US2719277A - Panel mounting structure for the electrode carrying end of a discharge lamp - Google Patents

Description

Sept. 27, L. E PANEL MOUNTING STRUCTURE FOR THE ELECTRODE CARRYING END OF A DISCHARGE LAMP Filed 001;. 6, 1951 IN V EN TOR.-

LEON A. RICE United States Patent Ofiice 2,719,277 Patented Sept. 27, 1955 PANEL MOUNTING STRUCTURE FOR THE ELEC- TRODE CARRYING END OF A DISCHARGE LAMP Leon A. Rice, Arcadia, Calif., assignor to Electrical Products Corporation, Los Angeles, Calif., a corporation of California Application October 6, 1951, Serial No. 250,145

Claims. (Cl. 3395tl) The present invention relates in general to lamp mountings and has more particular reference to bushing structures for receiving and making electrical connection with the ends of tubular discharge lamps.

Tubular discharge lamps conventionally comprise sealed glass tubing containing a gas or a mixture of gases adapted to become luminescent when electrically excited, the lamp being provided with electrodes at its sealed ends for the application of electrical potential for the excitation of the gas in the tubular glass envelope. The tubular envelopes of such lamps may be configurated in any desired manner to form letters or other design characters; and the lamps commonly are mounted for display upon usually sheet metal supporting panels, the electrode carrying portions of the lamp elements extending through openings formed in the panel to thus dispose the electrode containing portions of the lamp behind the panel in position for concealed connection in an electrical lamp energizing circuit disposed rearwardly of the panel.

It is an important object of the present invention to provide an improved bushing structure for receiving an electrode containing portion of a panel mounted lamp in fashion to insulate the same from the panel at a panel opening through which it extends, including inexpensive means operable to connect the so received lamp portion in an electrical circuit behind the panel.

Another important object is to provide a device of the character mentioned formed and arranged to inhibit the accumulation of water, ice or sleet at the mounted end of the lamp in position to form an electrical conducting path between the electrical lamp connection means and the panel 011 which the lamp is mounted, whereby substantially eliminating the possibility of lamp damage or destruction through the establishment of a short circuit path for lamp energizing power, from the lamp connection means to the grounded panel, along a path adjacent the mounted portions of the lamp.

Another important object is to provide a structure of the character mentioned, including a grounding element adapted for connection with the panel, and insulated support means, carried on said grounding element, for carrying lamp connection elements in the structure at a distance, sufiiciently remote from the supported lamp to prevent damage thereto as the result of establishment of a power short circuit from the lamp energizing elements of the structure to the grounded panel on which it is mounted, along said insulated support means.

A further object is to provide a device of the character mentioned formed without any pockets or cavities in which moisture may accumulate and form nitric acid capable of destroying the metal parts of the structure as the result of creation of ozone through the operation of the mounted lamp.

Another important object is to provide a lamp connection bushing structure of simple and inexpensive character and embodying novel attaching means facilitating the application of the structure upon a perforated panel, the attaching means being operable entirely from one side of the panel to mount the structure in position, thereby avoiding the necessity of employing an operator on both sides of a large panel in mounting the bushing structure.

Another important obiect is to provide an improved latch structure for mounting a device of the character mentioned on a support panel, a further object being to provide a latch structure adapted for operation entirely from one side of a panel in order to secure the device firmly in mounted position in a panel opening, or to release the device for removal from the panel.

Another important object is to provide a mounting structure of the character mentioned comprising a preferably glass bushing, an inexpensive formed sheet metal yoke or collar secured on the bushing, and providing means for latching the collar demountably on a mounting panel in position presenting the bushing in a panel opening, such fastening means being adapted to electrically connect, and hence ground, the collar on the panel, said collar providing means for supporting an insulating stem, offset substantially outwardly of the bushing, in position to carry, at the collar remote end of the stem, an electrical contact element in line with the axis of the bushing, and hence positioned to electrically engage an electrode connected ferrule or contact terminal on the bushing mounted end of a tubular discharge lamp.

The foregoing and numerous other objects, advantages and inherent functions of the invention will become apparent as the same is more fully understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment of the invention.

Referring to the drawings,

Figure 1 is a sectional view taken through a panel carrying a tubular gas discharge lamp having an electrode containing end portion extending in operative position in a connection bushing structure embodying the present invention.

Figure 2 is a sectional view taken substantially along the line 2-2 in Figure 1;

Figures 3, 4 and 5 are sectional views taken substantially along the lines 33, 44, and 55, respectively, in Figure 2; and

Figure 6 is an exploded perspective view showing the several parts of the device.

To illustrate the invention, the drawings show a bushing structure for receiving the electrode containing end portion 11 of a gaseous discharge tubular lamp 12 mounted on a support panel 13. The portions of the lamp 12 which extend in front of the panel may be carried on conventional support pedestals 14, of any suitable form. Such pedestals may comprise insulating material such as glass and may be secured on the panel in position extending outwardly of the forward surface thereof to support the tubular lamp in spaced position in front of the panel. An end of the tubular lamp may be bent, as at 15, to provide the end portion 11 in position extending through a panel opening 16 to dispose said end portion 11 in concealed position behind the panel for connection in a lamp energizing power circuit disposed rearwardly of the panel.

Tubular discharge lamps are commonly provided with electrodes 16, sealed in the opposite ends of the lamp element, and electrically connected with external connection terminals which may comprise metal caps or ferrules 17 mounted on the extremities of the lamp envelope, whereby the lamp may be connected for operation by electrically connecting the ferrules 17 in a lamp energizing circuit, the lamps being operated by the application of electrical power at relative high potential between the electrodes 16 at the opposite ends of the lamp element.

, The present invention provides an improved bushing structure 18 for electrically isolating the end portion 11 of the lamp from the panel 13 where the lamp extends through the opening 16, said bushing structure incorporating connection means 19, supported in and forming a part of the bushing structure and adapted for electrical connection with a lamp energizing circuit and with an electrode connected ferrule 17, when the lamp is in mounted position in the bushing structure, said connection means 19, of course, being electrically insulated from the panel 13.

Tubular gaseous discharge lamps are frequently mounted for operation in position exposed to the weather. As a consequence, rain, snow, sleet, and other forms of moisture, may accumulate upon the lamp, including the end portions 11 thereof, as well as upon the lamp mounting and supporting structure, including the bushing structure 18. Such accumulation of moisture affords an opportunity for the development of short circuit conditions between the ferrules 17, which are energized at relatively high voltage, and the panel structure 13, which is usually grounded for the sake of safety. Any substantial accumulation of moisture, snow, or sleet, on or around a lamp portion 11, between the panel 13 and the ferrule 17, may result in the formation of an electrical conducting pathway along and adjacent the lamp portions 11, and along which pathway power may flow from the ferrule to the grounded panel 13. Electrical power flowing through such a moisture formed short circuit path may develop relatively high temperatures in the neighborhood of the glass envelope portions 11, which may crack under the influence of such heat with the resultant destruction of the lamp.

Moreover, the operation of gaseous discharge lamps causes the establishment of electrostatic phenomena, at and along the envelope, including the end portions 11 thereof, and the resultant production of substantial quantities of ozone, in the atmosphere adjacent the lamp envelope. The reaction of such ozone with moisture and atmospheric dirt results in the production of nitric acid, which, of course, will attack any metal object with which it comes in contact, including the ferrules 17 and the power supply means 19 through which the ferrule is connected with the lamp energizing circuit. An important object of the present invention, accordingly, is to form the bushing structure 13 in fashion which will entirely avoid any possibility of the accumulation of moisture, snow, or sleet around the lamp portions 11 to thereby not only minimize the formation of nitric acid, but also to inhibit arcing along a conducting path provided by moisture or accumulated snow or sleet, in close adjacency to the lamp end portions 11.

With these ends in view, the bushing structure 18 comprises a preferably glass sleeve-like bushing element 20 medially thickened to form a peripheral rim 21 disposed between the opposite ends 22 and 22 of the sleeve, said ends being sized as to external diameter to fit freely within the panel opening 16. The internal diameter of the sleeve 20 is such as to freely receive the lamp portion element in position extending through the sleeve 20 when the same is mounted in the opening 16.

The bushing structure also comprises a preferably formed sheet metal retaining collar 23 adapted to snugly receive the rim 21 of the sleeve member 20, said collar having an inturned marginal flange 24 on one side thereof adapted to receive one end 22 of the bushing and to engage one side of the rim 21 to thereby retain the bushing member 20 in the collar. Means is-provided at the opposite side of the collar for fastening it upon the rim portion 21 of the sleeve member 20, such means preferably comprising integral lugs 25 adapted to be bent or crimped inwardly into position engaging the side of the rim 20 remote from the flange 24.

In order to support the contact means 19 in the bushing structure, the collar 23 is provided with a preferably integral outstanding web 26 projecting substantially radially of the collar 23 and of the central axis of the sleeve Cil ' at and outwardly of the rear face of the panel.

member 20, the contact means 19 being supported on one end of a post 27, the opposite end of which is secured on the web 26 at a substantial distance outwardly of the collar mounted sleeve member 20.

The post 27 preferably comprises glazed ceramic or other suitable electrical insulating material. For convenience, the post may have rectangular, preferably square, sectional configuration, although, of course, the invention is not necessarily restricted to the particular sectional shape of the post. The post also may be formed with a longitudinally extending internally threaded axial bore 28, the opposite ends of which are preferably countersunk, as at 29. The web 26, at its outer end, may also be formed with a centrally perforated depression 30 in position to fit into the countersunk opening in one end of the post 27; the post being secured on the web 26, as by means of a fastening member 31, preferably comprising a screw having a shank adapted to extend through the central opening of the depression 30 and to threadingly engage in the bore 28 of the post, the screw preferably having aconical head adapted to engage and seat in the depression 30. In order to prevent the post 27 from turning on the web 26 and thereby becoming loose on the fastening screw 31, the web 26 may be provided with upstanding flanges 32 outwardly of the depressed portion 30 in position to engage an adjacent pair of the sides of the post 27, at the web mounted end thereof.

The connection means 19 may comprise a helical coil 33 of relatively resilient conductor wire having an end mechanically and electrically connected on a formed sheet metal mounting plate 34 having a perforation adapted to receive a threaded stem 35. This stem is adapted for threading engagement in the bore 28 of the mounting post 27. A pair of nuts 36 may be provided for threaded engagement on portions of the stem 35, which project at the end of the post 27 in order, not only to secure the mounting plate on the post, but also in conjunction with apair of washers 37 to allow for the electrical connection of the post and the mounting plate 34, as well as the resilient contact element 33, in a lamp energizing circuit, a conductor of which may be so connected with the means 19 by securing the same clampingly between the washers 37 by operation of one of the nuts 36. In order to prevent the connection means from turning on the post, the mounting plate may be formed with dependent lips 32' in position'to engage an adjacent pair of the sides of the post 27, at the plate carrying end thereof.

It will be seen that the helical wire contact element 33 is presented in alignment with the axis of the bushing sleeve 20 so that when the bent end portion 11 of a lamp is in mounted position, in the bushing structure, more or less in coaxial alignment with the axis of the bushing 20, the contact ferrule 17 of the lamp will engage and make electrical contact with the member 33; and the parts will beheld together in mounted contact-making relationship by the attachment of the lamp 12 on its supporting pedestals 14.

Any suitable or preferred means may be employed for anchoring the bushing structure 18 on the panel 13 in position with the end 22 of the bushing sleeve 29 extending in and projecting through the panel opening 16, the remainder of the bushing structure, of course, extending The invention, however, contemplates novel and inexpensive attaching means operable entirely from the rear side of the panel for the purpose of attaching, or dismounting, the bushing structure. In this connection, it will be apparent that attaching means, operable entirely from one side of the panel, will have considerable value in connection with mounting the bushing structure on large panels, since it will eliminate thenecessity of employing two persons, one on each side of the panel, in order to attach the bushing structure.

The novel attaching means may comprise a finger 38 formed preferably integrally on and at one side of the collar 23, as at an edge thereof, said finger having a head forming integral oppositely extending ears 39, and a shank 40 of reduced width interconnecting the head of the finger with the rim of the collar 23. The collar 23 may also be formed with 21 preferably integral outstanding lug 41 at an edge thereof preferably diametrically opposite the finger 38. The lug 41 may be formed with an elongated slot or opening 42 adapted to slidingly receive the shank 45 of a latching finger 44. This latching finger may conveniently comprise a sheet metal stamping forming the shank or bar 45 and having a head providing oppositely extending ears 46 at one end of the shank. The opposite end of the shank may be formed with a longitudinal slit 47 defining legs 48 at the end of the shank on opposite sides of the slit. The shank 45 may be assembled in the opening 42, and a preferably helical spring 49 may be assembled around the shank and the parts retained in assembled position by twisting and bending the legs 48, as shown more especially in Figure 3 of the drawings, to form them as abutments for engaging and retaining one end of the spring 49, the opposite end of the spring bearing upon the back face of the lug 41. The slot 42 also is preferably formed with a medial enlargement 42' comprising registering notches formed in its opposite sides; and the shank 45 is formed with a necked portion 45' adapted to turn in said enlargement 42' of the slot, to allow the head of the finger 44 to be positioned in a plane extending radially of the axis of the bushing 20, and at right angles to the slot 42. The spring 49 is assembled under compression and will serve to normally urge the head of the finger toward the lug 41, and to latch the finger in the enlargement 42' when turned into position extending transversely of the slot 42.

The panel 13 also may be formed with slots 50 and 50 extending outwardly on opposite sides of the opening 16, said slots extending radially of the center of the opening and communicating with said opening at their inner ends.

The bushing structure 18 may be positioned on the panel from the rear thereof, at the opening 16, by first inserting the finger 38 in the slot 50 to engage the ears 39 with the front face of the panel 13 on opposite sides of said slot 50. Thereupon the structure 18 may be turned into position with the forward end of the bushing 20 extending in the opening 16. This will present the radially latched head of the finger 44 in registration with the radial slot 50. By inserting the tip of a screw driver, or similar device, between the spread legs 48, the finger 44 may be pushed against the influence of the spring 49 to turn the finger 44 in order to release the necked portion 45' from latched engagement in the slot enlargement 42 and to register the ears 46 with the forward face of the panel at the opposite edges of the slot 50. Upon release of the finger 44 in such turned position, the spring 49 will draw the unnecked portion of the shank 45 into the slot 42 as the bushing structure is drawn to mounted position on the panel. Engagement of the unnecked portion of the shank in the slot 42 will latch the finger against turning movement, thereby locking the bushing on the panel. When the finger 44 is so latched in the slot 50, the spring 49 will serve to hold the parts in latching position, thereby retaining the bushing structure 18 in centrally mounted, yet readily detachable, position on the panel.

The bushing structure, however, may be easily disconnected by pushing the finger, as by means of a screw driver applied in the slit 47 between the legs 48, to register the necked portion 45' with the slot enlargement 42. Thereupon the finger 44 may be turned into radial position releasing the ears from engagement with the panel on the opposite sides of the slot 50. The bushing structure may then be removed from the panel by a reversal of the positioning procedure; and it will be apparent that the structure 18 may be mounted on and dismounted from the panel by operations accomplished entirely from the rear side of the panel.

It will be seen from the foregoing that the bushing structure 18, not only provides substantial spacement between the post 27 and the end portions 11 of a lamp mounted therein, but also provides the metal yoke structure 23, which is grounded on the panel, at the lugs 25, when the bushing structure is mounted on the panel. Furthermore, the structure avoids enclosing the end portions 11 of the mounted lamp except Where the same extends through the relatively commodious sleeve 20, which is located sufficiently remotely from the contact making ferrule to assure that moisture, snow or sleet may not become packed around the lamp portions 11 to any extent between the ferrule 17 of the mounted lamp and the grounded panel. Moisture, snow or sleet will, of course, fall upon the structure and the lamp mounted therein as the result of natural precipitation; and the same may accumulate to some extent within the bushing 20. Such accumulation, however, will be at a point substantially remote from the ferrule 17 and the power supply means 19, including the contact element 33. It is possible also that snow, sleet and moisture may accumulate to some extent upon the post 27. Should such accumulation occur to an extent affording a conducting path along the surface of the post 27, any electrical power flow along such conducting path will become grounded directly to the panel through the metal collar or yoke 23 at the lugs 25 thereof and, hence, may not travel in dangerous proximity to any portion of the mounted lamp. Snow or moisture falling directly upon the lamp portions 11 will, of course, be immediately melted and evaporated by the heat generated and liberated by the lamp during operation.

Since the lamp portions 11 are substantially unenclosed, such evaporated moisture will not be retained around and in the vicinity of the lamp portions 11, but will be dissipated to circumambient atmosphere. Accordingly, the end portions 11 of the mounted lamp will at all times remain in substantially dry condition so that the danger of establishment of a short circuit power-flow path from the ferrule 17 to the grounded panel 13, along a path closely adjacent the lamp portions 11, or through the sleeve 20, is entirely eliminated in structures embodying the present invention. Since the structure thus provides for the maintenance of substantially dry conditions at and around the lamp portions 11, it will be obvious that the danger of nitric acid production, through the action of ozone on dirt and moisture, will also be entirely avoided.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the forms herein being preferred embodiments for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. A bushing structure for connecting the electrode carrying end of a tubular discharge lamp in a lamp energizing power circuit, comprising an assembly adapted for mounting on a lamp supporting panel, at an opening therein, said assembly including a sleeve element of insulating material adapted to extend in said opening in position to receive the electrode carrying end of the lamp in mounted position therethrough, a mounting post of insulating material and electrical conducting mounting means for supporting said post and sleeve in spaced apart relationship, including means for securing said mounting means on the panel to anchor the bushing structure thereon and for electrically connecting said mounting means with the panel when the bushing structure is in mounted position thereon, and contact making means adapted for connection with a power supply circuit and secured 'on said'post in position to make electricalcontact with the electrode carrying end portion ofthe'lamp when thesame is mounted in -position extending axially through saidsleeve element.

2. A bushing structure for connecting the electrode carrying end of a tubular discharge lamp-in 'alamp'energizing circuit, comprising an assembly adapted "for mounting on a lamp supporting panel, at an opening therein, said assembly including 'a sleeve'element "of-insulating material adapted to extend in said opening in position to receive'the electrode carrying end ofthe'lamp in mounted position therethrough, amounting post 'of insulating material and a sheet metal stamping forming a collar embracing said sleeve element and an outwardly extending mounting bracket-for said post to'support the same and said sleeve in spaced apart offset relationship, including meansfor connecting said stamping on and in electrical contact with the panel when the bushing structure is in mounted position'thereon, and contact making means adapted for connection with apower supply'circuit and secured on said post, remote from said stamping in position to make electrical contact with the electrode carrying end portion of the lamp when the samev is mounted in position extending axially through said sleeve element.

3. A mounting structure for connecting the electrode carrying end of a tubular discharge lamp in a lamp energizing circuit, comprising an assembly adapted for mounting on a lamp supporting panel, at an opening therein, said assembly including a sheet metalmember framing a collar and a post mounting bracket outwardly of said collar, a sleeve element of insulating material secured in said collar and having an end'adapted to 'extend in said opening in position to receive the electrode carrying end of the lamp in mounted position axially therethrough, a mounting post of insulating material secured on said bracket in spaced parallel relation with respect to the axis of said sleeve, mounting means for securing the sheet metal member on the panel to mount the bushing structure thereon, said sheet metal member being formed with lugs for securing the sleeve in the collar and for electrically connecting said member with the panel when the bushing structure is in-rnounted position thereon, and contact making means adapted for connection with alpower supply circuit and secured on said post in position to make electrical contact with the electrode carrying end portionmountedaxially through said sleeve element.

4. A bushing structure for-connecting the electrode carrying end of a tubular discharge lamp in a lamp energizing power circuit, comprising an assembly adapted for mounting on a lamp supporting panel, at an opening therein, said assembly including a sleeve of insulating material'adapted to extend in said opening in position to receive the electrode carrying end of the lamp in mounted position therethrough, contact making means adapted for connection with a power supply circuit, carrying means supporting said contact making means on said sleeve in position to make electrical contact with the electrode carrying end portion of the lamp when the same is mounted in position extending axially through said sleeve, releasable latch means, and support means mounting said latch means on said sleeve for securing the bushing structure on said panel, said latch means including a finger on one side of the sleeve and formed for interfitting engagement in a panel slot onone side of said panel opening, and a spring pressed latch member on the opposite side of the sleeve and formed for releasable engagement'in a panel slot on the opposite side of said opening.

5. A .bushing structure including a sleeve and means for mounting the same on a panel, at an opening therein sizedto receive the sleeve, comprising a latch finger and means to secure the same on one side of the sleeve in position to interlockingly engage with the panel at an attachment station on one sideof said opening, a spring pressed latch'bar support means carrying said latch bar for longitudinally shiftable movement on said sleeve, on the side thereof remote from said finger, said support means including a web portion formed with a latch bar slot therethrough, said latch bar comprising a fiat finger axially slidable in said latch bar slot, in non-turnable fashion throughout a portion of the length of said finger, said finger having a flat head insertable through an anchingslot formed in said panel on the side of said opening remote from said station, opposed outstanding ears on said head, said finger having a neck of restricted width to permit the same to turn in said latch bar slot to position said ears for engagement with the panel at the opposed sides of said anchoring slot, when said neck is in registration with said latch bar slot.

6. A bushing structure including a sleeve and means to mount the same on a panel, at an opening therein sized to receive the sleeve, comprising a latch finger on one side of the sleeve for interlockingly engaging the panel on one side of the opening, means forming a slotted latch guide on the sleeve, on the side thereof remote from said finger, a latch bar longitudinally movable in said guide between retracted and projected positions, spring means normally urging said bar toward retracted position in said guide, said bar and said guide being formed to prevent rotation of the bar in said guide when in retracted position therein, and to permit rotation thereof when in projected position, said bar having a head insertable through a panel slot, when in projected position, said head having opposed outstanding ears and being turnable in'projected position to dispose said ears for engagement with the panel at the opposed sides of said slot to latch the bushing structure on the panel.

7. A bushing structure including a sleeve and means to mount the same on a panel, at an opening therein sized to'receive the sleeve, comprising a latch finger on one side of the sleeve for interlockingly engaging the panel onone side of the opening, means forming a slotted latch guide on the sleeve, on the side thereof remote from said finger, a latch bar longitudinally movable in said guide between retracted and projected positions, spring means normally urging said bar toward retracted position in said guide, said bar and guide being formed to prevent rotation of the bar in said guide when in retracted position therein, to permit rotation thereof in projected position and to prevent retracting movement of the bar from projected position except when in predetermined relatively turned position, said bar having a head insertable through a panel slot, when in projected positioned turned from said predetermined position, said head having opposed outstanding ears and being turnable, in projected position, to said predetermined turned position, to dispose said ears for locking engagement with the panel at the opposed sides of said slot, and to allow the spring means to draw the bar to retracted non-turnable position latching the bushing structure on the panel.

8. A bushing structure as set forth in claim 7, wherein the latch guide comprises an car on the sleeve and formed withan elongated slot having a medial enlargement, the bar comprising a fiat finger formed for sliding, nonturning interfitment in said slot, said bar having a necked-in portion sized for turning movement in said medialenlargement.

9. A'bushing structure as set forth in claim 7, wherein thelatch guide comprises an ear on the sleeve and formed with an opening, the bar comprising a finger formed for sliding 'movement in said opening and having its head at one end of the finger on one'side of the ear and a longitudinal slot defining spaced legs at the head remote end of the finger on the other side of the ear, said spring means comprising a helical element encircling the finger and bearing at its opposite ends on said ear and on said legs, said legs being outwardly bent to engage and retain an end of the spring means.

10. A mounting structure for connecting the electrode carrying end of a tubular discharge lamp in a lamp energizing circuit, comprising a bushing assembly adapted for mounting on a lamp supporting panel, at an opening therein, said assembly including a sheet metal member forming a collar, a sleeve element of insulating material secured in said collar, said sheet metal member being formed with lugs for securing the sleeve in the collar and for electrically connecting said member with the panel when the bushing structure is in mounted position thereon, insulated means on said sheet metal member for supporting a lamp contact in axial alignment with said sleeve, and mounting means for securing the bushing on the panel comprising a latch finger on one side of said sheet metal member for interlockingly engaging the panel on one side of the opening, means forming a slotted latch guide on the sheet metal member, on the side thereof remote from said finger, a latch bar longitudinally movable in said guide between projected and retracted latching positions, spring means normally urging said bar toward retracted position, said bar and guide being formed to prevent rotation of the bar when in retracted position and to permit rotation thereof when in projected position, said bar having a head insertable through a panel slot when in projected position and being turnable to interlockingly engage said head in said slot and to position the finger for retracting movement to latch the bushing structure on the panel.

References Cited in the file of this patent UNITED STATES PATENTS 1,768,042 Ferguson June 24, 1930 1,937,322 Johnson Nov. 28, 1933 2,020,886 Hammar Nov. 12, 1935 2,205,051 Schmitt June 18, 1940 2,235,640 Kresge Mar. 18, 1941 FOREIGN PATENTS 474,328 Canada June 12, 1951

Images