July 26, 1960
L. S. THOMAS
2,946,865
ELECTRIC CONTROL BOX
Filed Oct. 24, 1958
2 Sheets-Sheet 1
197703195)’
July ‘26, 1960
2,946,865
L. S. THOMAS
ELECTRIC CONTROL BOX
Filed Oct. 24, 1958
2 Sheets-Sheet 2
INVENTOR.
230,5 51/2? j?a/was'
BY
?rral?‘y
United States Patent‘f)
CC
2,946,865
Patented July 26, 1950
2
:1.
making an industry wide safety feature available‘to most
all installations.
In, the drawings:
2,946,865
Figure'l is an'isometric'view of‘the'control'box em
bodying thisinvention with‘the door shown in an open
ELECTRIC CONTROL BOX
Leslie‘S; Thomas,» Orchard Lake, Mich., assignor to Gem
eralMotcrs Corporation, -Detroit,.Mich., a corporation
of Delaware
Filed on. 24; 1958,1SénNo; 769,384
3 Claims. (Cl; 200-50) '
position'to illustrate the‘location and‘relationship of the
various parts.
Figure 2 is an elevational view of the control box with
the ‘door in phantom and the actuating mechanisms shown
10 in'full’lines to illustrate the'location and'relationship of
the‘pa'rts when'the door is in a closed position.
Figure 3 is a sectional view of a portion of the control
box shown in Figure 2, taken substantially along the line
This'invention-relates ‘to electrical'control boxes and
more particularly to ‘a control‘box/having a-isafety link
agé‘rbetween' the main latch me'ch'anisrniand' the-switch
operating‘ mechanism to eliminate'some of the’da'ngers
which arise‘ due- to‘ the unauthorized personnel‘ ‘entering
the‘ control box.
‘
In?m‘ost installations- making use of electrical control
bo‘x'es;~' such'as- fuse boxes,v or switchiboxes‘ of some’type',‘
there is always the danger of unauthorized personnel'enteb'
ing 'the 'box' and the possibility‘ of ‘accidents ' resulting
therefrom. In order to‘ compensate "for these dangers, ‘it'
has‘ibeen the practice in the past to‘pro'v‘ide some ‘sort of
switch actuating mechanism which; is‘ directly connected
to" the" door? latch‘ mechanism‘ such that ‘the switch is
automatically shut o?' when the‘door- is opened. This
type of‘contr'ol'box, however, gives a great 'amountiof"
di?iculty when maintenance von-the switch‘means, or other
electrical equipmentlwithinthe‘box, becomes necessary.‘
Slcille'd‘maintenance personnel, ‘in order'to'repair th‘elcon
3;’3 and looking in the direction of the arrows.
Figure‘4 is‘ a sectional view of‘ a portion of the control
box shown in Figure 2, taken substantially along the
line 4-'—4 and looking in the direction of the arrows.
Figure'S is a sectional view of a portion of the control
box shown in' Figure 2,‘ taken substantially along, the
line 5—5 and looking inlthe direction of the arrows.
Referring'more particularly to the drawings, Figures
1 and i2-best show the over all control box and intercon
nected linkages. The control box itself comprises top and
bottom panels 10’and’12, side panels 14 and 16, and
aback panel 18. A ?anged rim 20 extends around'the
periphery of the open side of the box to provide a'dirt
seal and ltarnper proof closure surface for the door 22.
The door may be hinged to either of the side panels
14‘or 16‘ many suitable manner, such as by a piano
type hinge or aplurality of strap or butt hinges. The
door 22"'has a ?ange 24 surrounding the periphery and
facing inwardly- to overlie the ?ange 20 formed on the
control box.
tents of the box,v must be able "to‘actua'te the'switch when
A switch 26‘is mounted in the box, preferably adjacent
the‘door‘is-ope‘n. If vthe‘switch control'is interlocked'to 35 thev‘corner
formed by the side plate 14 and the top plate
the door actuatingimechanism' ‘for the safetyiof unauthori
10, and'serves to control any type of electrical system,
ized personnel it may'be‘seen that‘ maintenance on‘the
not? shown, which'may-be located in the lower portion
equipment-may be made only "when'the' door is'lop'en
of the box. A'switch handle 28, rotatably secured in the
andi'the ‘switch in‘the open‘ or 'olf position."
switch "26 and pivoted on'the shaft 30, actuates the switch
The ‘other possibility, in order tofcompensate‘ 'fo'r ‘thisv
26 to~v open or close the usual contacts.
7
disadvantage; is :to have'a switch‘*actuatingzmechanism
The
main
door
latch
mechanism
is
operated
by
a
handle
thatr'isi‘in'no ‘way connected orvcontrolled' by:th'e door
32'disp'osed'on' the outer surface of the door 22. A shaft
latch mechanism. This- possibility, however; is poor‘ from
34 extends through the door panel‘ 22, through a spacer
assafety. standpoint; due vto the inherent dangersof the
member 36, and supports- the lower latch cam 38." The
switch-beingiclos'ed when'the door is-in an=op'en=position. 45 latch
'cam is provided‘with'a knife edge 40, and it may be
The {device in! which this invention‘? is" embodied corn;
seen'fror'niviewing Figures ‘1 and'2. that rotation of the
prises three‘interconriectéd mechanisms, a main 'door latch
handle 32"will'rotate'the‘latch‘cahr'SS to carry the knife
mechanism, a switch actuating mechanism, and a connect
edge
40 behind’the'?anged‘portion 26 of the control box
ingmechanism-between the’door ‘latch and‘switch actua
when the'door'is closed. The lower latch cam 38 is
tion'.-~ With'this-control box it is- possible to actuate the 50
secured-for‘ro‘tation with‘the shaft 34 by the set screw 42.
An upper cam 44 of the same con?guration as the lower
cam 38 is ‘rotatablysecured to the innerside of the door
panel 22 by the ?anged‘spacer member ‘46 and the shaft
48. The'upper latch cam 44 may be secured to the
In ‘order'for maintenance personnel to enter the box while 55 shaft ‘48 in any convenient manner as by a Washer 56
theswitchiis in a closed‘ positionfa defeater mechanism
held in place by aconventional cotter-pin 52.
issprovided which ‘disconnects thevrconnecting mechanism
A connecting rod 54 is pivotally secured to the upper
from ‘ the switch actuating mechanism ~ to’ allow the main
and lower cams as at 56 and 58 and serves to rotate the
tenance operatorrto open the-door‘ without opening the
upper and lower latch-cams in unison. Rotation of the
switch.--- The'defeaterImechanism'isso arranged that'in 60 handle
32 and the lower latch cam 38 will lift the con‘
experienced or unauthorized ‘personnel could no'topen the
switch- mechanism by the‘door' latch structure whereby
closing the door'will‘require asecond‘operation to actuate
theswitch. However,- the door normally may be opened
unless the switch is ?rst opened, that is, in the oif'position;
box without a special tool, and thus-would be protected
from unauthorized entry. '
necting rod 54, which rotates the upper cam 44. A com
pression spring 60,‘ acting between a tab 62 secured to
the connecting rod 54 and a tab 64 secured to the inn’;
Thus, a control box is provided having‘ numerous safety
surface ‘of the doorii'panel' 22, biases the connecting rod,
features, the main feature being the possibility of2 skilled 65 and
consequently the latch cams, in the lower or opening
personnel entering-the box for- proper-maintenancepur
position,‘ the position shown in Figure 1.
poses and sat the same time eliminating thedangersin
The switch tactuatingimechanisrn includes a-plate‘é?
herent in-unauthorized personnel entering the control ‘box.
having-1 the’ apertures " 68 andv 70"‘for-medthe1'ein; A
The-device is relatively simple to-operate and inexpensive
bracket member‘72', or'a plurality thereof, extends from
to manufacture. Existing control» boxes couldibe-"mo‘di?ed 70 the ‘plate 66 inwardly of *the‘ box and "is pivoted‘ from ‘the
according .to the invention without ‘exorbitant ‘ cost, .thus
back panel 1855as=by ‘thepivot'sh'afti 74. The'bracket
22,946,865
member 72 may be Welded to the plate 66 such that the
plate 66 is pivotally movable with respect to the switch
26. The switch handle 28 extends through the aperture
68 in the plate 66 and movement of the plate about the
pivot point 74 will open or close the switch 26.
A pair of bearings 76 are secured to the inner surface
of the door panel 22, as by bolts 78, and are vertically
spaced thereon. A switch actuating rod 80 is vertically
movable in the bearings 76 and has ‘attached thereto the
The pivot pin 132 connecting the links 126 and 130,
has an extension 140, best seen in Figure 3, extending
through the link members 126 and 128 and is adapted
to be received in the notch 114 formed in the plate 106.
A stop tab 142 is secured to the switch actuating rod
80 and cooperates with the tip, 144 of the link member
130. The purpose of the abutment will be later de
scribed.
The operation of the control box is as follows: With
hinged switch actuating links 82 and 84, pivotally con 10 the door 22 open, the parts are in the position shown in
Figure 1. When it is desired to close the door and ac
nected as by the pin'86. The link member 84 extends
tuate the switch 26, the operator swings the door until
through the aperture 70 in the plate 66 and it may be seen
the preliminary latch hook 116 engages the latch bar 118.
that vertical movement of the rod 80 will rotate the
The latch handle =32 is then rotated to engage the latch
plate 66 through the links 82 and 84 to actuate the switch
cams 38 and 44 with the edge 22 of the control box.
handle 28;
'
As the latch cam 38 is rotated and connecting rod 54
A tab 88, having a slot 90 formed therein, is secured
raised, the links 126 and 130 also move vertically up
to the upper portion of the connecting rod 80 and pro
wardly with the connecting rod 54 and the extension 140
vides the actuator means for connecting rod. A switch
of the pin 132 engages the inclined surface 146 of the
actuating handle 92, located on the outer surface of the
door panel 22, extends through an opening 94 in the panel
and is secured to the rotating bracket plate 96 by the
plate member 106. The plate member 106 rotates against
the pressure of the spring 110, releasing the preliminary
bolts 98.
latch means and allowing the door to be fully closed.
Rotation of the handle 92 will rotate the
The extension 140 is received in the notch 114 in the
bracket plate 96 inside the door panel 22. A pin 100 is
plate 106 and the spring 110 returns the plate 106 to its
secured in the rotating bracket plate 96 and extends into
the slot 90 in the tab 88. It is obvious that rotation of 25 normal position. The parts are then as shown in full
lines in Figure 2.
the handle 92 will thus actuate the rod 80, the links 82
The switch actuating handle 92 may then be turned
and 84 and the plate 66 to open or close the usual con
tacts in the switch 26.
The defeater mechanism is actuated by a pin 102 which
extends through the door panel 22 and through a bearing
104. The pin 102 is secured in a plate 106 adjacent the
inner surface of the door 22, the connection being such,
that rotation of the pin 102 will rotate the plate 106.
from outside the box to close the switch 26, rotation of
the handle 92 rotating the bracket plate 96 and raising
the switch actuating rod 80, through the tab 88. The
pivoted links 82 and 84, extending through the aperture
70 in the plate 66, rotate the plate 66 about the pivot
point 74 to actuate the switch handle 28 and close the
The pin 102 is illustrated as having a slot in the outer 35 switch 26. At this time the stop tab 142 on the switch
actuating rod 80 is raised into abutment with the end
end, allowing the pin 102 and the plate 106 to be turned
144 of the connecting link 130. The parts are then as
by a conventional screwdriver. However, to prevent un
shown in dashed and dotted lines in Figure 2.
authorized personnel from operating the mechanism, the
The control box is thus operational, the door being
pin 102 may have some special con?guration in the end
closed and the switch 26 actuated, and the box may re
to permit operation only by a special tool. A tab 108
main as such for as long as necessary.
,
secured to the door panel 22 and a compression spring
When it is desired that the control box he opened the
110 abutting the plate 106, resiliently biases the plate 106
handle 92 is rotated to rotate the plate 66 and the switch
in the position shown in Figures 1 and 2.7 The purpose
handle 28 to open the switch 26. The stop tab 142 drops
of a push bar 112 rigidly secured to the plate 106 and
the notch 114 formed in the plate will be later described. 45 with the connecting rod 80 and out of the way of the link
130. A screw driver, or other convenient tool, is used
Preliminary latching means are provided for the door
to rotate the defeater pin 102, thus rotating the plate 106
22 by a hook member 116, secured to the plate 106, and
and freeing the extension 140 of the pin 132 from the
the preliminary latch bar 118, secured in any convenient
notch 114 of the plate 106. The handle 32 is forcibly
manner in the control box. The hook member 116 has
rotated by spring 60 to disengage the latch cams 38 and
a shoulder 120 formed thereon and an inclined surface
44 from the side ?ange 20, allowing the door to be
122 between the end of the hook member and the shoul
opened.
der 120. A complementary inclined surface 124 is pro
‘If‘the operator should wish to open the door without
vided on the end of the preliminary latch member 118.
opening the switch 26 he may do so by leaving the switch
It may be seen that by closing the door 22 the surfaces
122 and 124 will allow the hook member to slide past 55 actuating handle 92 in the switch-on position and rotating
the pin 102 and the defeater plate 106. The push bar 112
the end of the preliminary latch member 118, and the
rotates the connecting link member 130 out of engage
shoulder 120 to engage the end of the latch member 118.
ment with the stop tab 142 and at the same time frees
Thus, the door is retained in a partially closed position,
the extension 140 of the pin 132 from the notch 114.
the opening being such that there is no danger to per
The door actuator handle 132 is forcibly rotated by spring
sonnel operating the box. The switch actuator'mecha
60 to free the latch connections 38 and 44 from the side
nism may then be operated to close the switch 26.
?ange. The operator then has access to the-box with the
Secured to the connecting rod 54 of the main door
switch in the closed position.
latch mechanism is a link 126 which extends toward the
v If the door has not been latched when the switch 26
center of the door. An arcuate cam surface 128 is
is actuated, tab 142 on the rod 80 will engage the shoul
65
formed in the end of the member 126. A second link‘
der 144 on the ring member 130, thus raising the ring
130 is pivotally secured to the ?rst link member 126 by
a pivot pin 132. The joining surface of the link 130 is
members 130 and 126, lifting the latch mechanism and
complementary to the cam surface 128 of the ?rst link
member 126, the member 130 having a stop shoulder 134
of the box.
adapted to abut the edge of the ?rst link member 126
such that rotation past the shoulder ‘is not possible. The
links are biased into the position shown by the torsion
securing the latch cams 38 and 48 behind the ?ange 20
>
Thus it may be seen that a control box is provided
which allows access thereto only by a skilled operator,
and preventing entrance by unauthorized personnel. The
control box door may be opened with the switch either
spring 136 vacting on the'buttons 138. The position just
1n_the on or o? position at the desire of the operator, it
described is as illustrated in Figures ‘1 and 2.
a a
75 being assumed that the person opening the door is skilled
5
2,946,865
enough to know whether or not the switch should be on
or o?”.
‘I claim:
1. An electric control box comprising a plurality of
panels de?ning an open sided box, a switch secured in
said box, a door hingedly secured at one edge to one of
said panels, a latch handle rotatably secured to the out
side of said door and having a shaft extending through
apertures to raise and lower said bar and said switch
handle to actuate said switch, connecting means operable
between said latch means and said rod to move said rod
and said bar and said switch handle and open said switch
when said latch means are operated to open said door,
and independently operated defeater means engaging
said connecting means to disengage said connecting means
and actuate said latch means for opening said door with
said door, a ?rst latch cam secured to said shaft and
out actuating said switch and allow access to said switch
rotatable with said handle, a second latch cam rotatably 10 and said box when said switch is closed.
secured to said door and spaced from said ?rst latch
3. An electric control box comprising a plurality of
cam, a connecting rod pivotally secured to said ?rst and
panels de?ning an open sided box, a switch secured to a
second latch cams to rotate said second cam in conjunc
portion of said panels and within said box, a door hinged
tion with said ?rst cam when said ‘first cam is rotated
ly secured at one edge thereof to one of said panels,
by said handle and secure said door to said box in a 15 latch means rotatably secured to said door and engaging
closed position, switch actuating means secured to said
another of said panels to secure said door in a closed
door and vertically movable with respect thereto, means
position, switch actuating means secured to said door
pivotally secured to said switch and within said box
and vertically movable with respect thereto, means pivot
and engaged by said switch actuating means to open and
ally secured to said switch and within said box and
close said switch when rotated by said switch actuating
engaged by said switch actuating means to open and close
means, connecting means operable between said switch
said switch when rotated by said switch actuating means,
actuating means and said connecting rod to actuate said
a connecting link operable between said switch actuating
switch actuating means and open said switch when said
means and said latch means to actuate said switch actuat
connecting rod and said latch cams are disengaged from
ing means and open said switch when said latch means
said box to open said door, and independently operated 25 are operated to open said door, a defeater plate pivotaily
defeater means to disengage said connecting means and
secured to said door and having a notch formed therein
actuate said connecting rod and said latch cams to open
to retain said latch means in a closed position, said de
said door without actuating said switch actuating means
feater plate being rotatable to release said latch means
and to allow access to said switch and said box when said
and allow said latch means to disengage from said box
switch is in a closed position.
30 for opening of said door, and a push bar secured to said
2. An electric control box comprising a plurality of
defeater plate and rotatable therewith to disengage said
panels de?ning an open sided box, a switch secured to a
connecting link from said switch actuating means when
portion of said panels and within said box de?ned there
I said plate is rotated to disengage said latch means and
by, and having a switch handle extending therefrom, a
prevent said connecting link from actuating said switch
door hingedly secured at one edge to one of said panels, 35 actuating means and opening said switch when said latch
latch means rotatably secured to said door and engaging
another of said panels to retain said door in a closed
position, a bar pivotally secured to said switch within said
box and having spaced apertures therein, one of said
apertures engaging said switch handle for actuation there 40
of, a rod secured to said door and vertically movable
with respect thereto, link means secured to said rod and
movable therewith and extending through another of said
means disengages from said box and said door is opened.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,695,934
2,806,099
2,882,359
Wills ________________ __ Nov. 30, 1954
Rexroad _____________ __ Sept. 10, 1957
Edmunds et al _________ __ Apr. 14, 1959