US2683872A - Electrically-actuated signaling device - Google Patents

Description

July 13, 1954 G. R. FISH ELECTRICALLY-ACTUATED SIGNALING DEVICE 4 Sheets-Sheet 1 Filed March 20. 1951 July 13, 1954 G. R. FISH ELECTRICALLY-ACTUATED SIGNALING DEVICE 4 Sheets-Sheet 2 Filed March 20, 1951 //V VE'N 70/? GEORGE A. F/6/-/ Patented July 13, 1954 ELECTRICALLY-ACTUATED SIGNALING DEVICE George R. Fish, Norwalk, Conn., assignor to Edwards Company, Inc., N orwalk, Conn., a corporation of New York Application March 20, 1951, Serial No. 216,561

40 Claims.

This invention relates to electrically actuated mechanisms, particularly electric signalling devices such as an electric bell.

One of the objects of this invention is to provide a practical and efiicient electric signalling device which is constructed to provide dependable safeguards against foreign matter, such as water, moisture, dust, and the like, or against the hazards of explosive atmospheres, and thereby achieve reliable maintenance and safety of operation of the device. Another object is to provide a device of the above-mentioned character which is simple and practical in construction and assembly, may be installed with facility, and well adapted for long continued use or operation under adverse conditions such as those just mentioned above. Another object is to provide a signalling device that is well adapted to withstand the varying conditions of use and operation on shipboard, such as humidity, water, including submersion, and wide changes in temperature, including freezing temperatures, and the like.

Another object is to provide an electric gong signalling device in which the electric actuating parts are dependably protected and sealed, for example, against the elements of weather or the like, and yet the gong striker maintained unimpaired in achieving the desired audible signalling. Another object is to provide a gong and striker mechanism that is capable of dependable operation under conditions of moisture, wetness, rain, and even freezing; another object is to carry out this last-mentioned object by a construotion that is well adapted for fabrication, assembly, and installation. Another object is to provide an electric bell or like signalling device that can be safely operated throughout a wide range of varying conditions of practical use and maintain reliability or dependability of actuation.

Another object is, in general, to provide an improved device of the above-mentioned character. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which similar characters refer to similar parts throughout the several views,

Figure 1 is a front elevation of the signalling device as installed in use;

Figure 2 is a side elevation as seen from the right in Figure 1, certain parts being broken away to show certain other parts more clearly;

Figure 3 is an exploded view as seen from the right in Figure 1 or from the front in Figure 2, showing also the internal striker actuating mechanism in one form or embodiment thereof;

Figure 4 is an elevation as seen along the line 4-4 of Figure 3;

Figure 5 is a vertical sectional view as seen along the line 55 of Figure 3;

Figure 6 is a fragmentary sectional view as seen along the line AA of Figure 1, showing the relationship between gong, striker, and one form of striker actuating mechanism;

Figure '7 is a detached elevation of a sub-aw sembly as seen along the line 'l-'l of Figure 6;

Figure 8 is a detached elevation of a modification of the sub-assembly of Figure '7, as see along the line '!1 of Figure 6;

Figure 9 is an electrical diagram showing the connections in the embodiment of Figure 8;

Figure 10 is a fragmentary sectional View like that of Figure 6 showing the striker actuating mechanism arranged for ice-breaking and the relationship therebetween and the gong and striker;

Figure 11 is a fragmentary sectional view as seen along the line A-A of Figure 1, showing another form of construction for achieving certain other advantages and constructed for optional employment of the feature of ice-breakmg;

Figure 11 is a detached fragmentary portion of the view of Figure 11, on an enlarged scale, to show certain features more clearly;

Figure 12 is a detached elevation of the subassembly employed in Figure 11, being a fragmentary elevation as seen along the line l2-i2 of Figure 11;

Figure 13 is an electrical diagram showing a possible form of circuit connections in the form of Figures 11 and 12;

Figure 14 is a detached elevation of a modified form of sub-assembly as seen along the line EL -I2 of Figure 11;

Figure 15 is a fragmentary sectional view as seen along the line A-A of Figure 1, showing a modified form of construction adapted to achieve other advantages;

Figure 16 is a detached elevation of the subassembly employed in the form of Figure 15 and illustratively embodying an interrupter;

Figure 17 is a view like that of Figure 15 show- 3 ing the mechanism arranged for ice-breaking; and

Figure 18 is a diagram of the circuit connections employed where the device of Figures -17 employs an interrupter.

Referring to Figures 1, 2, and 3, I provide a casing which preferably comprises two separable parts which, when assembled, form a sealed or airtight enclosure; in the preferred form illustrated, this casing comprises companion parts 28 and 2|, of which the part 29 may be constructed in the form of a box and the part 2| in the form of a closure or cover plate therefor. The part 28 may have a bottom wall 22 and side walls 23 and they are provided with a suitable knock-out, one of which is shown in Figure 2 at 24, whereby to provide a hole or opening through which a conductor-carrying conduit (not shown) may be mechanically secured and placed in sealed connection therewith in any suitable or known manner,

thus to extend the electric circuit to the interior of the casing. The latter may be mounted in desired position in any suitable manner and, for example, if it is to be surface-mounted, the boxlike casing part may be provided with apertured ears or lugs 25 by which they may be bolted or otherwise secured to a wall or other support.

The conductors (not shown), usually two in number, thus brought into the casing are connected to binding screws 26 (Figures 5 and 3) of the socket part 2? of a separable two-conductor plug and socket connecting device, the plug part 28 (Figures 4 and 3) of which is carried by the companion casing part 2| in a manner later described. These separable connector parts be or" any suitable construction. The socket connector part 2?, comprising a suitable body of insulating material, is secured, as by screws (not shown), to a bracket plate 3|) stepped, as shown in Figures 2 and 3, to have a portion overlying a heavy boss 34 cast integrally with the casing wall 22 to provide good support for screws 32 by which the bracket 38 is secured to the boss 3 I The boss 3i makes it unnecessary to drill the screw holes through the back wall 22.

As shown in Figure 5, the socket-connected part 2'! has two spaced rectangular sockets or recesses 27 into which the two contact prongs 28 of the plug part 28 enter for making internal connection with the circuit of the conductors connected to the binding screws 26. The plug connector part 23 is rigidly mounted on the inside face of the cover plate 2| by means of a U-shaped bracket $3 to the cross-part of which the insulating body of the plug part 28 is secured, as by screws (Figure 4), the two arms of which U-shaped bracket being secured to the cover plate 2| in any suitable manner, as by stepping them (see Figure 3) at their free ends for reception in suitable spaced holes 3Q (see Figures 1 and 3), whereupon the reduced ends are peened or headed over. The resultant cold-flow of metal not only securely anchors each bracket arm to the front plate 2 l, but also expands the metal into the respective plate holes and achieves a good sealed joint, particularly where the metal of the parts is the same and of a composition like brass. The plug part 28 is provided with suitable means, such as conductive tabs or ears 28 (Figures 3 and 4), for securing the ends of conductors of the electric actuating mechanism, the connectors 28 being internally in connection with the respective prong parts 28*.

The separable plug and socket connector thus coacts to insure that the companion casing part must always be assembled to the mounted or secured casing part in the same way, and thus they coact to orient the companion casing parts upon assembly thereof. The companion casing part 20 comprises also a re-entrant casing part in the form of a metal tube 36, of brass, for example, that is closed or sealed 01f at its inner end, as at 36 (see also Figure 6), and it is integrally secured to the front plate 2| so that it extends upwardly and inwardly into the box-like casing part 20 at an inclination to the front plate 2| such that it makes an angle to the plane of the plate 2| substantially as shown in Figure 3 and makes an angle to the vertical axis XX as seen in Figures 1 and 4, substantially as is better shown in Figure 4, intersecting the plate 2|, preferably at a point laterally displaced from the axis XX (to the right in Figure 4 and to the left in Figure 1). As is better shown in Figure 3, the reentrant casing part or tube 36 projects somewhat through and beyond the external face of the plate 2|, the latter being provided with a suitable elliptical or oval hole (Figure 6) into which the metal tube 36 fits and to the walls of which it is secured,

' as by brazing, as indicated at 31 in Figure 6. The

part 36 is thus securely held at the above-described angularities to the axis XX, the angles being substantially on the order of magnitude as indicated in the drawings, and the brazed or soldered junction 31 makes a sealed joint.

The casing part 29 (Figures 1 and 3) may be provided with a peripheral flange 38 which underlies the marginal portions of the front plate 2|; in this marginal portion of plate 2| and in the casing flange 38 are provided suitable means that can coact with the plug and socket connector 21-28 to prevent assembly of the companion casing part 2|-36 to the casing part 28' excepting with the axis XX always vertical and with the re-entrant casing part 38 therefor always projecting upwardly and inwardly into the box-like casing part 20 and thereby also maintain the angularity shown in Figure 4; this means may comprise holes 38 and 38 conveniently on a diameter, in the flange 38 and studs 4-0 in the maginal portion of the front plate 2| for entry into the holes 38 and 38 The socket connector part 27 (Figure 5) is positioned transversely of and near the lower end of this vertical axis, and so is the plug connector part 28, the contact prongs of the latter entering the socket contacts of the former as the studs 4% enter the holes 38 and 38 The two casing parts are preferably detachably secured together and their junction sealed, as by screws 4| that pass through suitable holes in the marginal part of the closure plate 2|, being threaded into suitable bosses 38 formed in the casing flange 38. Projecting forwardly from the flange 38 is a circular gasket-locating flange 42 (Figures 1 and 3) which may be of the same diameter as that of the wall 23 of easing part 20 and of which it forms a part where, as is preferred, the flange 38 is separately constructed as a ring or collar and secured to the casing wall 23, as by brazing or the like, indicated at 43 in Figme 3; a rubber ring gasket .44 is seated in the external angle between the flanges 12 and 38, and when the screws 4| are tightened up, the gasket is compressed and forms a continuous seal between the plate 21 and the casing wall 23 (Figure 2), portions of the bosses 28 limiting the extent to which the screws M can draw the parts 2| and 20 together and acting to maintain them parallel. p

assuring uniform compression of the gasket 4 throughout.

Externally of the resultant sealed enclosure and in appropriate relation to the open end 36* of the re-entrant casing part 36, I mount a signailing means that is to be actuated by the electro-responsive means (later described) that is housed within the enclosure; in the illustrative embodiment, this signalling means comprises a gong 4-5 positioned to overlie the projecting part of the part 36 (Figures 1, 2, and 6) being securely fastened to a large stud or post 46 secured to the plate 2| and positioned on the axis XX (Figure l) Post 35, preferably circular, is provided with an end face 56 which is conformed as nearly as possible to the inside face of the central portion of the gong 55 to provide a substantial supporting area therefor; a screw 4?, provided with a lock washer, passes through a central hole E5 in the gong and is threaded into a threaded hole in the post 26 to clamp the gong 45 in position, and preferably there is interposed between these two parts a disc-like washer of a relatively hard but somewhat yieldable material, preferably nonmetallic, such as hard fiber or hard rubber, and i capable of yielding somewhat under the clamping pressure to conform itself to slight irregularities in the adjacent gong and post surfaces and thereby insure substantially uniform clamping pressure throughout.

Before assembling the gong to the post 46, there is inserted into the re-entrant casing part a gong striker in the form of a rod 59 and an actuator therefor in the form of a paramagnetic plunger 5 i, preferably with a spring 52 interposed between the sealed end 35 and the inner end of the plunger 5|, as is indicated in Figure 6. The spring is preferably made of a material like Phosphor bronze. The plunger 5| and the striker 5t! are made corrosion-resistant in any suitable way; for example, the plunger 5| may be or" soft iron, chrome-plated, and the striker rod 555 may be of stainless steel. The spring 52 is well protected, being completely enclosed between the inner end of plunger 5| and the sealed end of the tubular casing part 36 whose interior surface serves as a guidway for reciprocating movement of the plunger 5|, the relative diameters providing ample clearance, on the order of several thousandths of an inch, for adequate freedom of reciprocating movement throughout the conditions of practical use. Some compression or expansion of air between the inner end of plunger 5| and the sealed tube end 36 may take place during the strokes of reciprocation of the plunger, the air in that inner end space functioning somewhat like a spring, being desirably relieved to the desired extent by leakage in the clearance between the plunger and its guiding tube wall. Where, as is preferred, spring 52 is employed, the just-described action can serve to supplement the action of the spring itself.

In normal or at-rest position, the parts 55 and 5!, tending by their weight to slide downwardly (Figure 6), are preferably given a position wherein the striker 5G is out of contact with the gong is; this is of advantage in that water, as from condensation or rain or the like, that might run down along the inside surfaces of the gong 45, as viewed in Figures 1 and 2, is prevented from accumulating as it would at the point or area of engagement between the striker and the gong surfaces; such water runs to and tends to accumulate as it spills off on the inside face of the peripheral or skirt portion 45* (Figure 6) at the six oclock position as seen in Figures 1 and 2, where in sufiiciently low temperatures it might freeze and build up as it freezes. But the lower open end of the tubular casing part 36, while terminating close to the inside surface of the skirt-like gong portion is juxtaposed to that portion of the gong at a point angularly displaced from this six oclock position, illustratively at about the '7 oclock position as shown in Figure 1, so that the striker 5|] can impact against the gong 45 in a region free from accumulated water or ice, the withdrawn at-rest position of striker ts coacting toward achieving these advantages. Moreover, under such illustrative adverse weather conditions, the plunger and striker remain well protected as no water or the like can enter and remain in the tubular casing part 36, the externally projecting portion of the latter giving good protection, particularly against water running down the outside face of the cover plate 2|. Even if the structure as viewed in Figures 1, 2, and 6 were to be submerged or a water level rise above the lower end of re-entrant casing part the plunger 5| and the surfaces of part 35 along which it reciprocates, as well as the spring 52, remain dependably protected because the trapped air in the re-entrant casing part 35 prevents rise of water into the part 36; not only is dependable reciprocating action of the plunger 5! maintained under such conditions, but when those conditions are removed, the actuating parts remain unimpaired. The part 35 is also preferably corrosion-resistant, and while for some purposes it may be made of brass or the like, it is preferably chrome-plated or it may be made of stainless steel.

Within the sealed casing 2B2|-36 and assembled to the inwardly projecting portion of the tubular casing part 36 is a winding (Figures 3, 4, and 6) for producing a magnetic field and to coact in the actuation of the external paramagnetic plunger 5|, receiving its energy by suitable conductors connected to the connector tabs 28 of the plug connector 28 (Figure 4). Wind ing 55 is preferably wound in the form of a solenoid winding, for which the plunger 5| is the movable core, and preferably it is constructed as part of a sub-assembly unit. The winding 55 is wound upon a form or spool which may comprise a sleeve 55 and end plates 51 and 58 of suitable insulating material, such as hard fiber, having an internal diameter so that it may be easily slid onto the tubular casing part 36. It is preferably secured to a flat supporting plate 60 (Figures 3, 4, 6, and 7), shaped substantially as shown in elevation in Figure '7, having a relatively large cut-out or opening into which a portion of the winding unit projects; one of the insulating end plates 53 is extended, as at 58 (Figures 3 and 6) to project materially to the other side of the supporting plate Bil, and in the extension 58 are secured, as by eyelets, connector tabs El and 52 to which the ends of the winding 55 are permanently connected and to which the conductors that lead to the connector plug 26 may be connected, as by soldering, as indicated in Figure 3.

On the inside face of cover plate 2| are secured two spaced brackets 63 and 64; these may be of heavy brass sheet material, and each is substantially a right-angled triangle in shape with the hypotenuse resting against the cover plate 2| (Figure 3). These brackets are secured to the plate 2| in any suitable manner, as by integral ears or lugs formed thereon and that extend into suitable spaced holes in the plate 2| where they are peened or riveted over, as at 63 and 64 (Figure l), to form sealed joints. Brackets 53 and 64 are proportioned so that the flanges 63 and M thereof fall in a plane that is parallel to the axis of the tubular casing part 36. It is onto these parallel flanges 63* and 64 that the plate support 50 (Figure 7) slides as the sub-assembly of winding and plate support is assembled to the tubular casing part 36 by entering the inner end of the latter into the cylindrical bore of the winding sub-unit or spool. The plate support 65 is provided with slots 65, 66 (Figures 4 and 7) which are parallel to each other and parallel to the axis of the bore of the solenoid winding, and through the slots extend screws 61 and 68 (Figure 4) whereby the sub-unit may be adjusted lengthwise of the tubular part 36 and set and secured in a position to achieve the best coaction with the plunger this adjustment and setting is done empirically during assembly and testing.

Since gongs like the gong 45 are usually shaped out of suitably heavy sheet metal, there might be non-uniformity in thickness or the hole 55 (Figure 3) might be a bit off center. Such factors as these might upset the efiect of the abovedescribed internal setting of the winding and related parts were the gong to partake of rotary displacement or were it to be removed and then put back in some other rotary position. Accordingly, at a suitable point offset from the center, I provide in the gong supporting post 516 a pin 19 (Figures 1 and 3) that projects beyond the end of the post, and in the gong 45 I provide a hole H into which the pin is received and fits upon securing the gong to the post. The pin thus coacts to prevent rotary displacement of the gong and also, where one is employed, of the semihard interposed pressure distributing member 48 (Figure 3).

The winding 55, in so far as certain features of my invention are concerned, may be energized in any suitable manner to achieve the desired actuation of the plunger 5| and striker 50 for either single or repeated striking of the gong 45. If a circuit interrupter is employed, as is usually the case for direct current operation, the interrupter is also contained within the sealed housing and any sparking is rendered harmless, permitting the structure to be used with safety in explosive atmospheres. Sometimes, for alternating current operation, a rectifier is employed to utilize the pulses of half-waves, and in such case the rectifier is also housed in the sealed casing and similar safety of operation achieved. Such additional devices I preferably assemble to form part of the sub-unit that comprises the Winding 55 and plate support 66, connecting the devices in circuit with the winding on the sub-unit and leaving the terminal connector conductors, leading from the insulating extension 53* (Figure 3) for connection to the plug connector 28. For alternating current operation, particularly where the plunger and striker are to reciprocate synchronously, a circuit interrupter need not be employed.

In the preferred forms of my invention I employ a permanent magnet to coact with the plunger 5i to hold the striker 50 in the abovedescribed at-rest position wherein it is out of contact with the gong 45, and this permanent magnet may or may not, as desired, coact with the magnetic flux of the winding 55 in reciprocating the plunger 5|. An arrangement in which it does so coact will first be described, an arrangement in which the winding 55 is energized by alternating current to produce an alternating 8 magnetic flux, with which the unidirectional flux of the permanent magnet coacts to achieve synchronous reciprocation of the plunger and striker.

In this form, and referring first to Figure '7, I provide a permanent magnet 12 in the form of a rectangular bar or block of highly retentive magnetized material, such as Alnico, capable of producing a magnetic flux that is relatively large in relation to that produced by the winding for example, where the solenoid winding when energized by alternating current produces a peak magnetizing effect of about 850 ampere turns, equivalent to about an average or mean value of 600 ampere turns, the permanent magnet may have a magnetizing effect on the order of 1,400 ampere turns. The latter may be physically inter-related with the plunger 5| and winding 55 in any suitable manner so that the two fluxes can suitably interact, being additive on one half-cycle of energization of the winding 55 and subtractive on the other half-cycle. Preferably 1 position the permanent magnet 12 on to one side of the winding 55 and extend it by pole piece elements 73 and E4 to bring its unidirectional flux to coact as just described. Pole pieces or pole extension 13, i4 are conveniently in the form of plate-like parts of paramagnetic material, such as suitably heavy sheet steel, which may be given the desired shape and configuration, as by punchpress operations.

As is better shown in Figure 7, the permanent magnet '12 rests against the plate support til, which is preferably of brass, off to one side of the large substantially rectangular hole 66 in the plate 60, and it is received between two upstanding lugs or ears and 69 formed integrally with the plate support 66. In a direction lengthwise of the axis of the winding 5 the magnet "a is of the same length as the winding unit 53--555'!, so that these two parts are snugly received between the pole piece plates 53, "it, with the latter parallel to each other and at right angles to the axis of the bore of the winding unit; registering with this bore and of the same diameter are holes 13 and M in the extension poles l3 and 14, respectively. These have lugs or cars 13* and Hirespectively, that rest against the plate support 60 to which they are secured by screws #5, the end plates 73, M bridging across the opening 59* in the plate 60 and overlying the longitudinal edges of the opening, thereby holding the winding unit in its above-described position in which it projects downwardly through the opening. These end plates also have lugs '13" and 14 which overlie the permanent magnet 12 Figures 6 and '7) and the latter is thus securely held in place.

The relationship of the permanent magnet extension poles 13, 14 to the tubular casing part 63 and the plunger 5| in the latter is substantially as is better shown in Figure 6, wherein flux from the unidirectional field of the permanent magnet 72 flows in a magnetic circuit which includes the permanent magnet '12 and pole piece ?4, thence in a general radial direction from the annular surfaces about the hole Hi to the plunger 5 I, thereby crossing a relatively small radial flux gap represented principally by the material of tubular casing part 36, then from the inner or upper end of plunger 51 in a general axial direction along a correspondingly axial flux gap to the annular surfaces at the hole 13, and then along the pole extension 73 and back to the permanent magnet 12 the resultant pull exerted on the plunger 5! is resisted by the spring 52 which, as a result, may be compressed and the resultant balance of pull and spring forces holds the plunger in about the position shown in Figure 6 and the striker 56 out of engagement with the gong 35. By means of the slots 56-65 and the screws iii58 (Figures 4, 6, and 7), the entire sub-assembly (of Figure '7) may be adjustably positioned along the length of the tubular part 35, the latter extending through the bore of the sub-assembly, and that includes the holes 13* and li of the pole piece extensions.

When the winding 55 is energized with alternating current, the flux produced thereby is in efiect superimposed upon the unidirectional flux of the permanent magnet, in the above-described magnetic circuit. On one half-cycle the winding flux is in the same direction as the permanent magnet flux, and the plunger 58 is forcibly drawn upwardly, further compressing the spring and tending to shorten the above-mentioned axial flux gap between the plunger and the pole piece '53; on the succeeding half-cycle the winding flux is in opposite direction, the magnetic pull on the plunger 5! is greatly reduced, and the energy stored in spring 52 is thus released to snap the plunger 5! downwardly and cause striking of the gong 45, and upon the succeeding half-cycle, with the fluxes now additive, forcibly pull the plunger 5! upwardy to again compress the spring 52, these steps repeating themselves for so long as the circuit of winding 55 remains closed. The above-described adjustability of the sub-assembly along casing tube 36 may be utilized to achieve that setting which gives best ringing action, it being noted that the subassembly, when secured in position by the screws 61, 68, forms in effect a steadying support for the inwardly projecting tubular casing part 36.

The arrangement just described utilizes both half-waves of the energizing alternating current. Good efiects can be achieved, however, by unidirectionally energizing the winding 55, as with a succession of unidirectional pulses. For ex ample, a single-wave rectifier might be included in the circuit of winding 55 so that the latter is energized only by half-waves of one sign of the energizing alternating current; in such case the rectifier, which may be of any convenient form, such as a so-called copper-oxide-iron rectifier, may be included in the above-described sub-assembly, as is shown in Figure 8, wherein such a rectifier, generally indicated by the reference character 5'5, is shown insulatingly carried by a bracket It secured to the plate support 60 on one side of the winding unit, and in Figure 9 is diagrammatically shown how the winding 55 and rectifier i! of such a sub-assembly are connected in series across the connecting tabs 6!, 62 of the insulating plate extension 58 and from which conductors lead to the connecting plug 28. Where the power stroke of the plunger 5! is in response to energy released by the spring 52, as in the arrangement of Figure 6, the circuit connections are so made that the half-waves or pulses utilized to energize the winding 55 pass through the latter in a direction such that the corresponding flux produced in the above magnetic circuit is in the same direction as that of the permanent magnet.

The arrangement of Figure 6 is of advantage where it is desired to use a relatively long coil spring 52, particularly one that has a nonlinear force-deflection characteristic, as by giving it a tapered shape from one end to the other, in order to substantially compensate for the non-linear relationship between the magnetic force exerted on the plunger and the displacement of the plunger as the axial flux gap changes, an arrangement that coacts in achieving synchronous plunger actuation. The above-described angular position of the re-entrant tubular casing part it in relation to the interior of the sealed enclosure permits a substantial length of tubular part 35 to be nicely accommodated.

Under extremely adverse weather conditions it might be possible, in spite of the protective features above described, for the lower end of the striker 50 to become frozen against movement by ice or snow that might somehow accumulate or be formed, for example, in the angle between the plane of theopen end of the tubular casing part 38 and the adjacent inside face of the portion 35 (Figure 6) of the gong Q5, and to combat such a condition I may re-arrange the structure of Figure 6 in the manner indicated in Figure 10. The paramagnetic plunger means within the reentrant casing part 36 may comprise a multi-part plunger structure with the parts coacting with each other and with the permanent magnet field and the field of the winding so as to partake of substantially conjoint mo tion or reciprocation as a unit under certain conditions and to partake of substantial relative axial movement when the striker 50 is immobilized, as by an ice formation. Illustratively, for one part, I may use the plunger 55, as in Figure 5, with which the striker is mechanically connected, and for the other part a somewhat shorter plun er 5l above the plunger 5! and axially spaced from the latter by a coiled spring 52 preferably of non-magnetic material, such as brass or Phosphor bronze, and inside of which there extends downwardly a stem 5?, preferably of non-magnetic material, secured at its upper end to the upper plunger 5!". Plunger 5! b may be of chromium-plated soft iron. Between the upper end of the latter and the sealed inner end of tubular casing 36 is interposed a coiled spring 52 which, according to circumstances, may have a non-linear characteristic, if desired.

The several parts are so proportioned that, with the plunger 5! held retracted by the force of the permanent magnet flux, thus holding the striker 5!? out of direct contact with gong 45, spring 52 which, like spring 52*, may be under some strain in this at-rest position-holds the upper plunger 5! more or less out of the axial flux gap between the upper end of plunger 5! and the annular surfaces about the hole '13 in the extension pole 73, and in that position the lower end of the short stem 5! is spaced axially away from plunger 5i.

When the winding 55 is energized, as herein described, so that its flux is added to that of the permanent magnet along the above-mentioned axial flux gap, the plungers 5! and 51 move upwardly under the pull exerted on the plunger 5!, compressing both springs 52 and 52 and during this action, if the stem 5! is engaged by the lower plunger 5!, the latter can thereby directly increase the compression of the upper spring 52 and the energy stored therein. When the winding flux changes, as above described, to effect a downward stroke of movement of the striker 58, the plunger system is snapped or projected downwardly at substantial velocity as the energy in the two springs is thus released, and during this action some relative axial movement between the plunger parts 5i and 5H may take place under the action of spring 52 The pull 11 of the permanent magnet flux, upon conclusion of the downward stroke, restores the parts to the at-rest position above described.

However, should the striker 59 be frozen or otherwise immobilized, axial movement oi plunger under the control of the winding flux, does not take place and the inner end face of plunger 5! now becomes a flux-guiding face for flux of both permanent magnet and of the winding in an axial fiux gap reaching toward the lower end face of plunger Bi and to the annular surfaces about the hole 13 in pole piece is, exerting a powerful pull on the plunger 5 i to snap it downwardly toward the plunger 5!, aided somewhat by the spring 52 the pull increasing very rapidly as this fluxgap shortens; as a result, spring 52 yields and the stem 5!" is powerfully impacted against the plunger iii, the force of the impact being transmitted to the end of striker 5G to fracture any ice formation at that end. Rounding over or tapering the end of striker 59 is of aid as it acts like a wedge driven into the ice formation. When the energization of winding 55 is such as to diminish the magnetic flux in the now shortened air gap between the two plunger parts, the energy stored in spring 52 forces the plunger 5! upwardly toward its at-rest position, as suggested in Figure 10, thus completing one cycle of an ice-breaking stroke with the resultant retractile stroke for the plunger 55 relative to the striker 50.

It will now be clear that these cycles are repeated at great rapidity, particularly if the winding is energized with alternating current at suit able frequency, usually 60 cycles, the actuation of the ice-breaker plunger 5t being substantially synchronous therewith. Fragmentation and clearing of the ice formation results in freeing the striker 53 for movement, whereupon continued energization of the winding 55 achieves reciprocation of the system and striker st for sounding the gong, in the manner first above described.

The spring and plunger in Figures 6 and 10 are well protected against foreign matter and effects of weather and the like; nevertheless, it might be desired under some circrm'lstancesto eliminate use of a spring. With the gong 45 outside of the sealed casing and desirably detachably secured thereto as above described, when position it serves to prevent removal of the plunger-striker unit and of the spring, these in effect being external of the sealed enclosure. In Figures 11 and 12 I have shown a form of my invention which has the advantages of assembly and operation without such a spring.

I again employ a sub-assembly that is sleeved onto the inner closed end of the casing tube 36, as before, and it again comprises a plate support 68 having a bar or block type of permanent magnet '52 at one end, held in place by lugs Bil and $6 upstanding from the plate 66 and by overlying lugs 73 and 14 of the plate-like pole extensions T3 and M which are secured by lugs and screws to the support 60 as before. Preferably the permanent magnet 12 is somewhat longer and the spacing between the plate pole extensions :3 and Hi correspondingly larger in order to accommodate therebetween two windings 55 and 55 with a paramagnetic plate-like intermediate pole extension 83 (Figures 11 and 12) the intermediate pole piece 83 bridges across the plate opening 6B and its right-hand edge, as seen in Figure 12, abuts flatwise against the adjacent face of the permanent magnet 12 so as to be in good flux-conductive contact therewith. Intermediate pole piece 83 has a round hole 3*- therein, and the winding unit and sub-assembly can thus be sleeved onto the inner closed end of the casing tube 36 as shown in Figure 11 and adjustably secured by the screw and slot connection to the internal brackets 63 and 65. It is fixed in a position such that the flux from the permanent magnet 12 holds the plunger 5| (Figure 11) in the desired position with the striker 5Q appropriately spaced from the gong 45.

Plunger 5! is of a length shorter than the spacing between the endmost pole extensions i3 and 14, thus providing, when in mid-position, generally axial flux gaps between its ends and the respectively adjacent but spaced pole pieces 13 and 14, with about the central portion of plunger 5| surrounded by the intermediate pole pieces 33, being spaced therefrom by an annular radial flux gap of relatively small dimension, on the order of the thickness of the wall of the casing tube 36. Along these axial flux gaps, flux from the permanent magnet 72 can exert forces on the plunger 5| and these, when affected by the energization of the windings 55 and 55", illustratively in a manner later described, can effect synchronous reciprocation of the plunger and striker and correspondingly impact the gong synchronously.

To hold the striker 50 in an at-rest position out of engagement with the gong against the effect of the Weight on plunger and striker tending to slide them downwardly in Figure 11, I may utilize a relationship of parts as is there indicated; this includes giving the striker rod 58 such a length that when its end engages the gong 45, the plunger 5| is in a position where the axial flux gap between its upper end and pole piece 13 is shorter than the axial iiux gap be tween its lower end and the pole piece i l. Accordingly, permanent magnet flux in the mag netic circuit comprising the permanent magnet 12, pole piece 13, upper axial flux gap, piling 5i, intermediate pole 83, and back to the manent magnet 12, is greater than the permanent magnetic flux in the magnetic circuit comprising permanent magnet 12, intermediate pole piece 83, plunger 5|, lower axial flux gap, pole piece M, and back to the permanent magnet '52, and accordingly the pull on the plunger Si is greater in an upward direction and plunger and striker rod are moved into and held in an atrest position somewhat as shown in Figure 11, in which the plunger 5| has its axial mid-point substantially coincident with the central plane between the parallel pole pieces T3 and 83. Actually the plunger 5! is displaced a little bit downwardly from that point of coincidence because of the weight of the movable parts and because of the effect of axial pull downwardly by flux along the lower axial flux gap between the lower end of plunger 5| and the lower pole piece 14. This latter pull is materially diminished because that axial fiux gap is of materially greater length. This at-rest position is dependably maintained and in this arrangement the striker rod cannot be held constantly in contact with the gong 45 because that contact prevents the lower axial flux gap from ever becoming shorter than the upper axial flux gap, as earlier explained.

Windings and 55 are connected in series, as shown in Figure 13, across the connecting tabs 68 and 52 carried by the insulating plate 53, the serial connection being such that the windings produce magneto-motive forces and resultant axial flux in opposite directions. When energized by alternating current, on one halfwave winding 55 produces magnetic flux in the upper magnetic circuit, as viewed in Figure 11, in a direction opposed to the permanent magnet flux in that circuit and winding 55 produces magnetic flux in the lower magnetic circuit in the same direction as that produced therein by the permanent magnet; accordingly the flux in the lower axial flux gap is greatly increased (in the magnetic circuit comprising the lower part of permanent magnet 72, intermediate pole piece 33, lower part of plunger axial flux gap, lower pole piece H, and back to the permanent magnet 52) with the result that the plunger and striker are snapped downwardly with substantial velocity and energy. In this manner the plunger and striker are moved out of their at-rest position and at about the moment of impact the lower axial flux gap is exceedingly small, whereas the upper axial flux gap is now of substantial length. On the next and reversed half-wave, the flux of upper winding 55 is in the same direction across the upper flux gap as is the permanent magnet flux, in the upper magnetic circuit, and the flux from the lower winding 55 is in a direction opposing the permanent magnet flux across the lower axial flux gap, in the lower magnetic circuit, whereupon the plunger and striker are snapped upwardly, whereupon the succeeding half-wave sheets a downward stroke of movement, these actions and steps following in synchronous succession for so long as the circuit of the two windings is maintained closed.

When the circuit is open and the two windings deenergized, the plunger and striker are pulled and held into the atest position indicated in Figure 11 and as above described.

The adjustable setting of the winding and permanent magnet sub-assembly (as seen in Figure l2) lengthwise of the re-entrant casing tube 35 along the supporting brackets 63 and 84 is of advantage not only in assembly of the structure in course of manufacture, but also in empirically or during testing speedily achieving the coacting relation hips above described.

If desired, instead of using a single elongated bar type of magnet 72 as in Figure 12, two smaller or shorter permanent magnet blocks may be employed as shown at W and 12 in Figure 14, and in such case the intermediate pole piece can be extended to reach inbetween the two magnets 72 and '32 If the latter are arranged so that the north pole of magnet 72 engages pole piece it and the south pole of magnet 52 engages pole piece is, the windings 55 and 55 are again connected to produce flux in opposite directions. On the other hand, if one of the magnets 12 or la is reversed end for end, so as to reverse the direction of iiow of permanent magnet flux in its magnetic circuit, the windings 55 and 55' are connected to produce fluxes in the same direction. In either case the operation will now be clear in view of the description of the embodiment of Figures 11 and 12.

In these forms the flux-responsive structure for actuating the striker 55 may also be arranged to achieve ice-breaking action to free the striker in in it becomes immobilized by freezing, and this may be done by providing a coacting paramagnetic plunger til as indicated in Figure 11 and shown on a larger scale in Figure 11a; in this form the plunger fil which may be of soft iron chromium-plated, has a central or axial bore therethrough so that it may be sleeved onto the striker rod 56 for ease of axial movement relative thereto, striker rod being preferably made of any suitable non-magnetic material. Extending about the striker rod 50 and between the lower end of plunger 5| and the upper end of plunger til is a coiled spring 52 of such a strength and so dimensioned that, with the mov ing parts held in the at-rest position above described, the upper end of plunger 5| just about enters the opening 14 in the extension pole piece it, a collar 8'5 secured to the striker rod 56 limiting downward movement of plunger 5W along the rod 53, as is better shown in Figure 11a.

When the windings and 55 are energized as above described, the plunger 5| and striker 5B reciprocate as before, carrying plunger 51 along with it, and during the strokes of reciprocation little, if any, material relative axial movement between the plunger fil and plunger 5i need take place, plunger 51 barely, if at all materially, entering the axial flux gap between the pole pieces 74 and 83.

However, if striker rod 55 is immobilized, thus holding plunger 5! against movement out of its at-rest position, energization of winding 55 in a direction to add to the permanent magnet flux in the axial flux gap that extends downwardly from the lower end of plunger 5! to the upper end face of plunger 51*, exerts a powerful upward pull on plunger 5 I a pull which increases rapidly as the axial gap is shortened by upward movement of the plunger 51 thus compressing spring 52 and storing substantial energy in it; when the energization of the winding then changes to diminish the flux in the shortened axial flux gap, the energy stored in spring 52 is released and the plunger di is snapped downwardly at substantial velocity, its kinetic energy, when its downward movement is suddenly halted by the collar 86, being transmitted to the striker rod 59 to fragment or crush the ice accumulation or other cause that immobilizes the striker 53. Under the control of the winding flux, such reciprocation relative to the striker rod 5t and plunger 55 can be repeated in rapid succession, synchronously where the energization is by pe riodic or successive current pulses, and once striker 50 is freed, so as to release plunger 5i for reciprocation, the latter partakes of controlled reciprocation as before with plunger 5! moving along with it substantially as earlier described above.

In Figures 15 and 16 I have shown a winding 55 wound or mounted on a suitable insulating form or spool and provided with insulating end plates 5! and 58, as before, and assembled to the plate support 66 by metal end plates 87 and 38 secured by suitable ears and screws ?5. End plate 88 is of paramagnetic material, and adjacent one end thereof it is in fiatwise flux-conductive engagement with a small block-like permanent magnet 90 Whose opposite end face is in similar flux-conductive engagement with a companion paramagnetic plate member shaped substan' tially the same as plate 88 and being provided with ears or lugs through which pass screws t2 securing it to the plate support 59 and holding it parallel to the companion plate 88.

Permanent magnet block as rests against the plate support 58 between upstanding lugs and 65 and is further held against dislocation by overlying lugs Qi and 83 of the metal plates.

The winding unit 58-55-51 has a central channel or bore therethrough, as before, and the 15 parallel plates 81, 88, and 9| are provided with aligned circular apertures 81 88 and m which are aligned with the cylindrical bore of the winding unit, all or them being of a diameter so that the sub-assembly as seen in Figure 16 can be sleeved, or slid onto the internally projecting tubular casing part 35, as shown in Figuure 15, screws 6? and 58 securing the sub-assembly to the inclined brackets 53 and 64, adjustably by way of the slots 55 and 66.

The tubular casing part 36 again contains a plunger i and striker rod 50, and in the form shown the plunger 5|, in its at-rest position, is located with its magnetic center displaced upwardly to the right of the magnetic center of the solenoid winding. 55 so that upon energization of the latter, plunger 5| is drawn downwardly to impact striker 50 against the gong 45.

Intermediate of its ends, striker rod 55 carries a paramagnetic plunger 5i, which may be of chromium-plated soft iron, for coaction with the permanent magnet flux to which it is subjected by the extension poles 88 and 9! which, like the other extension poles above described, surround the tubular part 36; these parts coact to hold the striker 50 in an at-rest position where it is out of contact with the gong 45 and to give the plunger 5! and striker 50 a return or reverse stroke of movement at the conclusion of each power stroke eflected by the magnetic force of winding 55 on the part 5|.

The plunger 5 l is of a length in relation to the axial dimension of the permanent magnet circuit substantially as indicated in Figure 15, and permanent magnet fiux flowing axially in the plunger 5P tends to force and hold the plunger 5& with its mid-point substantially coincident with a mid-plane between the pole pieces 88 and 51. When winding 55 is given an energizing pulse, plunger 5| is forced downwardly to the left in Figure 15 to impact the striker 50 against the gong 45 and in the course of that stroke of movement, plunger or core 5| opens up, increasingly in axial direction, what is in eifect an axial flux gap between the upper end of plunger 5! and the flux guiding surfaces about the hole 58* in the pole piece 88, thus rapidly diminishing, at e. rapidly increasing rate, the pull or holding action of the permanent magnet flux on the plunger 5H and hence upon the moving parts; this means that the force opposing the magnetic iorce exerted by winding 55 on part 5! rapidly diminishes so that the rapidly increasing magnetic force of winding 55 on part 5!, effected not only by a rise in instantaneous current value in the winding 55 but also by the square law solenoid eifect, can cause the striker 56 to impact the gong 45 at high velocity and energy. Upon substantial collapse of the pulse of energizing current in winding 55, with resulting substantial collapse of the magnetic field produced by the winding 55, the flux of permanent magnet 55, flowing from pole piece 88 in general axial direction to the upper end of core 51, across the then relatively long axial flux gap, snaps the core 5% and the parts connected to it upwardly to the ri ht in Figure 15 to restore it to its at-rest position or to permit repetition of the justdescribed cycle of operation upon the ensuing pulse of energization of winding 55.

During gong striking stroke and the ensuing stroke of the moving parts, the effectiveness of change in the axial flux gap between core 5W and pole piece 88* is maintained by the substantial invariability of the annular radial flux gap between the concentric surfaces of the hole Sl in the pole piece 9| and the cylindrical surface of core 5W, that radial flux gap being of relatively small dimension. However, any desired characteristic of change in magnetic force on the core 5| in relation to axial displacement of the core 55 may be achieved by appropriately shaping the coacting flux guiding faces of the parts. For example, a higher rate of change in reluctance of the flux gaps in the magnetic circuit of the permanent magnet 90 may be effected as by appropriately changing the radii of the external surface of the core 5W, as is indicated in the fragmentary view of Figure 17 where an intermediate portion of core 5W is tapered, as indicated at 93, so that when the tapered portion, on downward movement of core 5H, comes more and more into juxtaposition to the flux face 55' of pole piece 9i, that radial flux gap is increased in effective radial dimension and its reluctance correspondingly increased.

In any case, the parts are so proportioned and the winding unit sub-assembly so adjusted lengthwise of the casing tube 35 that gong (see Figure 15) coacts with the permanent magnet circuit in that it prevents the core 5H from such excessive axial movement as would bring t out of the desired coacting relation with the permanent magnet circuit for effecting a return stroke of movement.

Winding may be energized in any suitable manner as will now be clear, with an appropriate energizing impulse or succession of pulses of current. Illustratively, but not by way of limitation, it may be energized from a direct current source with the aid of a suitable circuit interrupter which may be of any suitable type and may be related in any suitable manner to the magnetic field produced by winding and in Figure 16 anillustrative vibrating form of interrupter is shown and generally indicated by the reference character 95.

ihe interrupter may comprise a flat leaf spring 55 insulatingly supported in any suitable manner, as indicated at 91, from one end edge of the pole piece plate 88, its extreme end portion 55* being provided with suitable means for connecting an electric conductor thereto.- Leaf spring 56, preferably of steel, has secured to it, as by riveting, a soft iron plate-like armature 98 which terminates in juxtaposition to the vertical end edge face, as seen in Figure 16, of the winding unit end plate 81 which is made of sheet steel or the like. Accordingly parts 88, 96, 98, and 8'! form a magnetic circuit for flux produced by the winding 55, so that upon energization of winding 55 armature 98 is attracted and moved toward the part 81, lessening the flux gap therebetween. This movement ofv armature 98 is utilized to break the circuit of winding 55, and this may be done by a contact element 99 carried at the free and somewhat bent end of flat spring 96 and normally, under the action of spring 95, held in engagement with an adjustable stationary con.- tact which can be in the form of a contact screw H15 carried in a bracket 10! which is insula tingly supported in any suitable manner on the plate support and which is provided with a binding screw N12 for connecting the conductor thereto. By setting screw I00 against the bias of spring 95, the normal at-rest dimension of the flux gap between parts 98 and 81 may be adjusted to give the desired frequency of vibration and hence fre-- quency of circuit interruption and of energizing pulses for the winding 55. In Figure 18 is dia- 17 grammatically shown the series connection of the winding 55 and interrupter 95 across the connector tabs 6! and 82 carried by the insulating plate 58 of the winding unit.

The various adjustments described can be empirically arrived at in course of assembly or test and before the mechanism becomes sealed within the casing 2il2l36; with the interrupter also enclosed, the device may be safely used in atmospheres where there is risk of explosive content, any sparking at the interrupter contacts being thus rendered harmless. that in place of the interrupter 95, the sub assembly of Figure 16 may have mounted on it a rectifier like the rectifier i! of Figure 8 where impulse energization of that kind from an alternating current source may be desired, in which case the circuit arrangement is as shown in Figure 9; also, the interrupter arrangement shown in Figure 16 is intended to be illustrative of how an interrupter may be employed in not only the forms of Figures 15 and 17, but also in any other form, for example, that of Figures 8 and 10 where impulse energization in that manner is desired.

In Figure 17 I have shown the embodiment of Figure 15 arranged for ice-breaking action, and there I have arranged the paramagnetic plunger parts 5! and 51 for relative axial movement, in that striker 59 is mechanically connected to plunger 5% and plunger 5! is provided with a downwardly extending stem El preferably of non-magnetic material, being surrounded by a spring 52 which is interposed between the two plungers and normally holds them apart so that stem 5i is spaced from the upper end of plunger 51, somewhat as in the arrangement of Figure preferably a short cushioning spring 52 is interposed between the sleeved inner end of tubular casing 36 and the upper end of plunger 5F.

The at rest position of the parts is substantially as shown in Figure 17, being so held by the action of the permanent magnet flux on the plunger 5H. Should striker 5:; be immobilized, as by an accumulation of ice as above noted, the plunger 51 remains stationary upon subsequent impulse energization of the winding 55 and the flux of the latter, produced internally and coaxially of the tubular part 38 that is within the winding 55, exerts a strong pull in downward direction on the plunger 5! and in effect snaps the latter downwardly at substantial velocity and against the action of spring 52 which can be of relatively small strength, to impact the stem 58 against the plunger 55 and by the energy of the resultant blow driving the striker 56 into the ice formation; when the energizing impulse ceases or diminishes, the spring 52 moves the plunger 5! upwardly to position it to be again snapped downwardly upon the succeeding impulse energization of the winding 55 to repeat the cycle.

Such cyclic reciprocation is rapidly repeated as the impulse energization of the winding continues and when the striker 5-3 is freed, both plungers 5! and 5 i can partake of axial reciprocation somewhat as a unit, though in the course of the downward or power stroke, relative axial movement between them can take place in that, depending upon correlation of strength of spring 52 to other factors, downward movement of plunger 5! can take place at high enough velocity to impact against the plunger 51* before the eiiect of its inertia and the eiiect of the permanent magnet pull thereon are overcome by the It will be understood compression of the spring 52 in which case the striker 50 is suddenly impelled downwardly at good velocity to effect striking of the gong by the striker 50; when the current impulse energizing the winding 55 ceases or is sufficiently diminished, the permanent magnet flux, aided by some rebound of the striker 50, pulls the parts upwardly to substantially the at-rest position, at which moment the succeeding impulse of energizing current becomes operative upon the plunger system to repeat the cycle where repeated or substantial synchronous striking of the gong is desired. During these actions the spring 52 desirably serves yieldingly to limit the retrograde stroke of plunger 5| appropriately, and it can also act to prevent the plunger from actually striking closed end of the tubular casing part 36.

The construction in its illustrative embodiments will be seen to have numerous advantages from many viewpoints, such as manufacture, assembly, adjustment or testing, installation, and repair or replacement of parts. For example, a setting of internally adjustable parts once made and the structure assembled and sealed, cannot bet detrimentally disturbed by shift or displacement of the gong which cannot be rotativelydisplaced nor can it be removed and put back in other than its initial position.

Moreover, it will be seen that the invention provides a signalling device in which the various objects above set forth and also elsewhere indicated are successively achieved; the construction will be seen to be rugged and dependable, particularly under widely varying conditions of practical use, and particularly under adverse weather conditions such as are met with on shipboard, for example.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiments above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. A weatherproof and de-icing signalling construction comprising means forming a sealed casing having an opening in a wall thereof from which a re-entrant tube-like casing part extends upwardly and inwardly into the casing to form an air trap against the rise of water thereinto, a gong supported externally of said casing with a portion thereof adjacent said opening, a striker in said re-entrant casing part and reciprocable through said opening for striking said gong, paramagnetic means within said re-entrant casing part and protected against water by said air trap and reciprocably movable therein in strokes toward and away from said opening, said paramagnetic means comprising a plurality of paramagnetic plungers having means mechanically interrelating them for movement in the same direction on each stroke and for movement of one relative to the other, one of said paramagnetic plungers having mechanical connection with said striker whereby the latter is reciprocated into striking engagement with said gong upon movement of said plungers in said strokes and whereby, when said striker is immobilized by icing at its outer end and thereby the plunger connected to it is also immobilized, the other of said plungers may partake of movement toward and away therefrom, and magnetic fluxproducing means controlling actuation of said paramagnetic plungers and including electromagnetic winding means within said sealed casing and coacting upon energization to reciprocate both plungers to effect striking of said gong by said striker and, upon immobilization of said one plunger by icing of the striker, to reciprocate the other plunger relative thereto to dissipate its kinetic energy thereon through said striker to free itself from the icing.

2. A weatherproof and de-icing signalling construction as claimed in claim 1 in which said magnetic flux-producing means includes also permanent magnet means the flux of which acts upon said plunger that is mechanically connected to the striker to hold it and the striker, during de-energization of said winding means, in retracted position and in which the flux produced by said winding means, when energized, acts upon the other plunger.

3. A weatherproof and de-icing signalling construction as claimed. in claim 1 in which said magnetic flux-producing means includes also permanent magnet means the flux of which acts upon said plunger that is mechanically connected to the striker to hold it and the striker, during de-energization of said winding means, in retracted position and in which the other plunger surrounds and is slidable relative to the striker for reciprocation therealong toward and away from said striker-connected plunger and the flux produced by said winding means, when energized, acting upon the latter to effect striking reciprocation of the striker and, upon immobilization thereof, acts through said striker-connected plunger upon the other to reciprocate the latter relative to the former along said striker.

4. A weatherproof and de-icing signalling construction as claimed in claim 1 in which said magnetic flux-producing means includes also permanent magnet means the flux of which acts upon said plunger that is mechanically connected to the striker to hold it and the striker, during de-energization of said winding means, in retracted position and in which the other plunger is interposed between said striker-connected plunger and the inner end of said re entrant casing part for reciprocating movement toward and away from said striker-connected plunger, the flux of said winding means, when energized, acting upon the latter for striking r reciprocation of said striker and, upon immobilization thereof, acting upon said other plunger to reciprocate it into impacting engagement with said striker-connected plunger.

5. In a signalling construction, in combination, means forming a sealed casing having a substantially vertical wall externally of which is mounted a gong, said wall having an opening adjacent a part of the gong to be struck and a reentrant tube-like casing part extending from said opening inwardly and upwardly into the in- .terior of the sealed casing and forming an air trap to prevent rise of water thereinto, a paramagnetic plunger slidable in said tube-like casing part and protected against water by said air trap, said plunger having striker means operating upon said gong portion through said opening, means for holding said striker means in an at-rest position out of contact with said gong to prevent water accumulation and freezing thereat and for actuating said plunger to cause striking of said gong comprisingpermanent magnet means producing a magnetic field the flux of which exerts a magnetic force on said plunger H to hold it and said striker means against descent 20 in said tube-like casing part, and electro-mag netic winding means within said sealed casing and extending about said tube-like casing part to produce a magnetic field, when energized, the flux of which acts upon said plunger through the walls of said tube-like casing part.

6. In a signalling construction, in combination, means forming a sealed casing having a substantially vertical wall externally oi which is mounted a gong, said wall having an opening adjacent a part of the gong to be struck and a re-entrant tube-like casing part extending from said opening inwardly and upwardly into the interior of the sealed casing and forming an air trap to prevent rise of water thereinto, a paramagnetic plunger slidable in said tube-like casing part and protected against water by said air trap, said plunger having striker means operating upon said gong portion through said opening, means for holding said striker means in an at-rest position out of contact with said gong to prevent water accumulation and freezing thereat and for actuating said plunger to cause striking of said gong comprising spring means in said tube-like casing part and interposed between the inner end thereof and said plunger for impelling the plunger and striker means downwardly to strike said gong, permanent magnet means exerting upward force on said plunger and partially compress said spring means to hold said plunger in a position with the striker means out of contact with said gong, and an electro-magnetic winding about said re--entrant tube-like casing part and producing, when energized by current pulses of one sign, a magnetic field for each pulse in a direction additive to that of said permanent magnet means and thereby further compress said spring means during each of said energizing pulses.

7. In a signalling construction, in combination, means forming a sealed casing having a substantially vertical wall externally of which is mounted a gong, said wall having an opening adjacent a part of the gong to be struck and a re-entrant tube-like casing part extending from said opening inwardly and upwardly into the interior of the sealed casing and forming an air trap to prevent rise or water thereinto, a paramagnetic plunger slidable in said tube-like casing part and protected against water by said air trap, said plunger having striker means operating upon said gong portion through said opening, means for holding said striker means in an at-rest position out of contact with said gong to prevent water accumulation and freezing thereat and for actuating said piunger to cause striking of said gong comprising permanent magnet means within said sealed casing and having spaced pole extensions related to the walls of said "re-entrant tube-like casing part to direct unidirectional magnetic fiux thercthrougli for action upon said plunger to hold it and said striker means against descent into engagement with said gong, and means comp ising an electro-rnagnetic winding within said sealed casing to produce a magnetic field, when energized, coacting to project said plunger and striker means downwardly.

8. In a signalling construction, in combination, means forming a sealed casing having a substantially vertical wall externally of which is mounted a gong, said wall having an opening adjacent a part of the gong to be struck and a reentrant tube-like casing part extending from said opening inwardly and upwardly into the interior of the sealed casing and forming an air trap to prevent rise of water thereinto, a paramagnetic plunger slidable in said tube-like casing part and protected against water by said air trap, said plunger having striker means operating upon said gong portion through said opening, means for holding said striker means in an at-rest position out of contact with said gong to prevent water accumulation and freezing thereat and for actuating said. plunger to cause striking of said gong comprising permanent magnet means within said sealed casing and having pole extensions axially spaced relative to the axis of said re-entrant tube-like casing part to produce unidirectional magnetic flux within said re-entrant casing part, said plunger having two parts, one of which is acted upon by said flux to hold it and said striker means against descent into engagement with said gong, and an electro-magnetic winding within said sealed casing and producing, when energized, a magnetic field acting through the walls of said re-entrant tube-like casing part and upon the other part of said plunger.

9. In a signalling construction, in combination, means forming a sealed casing having a substantially vertical wall externally of which is mounted a gong, said wall having an opening adjacent a part of the gong to be struck and a re-entrant tube-like casing part extending from said opening inwardly and upwardly into the interior of the sealed casing and forming an air trap to prevent rise of water thereinto, a paramagnetic plunger slidacle in said tube-like casing part and protected against water by said air trap, said plunger having striker means operating upon said gong portion through said opening, means for holding said striker means in an at-rest position out of contact with said gong to prevent water accumulation and freezing thereat and for actuating said plunger to cause striking of said gong comprising permanent magnet means within said sealed casing and having two pole extensions spaced along the axis of said re-entrant tube-like casing part to produce through the walls and within the latter unidirectional magnetic flux along the axial flux gap between said spaced pole extensions and into which axial flux gap the upper portion of said plunger extends, said gong acting through said striker means to prevent descent of said plunger completely out of said axial flux gap whereby the pull of said flux on said plunger returns and holds said striker means out of engagement with said gong, and electro-magnetic winding means within said sealed casing and coacting to project said plunger and striker downwardly.

10. In a signalling construction, in combination, means forming a sealed casing having a sub stantially vertical wall externally of which is mounted a gong, said wall having an opening adjacent a part of the gong to be struck and a reentrant tube-like casing part extending from said opening inwardly and upwardly into the interior of the sealed casing and forming an air trap to prevent rise of water thereinto, a paramagnetic plunger slidable in said tube-like casing part and protected against water by said air trap, said plunger having striker means operating upon said gong portion through said opening, means for holding said striker means in an at-rest position out of contact with said gong to prevent water accumulation and freezing thereat and for actuating said plunger to cause striking of said gong comprising permanent magnet means within said sealed casing and having a plurality of axially spaced pole extensions along said re-entrant tubelike casing part between two of which is formed one axial flux gap andtwo of which form a second axial flux gap, for flux from said permanent magnet means, said twoaxial flux gaps being substantially axially aligned for flux conduction within said tube-like casing part for coaction with said plunger whereby the magnetic forces exerted axially on said plunger tend to force it to substantially bridge one or the other of said axial flux gaps, and electro-magnetic winding means in said sealed casing and coaxial with said re-entrant tube-like casing part for affecting the relative eifects of the permanent magnet fluxes in said two flux gaps and thereby effect movement of said plunger and striker means.

11. In a signalling construction, in combination, means forming a sealed casing having a substantially vertical wall externally of which is mounted a gong, said wall having an opening adjacent a part of the song to be struck and a reentrant tube-like casing part extending from said opening inwardly and upwardly into the interior of the sealed casing and forming an air trap to prevent rise of water thereinto, a paramagnetic plunger slidable in said tube-like casing part and protected against water in said trap, said plunger having striker means operating upon said gong portion through said opening, means for holding said st iker means in an at-rest position out of contact with said gong to prevent water accumulation and freezing thereat and for actuating said plunger to cause striking of said gong comprising permanent magnet means within said sealed casing and having three pole extensions axially spaced along said re-entrant tube-like casing part and thereby providing two axially aligned flux gaps within said tube-like casing part for coaction with said plunger, whereby said plunger tends to assume a position in which it substantially bridges one of said axial flux gaps or the other, and electro-magnetic winding means within said sealed casing eifective, when energized, to alternately change the effective fiux values in said two axial flux gaps and thereby effect reciprocation of said plunger and striker means.

12. In a signalling construction, in combination, means forming a sealed casing having a substantially vertical wall externally of which is mounted a gong, said Wall having an opening adjacent a part of the gong to be struck and a reentrant tube-like casing part extending from said opening inwardly and upwardly into the interior of the sealed casing and forming an air trap to prevent rise of water thereinto, a paramagnetic plunger slidable in said tube-like casing part and protected against water in said air trap, said plunger having striker means operating upon said gong portion through said opening, means for holding said striker means in an at-rest position out of contact with said gong to prevent water accumulation and freezin thereat and for actu ating said plunger to cause striking of said gong comprising permanent magnet means within said sealed casing and having three pole extensions axially spaced along said re-entrant tube-like casing part and thereby providing two axially aligned flux gaps within said tube-like casing part for coaction with said plunger, whereby said plunger tends to assume a position in which it substantially bridges one of said axial flux gaps or substantially bridges one of said axial flux gaps or the other, stop means to prevent downward movement of said plunger beyond that point at which the lower of said two axial flux gaps is effective to hold the plunger against the upward pull of the flux in the upper flux gap, and electromagnetic winding means within-saidsealed casing which, when energized, overcomes the holding force of the upper flux gap on said plunger and thereby controls descent thereof to strike said gong with said striker means.

13. In a signallin construction, in combination, means forming a sealed casing having a substantially vertical wall externally of which is mounted a gong, said wall havin an opening adjacent a part of the gong to be struck and a reentrant tube-like casing partextending from said opening inwardly and upwardly into the interior of the sealed casing and forming an air trap to prevent rise of water 'thereinto, a paramagnetic plunger slidable in said tube-like casin part and protected against water .in said air trap, said plunger having striker means operating upon said gon portion through said opening, means for holding said striker means in an at-rest position out of contact with said gong to prevent water accumulation and freezing .thereat and for actuating said plunger to causestriking of said gong comprising permanent magnet means within said sealed casing and having three pole extensions axially spaced along said re-entrant tube-like casing part and thereby providing two axially aligned flux gaps within said tube-like casing part for coaction with said plunger, whereby said plunger tends to assume a position in which it substantially bridges one of said axial flux gaps or the other, stop means to prevent downward movement of said plunger beyond that point at which the lower of said two axial flux gaps is effective to hold the plunger against the upward pull of the flux in the upper flux gap, and electromagnetic winding means within said sealed casing and coacting, when energized, to oppose the permanent magnet flux in said upper flux gap and to aid the permanent magnet flux in the lower of said axial flux gaps and thereby effect descent of said plunger and striking of said gong with said striker means.

14. In a signalling construction, in combination, means forming a sealed casing having a'substantially vertical wall externally of which is mounted a gong, said wall having an opening adjacent a. part of the gong to be struck and a reentrant tube-like casing part extending from said opening inwardly and upwardly into the interior of the sealed casing and formin an air trap to prevent rise of water thereinto, a paramagnetic plunger slidable in said-tube like casing part and protected against water by said air trap, said plunger having striker means operating upon said gong portion through said opening, means for holding said striker means in an at-rest positicn out of contact with said gong to prevent water accumulation and freezing thereat and for actuatin said plunger to cause striking of said gong comprising permanent magnet means-within said sealed casing and having pole extensions axially spaced relative to the axis of said reentrant tube-like casing part, one of which pole extensions comprising an axially extending part to produce between the latter and another of said pole extensions a unidirectional magnetic flux within said re-entrant casing part that acts upon said plunger to hold it and said striker means against descent into engagement with said gong, and an electro-niagnetic winding coaxial with said re-entrant tube-like casing part and said pole extension part and by its magneto-motive .force alter the holding forceoi the permanent 24 magnet flux on-said plunger and cause movement of the latter-and said striker means.

15. In a signalling construction, in combination, means forming a sealed casing having a substantially vertical wall externally of which is mounted a gong, said wall having an opening adjacenta partof thegong to be struck and a re-entr-anttube-like casing part extending from said opening inwardly and upwardly into the interior of the sealed casing and forming an air trap to prevent rise of water thereinto, aparamagnetic plunger slidable in said tube-like casing part and protected against water by said air trap, said plunger having striker means operating upon said gong portion through said opening, means for holding said striker means in an at-rest position out of contact with said gong to prevent water accumulation and freezing thereat and for actuating said plunger to cause striking of said gong comprising permanent magnet means within said sealed casing and having pole extensions axially spaced relative to the axis of said re-entrant tube-like casing part to produce unidirectional magnetic flux within said 're-entrant casing part, said plunger having two parts, oneof which is acted upon by said flux to hold it and said striker means against descent into engagement with said gong, said part being of varying cross-section to increase the reluctance in the path of flow of said flux upon downward movement of the plunger, and an electro-magnetic winding within said sealed casing and producing, when energized, a magnetic field acting through the walls of said reentrant tube-like casing part and upon the other part of said plunger.

16. In a signallingconstruction, in combination, means forming a sealed casing and comprising at least two separable casing parts and provided with-means forming a sealed connection therebetween, a wall member, said sealed casing means having an aperture with a re-entrant tubelike casing'part extending from said aperture inwardly and upwardly into the interior of the sealed casing and forming an air trap to prevent rise of water thereinto, a signalling device supported externally of said casing and in operative relation to said aperture, and means for activating said signalling device comprising a movable paramagnetic member in said re-entrant tubelike casing part and protected against water by said air trap and having means responsive to its movement and operable through said aperture for activating said signalling device and means for controlling actuation of said movable paramagnetic member and comprising electromagnetic means within said sealed casing for coacting through the walls of said re-entrant tube-like casing part to effect movement of said paramagnetic member.

1'7. In a signalling construction, in combination, means forming a sealed casing that has an inwardly and upwardly extending casing part that is re-entrant from an opening in a wall of the casing and thereby forming an air trap to prevent rise of water thereinto, a signalling device external of said casing and operatively related to said opening, and means for activating said signalling device comprising a movable paramagnetic member in said re-entrant casing part and :plunger actuating means including electro-magnetic means within said sealed casing for coacting magnetically through the walls of said re-entrant casing part with'said paramagnetic "member.

18. In a signalling construction, in combination, means forming a sealed casing having a substantially vertical wall externally of which is mounted a gong, said wall having an opening adjacent a part of the gong to be struck and a re-entrant tube-like casing part extending from said opening inwardly upwardly into the interior of the sealed casing and forming an air trap to prevent rise of water thereinto, a paramagnetic plunger slidable in said tube-like casing part and protected against water by said air trap, said plunger having striker means operating upon said gong portion through said opening, and means for actuating said plunger comprising electromagnetic means within said sealed casing for producing a magnetic flux that operates upon said plunger through the wall of said re-entrant tube-like casing part.

19. In a signalling construction as claimed in claim 18 in which said gong has a dished portion that overlies and covers over said opening and in which said re-entrant tube-like casing part extends at an angle to the central vertical axis of the gong with its axis intersecting the gong at a point displaced from said vertical gong axis whereby the gong portion struck by said striker means is of an angularity or curvature to prevent accumulation of water thereat.

20. In a signalling construction, in combination, means forming a sealed casing and com prising at least two separable cas ng parts provi ed with means forming a sealed connection therebetween, one of whi h parts has an inwardly and upwardly extending casing part that is re-entrant from an opening therein and thereby forming an air trap to prevent rise of water into said re-entrant casing part, a signalling device external of said casing and operatively related to said opening, means for activating said signalling device comprising paramagnetic means in said re-entrant casing part and protected against water by said air trap with means within said sealed casing for producing a magnetic flux for coaction through the walls of said reentrant casing part with said paramagnetic means, and means for securing said two separable casing parts together and including means preventing assembly to the other part of that casing part which has the re-entrant casing part with the latter in inverted position.

21. In a signalling construction, in combination, means forming a sealed casing having mounted externally thereof a gong with its axis substantially horizontal and with the concave side thereof toward the casing means, said casing means comprising at least two separable casing parts provided with means forming a sealed connection therebetween, one of said parts having an opening with which the open end of a tube memher, which extends into the interior of said casing and is closed off at its inner end, is in sealed connection, the line of the axis of said tube member as extended through said open end intersecting said concave side of said gong at a point below the diameter of the gong and displaced from the vertical diameter thereof, movable paramagnetic means in said tube member for activating said gong through the outer open end thereof and operating thereon at substantially said point on the concave side of said gong, and means within said sealed casing for producing magnetic flux which acts upon said paramagnetic means through the walls of said tube member.

22. In a signalling construction, in combination,

means forming a sealed casing and comprising at least two separable casing parts provided with means forming a sealed connection therebetween, one of said parts having an opening with which the open end of a tube member, which extends into the interior of said casing and is closed off at its inner end, is in sealed connection, a signalling device external of said casing and operatively related to said opening, movable paramagnetic means in said tube member for activating said signalling device through the outer open end thereof, and means within said sealed casing for producing magnetic flux which acts upon said paramagnetic means through the walls of said tube member, said tube member extending into said sealed casing in upward direction and forming an air trap to prevent rise of water thereinto, and slidably supporting and guiding said paramagnetic means, and means responsive to slidable actuation of said paramagnetic means and coacting with said signalling device through the outer open end of said tube member.

23. In a ignalling construction. in combination, means forming a sealed casing and comprising at least two separable casing parts provided with means forming a sealed connection therebetween, one of said parts having an opening with which the open end of a tube member, which extends into the interior of said casing and is closed off at its inner end, is in sealed connection, a signalling device external of said casing and operatively related to said opening, movable paramagnetic means in said tube member for activating said signalling device through the outer open end thereof, and means within said sealed casing for producing magnetic'flux which acts upon said paramagnetic means through the walls of said tube member, said opening being in a substantial- 1y Vertical wall portion of the casing part and said tube member extending upwardly into the sealed casin at an acute angle to said substantially vertical wall.

24. In a signalling construction as claimed in claim 23 in which the open end portion of said tube member projects downwardly at an acute angle through and beyond said opening to the exterior of the casing wall and forms a water shed.

25. In a signalling construction as claimed in claim 23 in which said flux-producing means comprises electromagnetic winding means having an axial bore therein dimensioned to slide over said tube member and being thereby sleeved onto the latter from the inner end thereof for producing a magnetic field acting upon said plunger means through the walls of said tube member, said winding means having a framelike support means therefor that falls in a plane parallel to the axis of said bore and said casing having internal support means that extends at said acute angleto said vertical wall to slidably receive thereon said frame-like support.

26. In a signalling construction, in combination, means forming a casing having an opening in a wall thereof with one end of tube member rigidly secured thereto at said opening and extending inwardly of said casing like a cantilever, a gong supported externally of said casing with a portion thereof adjacent said opening, paramagnetic plunger means in said tube member and having striker means operable upon said gong through the outer end of said tube member, a control unit comprising spaced pole piece mem bers, electro-magnetic winding means and permanent magnet means coacting therewith to proplunger means in an at-rest position.

2'7. In a signalling construction, in combination, means-forming a .casing having an opening in a wall thereof withone end of a cantilever tube member rigidly, secured thereto'at said opening and extending. inwardly of said casing, a gong presenting aperipheralportion thereof adjacent saidopening, said casing and said gonghaving interfitting means for non-rotatively securing said gongatits center to said casing-to prevent presentation of any other peripheral portion thereof 'to said opening, paramagnetic plunger means in said tube member and having striker ,meansoperable upon said-peripheral portion of said gong through the .outer end of said tube member, a control unit sleeved onto said canti- ',lever tube member from the inner 'end thereof and comprising electro-magnetic windingmeans for producing a magnetic field acting upon said plunger means through the walls of said 'tube -member'whereby the coaction'between saidmagnetic field, said plunger means, said striker means, and said gongportion may be determined by shifting said control unit along said tube mem- "ber, said casing havingtherein a guidewaydorming support extendingparallel to and spaced from said'tube member for slidablyreceiving-said control unit, and means forsecuring saidunit in adjusted .position along said support, .said interfittingmeans, in preventing rotary displacement of said gong portion, ,preventing impairment of the setting of the aforesaid coaction.

"28. In a signalling construction as claimed in claim '27 in which said control unit comprises permanent magnet means .pro'ducing a'magnetic field acting upon said paramagnetic means, during de-energization of said winding means, to hold it and said striker in retracted position.relative to said gong and tube member.

29. In a signalling construction, in combination, ,a supporting frame. carrying a signalling element, movable paramagnetic means for actuating said signalling element, said supporting frame having means movably supporting said paramagnetic means for coaction withsaid signalling element, a control unit 'for'holding ,said paramagnetic means in an at-rest position and for actuating it -comprising permanent'magnet means producing a magnetic field the flux of which exerts magnetic force on said paramagnetic means to hold it in at-rest ,position.and electromagnetic Winding meansfor producing, when energized, a magnetic field coacting to effect movement of said paramagnetic means, saidsupporting frame having support means by which said control unit is movably supported relative to saidparamaggnetic means wherebyitheposition of saidpermanent magnet means and said winding means relative to said movable paramagnetic means may be determined, and means for securing said control unitin position.

30. In a signalling construction, in combination, a supporting frame carrying a signalling element, movableparamagneticmeans-for actuating said signalling element, said-supporting frame 28 having means movably supporting said paramagnetic means for coaction with said signalling element, a control unit forholding said paramagnetic means in an at-rest position and for actuating it comprising permanent magnet means producing a magnetic field the flux of which exerts magnetic force on said paramagnetic means to hold it in at-rest position and electromagnetic windingmeans for producing, when energized, a magnetic field coacting to eiiect movement of saidparamagnetic means, said;permanent magnet means and said winding means having means interrelating both to a common flux gap across which the fiux of both magnetic means is effective whereby the flux of said winding means, when energized, by alternating current, is alternatelyadditive to and subtractive from the flux of said permanent magnet means, said supporting frame having support means by which said control unit is movably supported relative to said paramagnetic means whereby the position of said permanent magnet means and said winding means relative to said movable paramagnetic means may be-determined, and means for securing said control unit in position.

31. In a signalling construction, in combination, a supporting frame carrying a signalling element, movable paramagnetic means for-actuating said signalling element, said supporting frame having means movably supporting said paramagnetic means for coaction with said signalling element,;a control unit for holding said paramagnetic means in an at-rest position and foractriatingit comprisingpermanent magnet means producing a magnetic field the flux of which exerts magnetic force on said paramagnetic means to hold it in at-rest position and electromagnetic winding means for producing, when energized, a magnetic field coacting to effect movement of said paramagnetic means,'said control unit carrying a rectifier in .circuit with said winding means whereby the latter produces its magnetic field only on alternating half-waves of energizing alternating current, said supporting frame having support means by which said control unit is movably supported relative to said paramagnetic means whereby the position of said permanent magnet means and said winding means relative to said movable paramagnetic means may be determined, and means for securing said control unit in position.

32. In a signalling construction, in combination, a supporting frame carrying a signalling element, movable paramagnetic means for actuatingsaid signalling element, said supporting frame having means movably supporting said paramagnetic means .for coaction with said signalling element, a control unitfor holding said paramagnetic means in an at-rest position and for actuating it comprising permanent magnet means producing .a magnetic field the flux of which exerts magnetic force on said paramagnetic means to hold it in .at-rest position and electromagnetic winding means for producing, when energized, a magnetic field coacting to effect movement of said paramagnetic means, said permanent magnet means of said control unit having spaced extension poles forming a flux gap to which said paramagnetic .means is subjected for being held in at-rest position, said flux gap being substantially independent of the fluxof themagneticfield of said winding means, said supporting frame having support means by which said control unit is movably supported relative to said paramagnetic means whereby the position of said permanent magnet means and said winding means relative to said movable paramagnetic means may be determined, and means for securing said control unit in position.

33. In a signalling construction, in combination, a supporting frame carrying a signalling element, movable paramagnetic means for actuating said signalling element, said supporting frame having means movably supporting said paramagnetic means for coaction with said signalling element, a control unit for holding said paramagnetic means in an at-rest position and for actuating it comprising permanent magnet means producing a magnetic field the flux of which exerts magnetic force on said paramagnetic means to hold it in at-rest position and electromagnetic winding means for producing, when energized, a magnetic field coacting to effect movement of said paramagnetic means, said control unit carrying a current interrupter in circuit with said winding means and coacting with magnetic flux produced thereby for energizing said winding means in successive pulses of energizing current, said supporting frame having support means by which said control unit is movably supported relative to said paramagnetic means whereby the position of said permanent magnet means and said winding means relative to said movable paramagnetic means may be determined, and means for securing said control unit in position.

34. In a signalling construction, in combination, a supporting frame carrying a signalling element, movable paramagnetic means for actuating said signalling element, said supporting frame having means movably supporting said paramagnetic means for coaction with said signalling element, a control unit for holding said paramagnetic means in an at-rest position and for actuating it comprising permanent magnet means producing a magnetic field the flux of which exerts magnetic force on said paramagnetic means to hold it in at-rest position and electromagnetic winding means for producing, when energized, a magnetic field coacting to effect movement of said paramagnetic means, said permanent magnet means of said control unit having a plurality of extension poles between which are formed two spaced flux gaps for permanent magnet flux and into either of which said paramagnetic means is movable, said winding means coacting with at least one of said flux gaps to affect the permanent magnet flux therein, said supporting frame having support means by which said control unit is movably supported relative to said paramagnetic means whereby the position of said permanent magnet means and said winding means relative to said movable paramagnetic means may be determined, and means for securing said control unit in position.

35. In a signalling construction, in combination, a supporting frame carrying a signalling element, movable paramagnetic means for actuating said signalling element, said supporting frame having means movably supporting said paramagnetic means for coaction with said signalling element, a control unit for holding said paramagnetic means in an at-rest position and for actuating it comprising permanent magnet means producing a magnetic field the flux of which exerts magnetic force on said paramagnetic means to hold it in at-rest position and electromagnetic winding means for producing, when energized, a magnetic field coacting to effect movement of said paramagnetic means, said permanent magnet means on said control unit having a plurality of spaced poles to provide two flux gaps for the permanent magnet flux that coacts with said paramagnetic means and said winding means being related thereto to alternately change, upon energization by alternating current, the effective flux values of said two flux gaps and thereby efiect actuation of said movable paramagnetic means, said supporting frame having support means by which said control unit is inovably supported relative to said paramagnetic means whereby the position of said permanent magnet means and said winding means relative to said movable paramagnetic means may be determined, and means for securing said control unit in posi tion.

36. In a signalling construction, in combination, a signalling element and a reciprocable striker and paramagnetic plunger means therefor having means guiding them for reciprocation in reversible strokes, said paramagnetic plunger means comprising two paramagnetic plungers having means mechanically inter-relating them for movement in the same direction on each stroke and for movement of one relative to the other, and magnetic flux-producing means controlling said paramagnetic means and comprising permanent magnet means acting thereon to hold it and said striker in an at-rest position and electro-magnetic winding means coacting upon energization to reciprocate both plungers for striking actuation of said striker and, upon one of said plungers becoming immovable, to reciprocate the other plunger relative thereto.

37. A signalling construction as claimed in claim 36 in which said permanent magnet means is provided with extension poles spaced along the line of movement of said paramagnetic means to provide an axial flux gap for one of said plungers to coact with for being held in said at-rest posi tion, said electromagnetic winding means and said other plunger being magnetically interrelated so that the flux of said winding acts upon said other plunger substantially independently of said axial flux gap.

38. A signalling construction as claimed in claim 36 in which said permanent magnet means is provided with extension poles spaced along the line of movement of said paramagnetic means to provide an axial flux gap for one of said plungers to coact with for being held in said atrest position, said electromagnetic winding means being magnetically interrelated to said extension poles so that flux produced by it when energized coacts with permanent magnet flux in said axial flux gap to effect reciprocating actuation of both plungers and to effect reciprocation of only one of them when the other becomes immovable.

39. A signalling construction as claimed in claim 36 in which said permanent magnet means is provided with a plurality of spaced extension poles spaced along the line of movement of said paramagnetic plunger means to provide several axial flux gaps for permanent magnet flux which coact to hold said paramagnetic means in at-rest position and in which said electromagnetic winding means coacts, when energized, to cause effective flux values in said two axial flux gaps to be alternately preponderant over each other and thereby effect reciprocation of said paramagnetic plunger means and upon one of said plungers becoming immovable and thus becoming a stationary part of the magnetic circuit, to efiect reciprocation of the-other plunger relative thereto.

40. In a signalling construction, in combination, means forming a sealed casing that has an inwardly and upwardly extending tubelike casing part that is .re-entrant from .an

opening in a wall of the casing :and there- 'by forming an air trap to prevent .rise of water thercinto a signalling device external of said casing-and operatively related to said opening, reciprocable paramagnetic plunger means -in :saidtube-like re-entrant casing part and having a part which, uponreciprocation of said plunger means, coacts through said opening withsaid signalling device, said-signalling device beingpositioned in the path of reciprocating movement of "said plunger part whereby the signalling'de- -vice may act to block removal of said plunger means and plunger part from said re-entrant .casing part, and plunger-actuating means including electro-magnetic 'means within said sealed casing for coacting, when energized, magnetically through the walls of said re-entrant casing -gpart with said plunger means for reciprocating thelatter and permanent magnet means within said sealed casing for eoacting magnetically through the wallsof saidre-entrantcasing part with said paramagnetic plunger means andproviding a magnetic field operating upon the latter, during deenergization of said electromagnetic means, to hold said plunger means in inwardly .retracted position relative to said re-entrant casing part and thereby hold said plunger partaway from said signalling device.

References Cited in the file of this patent UNITED STATES PATENTS

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