevis 220 and swings the bracket 212
downwardly, swinging the dielectric crossbar 86 downwardly and
locking the toggles 172. This releases the compressed spring 252
which now fires the bracket 212 and the moving contact assemblies
66 and 102 downwardly. A ramp 298 is formed on the corner of the
detent above the hook 216 so that the bracket 212 cams the detent
aside as it moves downwardly to the open position. It should be
noted that when the dielectric crossbar 86 is swung downwardly, it
rotates the crank 76 and 90 to unclamp the bars 68 from the
terminal 30. At this time the end 112 of the moving auxiliary
arcing contact is abutting the edge of the terminal 30, and the
compression spring 124 biases the dielectric crossbar 120 and the
main moving contact bars 68 away from the terminal 30. In the event
that a chute is missing and the moving contact is halted in the
intermediate position of FIG. 3 with the toggle unbroken, on
opening movement the handle will swing the moving contact bars
downwardly without any compression of the spring 252.
Referring now to the provision for remote control of the switch
opening operation the mechanisms illustrated more particularly by
FIGS. 8 to 10 will now be described.
A screw-threaded rod 300 is releasably engaged by a split nut 301
which comprises parts 302 and 304 carried by arms 306 and 308
pivotally mounted on shouldered screws 310 and 312 for movement
into and out of engagement with the threaded portion of rod 300 in
frame 314 which is secured to plate 16. A handle 316 is provided at
the front of plate 16 (FIGS. 1 and 8) for rotating rod 300 which
extends through an opening 318 in said plate. When said split nut
301 engages rod 300, the latter is longitudinally movable in one
direction, pursuant to rotation of the handle, to compress, i.e. to
charge, spring 320 which is captured between the end 322 of frame
314 and a collar 324 fixed to said rod. When nut 301 is released
from rod 300 the latter is movable longitudinally by the charged
spring 320, without rotation of said rod, toward panel 22.
Rod 300 is coupled operatively to bar 86 by mechanism including
bellcrank lever 326 which is pivotally mounted on stationary
bracket 328 and is pivotally connected at one end to collar 324 and
at its other end to the lower end of link 330. A stop 331 limits
the movement of bellcrank 326 in a clockwise direction viewing FIG.
8 and thereby limits the longitudinal movement of rod 300 to the
right. Said link 330 is pivotally connected at its upper end to
bellcrank lever 332 which is pivotally mounted on stationary
bracket 334. The upper arm of lever 332 carries an adjustable
member 335 which bears against bar 86 for moving said bar 86 to
open the switch when split nut 301 releases rod 300.
It will be noted that the rib-defining grooves of rod 300 are such
that the confronting sides 334' of each groove define an obtuse
angle therebetween so that the discharging force of spring 320,
when latch arm 336 (FIGS. 9 and 10) which is pivotally mounted nut
part 302 by the pivot 338 is disengaged from nut part 304, is
effective to release the nut 301 from rod 300 so that the latter
can move longitudinally without rotation. More particularly, latch
arm 336 carries a roller 340 which engages nut part 304 when nut
301 is in threaded engagement with rod 300. Spring 341 is connected
at one end to plate 16 as indicated at 342 (FIG. 9) and at its
opposite end to pin 344 on arm 308. Nut part 304 has an inclined
portion 345 over which roller 340 can move to and from the two
positions shown in FIG. 9, the position of said roller at the left
being in the latching position of arm 336 and the position of said
roller at the right being in the unlatched position of said
arm.
A solenoid 346 is mounted on a bracket 347 secured to casing 314.
The solenoid plunger 348 is connected to arm 350 of latch arm 336
so that when the solenoid in energized, which can be done by
closing a switch at any selected location, roller 340 is retracted
and nut 301 is moved out of operative engagement with rod 300. A
manually operable pin 352 accessible at the front of plate 16 is
operatively connected to arm 350 in slot 353 to move said arm for
disengaging nut 301 with and from rod 300.
While I have shown and described the preferred embodiment of my
invention, it will be understood that the invention may be embodied
otherwise than as herein specifically illustrated or described, and
that certain changes in the form and arrangement of parts and in
the specific manner of practicing the invention may be made without
departing from the underlying idea or principles of the invention
within the scope of the appended claims.
* * * * *