US2130706A - Electrical switching device - Google Patents

Description

Sept. 20, 1938. H. M. SALMOND ELECTRICAL SWITCHING DEVICE Filed July 2, 1934 4 Sheets-Sheet l 48 JW 7421M /3 Qua;

Sept. 20, 1938. H. M. SALMOND ELECTRICAL SWITCHING DEVICE 4 Sheets-She et 2 Filed July 2, 1954 Fig.6a.

Sept 20, 1938. H. M. SALMOND ELECTRICAL SWITCHING DEVICE Filed July 2, 1954 4 Sheets-Sheet 3 #04, Z Wz/M Sept. 20, 1938. H. M. SALMOND ELECTRICAL SWITCHING DEVICE Filed July 2, 1934 4 Sheets-Sheet 4 0 3% W /3 B, B 2%, w; H fi w w a E UNA/MW M g "1 4 o o I T. .4 7 l L WAY w w W m 1 71 W w 9 0 o E 0 M w JU i J 0 .1. N WW w a A? w j Z ,0 aura U n r m X 1 9 -l I |-I| 1-1 Aw n n MW a D.- o 7 ill? 5 Mi 0 m 9W M E 0 4 E 9 7 I T w F l\ m m m m air Be M ATTORNEY Patented Sept. 20, 1938 UNITED STATES PATENT OFFICE ELECTRICAL SWITCHING DEVICE Application July 2, 1934, Serial No. 733,520 In Great Britain July 28, 1933 17 Claims.

This invention relates to electrical switching devices of the kind in which a pendulum controls the operation of the switch contact elements. An object of the invention is to provide an electrical switching device for use upon vehicles and crafts in which the switch contact elements are actuated by a comparatively powerful spring under control of a pendulum subject only to small reaction.

Another object of the invention is to provide a switching device in which the switch contact elements are actuated by a spring operated member interconnected to a pendulum by a pivotally .mounted lever element.

A still further object of the invention is to provide an automatically operable switching device adapted to disconnect all electrical circuits in a vehicle or craft in an accident.

With these and other objects in view, the invention will be better understood from the following detailed description taken in connection with the accompanying drawings wherein:

Figure 1 shows an electrical switch controlled by a pendulum together with a diagrammatic representation of a circuit controlled by the switch.

Figure 2 shows a slightly difierent form of switch mechanism to that shown in Figure 1.

Figure 3 shows a mechanism in which the pendulum is of a difierent form from that shown in Figures 1 and 2. i

Figures 4 and 4a show arrangements of mechanism employing a multiple catch arrangement in side elevation and front view.

Figures 5 and 5a show a still further modification of a pendulum device.

Figures 6 and 6a show respectively side elevation and front view of a mechanismland switch device arranged to be locked in operated and non-operated positions.

Figures 7 and 7a show respectively side view and front elevation of an instrument comprising a pendulum controlled switch device mounted in a protecting case.

Fig. 8 is a vertical sectional view of my device taken on the line Ill-40 of Fig. 9, showing the switch mechanism in unset position, with ignition circuit open.

Fig. 9 is a vertical sectional view taken on the line Il-Il of Fig. 8, showing the switch spring contact elements, and operating cams and levers.

Fig. 10 is a vertical sectional view similar to Fig. 8, with the switch mechanism set and the ignition circuit closed.

Fig. 11 is a vertical section taken on the line iii-13 of Fig. 10. v

Fig. 12 is a horizontal sectional view taken on line H-ll of Fig. 10, showing details of the switch mechanism, and 1 Fig. 13 is a detail of the arcuate sector cam which engages the pendulum cam.

Referring to Figure 1 of the drawings, numeral 2 represents a pivotally mounted pendulum comprising a mass 3 and a mushroom shaped head 10 l, the pendulum being mounted by means of a ball 5 supported in a socket device 6 carried by bracket 1 itself secured to a mounting plate 8 of the device.

The switch mechanism comprises a rigid con- 15 tact element 9 provided with a current conducting contact engaging a similar contact carried by the leaf spring contact element I0. In addition a further rigid contact element II is provided with a contact adapted to be engaged by a similar contact carried by another leaf spring l2.

The switch is so arranged that it is adapted to be operated by a leaf spring I3, sufllciently powerful to actuate springs l0 and II, but normally engaged by the toe H of a lever device [5 carrying at its other end a member l6 adapted to engage head 4. The lever 15 is pivotally mounted at I1 and is provided with a heel IS, the arrangement being such that spring I3 is normally retained in the position indicated in Figure 1, but is released when the mass 3 of the pendulum is displaced, for example, due to the tilting of the mechanism or as a result'oi exceedingly violent impact.

When spring I3 is released it opens the normally closed contact points carried by elements 9 and I0 and closes the contact carried by elements II and I2 and the switch remains in this position until operating handle I9 is pressed downwardly to a sufllcient extent to force the end of 40 spring I; into engagement with the heel ll of lever l5, whereby the element [6 is'lifted clear of head 4 so that pendulum 2 can assume its normal position indicated in Figure 1.

Figure 1 shows how the switch controls the electrical supply resources on a vehicle or craft which sources comprise battery 20 and generator 2!. Normally one lead is taken from the battery output terminal to the electrical system on a vehicle including the lamps and ignition coil as. well as various electrically operated devices. This lead is cut and connected to a connector 22 itself connected by leads to normally closed contacts 9 and III in such a manner that all currents supplied by battery (it except to the selfstarter flow over the normally closed contacts.

The generator 2| has its output terminal connected to one of elements it or 112, the other being connected to earth or to the other terminal of the generator, the arrangement being such that when spring l3 operates spring contacts ill and N2, the generator is short circuited.

As will be noted the lever is provided with toe and heel parts l4 and it so arranged that the spring it engages the lever in a plane parallel and closely adjacent to that through the center of the lever l5 so that, although the tension of spring it may be quite considerable, the force supplied by element 55 to the head 4 of the pendulum i is comparatively small.

Referring to Figure 2, the lever i5 controls a knife blade switch comprising blade 23 and fixed contacts 24, a projecting catch 25 being engaged by toe M of the lever l5, a helical spring 28 actuating the switch and a projecting member 2i serving to reset the mechanism after actuation as a result of an accident or the like.

Referring to Figure 3, this figure shows a slightly differently shaped lever l5 and an operating member 28 actuated by a helical spring adapted to actuate a contact assembly substantially as indicated in Figure 1. The pendulum device shown in Figure 3 however, differs substantially from that described in Figures 1 and 2 and comprises a cam device 25 carried by *arms 38 pivotally mounted at 86 upon a collar or the like 32, itself mounted to pivot or rotate upon a pin or the like 38. The element l6 of lever l5 normally rests upon cam 29 and if the device is turned sideways the cam will move away from element it whereby the lever will be released when the pendulum attains a predetermined angular displacement depending upon the length of cam 29.

In the case where the mechanism shown in Figure 3 may be subject to impact in a forward direction the cam 29 will move forward in a forward direction causing release of the lever l5, with resultant operation of the switch.

The contactor 28 is mounted upon a spindle provided with hand operated means so that upon rotation against the action of the operating helical spring the catch 28 will engage heel ill of lever l5 and bring element l6 into a position in which the pendulum and cam 29 assume the normal position indicated in Figure 3.

In Figure 4, is shown a modification of the lever arrangement in which toe M of lever I5 does not engage the switch controlling element directly but engages the long arm 35 of a lever 36 having a toe 31 engaging the switch controlling element 38, a heel 39 being provided upon lever 36 for effecting restoration to normal of the mechanism. The switching device comprises a rotatably mounted drum 40 provided with conducting segments 4| and a contacting brush element 42. The switch may be arranged to open or close the circuit as desired but the drum is actuated by a helical spring 43. The pendulum device takes the form of a flail 44 and lever I5 is provided with a cam 45 engaging a cam shaped portion 46 upon pendulum 44. The pendulum is pivotally mounted at 4'! upon a stud or the like 41 itself rotatably mounted in a supporting plate or the like 8. I

As will be observed, the point of engagement between lever l5 and the pendulum of Figures 3 and 4 is vertically below the point of support of the pendulum. The shape of cams 29 and 45 is ensures such that the pendulums when rotating angularly do not effect appreciable movement of lever l5, but the shape of cam and cam 45 is such that when the pendulums move in a forward direction, a movement against the action of the switch actuating springs is effected and the angles of these cam elements are so arranged that the pendulums do not release unless the device is subject to impact of considerable violence.

In Figures 5 and 5a is shown a modified form of the pendulum comprising a mass 48 carried by arms e supported by a pivot support 55, the arms .orming a cam 5i adapted to engage the elemen it of lever l5, the arrangement being such that upon sldeway angular displacement of the pendulum the element I6 is released from the cam 5i when the angle of displacement attains 'a predetermined value and in the case of impact in a longitudinal direction the mass ill swings forward or backwards whereby element i5 is again released from 'cam 5| thus enabling lever iii to release the switch controlling element.

In Figures 6 and 6a is shown a form of mechanism in which means are provided for operating the contact assembly so as to disable the electrical system upon a vehicle by means such as a key the device thus being capable of preventing unauthorized operation of a vehicle.

The pendulum and lever arrangement are practically identical to those described in connection with the previously described figures, and the contact assembly is that shown in Figure 1 except that spring i3 is mounted adjacent the spring assembly and is adapted to eiTect actuation thereof by an extension i3 The means for actuating the switch assembly comprises a rotatably mounted shaft 52 provided with a projecting arm 58 adapted to operate springs l8 and it when the shaft is rotated in an anti-clockwise direction. A further arm 54 carried by the shaft serves to engage spring it to restore the same into set position in engagement with the toe 3'! of lever 36.

In order to ensure correct positioning of the shaft 52, a cam 55 is mounted thereon and is adapted to be engaged by a spring 56 secured to the mounting plate 8 of the instrument.

When the cam is shaped as shown the shaft has two normal positions of 90 angular displacemerit, and inthe normally set position the arms 53 and 54 are so disposed that they do not prevent operation of the device in case the lever l5 should be released by the pendulum.

The shaft 52 may be mounted by bracket elements fixed on the plate 8 and provided with tubular extensions 51 housing split sockets 58 to which the shaft 52 is secured. In order to prevent unauthorized operation of shaft 52 a spring 59 mounted upon tubular extensions 51 is adapted to engage the slot in sockets 58 from which it must be ejected by means of a key 60 which may haveslots provided therein adapted to engage pins disposed in the slot in sockets 58 so as to prevent insertion ofkeys other than those intended to operate the mechanism. The tubular indent'in cam in which position the springs I0 and I2 open the battery circuit of the car and short circuit the dynamo and disable the high tension system.

A spring 6| also mounted upon tubular extension 51 is adapted to engage the slot in the socket 58 when this has been rotated 90, and upon withdrawal of the key this spring locks the shaft 52 and the switch mechanism in the operated position.

Figures 7 and 70 show a practical embodiment of the invention in which a switch mechanism comprising a contact assembly and automatically operable release mechanism is mounted in a protective casing so as to be capable of being mounted .for example under the bonnet of a motor car. Electrical leads'are provided from the instrument to the battery and dynamo as well as to the high tension magneto if such is provided upon a car, and an additional earth connection is provided from the instrument to effect the appropriate circuit changes.

Referring to Figure 7, numeral III indicates the bottom of a protective casing, ll being the top thereof capable of being secured to the bottom in any suitable manner. The mechanism of the instrument is mounted upon a mounting plate 13 carried by a suitable number of posts 14 securedto the casing bottom 18. The pendulum 15 is provided with a central cam surface 16 and is suspended from a support TI by means of extending lugs which engage a pin 18 mounted in support I1 in such a manner the pendulum is free to swing in planes at right angles to plate 13. The support 11 is carried by a stud 19 fixed to plate 13 in such a manner that it is capable of rotation in a plane parallel to plate 13. The cam I6 engages a triangular are shaped cam 88 carried by lever 8| pivotally mounted by pin and bracket means upon plate 13. Lever 8| is provided with toe 82 and heel 83 which are engaged by the long arm of a lever device 84 pivotally mounted by pin and bracket means on plate 13.

The lever 84 is provided with toe 85 and heel '86 adapted to engage a cam device 81 fixed upon a spindle 88 mounted by a pair of brackets upon plate I8 so as to be capable of rotation but fixed against endway displacement, a resetting handle 89 being secured to an extension of shaft 88 projecting through the protective casing. A helical spring 98 is carried by shaft 88 and arranged to rotate the shaft in a clockwise direction when cam 81 is released by lever 85. The contact assembly comprises fixed contact elements 9| and 92 and spring contacts 98 and 94. The cam 81 is provided with a projecting stud or pin 95 carrying an insulating sleeve adapted to engage spring contacts 93 and 94, the arrangement being such that spring 98 is held in, a normally open position as shown in Figure '7, but upon release of cam 81 by lever 84 the stud 95 is rotated until it engages a stop 96 which is connected to a terminal which in its turn may be connected to the high tension magneto if such is employed upon a vehicle or craft whereby the same is switched off when the instrument operates.

Stop 96 is insulatingly supported from mounting plate I3 and is provided with binding post H3. The contact assembly is supported by a stud 4 attached to mounting plate 13. The stud H4 is advantageously of metal and forms 'part of the switch circuit, and is electrically connected to mounting plate 13. Binding post I28 is attached to stud H4. Shaft 88 is journalled in a pair of spaced supporting plates H8,

1, which are attached to mounting plate 18.

The insulating sleeve on stud 95 permits spring 98 to close its contact with the contact upon element 9|v and subsequently the spring 94 is forced away from engagement with contact 92 whereby the circuit over these contacts is opened.

When the instrument of the present invention is employed upon a vehicle, electrical leads are takenfrom the battery so that all the current supplied by the battery to the electrical system except the self-starter is normally flowing over contacts 92 and 94. Contact 9| is connected to the dynamo output terminal and contact 93 is connected to the instrument which is connected to earth. When the instrument operates it will be observed that contacts 9! and 93 close before contacts 92 and 94 are opened, this has been found desirable in practice as the dynamo is disabled before the battery circuit is open, whereas liability to damage the electrical devices and lamps exists if the battery circuit is opened before the dynamo is put out of action.

When the instrument is employed upon a vehicle it is mounted so that the pendulum hangs vertically downwards, centrally over cam 80, and when the vehicle is overturned or when it at tains an angle of approximately 45 the cam 18 disengages cam 88, and, as a result of the action of spring 90, lever 84 turns in an anticlockwise direction as shown in Figure 7 due to the disengagement of toe 85 with cam 81, and lever 8| turns in a clockwise direction due to the disengagement of the long arm of lever 84 with toe 82, and as soon as cam 18 releases cam 88 the lever 8| releases lever 84 and this therefore releases cam 81 which is rotated so as to effect closure of springs 9| and 93 and opening of contacts 92 and 94 before coming into contact with the stop 96 whereby this element is connected to earth. The radius of the cam 80 may be struck from the center of pin 19 so that no movement of lever 8i is produced when the pendulum rotates in a plane parallel to plate 13. Alternatively, the radius may be struck from slightly above the center of pin 19 in which case a slight lift of the cam 88 and lever 8|, against the action of spring 90, is produced when the pendulum is displaced from its normal central position and this arrangement tends to retain the pendulum in a central position.

In the case where a vehicle is subject to impact,

the pendulum 15 moves forward owing to its inertia and cam 16 is caused to lift cam 80 and the long arm of lever 8| against the action of spring 99 to a predetermined extent so as to prevent release in case of a minor impact, for example, when the brakes of a vehicle are suddenly applied or when a slight impact with another vehicle or an obstacle takes place which is not likely to cause serious injury to the driver or damage to the vehicle. The inclination of the cam 18 is however, such that in the case of a violent impact release of lever 8| takes place without fail. The inclination of carn-16 as indicated in Figure 7, is 45 and this has been found to be suitable for practical purposes,

The casing comprising parts 18 and II is adapted to be mounted upon a'vehicle, for example,

under the bonnet, and, to facilitate mounting,

a pair of lugs or the like I I8, I I9 are secured to the casing bottom whereby the instrument may be secured in a horizontal position with the part II of the'casing pointing in the direction of travel of the vehicle.

Electrical leads I00 soldered or sweated to tags 9.8 upon the contact assembly and secured by clamping devices 99 to the bottom of the casing are provided for connection to the electrical system upon a vehicle or craft.

In the case of switch devices for use on aeroplanes it is desirable that cams 45 and are shaped somewhat as indicated in dotted lines in Figure 4a so as to tend to retain the pendulum in normal position although the instrument is turned sideways or upside down. In order to enable the mechanism to be reset, helical springs 840 and till may be provided upon the pivot spindles of levers 34 and ill, Figure 7, tending to rotate the same in a direction to effect disengagement, also a helical spring llll or the like may be attached to the pendulum l5 so as to tend to retain the same in its normal position, the spring being capable of sufiicient extension to efiect release in case of impact. When a spring 7130 is attached to pendulum 715, the cam 30 may be shaped as shown in Figure 7a as the spring prevents disengagement between cams l6 and 80) except in the case of violent impact. It is of course to be understood that the various parts of the device may be designed and constructed in various other ways, and the various mechanisms arranged in other combinations than illustrated, and therefore I do not wish to be limited in any manner except as set forth in the following claims.

Having thus fully described my invention, what I claim as new and desire to protect by Letters Patent is:

1. A switch for rendering inoperative the electrical circuits of a vehicle upon a condition of collision or the like, comprising: a plurality of electrical contact elements, spring-biased means for maintaining said contact elements in contact under normal conditions, spring means effective to oppose and overcome said last-mentioned means to open said contact elements, latch means for maintaining said last spring means retracted andinoperative, pendulum means associated-with said latch means and eiiective to release the same upon the occurrence of an abrupt acceleration or deceleration of the vehicle, said spring means being provided with a manual positive control operable with a single movement to reset said contact elements in closed position when said pendulum means has returned to normal position.

2. A switch for rendering inoperative the electrical circuits of a vehicle upon a condition of collision or the like, comprising: a plurality of electrical contact elements, means for maintaining said contact elements in contact under normal conditions, means efiective to overcome said last mentioned means and open said contact elements, latch means for rendering said contact opening means inoperative, and pendulum means having a cam element normally in positive locking abutment with said latch means but displaceable to release said latchmeans upon a swinging of the pendulum occasioned by an abrupt acceleration or deceleration of the vehicle.

3. A switch for rendering inoperative the electrical circuits of a vehicle upon a condition of collision or the like, comprising: a plurality of electrical contact elements, means for maintaining said contact elements in contact under normal conditions, means effective to overcome said last-mentioned means and open said contact elements, latcn means for rendering said contact opening means inoperative, pendulum means associated with said latch means and efiective to completely release the same upon the occurrence arsavoe of an abrupt acceleration or deceleration of the vehicle, and manually operable latch-resetting means for reclosing said electrical contact elements.

4. A switch for controlling the electrical circuits of a vehicle upon a condition of collision or the like, comprising: a plurality of electrical contact elements, means for normally maintaining at least one pair of said contact elements in closed-circuit relationship, means for normally maintaining another pair of said contact elements in open-circuit relationship, means effective to oppose and overcome each of said two last-mentioned means and invert the normal contact positions, latch means for rendering said contact-inverting means ineffective, and pendulum means associated with said latch means and effective to release said latch means upon the occurrence of an abrupt acceleration or deceleration of the vehicle.

5. An electrical switching device for rendering inoperative the electrical circuit of a vehicle upon a condition of collision or the like, comprising a plurality of electrical contact elements, a spring actuated member electrically independent of said contact elements for actuating said contact elements, a lever, a pivotal support for said lever, said pivotal support being attached to said lever at a point along the length thereof to divide said lever into two sections of uneven length, means formed in the shorter of the two sections of said lever for engaging said spring member and hold- .ing said member under tension, means engaging the free end of the other of said sections for tripping said lever and releasing said spring for actuat'ing said contact elements and pendulum means for controlling said last means.

6. An electrical switching device for rendering inoperative the electrical circuit of a vehicle upon a condition of collision or the like, comprising a plurality of electrical contact elements, a

spring member electrically independent of said contact elements for actuating said contact elements, a lever, a pivotal support for said lever, means at one end of said lever for engaging and holding said spring under tension, means engaging the other end of said lever for tripping said lever and releasing said spring for actuating said contact elements, pendulum means for controlling said last means and resetting means for resetting said lever after it is tripped.

7. An electrical switching device for rendering inoperative the electrical circuits of a vehicle upon a condition of collision or the like, comprising a plurality of electrical contact elements, a spring member electrically independent of said contact elements for actuating said contact elements, a lever including catch means for holding said spring member in a predetermined position, means associated with said contact elements for engaging said spring member when the latter is released by said catch means, pendulum means for engaging said lever to release said catch means from said spring for actuating said con tact and resetting means for resetting said lever after it is released.

8. A switch for effecting changes of the electrical circuits upon vehicles and craft upon a condition of impact, comprising a vfreely suspended pendulum, supporting means comprising a pair for maintaining said switch mechanism in actu-- spring action, a spring urged member normally held in tensioned position by said pendulum and lever and adapted when released upon occurrence of impact to actuate said contact elements to eifect desired circuit changes and manually operable resetting means for resetting said lever after it is released.

9. An electrical switching device for rendering inoperative the electrical circuits of a vehicle upon a condition of collision or the like, comprising: a panel member, a pendulum' pivotally supported on said panel member, a first lever also pivotally supported on said panel, means attached to said first lever for slidably engaging said pendulum, said first lever having a first latch device, a second lever pivoted with respect to said first lever and having an end engageable with said first latch device of said first lever, a rotatable shaft, a spring attached to said shaft, said second lever having a second latch device, means on said shaft for engaging said second latch device of said second lever when said shaft is rotated against said spring, an electrical contact device, and means for actuating said electrical contact device when said shaft and said levers are released by movement of said pendulum so that said shaft is rotated by the action of said spring.

0. An electrical switching device for rendering inoperative the electrical circuits of a vehicle upon a condition of collision or the like, comprising: a rotatable shaft, a spring attached to said shaft to prevent the rotation of said shaft except with or against the tension of said spring, electrical contacts positioned to be actuated upon the rotation of said shaft, a lever and latch device, means cooperating with said shaft for engaging said lever and latch device when said shaft is turned against thetension of said spring to hold said shaft in this tensioned position, a cam attached to said lever and latch device, and a pendulum having means for engaging said cam to hold said shaft in said tensioned position until a condition of collision or the like disengages said cam from said pendulum means.

11. An electrical switching device as set forth in claim 9 including manually operable means .for said shaft to reset the switching device after in claim 10 including manually operable means attached to said shaft to reset the switching device after the switching device has been actuated.

13. In a crash actuatable safety switch, a switch mechanism, actuating means for opening and closing said switch mechanism and comprising a spring normally maintaining said switch mechanism in a released position and further comprising latch engaging means, a latch mechanism engageable with said latch engaging means for maintaining said switch mechanism in actuated position, a cam having cooperating means engageable with said latch mechanism for locking the same, and a pendulum having a cam surface engageable with said cam, whereby movement of predetermined amplitude of said pendulum beyond cam engaging position unlocks said latch mechanism and releases said switch mechanism.

14. In a crash actuatable safety switch, a switch mechanism, actuating means for opening and closing said switch mechanism and comprising a spring normally maintaining said switch mechanism in a released position and further comprising latch engaging means, a latch mechanism engageable with said latch engaging means ated position, a cam having cooperating means engageable with said latch mechanism for locking the same, a pendulum having a cam surface engageable with said cam, and supporting means comprising a pair of independent pivots for pivotally supporting said pendulum with two degrees of rotative freedom, whereby movement of predetermined amplitude of said pendulum beyond cam engaging position unlocks said latch mechanismand releases said switch mechanism.

15. In a crash actuatable safety switch, a switch mechanism, actuating means for opening and closing said switch mechanism and comprising a spring normally maintaining said switch mechanism in a released position and further comprising latch engaging means, a latch mechanism engageable with said latch engaging means for maintaining said switch mechanism in actuated position, a cam having cooperating means engageable with said latch mechanism for looking the same, a pendulum having a cam surface engageable with said cam, said cam having its periphery engageable with said pendulum cam surface substantially'in the form of a circular arc, and a pivot for supporting said pendulum for movement substantially parallel to the plane of said arc, said are being substantially struck about said pivot as a center, whereby movement of predetermined amplitude of said pendulum beyond cam engaging position unlockssaid latch mechanism and releases said switch mechanism.

16. In a crash actuatable safety switch, a switch mechanism, actuating means for opening and closing said switch mechanism and comprising a spring normally maintaining said switch mechanism in 9. released position and further comprising latch engaging means, a latch mechanism engageable with said latch engaging means for maintaining said switch mechanism in actuated position, a cam having cooperating means engageable with said latch mechanism for locking the same, a pendulum having a cam surface engageable with said cam, said cam having its periphery engageable with said pendulum cam surface in the form of a circular arc, said pendulum cam surface being recessed in a direction substantially perpendicular to the plane of said arc, and a pair of mutually perpendicular comechanism and releases said switch mechanism.

17. 'In a crash actuatable safety switch, a switch mechanism, actuating means for opening and closing said switch mechanism and comprising a spring normally maintaining said switch mechanism in a released position and further comprising latch engaging means, a latch mechanism engageable with said latch engaging means for maintaining said switch mechanism in actuated position, a cam having cooperating means engageable with said latch mechanism for locking the same, a pendulum having a cam surface engageable with said cam, said cam havingv its periphery engageable with said pendulum cam surface in the form of a circular arc,'said pendu lum cam surface .being recessed in a direction substantially perpendicular to the plane of said arc, and a pair of mutually perpendicular coopersaid pendulum moves perpendicular to the plates of said. are being positioned substantially above the point where said cam arc meets said cam surface when said pendulum is in normal position, whereby movement of predetermined amplltude of said pendulum beyond cam engaging positlon unlocks said latch mechanism and re leases said switch mechanism.

HUBERT MACKENZIE SALMOND.

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