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Патент USA US3052796

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Sept. 4, 1962
R. J. BERTLING
3,052,786
ELECTRICAL SWITCH
Filed Dec. 17, 1959
30
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4 Sheets-Sheet 1
Sept. 4, 1962
R. J. BERTLING
3,052,735
ELECTRICAL SWITCH
Filed Dec. 1'7, 1959
4 Sheets-Sheet 2
IN VEN TOR.
Fomzid J Berélézgy
2/114!
Sept. 4, 1962
R. J. BERTLING
3,052,786
ELECTRICAL SWITCH
Filed D60. 17, 1959
4 Sheets-Sheet 5
sePt- 4, 1962
R. J. BERTLING
3,052,786
ELECTRICAL SWITCH
Filed Dec. 17, 1959
a7 72
4 Sheets-Sheet 4
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INVENTOR.
RomzZd J Bertlény
United States Patent
ice
1
3,052,786
Patented Sept. 4, 1962
Id
Similarly when the switch blade moves through the last
portion of its closing operation, the contact ?ngers are
returned to their initial position whereby contact pres
3,052,786
ELECTRICAL SWITCH
Ronald J. Bertling, South Milwaukee, Wis., assignor to
McGraw-Edison Company, Milwaukee, Wis, a corpo
sure is re-established.
FIG. 1 illustrates a rotating insulator type sidebreak
ration of Delaware
disconnect switch incorporating a preferred embodiment
of the instant invention and designated generally by the
Filed Dec. 17, 1959, Ser. No. 860,212
12 Claims. (Cl. 200-—170)
reference numeral 11. Switch 11 is shown mounted
on a horizontal channel member 12 which supports a ver
This invention relates to electrical switches and, more
particularly, to contact structure for electrical disconnect 10 tical stationary insulator 14 and a spaced apart rotatable
insulator 16 which is mounted on a bearing 17 for ro
switches.
tation about a vertical axis under the action of a lever
In electrical disconnect switches, wherein a switch
18 and supported on the channel 12 by a bearing mount
blade is pivoted into and out of engagement with a station
19.
ary contact jaw, it is necessary that the contact pressure
A contact blade mounting bracket 20 and clamping
be su?iciently high to provide good electrical contact. On
assembly 21 support a contact blade 22 on the upper end
the other hand, excessively high contact pressure tends
of insulator 16 for rotation in a horizontal plane into and
to impede movement of the switch blade into and out of
out of engagement with stationary contact structure 24
engagement with the contact jaw which causes exces
mounted on the upper end of stationary insulator 14 by a
sive wear.
conductive contact support bracket 26.
It is an object of the invention to provide a high pres
The stationary contact structure 24 includes a pair of
sure contact jaw for disconnect switches wherein contact
contact ?ngers 28 each of which is pivotally mounted on a
pressure is relieved during movement of the switch blade
bearing assembly 30 and each carries a pair of leaf
into and out of its closed position.
type contact spring assemblies 32 for providing contact
It is another object of the invention to provide a high
pressure contact jaw which does not inhibit the opening 25 pressure when the switch is in the closed position shown
by full lines in FIG. 2.
or closing movement of the contact blade.
It is a further object of the invention to provide a
. '
In order to open the switch from its closed position
shown ‘by full lines in FIGS. 1 and 2, operating lever 17
pivotable contact jaw which is snap acting into closed
position thereby tending to be held in said closed posi
is rotated in a clockwise direction as viewed in FIG. 2 from
tion against the effects of electrical or other external 30 its full to its dashed position by any suitable switch op
erating means which is not shown but which is well known
forces.
in the art. This rotates insulator 16 through a correspond
It is a still further object of the invention to pro
ing angle to move switch arm 22 out of engagement with
vide a rotatable contact jaw whose limit stops are com
contact jaws 28 and through an approximately 90 degree
pletely enclosed so that its operation cannot be effected
angle to its dashed position. As contact blade 22 rotates
by the collection of ice.
These and other objects and advantages of the inven
through the initial portion of this angle, its high pressure
tion will become more apparent from the detailed descrip
tion of the invention taken with the accompanying draw
engagement with contact ?ngers 28 causes them to rotate
‘embodying the instant invention;
fingers 28.
from their position shown by full lines in FIG. 2 to their
dashed position. Further rotation of switch blade 22
ings in which:
FIG. 1 shows an elevational view of a disconnect switch 40 toward its fully open position disengages it from contact
An arcing horn assembly comprising a movable arcing
FIG. 2 shows a top plan view of the disconnect switch
blade 38 carried by ‘contact blade 22 and a stationary
shown in FIG. 1;
arcing horn 44} carried by the stationary support bracket
FIG. 3 is a top view of the pivotal contact jaw showing
45 26 is provided so that the contact ?ngers 28 and the con
each of its alternate positions;
tact tip of switch blade 22 will not be subjected to arcing
PEG. 4 is a view taken along lines 4—4 of FIG. 3;
upon the opening or the closing of the switch 11.
FIG. 5 is a view taken along lines 5—5 of FIG. 3;
The swiveling action of stationary contact assembly 24
FIG. 6 is a view taken along lines 6——6 of FIG. 4;
described above, can best be seen by reference to FIG. 3
FIG. 7 shows the developed cam surface upon which
As contact blade 22 begins rotating from its closed posi
the contact ?ngers of the preferred embodiment of the
tion shown by full lines the frictional force resulting from
invention pivot;
the high pressure engagement between contact ?ngers 28
FIG. 8 is a partial sectional view of an alternate em—
sets up a counterclockwise torque in said contact ?ngers
bodiment of the instant invention;
causing them to rotate on bearing assembly 30 until they
PEG. 9 is a view taken along lines 9-9 of FIG. 8;
and
FIG. 10 is a view taken along lines 10—18 of FIG. 9.
In general terms the invention comprises an electrical
55
reach the position shown by dashed lines whereupon fur
ther motion is arrested by an internal stop which will be
discussed in greater detail hereinafter. Contact blade 22
thereafter continues to its fully open position. Con
switch having a movable switch blade, stationary contact
tact ?nger support arms 29 extending laterally from each
?ngers engageable ‘by said switch blade, contact spring
means, and means for relieving the contact spring pres 60 contact ?nger engage when the switch is open to prevent
sure as the switch blade moves out of engagement with
collapse of the ‘stationary contact assembly 24. When
the switch 11 is reclosed contact blade 22 is rotated to the
said stationary contacts and for re-establishing said con
position shown by dashed lines in FIG. 3 whereupon it
tact pressure upon the ire-engagement thereof.
engages the contact ?nger support arms 29 which rotates
According to a more speci?c aspect of the invention, 65 the contact ?ngers 28 in a clockwise direction from their
the stationary contact means includes opposed contact
dotted to their full position whereupon they engage a
?ngers pivotally mounted on a cam surface for movement
second internal stop.
between ?rst and second positions as the switch blade
The invention comprises a means for relieving the con
moves through the initial portion of its opening opera
tion.
tact pressure as contact blade 22 moves from its full to
The cam surfaces are so formed that such pivotal 70 its dashed position shown in FIG. 3 and for re-establish
movement operates ‘to displace a portion of each contact
?nger away from its associated contact pressure spring.
ing it upon movement in the opposite direction so that the
amount of torque on operating levers 17, necessary to
3,052,786
3
4
move contact blade 22 into and out of engagement with
of and into its engaged position between contact ?ngers
28, shown by dashed lines in FIG. 3, when the switch 11
is being opened and closed. Also, the amount of force
contact ?ngers 28, is considerably reduced. In the pre
ferred embodiment of the invention shown in FIGS. 4, 5
and 6, the pressure relief means comprises a cam surface
necessary to pivot contact ?ngers 28 into and out of their
closed position shown full in FIG. 3 is only a fraction of
upon which the contact ?ngers pivot so that as they move
between their closed and open positions their pivoted
the force that would be necessary to close the switch if
ends 44 are allowed to move closer together thereby re
the contact pressure were to remain constant.
laxing contact springs 32 and relieving the contact
Referring again to FIG. 7 it can be seen that barrier
portions 69 of the cam surfaces 59 is raised relative to
As seen in FIGS. 4 and 5, the contact springs 32 are 10 portions 66 and 68. Thus, the contact ?ngers are forced
loaded by means of tie bars 50 which extend through
to overcome said barrier portion when the area of en
opposed leaf spring assemblies on each of the contact
gagement with bearing posts 63 change from one of the
?ngers 28 and which are retained in bearing relation with
portions 66 and 68 to the other. In this manner the con
said leaf spring assemblies by means of retainer pins 52
tact ?ngers tend to snap into position as they rotate be
pressure.
'
which extend transversely through each end. One end of 15 tween their open and closed positions thereby providing
each of the longest leaf springs 54 is perforated for em
a more positive action. In addition, barrier portion 69
bracing an anchoring pin 56 integral with and extending
tends to prevent the contact ?ngers from being moved
laterally from each of the contact ?ngers 28. A shoulder
out of the closed position under the in?uence of short
58 on pin 56 provides a pressure pad at one end of leaf
circuit magnetic forces and the like.
spring 54 while the other end thereof engages a second
Because of the shape of cam surface 59,‘movement of
pressure pad 60 on the opposite side of tie rod 50 and
integral with contact ?ngers 28.
It can be seen from FIG. 4 that when the switch is in
contact ?ngers in either direction will be arrested when
the concave ends 70 or 71 of said surface engage the hear
ing posts 63. This eliminates the necessity for external
its closed position the distance between corresponding
stops to limit the pivotal movement of contact ?ngers 28,
pressure pads on each of the contact ?ngers 28 is greater 25 thereby greatly diminishing the danger that ice forma
than the distance between the pins 52 on each end of
tion will inhibit the operation of the switch.
the tie bars 50 plus the thickness of leaf spring assemblies
The current path from, switch blade 22 to conductive
32. Thus, the ends of said leaf spring assemblies are
support bracket 26 and through stationary contact struc
bowed outwardly to provide contact pressure at each of
ture 24 has a ?rst exchange point between switch blade 22
the pressure pads 58 and 60.
30 and contact ?ngers 28 and a second exchange point be
Referring now to FIGS. 4, 5 and 6, the bearing assem
tween cam surface 59 and bearing posts ‘63. From FIG.
bly 30 is shown to include an annular housing 61 which is
4 it can be seen that when the switch is in its closed posi
?xedly mounted to bracket 26 by a conductive base por
tion leaf spring assemblies 32 provide contact pressure for
tion 62 and which has a pair of substantially coaxial, in
both of these exchange points.
wardly extending bearing posts 63 integral therewith. 35 FIGS. 8, 9 and 10 show an alternate embodiment of the
The pivotal end 58 of each of the contact ?ngers 28 is
invention in which the cam- surface 80 is formed in the
provided with an annular bearing portion 65 which are
bearing assembly 82 rather than on the contact ?ngers.
disposed in a coaxial relationship on the interior of hous
More speci?cally, assembly 82 is provided with a recess 83
ing 60. A cam surface 59 is for-med on diametrically
in each of its opposite sides for receiving a hinge pin 84
opposite edges of each of the bearing portions 65 and each 40 integral with the ends of contact ?ngers 86. The cam
of said cam surfaces is in engagement with one of the
‘bearing posts 63. The development of cam surfaces 59 is
shown in FIG. 7 to have a shallow portion 66, a depressed
surface 80 is formed on an undercut portion 87 at the
rear of recess 83 and includes an upper portion 88 and
a downwardly sloping portion 90.
portion 68 and a barrier portion 69. It can be seen from
A horseshoe shaped force transmitting member 92 is
FIGS. 4 and 5 that opposed cam surfaces 59 in each of 45 disposed circumjacent hinge pin 84 with its rear portion
the contact ?ngers 28 are formed with corresponding por
94 disposed in undercut portion 87 and in engagement
tions in a symmetrical relationship.
with cam surface 80. As seen in FIG. 10 rear portion 94
When the switch is in its closed position, as shown in
extends downwardly to form a cam follower 95. Each
vFIG. 4, bearing posts 63 are in engagement with the shal
of the front corners ‘96 and 98 of member 92 engages a
low portions 66 of each of the cam surfaces 59. The 50 notch 98 formed in the upper end of an anchor pin 99
depth of these portions is so chosen that the pivotal ends
which is slidably received through one of a pair Of aper
44 of contact ?ngers 28 will be forced a predetermined
tures 100 formed in contact ?ngers 86 and whose outer
distance apart. As a result, the distance between pressure
ends engage leaf spring assemblies 105.
‘pads 58 will be suf?cient to hold leaf spring assemblies
As seen in FIGS. 9 and 10, the front portion of member
32 in a ?exed state whereby contact pressure is provided. 55 92 is received in a notch 104 out in the front of hinge pin
When the contact jaw assembly is rotated to its open
84 while each of the corners 96 rest on notches 98 formed
position as shown by the dotted lines in FIG. 3 and in
in the upper ends of anchor pins 100. As a result, mem
'FIG. 5, contact ?ngers 28 will rotate in a counterclockwise
her 92 is locked to contact ?nger 86 so ‘that it is forced
direction as shown in FIG. 6 thereby moving the shallow
to rotate therewith.
portion 66 of cam surfaces 59 from engagement with bear
When the switch contacts are in closed position, the
ing posts 63 and moving depressed portions v68 into en
cam follower 95 is on the upper portion of cam surface
gagement therewith. Because of the greater depth of
80 so that its corners 96 are tilted downwardly as shown
depressed portions ‘68, the pivotal ends 58 of contact
?ngers 28 are free to move closer together thereby dimin
in FIG. 9. As a result, anchor pins 100 are forced out
wardly to ?ex contact springs 105. When the contact
ishing the spacing between pressure pads 58 so that leaf 65 ?ngers 86 are rotated in a counterclockwise direction as
spring assemblies 3-2 are relaxed. In this manner, the
viewed in FIG. 8 and toward open position, cam follower
contact pressure between contact ?ngers 28 and switch
95 is moved to the lower portion 90 of cam surface 80,
blade 22 is diminished.
thereby releasing the pressure on corners 96 and allowing
' ‘ I From the foregoing ‘it will be apparent that the contact
anchor pins ‘100 to move upwardly as viewed in FIG. 9
pressure is greatest when the contact ?ngers 28 and the 70 and thereby relax pressure springs 105. Integral stop
switch blade 22 are in their closed position shown in FIG.
portions 106 are formed on contact ?nger 86 for engage
4 and by the ‘full lines in FIG. 3 and at a minimum when
ment with the face 107 of the rear portion of recess 83
f‘thecontact'?nvgers 28 are in their open position shown in
so that the rotational angle of contact ?nger 86 is limited
FIG. 5 and by the dashed lines in FIG. 3. As a result rela
to the desired value.
tively little force is required to move switch blade 22 out
While only a few embodiments of the invention have
3,052,788
5
been shown and described, others will become apparent
to those skilled in the art once applicant’s inventive con
cept is known. Accordingly, it is intended to cover in
the appended claims all embodiments that fall within the
true spirit of the invention.
I claim:
‘
of said contact ?ngers are displaced relative to said con
tact spring means during pivotal movement toward said
second angular position so that said contact pressure is
relieved, movement of said switch blade toward closed
position being operative to pivot said contact ?ngers to~
ward their ?rst position whereby said contact pressure is
re-established.
5. An electrical switch having a switch blade pivotally
mounted for movement between open and closed posi
tions, stationary contact ‘means engageable by said switch
blade when said switch is in its closed position and in 10 tions, stationary contact means including a pair of op
posed contact ?ngers having contact tip means near one
cluding opposed contact elements, contact spring means
end engageable by said switch blade when the latter is in
normally urging said contact elements into high pressure
its closed position, leaf spring means disposed adjacent
engagement with said switch blade, and spring pressure
each of said contact ?ngers in substantially parallelism
relief means actuable by said switch blade to substantially
therewith and engaging each of the opposite ends thereof
reduce said contact pressure as said switch blade initiates
for urging said contact ?ngers into high pressure engage
its pivotal movement toward open position and prior to
ment with said switch blade, tie bar means engaging a
the disengagement thereof from said contact ?ngers, said
central portion of each of said leaf spring means for hold
spring pressure relief means also being operative to re
ing said portions in a ?xed spacial relation, pressure relief
establish said contact pressure as said switch blade com
pletes its movement toward closed position and after the 20 means for moving the other end of said contact ?ngers
toward each other when said switch blade moves toward
engagement thereof with said contact ?ngers.
open position so that said leaf spring means are relaxed
2. An electrical switch having a switch blade pivotally
and said contact pressure is relieved, said pressure relief
mounted for movement between open ‘and closed positions,
means being operative to move said other ends of said
stationary contact means including opposed contact ?ngers
having contact tip means near one end that are engageable 25 contact ?ngers toward their initial positions when said
switch blade is moved toward its closed position whereby
by said switch blade when said switch is in its closed posi
said contact pressure is re-established.
tion, contact spring means engaging the outer surfaces of
6. An electrical switch having a switch blade pivotally
said contact ?ngers for norma?y urging them into high
mounted for movement between open and closed posi
pressure engagement with said switch blade, and spring
pressure relief means actuable by said switch blade for 30 tions, stationary contact means including a pair of opposed
contact ?ngers having contact tip means near one end en
moving the other ends of said contact ?ngers to substan
gageable by said switch blade when the latter is in its
tially reduce said contact pressure as said switch blade
closed position, a bearing member, each of said contact
initiates its pivotal movement toward open position and
?ngers being pivotally mounted near its other end on said
prior to the disengagement thereof from said contact
bearing member and about a common axis that is substan
?ngers, said spring pressure relief means also being oper
tially parallel to the pivotal axis of said switch blade, leaf
ative upon movement of said switch blade toward closed
spring means disposed adjacent each of said contact ?ngers
position to move said other ends of the contact ?ngers to
in substantial parallelism therewith and engaging each of
their initial positions and thereby re-establish said contact
the opposite ends thereof for urging said contact ?ngers
pressure after the re-engagement of said switch blade with
into high pressure engagement with said switch blade, tie
said contact tip means.
bar means engaging a central portion of each of said leaf
3. An electrical switch having a switch blade pivotally
spring means for holding said portions in a ?xed spacial
mounted for movement between open and closed positions,
relation, the frictional force generated between said switch
stationary contact means engageable by said switch blade
blade and said contact ?ngers being operative to pivot said
when said switch is in its closed position and including
contact ?ngers between ?rst and second angular positions
opposed contact ?ngers, cam means, each of said contact
when said switch blade is pivoted toward its open position,
?ngers being pivotally mounted on said cam means, con
cam means disposed between the other end of each con
tact spring means urging said contact ?ngers toward high
tact ?nger and said bearing member so that said other ends
pressure engagement with said switch blade, the frictional
are moved toward each other as said contact ?ngers pivot
force generated between said switch blade and said con
tact ?ngers operating to pivot said contact ?ngers on said 50 toward their second angular positions whereby said leaf
1. An electrical switch having a switch blade pivotally
mounted for movement between open and closed posi
cam means between a ?rst and a second angular position
when said switch blade is pivoted toward open position,
said cam means being so arranged that pivotal movement
of said contact ?ngers toward their second angular posi
tion is operative to displace portions thereof relative to
said contact spring means so that said contact pressure is
relieved, movement of said switch blade toward closed
position being operative to pivot said contact ?ngers to
their ?rst angular position so that their pivotal ends return
to their initial position whereby said contact pressure is
re-established.
4. An electrical switch having a switch blade pivotally
mounted for movement between open and closed positions,
stationary contact means engageable by said switch blade
when said switch is in its closed position and including
opposed contact ?ngers each pivotally mounted on a bear
ing member about a common axis that is parallel to the
pivotal axis of said switch blade, contact spring means
urging said contact ?ngers into high pressure engagement
with said switch blade, the frictional force generated be
tween said switch blade and said contact ?ngers operating
to pivot said contact ?ngers between ?rst and second an
gular positions when said switch blade is pivoted toward
spring means are relaxed and said contact pressure is re
lieved, movement of said switch blade toward closed posi
tion being operative to pivot said contact ?ngers toward
their ?rst angular position whereby said contact pressure is
re-established.
7. An electrical switch having ‘a switch blade pivotally
mounted for movement between open and closed posi
tions, stationary contact means including a pair of opposed
contact ?ngers having contact tip means near one end
engageable by said switch blade when the latter is in its
closed position, a bearing member having a pair of op
posed bearing posts, each of said contact ?ngers being
pivotally mounted near its other end on said bearing
member and about a common axis that is substantially
parallel to the pivotal axis of said switch blade, spring
'means engaging the outside of each of said contact ?ngers
for urging them toward high pressure engagement with said
switch blade, the frictional force generated between said
switch blade and said contact ?ngers operating to pivot
said contact ?ngers between ?rst and second angular posi
tion when said switch blade is pivoted toward its open
position, a cam surface formed on the pivotal end of each
contact ?nger for engagement with said bearing post
means, said cam surfaces being so formed that said pivotal
?ngers and said bearing member so that the pivotal ends 75 ends are moved toward each other as said contact ?ngers
open position, cam means disposed between said contact
3,052,786
8
pivot .toward their second, angular positions whereby said
tions, stationary contact means including a pair of op
contact pressure is relieved, movement of said switch
posed contact ‘?ngers having contact tip means near one
blade toward closed position being operative to pivot said
contact ?ngers toward their ?rst position whereby said
contact pressure is re-established.
end engageabilerby said’switch blade when the latter is in
its closed position, a bearing member having a pair of
5 opposed bearing posts, each of said contact ?ngers being
pivotally mounted near its other end on said’ bearing
member and about a common axis that is substantially
parallel to the pivotal axis of said switch blade, spring
means engaging the outside of each of said contact ?ngers
' 18. An electrical switch having a switch blade pivotally
mounted for movement between open and closed posi
tions, stationary, contact means including a pair of op
posed contact ?ngers having contact tip means near one
end engageable by said switch blade when the latter is in
its closed position, a bearing member having a pair of
opposed bearing posts, each of said contact ?ngers being
10
for urging them toward high pressure engagement with
said switch blade, the frictional force generated between
said switch blade and said contact ?ngers operating to
pivot said contact ?ngers between ?rst and second angular
positions when said-switch blade is pivoted toward its
parallel to the pivotal axisof said switch blade, leaf spring 15 open position, a cam surface formed on the pivotal end of
each contact ?nger for engagement with said bearing post
means disposed adjacent each of said contact ?ngers in
means said cain surfaces each having a ?rst depressed por.
substantially parallelism therewith and engaging each of
tion for engaging said bearing posts when said contact
the, Opposite ends thereof for urging said contact ?ngers
?ngers are in their second position so that said pivotal
into high pressure engagement with said switch blade, tie
pivotally mounted near its ‘other end on one of said bear
ing posts and about a common axis that is substantially
bar means engaging a central portion of each of said leaf 20 ends are moved toward each other as said contact ?ngers
spring means for holding said portions in a ?xed spacial
relation, the frictional force generated between said switch
blade and said contact ?ngers operating to pivot said con
tact ?ngers between ?rst and second angular .positions
when said switch blade ispivoted toward its open position, 25
pivot toward their second angular positions whereby said
a cam surface formed on the pivotal end of each contact
being operative to pivot said contact ?ngers toward their
?nger for engagementwith one of said bearing post means
?rst angular position whereby said contact pressure is re
established, said cam surfaces each having a raised portion
so that said pivotal ends are moved toward each other
contact pressure is relieved, said cam surfaces each hav
ing 1a second shallow portion for engaging said bearing
post-s when said contact ?ngers are in their ?rst position so
that movement of ‘said Switchblade toward closed position
as said contact ?ngers pivot toward their second angular
~ intermediate their ends so that a snap action is achieved
positions, whereby said leaf spring means are relaxed and 30 as said contact ?ngers pivot between their ?rst and second
angular positions, the end of each of said cam surfaces
said contact pressure is relieved, movement of said switch
being concave for abutment with said bearing posts so that
blade toward closed position being operative to pivot said
the pivotal angle of said contact ?ngers is limited.
contact ?ngers toward their ?rst position whereby said
‘11. An electric switch having stationary contact means,
contact pressure is re-established.
9. An electrical switch having a switch blade pivotally 35 a switch blade movable between connected and discon
nected positions relative to said stationary contact means,
mounted for movement between open and closed posi
a ?rst means for providing contact pressure when said
tions, stationary contact means including a pair of opposed
switch blade is in its connected position, and a second
contact ?ngers having contact tip means near one end
means operable as movement of said switch blade toward
engageable by said switch blade when the latter is in its
its disconnected position is initiated for relieving said
closed position, a bearing member having a pair of op
contact pressure prior to the disengagement of said switch
posed bearing posts, each of said contact ?ngers being
pivotally mounted near its . other end on said bearing
blade from said stationary contact means, said second
means also being operative upon movement of said switch
blade toward its connected position to re-establish said
parallel to thepivotal axis of said switch blade, spring
means engaging the outside of each of said contact ?ngers 45 contact pressure after contact between said switch blades
and said stationary contact means has been established.
for, urging them toward high pressure engagement with
‘1-2. An electric switch having a switch blade mounted
said switch blade, the frictional force generated between
for movement between open’ and closed positions, station
said switch blade and said contact ?ngers operating to
ary contact means engageable by said switch blade when
pivot said contact ?ngers between ?rst and second angular
member and about a common axis that is substantially
positions when said, switch blade is pivoted toward its open
it is in its closed position and including opposed contact
position, a cam surface formed on the pivotal end of each
elements resiliently urged into high pressure engagement
contact ?nger for engagement with said bearing post
with said switch blade when the latter is in its closed
means said cam surfaces each having a ?rst depressed
position, and contact ‘pressure relief means operative
portion for engaging said bearing posts when said contact
to relieve said contact pressure as'said switch blade moves
?ngers are in their second position so that said pivotal ends 55 toward its open position and prior to the disengagement
of said switch blade from said stationary contact means,
are moved, toward each other as said contact ?ngers pivot
said contact pressure relief means also being operative
upon movement of said switch‘ blade toward its closed
position to re-establish said contact pressure after’ contact
second shallow portion for engaging said bearing posts
when said contact ?ngers are in their ?rst position so that 60 ‘between said switch blade and said stationary contact
toward their second angular positions whereby said con
tact pressure is relieved, said cam surfaces each having a
movement of vsaid switch blade toward closed position
being operative to pivot said contact ?ngers toward their
?rst angular position whereby said contact pressure ‘is re
established.
,
means has been re-established.
' References Cited in the ?le‘ of this patent
UNITED STATES PATENTS
.
10. An electrical switch having a switch blade pivotally
mounted for movement between open and closed posi
‘
1,965,272,
Wilkins _,,_ ________
__;____'_ July
3, 1934
,
,
_ 2,960,590
Kussmaul et al ______ ..__,___ Nov. 15, 1960
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