US2337267A - Insulating device - Google Patents

Description

De. 21, 1943. H, R, OWEN 2,337,267

INsULATINQ DEVICE Filed March 29, 1941 2 sheets-sheet 1 j@ .1. ,626 a? u 7 26 /9 6 elllllllllll-m. w n A A Trae/va K5.

Dec. 21, 1943. Hf R. OWEN '2,337,267

INSULATING DEVICE Filed March 29, l19.41 2 Sheets-Sheet 2 FOR THE FIRM A rro @N5 VJ.

V HA APR/5, hec/1f, F0572@ d Hake/.s 436 y l f Patented Dec. 2l, 1943 UNITED STATS il@ Nr orrlce INSULATING DEVICE- Harold R. Owen, Venice, Calif., assignor to Electrical Products Corporation, Los Angeles, n

8 Claims.

This invention relates to insulating devices and particularly to insulators of the kind to be mounted on plates of metal or other material and to electrically insulate elongated electrically chargeable bodies disposed either alongside the plates or extending through apertures in the plates. One field in which the invention is particularly useful is that of luminescent tube signs in which the tubes are mounted in spaced, parallel relationship to a plate which is the sign face and are mounted on the sign face by means of insulating supports secured to the sign face and extending outwardly therefrom.

It is one object of the invention to provide an insulating device, the parts `of which may be secured to and assembled upon the plate by perative access to only one side of the plate.

It is another object of the invention toprovide an insulating device of the character described which may be readily and speedily installed upon a plate without the use of attaching screws or rivets.

It is another object of the invention to provide an insulating device of the character described which shall be simple in construction and inexpensive to manufacture.

It is still another object of the invention to provide an insulating device of the character de-l scribed by the use of which the luminescent tube s may be spaced from the sign face plate at the minimum distance providing an air gap of adequate dielectric strength to prevent breakdown between tube and plate, and which shall have no metal parts disposed between the tube and plate which might contribute to a breakdown.

It is still another object of the invention to provide an insulating device of the character described by which a luminescent tube may be adjusted to vary the distance between it and the sign face plate.

It is yet another object of the invention to provide an insulating device of the character described by which, though the insulator is secured to the face plate. the position of the tube with respect to the sign face plate, in a direction transversely of the tube axis, may be varied within narrow limits to obviate the subjection of the tube to transverse stresses which might fracture it.

It is another object of this invention to provide an insulating device having two principal parts or members, one of which is a post of glass or other insulating material, and the other of which is a preferably metallic supporting device or holder for the post capable of ready installation in a perforation in a sign face plate in a secure relationship to the plate such that it is not accidentally displaceable from the plate by gravity, by vibratory or other movement of the plate,

or by other displacing forces.

It is another object of the invention to provide in an insulating device of the character described having such a post and post holder, such a structural relationship between the post and holder that when the two are installed in assembled position upon the sign face plate, the post may be securely held against accidental removal from the support and the support may in turn be securely held against accidental removal from the sign face plate.

The invention is adaptable for use in a number of different elds. In the following description and in the drawings, the inventionis shown embodied in devices adapted for use on luminescent tube signs, but it is not therefore to be understood that the invention is confined to such embodiment. In its broader aspects the invention is applicable to devices for mounting a body on a plate in spaced relationship thereto,.particularly an elongated body in parallelism with a plate, and also particularly in a manner to provide adjustability of the spacing distance between the body and plate.

In the drawings which are for illustrative purposes only:

Fig. 1 is a utility view showing several diierent devices exemplifying several different forms of the invention respectively;

Fig. 2 is a sectional View of one of the devices shown in Fig. 1 taken along the line 2--2 of Fig. 1;

Fig. 3 is an elevational view of the insulating device shown in Fig. 2 taken in a plane at right angles `to the sectional plane of Fig. 2;

Fig. 4 is a transverse sectional view taken along the line 4-4 of Fig. 2;

Fig. 5 is a longitudinal sectional view taken along the line 5-5 of Fig. 4;

Fig. 6 is an elevational view partly in section of a modified form of the insulating device of Figs. 2 to 5, which also embodies the invention.

Fig. 7 is a transverse sectional view taken along the une 1 1 of Fig. 6;

.by the same numerals.

sulating devices of Fig. l, taken along the line I2i2 of Fig. 1;

Fig. 13 is a longitudinal sectional View of yet another of the insulating devices shown in Fig. l, taken along the line I3l3 of Fig. l;

Fig. 14 is a longitudinal elevational view of another of the insulating devices shown in Fig. 1;

Fig. 15 is a perspective View of the insulator shown in Fig. 11.

Fig. 16 isY a plan Vview of theV sheet metal stamping from which is formed the holder used in the forms of the invention shown in Figs. 2 to 10, 12 and 13.

Fig. 1 shows a luminescent tube sign box assembly using several devices illustrative of several forms of embodiment of the invention. The assembly is shown in longitudinal section along Aa plane perpendicular to the front face of the sign. The sign box Il) comprises a, front plate il which is the face of the sign, a rear wall i2, end walls I3, two side walls, only. one of which, ifi, appears in the figure, and partition wallsv I5.' y

Current of service voltage is led over conductors I6 into atransformer I1 where the voltage is converted to one suitable` for use in'luminescent tubes. Luminescent tubes I3 and i9 are lsupplied With current from the transformer Il by conductors 20 and 2I andare electrically connected to each other byV aconductor 22; The tubes I8 and i9 and conductors 2i!v and ZI are mounted upon, insulated from, and their positions determined with respect to the adjacent box walls by means of insulating devices 23, 2li, 25, 25, and 2T, Those insulating devices shown inFig. 1 which are of the sameconstruction'are designated devices 23 mountedin the partition -wallsrI5 are of thesameconstruction. Thetwo. insulating devices 25/are of the sameconstruction which, however, isa construction different from that of the. insulators 23. All of the insulating devices 23 to. 2'I incusive are embodiments in various formsof the invention Aherein disclosed. The insulating devicesY designatedlby the numerals 23, 24, and 26, not only insulate a tube or conductor from an adjacent box wall, but also serve to support it thereon. The insulating. devices 25, 2l' insulate the tubes I8 and. I9, respectively, from the sign face plate Il, but do not serve to secure the tubesin mounted .position upon the face plate. They do. determine the position of the tubes with reference to the plates, inthesensethat, as will be later. explained, they preventlateral movement of the tube ends 28 and 2S, respectively, to positions offco'ntact with the edges of theapertures in the signface plate II through which they pass.

The structural characteristics of the several insulating devices 23 to 2l. inclusiva-land the na'- ture of their relationship .to the luminescent tubes I8 and I9 and conductors 2t. and 2l will appear from a detailed description of the several insulating devices.

lInsulating devices 2t are shown in Figs. 2 to 5, inclusive. Each of the devicesrt comprises a post 3Ilfof glass or other insulating material, a clip 3|, and lashing wire 32.,

Thelclip or holder 3 IV is preferably made from a metal stamping 33.(Fig. V16) of a general rectangular shape` formed with a central portionor base 33a, anges 34'on the sides of the base midav Thus thev two insulating` end portions of the stamping 33 is bent back upon itself along a line adjacent the aperture 36 to @form a narrow double-walled flange 3l, is then bent to form a wall 33 at right angles to the central apertured portion of the stamping, is bent radially outwardly to form a wall 3Q parallel to the central portion ci the stamping, and is finally bent away from the central apertured portion of the stamping to provide a .radially outwardly bowed jaw e. The jaw 5S is so shaped that its bifurcated tip ll projects inwardly to points axially aligned well within the perimeterv of the circle 365., The holder 3l by virtue of the aperture 36 and the separation of the jaws 6G is open along axial lines from end to end.

The clip 3l is installed in a rectangular aperture i2 in the sign face plate li. rihe width of the clip, or,` what is the same thing, the length of the walls 3l, 3S, and 39, and the distances between the outside faces of the walls 38 are oi such dimensions that the walls 35 snugly iit within the aperture :l2 preventing the clip from transverse movement with respect to the peripheral edges oi the aperture d2. The walls 38 provide the holder withy a'grornmet-like seat for a coaxial and nonerotative t within the aperture i2 of the plate ii;

Axial movement ci the clip with respect to the face plate lI in a rightward direction, as shown in Fig. 2, which will be herein referred to as an inward direction, is prevented by. means oi the double-,walled flange 3l and the flanges 36. Axial movement of the clip in the opposite direction .is prevented by the walls It is obvious thateitherthe doublewalled ange 3l or the iianges but not both may be omitted from the constructionof the clip in so far as preventing axial movement ofthe clip in. an inward direction is concerned, and the wall 39 may be omitted in so far as axial movement of the clip in an outward direction is concerned., provided, in the latway between thek ends of the stamping, with notches 3,5 disposed centrally of eachoi` its ends, and a central circularl aperture' tt. in the base. 33a. Referring now to Figs. 2 to 5, each of the 'axislof the post .and providing a recess 5l.

ter case, that the jaws Il@ are radially outwardly bowed as shown in thedrawinga Y rihe4 glass post. 3d has a shanleor stem Q3 and a head t4. The shank wis formed withsuitable peripheral shoulders, for example, threads l5 extending from its inner end` l .a major portion of the distance to the. head The. shank is further., provided withr an integrally annular flange orcollar il disposed between the threads 1552116. theV head M.

The headflll is formed `with a at end face e8 lyingr in a plane perpendicular to the axis of the post and with a pair of diametrically eppositely projecting lugs 4S. Each of the lugs i9 is formed with an ear Fail extending inwardly parallel to the A luminescent tube 52 is lashed to the post in a position in which it is seated upon the end face 48 of the post by the flexible lashing wire. 32. The wire. is looped under the two lugs 49 passing through the recesses 5I and is double-stranded over. thetubes 52 in the manner shown in Figs. 2 and 3.

lin Figs. 2 and 3 the, axis 53 of the tube is shown perpendicular to and lying exactly in the plane of the axis of the post. In the manufacture and assembly of the sign parts, it may result from deviations in dimensions thatthe tube axis 53 is transversely displaced with respect tothe post axis and is `nearerone er the other cf the lugs t9. vWhen such is the case they tube 52 may be lashed to the head il of the post in a transversely oifset'position, as shown in dotted lines in Fie'A 2, eliminating the application of a bending stress to the tube which might result in its fracture. The flat character of the end face 48 makes it possible to thus offset the tube 52 on the head 44. If the head 44 were provided with a concavely recessed head such as is shown in Fig. 6, in accordance with the usual design of tube-supporting glass insulating posts, it is obvious that this transverse shifting of the tube with respec-t to the head to accommodate mis-alignment of the tube with the plate perforation 42 would be impossible of accomplishment.

In using the insulating mount shown in Figs. 2 to 5, the holder 3| is grasped between the thumb and ngers applied to the double-walled flange 37, and with the jaws 4t in advance is pushed through the plate aperture 42. In an obvious manner, the jaws 4B and with them the walls 38 and 3Q are sprung inwardly by engegement of the jaws with the Walls of the aperture 42 as they are forced through the plate and thereafter recoil outwardly causing the holder Walls 38 to snugly iit within and engage the walls of the aperture 42 in a position in which the doublewalled flange 37 prevents further inward movement of the holder and the walls 39 prevent outward movement of the holder through the plate il.

The post 30 is then inserted through the opening 35 of the holder 3l with the post end 4S in advance, and pushed inwardly, the thread-engaging tips 4I riding over the crests of the threads 45 until the annular flange 47 engages the holder base 33a. As the post shank 43 passes between the tips 4i of the jaws 4G, the jaws are spread apart and caused to apply a radially inwardly acting pressure to the shank 43, and to press the walls 33 more tightly against the walls of the aperture 42.

The post 3i? is next rotated until the ange 47 is pulled tightly against the base 33a of the holder 3! as the tips 4l of the jaws 40 apply a resilient pressure to the outwardly directed side walls of the threads 45. The rectangular shapes of the base 33a and aperture 42 prevent rotation of the base in the aperture. The rotation of the post 3d is continued suiciently to bend the jaws 40 without permanent deformation thereof and the rotation of the post is stopped with the end 44 disposed perpendicularly to the direction which the luminescent tube 52 will have after installation. it will be apparent that by turning the post on its axis one or two times sucient stress will be set up in the jaws 4U to securely clamp the post Sil against either longitudinal or ransverse movement and will also bring about a tighter grip of the holder upon the plate I i.

The tube 52 is then lashed into position upon the end 44 of the post Si) by disposing it without iiexing stresses against the end face 4S and lashing it thereto in the manner above described.

Figs. 6 and 7 show a modification of the insulating device 26. This modified insulating device is generally designated by the numeral 2&57'.

In the device 267' a collar 477' preferably made from an infrangible insulating material, such as hard rubber, is substituted for the collar 47 or the device 26. This collar is internally threaded for engagement with threads 457' of a glass post 307'.

In using the device 2.57', the collar 477' is threaded upon the post 397' and placed in a position adjacent the head 447' ofthe post. The post is then thrust inwardly through the wall I I7' to approximately the position required for proper spacing of tube 527' from the plate i i7' and thereafter the collar 477' is screwed inwardly upon the post to the point where it engages the outer surface of the plate H7'. Rotation of the collar 477' is continued suiciently to bend jaws 3I7' Without permanent deformation thereof. The rotation of the post is stopped with the end 447' disposed perpendioularly to the direction which the luminescent tube 521i will have after installation.

Fig. 8 shows an insulating mount in which is used a post 39a having a head 44a of the usual design. It is formed with an axially inwardly concaved end face 48a and lugs 49a to provide a cradle of a conformation to receive a glass tube 53a, which is lashed to the post Sta by means of lashing wire 32a in a manner similar to that described in connection with the form of the invention shown in Figs. 2 to 5 inclusive.

Since with this construction of head the tube is held rigidly against transverse displacement with respect to the head, it becomes necessary to otherwise compensate for any misalignment of the tube aXis 53a with the axis of the rectangular aperture 4a in the plate lia. This is accomplished by forming the circular aperture 36a of the holder 3 la with a diameter such as to provide a substantial clearance between the walls of the aperture 3M and the crests of the threads 45a of the shank 43a of the post 30a, and by omitting the feature of an annular ange on the post such as flange 47 of the form of the invention shown in Figs. 2 to 5 inclusive.

When the post shown in Fig. 8 is pushed into position in the plate lia, it is thereafter rotated in either direction, the engagement of the tips lila with the threads 45a serving to regulate to a nicety the distance between the cradle 48a and the plate Ha and to permit disposition of the head 44a transversely of the axis of the tube 52a.

The clearance between the shank 43a and the aperture Stia provides the head 44a with a freedom to swing transversely to the axis of the tube 52a within a limited arc about the point of engagement of the tips 4ta and the threads 45a to allow the tube 52a to assume positions of slight i displacement with respect to the plate aperture 42a to compensate for any misalignment of the tube with the aperture 42a. In an insulating mount thus constructed, it is obvious that inward screwing of the post 38a will not tighten the grip of the tongue 4ta upon the shank 43a nor will it tighten the grip of the holder tia upon the wall of the aperture 42a of the plate i i a,

The threads of the post 3@ or 59a may be so designed as to their crests and as to the slope of their side walls that either of these posts may be moved inwardly or outwardly without rotation by application of a pulling or pushing translative force of sufficient strength. It is desirable to be able to translatively push the post readily into approximately its ultimate position of assembly, but in some installations it may be also desirable to preventl removal of the post by a translative pull. This may be accomplished by forming the threads of the post of the buttress type, as shown in Fig. 9, with the outwardly facing walls 54 of threads 45h of post 3th arranged either perpendicular to the axis' of the post or at such a slight inclination thereto that the thread engaging tips of the holder tongue will not ride over the threads when the post is pulled outwardly.

Fig. l0 shows a modification of the invention in which a post S'c is formed with annular ridges 45C on its shank 43o. Crowns 55 of these ridgesA are rounded and depressions '56 between the ridges are preferably also rounded. The tips tlc of In this form of the invention, the head Li-c' isv placed in proper position transversely oi the axis of the tube 52o by rotating the post. This rotation does not, of course, cause a longitudinal movement thereof with respect to the plate .l ib. This form of the invention is in reality a modication of the form shown in Fig. 8 in that it is more particularly adapted for use with a post which is not provided with a collar such as that designated by the numeral Il? in the form of the invention` shown in Figs,.2 to 5, inclusive. Such a collar is useless except in combination with spirally disposed threads on the shank of the post and due to the iluted character of the post shown in Fig. l0, it becomes impracticable to design tl e apertured holder base to restrain the post against 'transverse play within the aperture 36o, without the use of a clamping collar.

Fig. 11 shows the insulating device 2l cf Fig. l. In this device the post takes the form ci an insulating cylinder or bushing 36d. The cylinder is provided preferably, although not necessarily, at its outer end with a iiange llild. Its inner end is threaded as shown at 15d and is formed with a iiange lid at the outer end of the threads 65d.. The threaded portion of the post is inserted through an opening ld of a plate lid and is secured in position-in the plate i id by a holder Bid which is in all respects similar from a functional standpoint to the holder 3| shown in Figs. 2 to 5 inclusive, but is constructed from a length of spring wire bent to provide an annular ring 33d seated between the ilange 'iid and the plate ild, and to further provide tongues Mid and thread-engaging tips @ld on the tongues Mld.

The cylinder Sed does not directly engage nor is it directly secured to a tube 52d. mie tube 52d is disposed coaxially within the cylinder 35M which prevents contact between the tube 52d and the Walls of the aperture 42d and interposes an insulating wall therebetween, thereby determining the position of the tube 52d with respect to the plate l id Fig. 14 shows the insulating device 25 of Fig. 1. The holder Sie of this device isof identical construction with the` holder iid shown in Fig. 11. The post 39e taires the form of a receptacle having a closed end El on which is supported a conductor-terminal 5S adapted for connection to a conductor cable outside of the receptacle andv to the electrode of the luminescent tube 52e inside of the receptacle.

Apertures ld andv 42e, shown in Figs. 1i, le, and 15, are circular instead of having the shape of rectangles as do apertures 42,' figa, and :12o of the `forms of the invention shown in Figs. 2 to 1.0, 12 and 13 but are notched at 5%, to receive axially disposed sections 33d of the length of wire from which the holder Bld or Sie is formed. These wire sectionsw i3d engage the walls oi the notches 59. rihis engagement prevents rotation of the holder` sid or Sie when the post or .bushing Sd or 3de isrotated to screw the bushing into position with respect to the plate Hd, and also prevents transverse displacement of the holder tid or 3io in the aperture 42d or, 42e.

The wire sections 33d in these respects correspond to thefwalls 3B of the holder 25, functioning as seats for the holder.

Fig. 12 shows an insulating device 2li of Fig. l. It is similar to the insulating device 2li shown in Figs. 2 to 5, inclusive, with the exception of the head 13M which takes the form of an insulating cylinder with its axis perpendicular to the axis of the post 3M. The head ilif is adapted to support a conductor 6l and insulate it from the plate i I f which is a wall ofva bracket $2 secured to the plate Il in the manner shown in Fig. l.

Fig. 13 shows an insulating device 23 having a holder Slg similar to the holders 3i, Sia, 3io, and 3U, but the posts of which take the form of a cylindrical bushing similar to that shown in Fig. ll. This device is adapted for supporting flexible conductors, such as a conductor 69, on plates such as i5, through which they may pass and insulating them therefrom.

All of the insulating devices 23 to 2 inclusive are capable of determining the position of an electrically chargeable body with respect to a. plate. Devices 2li, 25, and 2l limit transverse movement of the elongated electrically charged body and permit longitudinal movement thereof with respect to the device. These four devices when placed in a horizontal position are also capable of acting as supports for the elongated electrically chargeable body. Whcn thus disposed horizontally in a vertical plate, they form insulating mounts for the elongated electrically chargeable body.

The insulating device 2li is adapted for determining the position of the elongated electrically chargeable body with respect to the plate in a definite xed relationship to the plate- The devices and Zlio determine the position of the elongated electrically chargeable body at a ixed distance from the plate and in parallelisrn therewith but permit a very limited variation in the relative positions of the body and the plate in directions parallel tothe plate and transverse to the axis of the body. They also are insulating mounts.

All of the forms of the invention shown and described herein are adapted for assembly on an aperture plate by operative access to but one side of the plate. This characteristic is of special value in the assembly and installation oi luminescent tube signs. Both for structural strength and to provide a housing for the transformer and current distributing conductor, the frame of such a sign is usually in the form of an enclosed box, the several walls of which are permanently secured together by welding or other suitable means. While the side walls, as, for instance, the side wall Hi shown in Fig. 1, are provided with manual access apertures (not shown), even with the help of the apertures, it is desirable in order to enable the operator to install such insulating devices as those designated 23 and 2t in Fig. l, that these insulating devices be adapted for assembly and installation from one side only. of the plates on which they are mounted. Devices 25, 25, `and 2l may, by virtue of this characteristic, be installed in the tace plate il by an operator working entirely from the outside of the box i3.

Devices 25, 2da and 25o illustrate how the invention makes it possible' to mount the luminescent tubes or other. elongated electrically chargeable body in close proximity to the plate H. It is cf advantage in many signs that the luminescent tube be mounted as close as possible to the sign face plate. I f the luminescent tube is spaced a very substantial distance from the plate, and the sign is viewed from an angle to the plate, the reflected light from the tube against the plate and thence to the eye of the observer has the ciect of producing a second visible character outline parallel to that visible to the observer by direct light radiation from the tube. While such a double-lined. eiect upon the eye of the observer is sometimes of advantage, in other cases it is a definite disadvantage. It is apparent that the closer the luminescent tube is disposed to the sign face plate, the less pronounced is this double liningy and blurring of the sign character.

The metallic holder of this invention projects but very slightly from the sign face plate toward the luminescent tube. Since the post 30 is made of insulating material, it is apparent that this absence of any substantial projection of the holder l toward the tube enables'the use of a post so short that the nearest point on the lashing wire 32 to the plate H may be the minimum distance for preventing electricalbreak- 5;; vez'. n the a wif: and the plate. This distance is specied by the Underwriters Association as 1/4. It will be also observed that in those forms of the inventien in which an insulating collar. is employed such as that shown in Fig. 2 designated bythe numeral l?, the dielectric resistance to an electric discharge between the wire 32 and the plate ii through the air adjacent the post surfaces is increased.

While in the drawings and description the inties of giving form to the principles of the inventicn. The scope of the invention is defined in the appended claims.

I claim as my invention:

l. In an insulating mount for determining the position of an elongated, electrically chargeable body with respect to an apertured plate and adapted for assembly on the plate by operative access to an outside only of said plate, the combination of: an axially open holder having a seat for coaxial nt within said aperture; means on said holder to engage said plate to retain said holder from axial movement inwardly of said aperture; radially inwardly yieldable means on said holder to engage said plate to normally retain said holder from axial movement outwardly of said aperture; an insulating member having a shank of a size for coaxial disposition within said holder, with an appreciable clearance between said shank and said holder at said seat; means on the outer end of said member for rigidly mounting said elongated, electrically chargeable body on said member in parallelism with said plate; and means on said holder disposed axially inside of said seat for engaging said shank in a manner to transversely fix said shank with respect to said holder at the point of engagement and inhibit outward movement of said shank with respect to said holder, said shank being unrestrained by said holder from angular movement within the limits of said clearance about said shank engaging means.

2. In an insulating mount for determining the position of an elongated, electrically chargeable body with respect to an apertured plate and adapted for assembly on the plate by operative access to an outside only of said plate, the combination of: an axially open holder having a seat for a coaxial lit Within said plate aperture; flanges on said holder at the outer end of said seat for preventing axial movement of said holder inwardly of said aperture; radially inwardly springable flanges on said holder at the inner end of said seat to contact the inner face or said plate for normally preventing axial movement of said holder outwardly of said aperture; a circumferentially ridged insulating post of a size to loosely lit within said holder at said seat; a cradle for a luminescent tube and means for lashing said luminescent tube fixedly in said cradle on'the outer end of said post in parallelism with said plate; and at least two oppositely disposed, radially outwardly springable'jaws on said holder projecting axially inwardly from said seat and each free to be sprung independently o1' any other jaw about its connection with said seat as a center so as to have its free end move in a direction substantially normal to the axis of said post, and eacn formed to normally yieldabiy press radially inwardly on said ridged post with its terminal tip in engagement with the side walls of said ridges.

3. In an insulating mount for determining the position of an elongated, electrically chargeable body with respect to an aperturcd plate and adaptedv ior assembly on the plate by operative access to an outside only of said plate,the combination oi': an axially open holder having a seat adapted to coaxially and non-rotatively llt within said plate aperture; flanges on said holder at the outer end of said seat i'or preventing axial movement of said holder inwardly of said aperture; radially inwardly springable flanges on said holder at the inner end oi said seat for normally preventing axial movement of said holder outwardly of said aperture; an externally threaded insulating post sized to loosely t within said holder at said seat; means on the outer end of said post for rigidly mounting said elongated, electrically chargeable body on said outer end in parallelism with said plate; and at least two oppositely disposed, radially outwardly springable jaws on said holder projecting axially inwardly from said seat and each free to be sprung independently of any other jaw about its connection with said seat as a center so as to have its-free end move in a direction substantially normal to the axis of said post, and each terminating in a radially inwardly and axially inwardly directed tip i'orined to normally yieldably press radially inwardly on said threaded post in engagement with the side walls oi' said threads.

ll. ihe combination delinea in claim 3 in which the side walls or said threads are disposed at such an angle with respect to the axis of the post that said tips will ride over said threads when a force is applied axially to said post in either direction.

5. n an insulating device for determining the position of an elongated, electrically chargeable body with respect to an apertured plate and adapted for assembly on the plate by operative access to an outside only of said plate, the combination of: an axially open holder having a seat adapted to coaxially nt within said plate aperture; iianges on said holder at the outer end of said seat for normally preventing axial movement of said holder inwardly of said aperture; radially inwardly springable flanges on said holder at the inner end of said seat for normally preventing axial movement of said yholder outwardly ofr saidjv aperture; an insulating member having a shanksof ansize for coaxial disposition within said holder; means on said member for determining the position of saidelongatedijelectrically chargedbody with respect to said plate; and at least two oppositely disposed, radially voutwardlyspringable jaws on said holderproposition of an elongated, electrically chargeable body with respect to an apertured` plate and adapted for assembly on the vplate by ,operative access to an outside only of said plate, the combination of: an axiallly open holder having a seat adapted to -non-rotatively fit withinl said plate aperture; flanges on said holder at the outer end of saidseatforpreventing axial movement of said holder inwardlyv of said aperture;p radially inwardly springable anges on said holder at the` inner end of saidseat for preventing axial movement of` said holder outwardly `of said aperture; a threadedsinsulating post sized to t withinv said holder; means on said post. for determiningthe position of said elongated, electrically chargeable body with respect to said plate; at least two oppositely disposed, radiallyspringable jaws on said.

holder projecting. axially inwardly from said seat and formedA to yieldably press` radially inwardly on said threaded post with. their. terminal tips in engagement; withthe outwardlyv directed side walls oisaidithreadsrsaid outwardlydirected side Walls being disposed atan angle to lock said lpost against outwardmovem'ent with respectto .said

plate; Vand a radial projection axially fixed' on said post. adapted tov press toward the outer face of saidvr plate in. the; course-.ofA an= inward movement ofrsaid post withlrespect tosaid plata.

'7.In an insulating. Edevice for determining the position of anz elongatedelectricallyy chargeable body with respect to an apertured plate `and adapted for assembly onvthe plate by operative access to an outside` only of said plate, thev combination of: an axially open' holder having a seat adapted to non-rotatively fit within said plate aperture; flanges on said holder at the outer end of said seat for preventing axial movement of saidholder inwardly of said aperture; radially inwardly springable iianges on said holder at the inner end of said seat for preventing axial movement ofsaid holder outwardly of said aperture; a threadedv insulating post sized to` fit within said holder; means on said post for determining the position of said elongated, electrically chargeable body with respect to said plate; at least two oppositely disposed, radially springable jaws on said holder projecting axially inwardly from said seat and formed to yieldably press radially inwardly on said threaded post with their terminal tips in engagement with the outwardly directed side walls of said threads, said outwardly directed side walls being disposed at an angle to lock said post against outward movement with respect to said plate; and a collar threadedly mounted on said post and adapted to press toward the outer face of said plate. y

8. In an insulating mount for determining the position of an elongated, electrically chargeable bodyl with respect .to an apertured plate and adapted for assembly on the plate by operative access Ato an outside only of said plate, the combination of: an axially open holder having a seat adapted to non-rotatively fit within said plate aperture; flanges on said holder at the outer end of said seat for preventing axial movement of sad holder inwardly of said aperture; radially inwardly springable `flanges on said holder at the innerv end of said seat for preventing axial movement of said'holder outwardly of said aperture; a threaded insulating pest sized to t within said holder; a head on the outer end of said post having a dat end face in a plane parallel to said plate; means for lashing a frangible tube lagainst said end face'of said post; axially resilient means on said holder projecting inwardly from said seat for clamping transversely and threadedly engaging saidV threaded post; anda radial projection axially iixed on said post adapted to move toward the outer faceof said plate in the vcourse of an inward movement of said plate through said ap'erture. v

`HriaoLD R. OWEN.

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