US 3663780 A
A button switch which includes a base and a button telescopically mounted on the base. The base and button are hollow and there is a spring positioned within the hollow interiors to urge the button outwardly away from the base. An interlock between the button and the base limits movement of the button. There are electrical terminals mounted on the base and movable electrical contact shoes mounted on the button and positioned for sliding contact with the terminals.
Claims available in
Description (OCR text may contain errors)
United States Patent Golbeck 1 May 16, 197 2 54] SWITCH IN A BUTTON 2,982,837 5/1961 Brantingson ..200/159 R 2,907,852 10/1969 Long et al. .....200/l59 R  Inventor. Bernard J. Golbeck, Crystal Lake, [11. 3263036 7/1966 Flanagan Nico/16 F x  Assignee: Oak EIeCtrO/Nectics Corp., Crystal Lake, 3,476,891 11/1969 Lis ..200/16 F Ill.  Filed: June 8 1970 Primary Examiner-J. V. Truhe Asszslanl ExammerGale R. Peterson  Appl. No: 44,310 AttorneyParker,Carter& Markey 52 us. Cl. ..200/167, 200/159 R [571 ABSTRACT [51 Int. Cl. ..H0lh 9/16 A button switch which includes a base and a button te|escopi  Field of Search ..200/l67, 159 R, l59 A, 69, Cally mounted on the base. The base and button are hollow 200/71 16 F and there is a spring positioned within the hollow interiors to urge the button outwardly away from the base. An interlock  References cued between the button and the base limits movement of the but- UNn-ED STATES PATENTS ton. There are electrical terminals mounted on the base and movable electncal contact shoes mounted on the button and 3,52 l ,015 l WOOldl'ldgC 6t 81 R positioned for ontact the terminals 2,980,784 4/1961 Giohs et al. 3,238,334 3/1966 Lopasic et a1 ..200/1 21 8 Claims, 30 Drawing Figures 4 4 a: i x 34 if i I I l y; 7d
Patented May 16, 1972 '7 Sheets-Sheet l ff 1 Kw Patented May 16, 1972 3,663,780
7 Sheets-Sheet L3 Patented May 16; 1972 3,663,780
'7 Shee ts-Shoet ij Patented May 16, 1972 7 Sheets-Sheet 4 Pakented May 16, 1972 '7 Sheets-Sheet 5 SUMMARY OF THE INVENTION The present invention relates to a telescopic button switch and particularly to a reliably operable simply constructed switch of the type described.
One purpose is a telescopic button switch including a lamp within the switch interior to illuminate the button.
Another purpose is a telescopic switch construction suitably formed of plastic or the like which includes a removable lens.
Another purpose is a telescopic button switch, including means for maintaining alignment of the button on the base.
Another purpose is a telescopic button switch including means for mounting the switch on a support and for maintaining alignment of the switch on the support.
Another purpose is a button switch of the type described which. can be inserted in a printed circuit board and dip soldered in place.
Another purpose is a button switch of the type described which can be used in multiples to form a keyboard.
Another purpose is a telescopic button switch including improved electrical contact means.
Another purpose is a button switch suitable for use in multiples, including means for preventing operation of more than one adjacent switch at a time.
Another purpose is a telescopic button switch, arranged in multiples, so that only one button may be depressed at a time.
Another purpose is a button switch of the type described which is arranged for push-to-latch and push-to-release actuation.
Other purposes will appear in the ensuing specification, drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated in the following drawings wherein: 1
FIG. 1 is a side elevation, with portions broken away, of a telescopic button switch of the type described,
FIG. 2 is a side view taken from the right side of FIG. 1,
FIG. 3 is an enlarged vertical section through the button switch of FIGS. 1 and 2,
FIG. 4 is a section along plane 4-4 of FIG. 3,
FIG. 5 is a section along plane 5-5 of FIG. 4,
FIG. 6 is an end view'of one of the electrical terminals used in FIG. 5,
FIG. 7 is a top plan view of the base for the button switch,
FIG. 8 is a bottom view of the switch button,
FIG. 9 is a bottom view of the switch base,
FIG. 10 is a side view ofthe switch base,
FIG. 11 is a partial top plan view of the support for the button switch,
FIG. 12 is a vertical section, similar to FIG. 3, illustrating a modified form of the invention,
FIG. 13 is a section along plane 13-13 ofFIG. 12,
FIG. 14 is a side view, in section, of a portion of the button illustrated in FIG. 12,
FIG. 15 is a bottom view of the button portion illustrated in FIG. 14,
FIG. 16 is a side view illustrating the electrical terminal structure of FIG. 12,
FIG. 17 is an enlarged partial section illustrating a modified form of electrical contact structure,
FIG. 18 is a side view of the contact structure of FIG. 17
FIG. 19 is a section along plane 19-19 ofFlG. 17,
FIG. 20 is an enlarged bottom view of the contact shoe of FIG. 17,
FIG. 2] is a section along plane 21-21 of FIG. 22,
FIG. 22 is a side view, with portions broken away, of the switch array shown in FIG. 21,
FIG. 23 is a side elevation, in section, of a modified switch array,
FIG. 24 is a view, in partial section, taken along plane 24- 24 of FIG. 23,
FIG. 25 is a side elevation, in section, of a modified form of button switch,
FIG. 26 is a side view of the button stem of FIG. 25,
FIG. 27 is a top plan view in partial section of a modified switch array,
FIG. 28 is a side elevation, in half section, of the structure in FIG. 27,
FIG. 29 is a partial section along plane 29-29 of FIG. 28, and
FIG. 30 is a partial plan of a detail shown in FIG. 29.
DESCRIPTION OF THE PREFERRED EMBODIMENT The button switch illustrated in FIGS. 1-10 includes a generally hollow button 10 and a hollow base 12. As shown herein, both the button and the base are generally square in cross section, although obviously the invention should not be limited to this particular shape. The button may be rectangular, round, elliptical, etc., as the cross sectional shape forms no part of the invention. The base 12 is mounted upon a support 14, which in turn is mounted, upon a printed circuit board 16.
The base 12 includes side walls 18, 20, 22 and 24 and a bottom 26. Rails or the like 28 may extend outwardly from each of the four comers of the base to align the button as it telescopically moves on the base. The bottom 26 may have a pair of oppositely disposed openings 30 for the passage of electrical terminals 32 and 34 which provide electrical current for a lamp or the like 36 positioned within the switch. There are also three pairs of openings 38, 40 and 42 for the passage of the switch terminals as described herein. Feet 44 are positioned at each of the corners of the bottom 26 to mount the base upon the support member 14. Also, there are a pair of circular feet 46 and 48 which are unsymmetrically positioned on the bottom 26 to provide proper alignment of the base upon the support 14.
The support 14 may include an opening 50 for the passage of all of the electrical terminals. At opposite sides of the opening 50 are apertures 52 and 54 which receive the circular feet 46 and 48 to properly position the switch upon the support 14. Ridges or the like 56 surround the base 12 and also assist in properly positioning the base upon the support 14. There are a plurality of circular openings 58 in the printed circuit board 16 for the passage of the various contacts used in the switch and after assembly of the switch upon the support 14 and upon the printed circuit board 16, the contacts may be conventionally dip soldered to the printed circuit board.
Sides 20 and 24 of the base 12 include slots, one of which is indicated at 60 in FIG. 10. There are projections 62 at the lower end of the slots 60 and these projections are used to attach the button to the base and to limit movement of the button upon the base.
The button 10 includes an outer skirt 66 and a generally centrally positioned lens 68. There are grooves 70 in opposite sides of the skirt 66, with the lower end of the grooves 70 terminating in a pair of slanted surfaces 74 and 76. In the assembled construction of FIG. 3, the slanted surface 74 is positioned against a mating slanted surface 78 formed at the lower end of projections 62. The projections 62 will ride in the slots 70 as the button is telescopically moved on the base. In assembly, since the button is preferably formed of a flexible material, for example plastic, the button may be forced down upon the base and the projections 62 will force portions of the skirt to expand outwardly so that the button snaps on the base. The mating slanted surfaces 78 and 74 not only limit upward movement of the button, but also fasten the button to the base. However, the button may be removed from the base, either by a strong upward pull, stronger than in normal usage, on the button itself, or by reaching under and slightly expanding the bottom skirt area of the button to release that area from about the projections 62.
The button skirt 66 may have slots or grooves 80 at each corner, which grooves will contain the rails 28 to provide alignment between the button and base during movement of the button.
The lens 68 may have two downwardly extending fingers 82, the lower ends of which have hooks 84. The lens may be snapped into the button so that the hooks 84 will fit within the grooves 70 in the button skirt. Thus the lens is assembled to the button and the button may then be assembled onto the base.
Lamp 36 may have a base 85 connected to terminals 32 and 34 and seated upon a center section 86 of the bottom 26. A coiled spring or the like 87 surrounds the lamp 36 and bottoms upon a ledge of the base 85. The upper end of the coil spring 87 fits within an annular groove 88 in a central section of the button. Thus, the spring 87 will normally urge the button to the out or up position illustrated in FIG. 3. FIG. 1 illustrates in phantom lines the down or operated position of the button 10. The center section of the button, illustrated at 90, has a conical upper surface 92 to spread the light from lamp 36 throughout the entire area of the lens 68. The center section also has a downwardly-extending skirt 94 which rides inside of the base walls 18, 20, 22 and 24 to provide stability in operation of the button.
At each side of the base is a set of three terminals, one set of which is illustrated in FIG. 5. The terminals are indicated at 96, 98 and 100, and will extend through the openings 38, 40 and 42 formed in the bottom 26 of the base. Terminal 96 extends upwardly toward the button the greatest distance and has a contact area 102 which extends over terminal 98. In like manner, terminal 100 has a contact area 104 which extends over terminal 98. Thus, the actual contact areas of the three terminals are in vertical alignment. Each terminal, as illustrated in FIG. 6, may have a lower section 106 with the contact area being the upper section, slightly offset to the side, as illustrated at 108.
There are a pair of electrical contact shoes 1 10, one on each side of the button. The shoes 110 move in a path parallel to the path of movement of the button and perpendicular to the terminal contact areas. In the position of FIG. 5, terminals 96 and 100 are connected by shoe 110. This is the up position of the switch. In the lower or operated position of the switch terminals 98 and 100 will be connected together by the contact shoe 110. The switch illustrated in FIGS. 1-10 is a double-pole double-throw switch as there are terminals on each side of the switch.
FIGS. 12-16 illustrate a modified form of momentary button switch. A button 112 includes a skirt 114, a lens 116 and a center section 118. The skirt, lens and center section may all be formed separately and then fastened together by suitable means to complete the button structure. At each side of the center section 118 there are a pair of fingers 120, illustrated in FIG. 14, with the lower end of each finger terminating in a hook or outwardly-extending portion 122. The base 124 may have inwardly-extending projections 126 at opposite sides which will cooperate with the hooks 122 in fastening the button to the base, somewhat in the manner described in connection with FIGS. 1-10. In this instance, however, the hook portion on the button is inside, whereas in FIGS. 1-10 it was outside. There are grooves 128 on opposite sides of the interior surface of the base 124 within which the hooks 122 will move as the button is reciprocated on the base. The hooks 122 and the inwardly-directed projections 126, as well as the grooves 128, provide a stop for limiting up and down movement of the button on the base.
A lamp 130 having a base 132 provides illumination for the switch. The base 132 may be connected to electrical terminals 134 and 136, which extend downwardly through the bottom 138 of the switch base. A coiled spring or the like 140 surrounds the lamp 130 with the lower end of spring 140 bottoming on a flange of the base 132 and the upper end of the spring 140 being positioned on a ledge 142 in the center section 118 of the button.
The principal difference between the structure of FIGS. 12-16 and the structure of FIGS. 1-10 is a reversal in the position of the hooks which hold the button to the base. Also, the button, as illustrated in FIGS. 12-16, is composed of three elements, whereas in the structure of FIGS. l-l0, it is composed of two elements. In some applications the skirt of FIG. 12 may be eliminated and merely the lens and center section can be utilized. This is particularly the case when buttons of the type disclosed are used in multiples to provide a keyboard or the like.
In the structure of FIGS. 12-16, the button is assembled onto the base by forcing it downwardly so that the hooks 122 will be moved inwardly by the slanted surfaces at the upper side of projections 126. Once the hooks are beyond projections 126 they will snap outwardly to thus hold the button in place on the base.
The button switches of FIGS. l-10 and 12-16 are momentary switches in that the buttons return to a normal position as soon as pressure on the button is released.
In FIG. 16 the electrical terminal structure is shown to include three terminals 144, 146 and 148. The contact shoe is illustrated at and moves in a path parallel to the button. The contact areas of the terminals 144, 146 and 148 extend in a direction perpendicular to the path of movement of the shoe 150 much the same as disclosed in the structure of FIG. 5.
FIGS. 17-20 illustrate a modified form of terminal and contact shoe. The button and base structure has been largely omitted, but may be substantially the same as described above. A lamp 152 has a base 154 which seats upon a central section 156 of the switch base structure. Electrical terminals, indicated at 158, 160 and 162 extend upwardly on opposite sides of the lamp 152. A pair of contact shoes are illustrated at 164 and 166, with each shoe having a pair of sides and 172. The sides may have inwardly-directed dimples 168. The ends of the sides 170 and 172 are directed toward each other as at 174 and 176. Thus, as the shoe rides downwardly upon the upwardly-directed terminals, the ends will be separated and will be on opposite sides of the terminals. In the up position of FIG. 18, there is electrical connection between terminals 160 and 162. As the shoe moves downwardly, terminal 158 will be connected to the left side of the shoe, but the ends 174 and 176 on the right-hand side of the shoe will not make contact with terminal 162, as they will be positioned in a gap 178 formed in the terminal. The shoes 164 and 166 move in a path parallel to the terminals, whereas, in the previouslydescribed terminal structures, the shoes moved in a path perpendicular to the terminals. As illustrated in FIG. 19, the shoes 166 and 164 are symmetrical. The shoes can only be disposed in proper position in the button.
FIGS. 21 and 22 illustrate button switches arranged in multiples, for example in a keyboard configuration. Portions of three switches are illustrated in FIG. 21, with the bases being indicated at 180, 182 and 184. The bases -184 may be held together by lugs or the like 186 which extend outwardly from each base and fit into mating grooves or the like 188. Thus, the switch sections are held together in an array, for example in a keyboard or in a multiple-switch instrument or the like. The switches illustrated in FIGS. 21 and 22 are generally the same as described earlier, except that buttons 190 and 192 do not have a skirt. The Buttons may be attached to the base in the same manner as shown in FIGS. 12-16 by hooks 194 and slots 196.
There are aligned apertures 198 and 200 in adjacent sides of bases 182 and 184. There will be similarly aligned apertures in other areas of the switch array, although only this particular portion of the construction will be described in detail. Positioned within the aligned apertures 198 and 200 is a pin 202 which has conical ends 204. Each of the buttons 190 and 192 may have grooves 206 and 208 in alignment with the apertures or openings 198 and 200. The total length of pin 202 is greater than the combined width of the walls of the adjoining portions of the bases. Thus, the pin will always extend into one of grooves 206 or 208. If button 190 is depressed, the conical sides of groove 206 will force pin 202 to the right into groove 208. It will be then impossible to depress button 192. In like manner, pin 210 illustrated in FIG. 21 at the upper left of base 182, will also be forced outwardly. Thus, the button movable on base 180 will also be unable to be depressed. The structure illustrated in FIGS. 21 and 22 provides blockout in that it prevents any adjacent button from being operatedonce a particular button has been depressed. Not only may such buttons be arranged in a row, as illustrated in FIGS. 21 and 22, but they may be arranged in an array such that a central switch is completely surrounded by other switches. With such a construction only one button at a time can be operated.
FIGS. 23 and 24 illustrate another form of blockout utilizing a telescopic button switch. A button is indicated at 212 and may have a generally central stem 214 mounting a coil spring 216. The base in this form of the invention may have a plurality of walls 218 which define a plurality of cavities or chambers 220. A button 212 will be positioned within each chamber 220. Also within each chamber and forming a part of the base is a central section 222 having a bore 224. The central section 222 extends generally the width between opposite sides of the button 212 and has a passage 226 which receives blockout members 228 and 230. Members 228 and 230 are identical, and have feet 232 and slanted end walls 234. Opposite sides of the button 212 have slots or grooves 236 so that when the button is depressed it can come down upon the blockout members 228 and 230, with the center stem 214 pushing the blockout members 228 and 230 in opposite directions. The blockout members will be pushed toward adjacent buttons with the result that if the button 212 is held in a down position, it will be impossible to depress an adjacent button.
FIGS. 23 and 24 illustrate only two blockout members 228 and 230. There is also a blockout stop 240 illustrated in FIG. 24. The stop 240 is inserted into a somewhat L-shaped opening 242 in the center section 222 of chamber 220. When blockout member 228 moves to the right, it will contact stop 240. The stop is necessary in order to prevent member 228 from moving completely through slot 226 to the point where it would always prevent operation of an adjacent switch. Stop 240 is utilized in the end chamber of an array or multiple of switch sections.
No contacts are shown in the structure of FIGS. 23 and 24, but they have only been omitted for ease of description. The same is true in other forms of the invention which describe button switches used in multiples. There may be two sets of three contacts, one cluster of three contacts, or any particular combination of contacts, depending upon use of the switches.
FIGS. 25 and 26 illustrate a button switch having a push-tolatch and push-to-unlatch operation. A button 244 is telescopically mounted in a base 246. The base has a bottom 248 which supports a coil spring 250. The button 244 has a central stem 252 against which the upper end of the spring 250 seats. Opposite sides of the button 244 have outwardly-directed stops 254 and 256, which ride in grooves 258 and 260 formed in the base 246. The stops 254 and 256, which may be integral with the button or separate, prevent outward movement of the button beyond a certain limit. The button, however, may be completely removed, as in the other forms of the invention, by pressing the stops 254 and 256 inwardly so that they can pass out of the base area.
The spring 250 has an upwardly-bent section 262 which terminates in a centrally-directed end 264. The end 264 rides within a ramp 266 formed on one side of the central stern 252 of the button. The configuration of the ramp is illustrated in detail in FIG. 26. The ramp has a lower section 268 of generally uniform depth. There is a ramp section 270 which has a gradually decreasing depth, and a slight curvature away from the centerline of spring section 262. An upper ramp section 272 has a generally uniform depth with a flat bottom area. Cam surfaces 271 and 273 form the upper wall of ramp section 272 with the surfaces joining slightly off-center. A wall 274 divides ramp section 270 from ramp section 272. At the left side there is a second wall 276 followed by a further ramp section 278 which swings back toward center and decreases in depth back to the ramp section 268.
In operation, when button 244 is depressed, wall 279 will direct wire end 264 up ramp section 270 until it crosses wall 274 and passes into ramp section 272. If the button is now released, spring 250 will move it upward until wire end 264, moved downward by cam surface 271, strikes the flat bottom of ramp section 272. The button is now latched. When the button is subsequently pushed down, wire end 264 will be moved up and to the left by cam surface 273 which joins surface 271 to the right of center. The wire end 264 will cross wall 276 and pass into ramp section 278. When the button is subsequently released, it will move outwardly to its full open position and wire end 264 will return to the position of FIG. 25.
FIGS. 27, 28, 29 and 30 illustrate the combination of blockout and push-to-latch and push-to-unlatch operation. A base is indicated generally at 280 and includes a number of chambers 282, each of which may receive switch constructions. A button is indicated at 284 and has a central stern 286 surrounded by a coil spring 288, much the same as disclosed in FIGS. 23 and 24. There are a pair of blockout members 290 and 292 which will be pushed in opposite directions when the button is depressed by the central stem 286. The base structure 280 again will include a central section 294 having a passage 296 for the stem 286 and slots 298 for the passage of the blockout members 290 and 292.
A latch bar 300 extends through chambers 282 and will extend generally the length of the module incorporating the button switches. The latch bar is positioned in grooves 302 in the side walls 304 of the base 280. In each of the chambers 282 the latch bar 300 has a projection 306 illustrated particularly in FIG. 30. The projection 306 is generally triangular in configuration and has three legs indicated at 308, 310 and 312. Legs 310 and 312 are reduced in width, as at 314 and 316, illustrated in FIG. 30, to receive a spring member described hereinafter. There may be dimples or the like 318 on one side of the latch bar 300 to properly position the latch bar adjacent the side wall 320 of the button 284.
A spring member indicated generally at 322 includes a bottom support section 324, a pair of spaced upright sections 326 and forwardly-extending side sections 328, the ends of which are in-turned toward each other, as at 330. The side sections 328 will be positioned outside of legs 310 and 312, which are cut back, as at 314 and 316.
There is a latch projection in each chamber 282. However, it is only necessary to have a spring in one of the chambers. When a button is depressed the lower slanted surface 332 on the bottom of the button will hit leg 308 of the latch projection, causing the latch to pivot in its slots 302. Thus, the latch will pivot out of the way of the button as it moves downwardly against the force of spring 322. There is a hole or gap 334 in the button wall. After the button has swung the latch bar to the right, continued downward button movement will cause the triangular-shaped latch projection to spring back into the opening 334 because of the force from spring 322. Thus, the button when released, will be held in a latched position.
When any other button associated with the latch bar is depressed, downward movement of that button will swing the latch bar to the right against the force of spring 322 to release any previously depressed button. However, the button that is being depressed, and which has moved the latch bar, will subsequently be held in a latched position.
The structure illustrated in FIGS. 27-30 illustrates both latching and blockout. Only a single button can be depressed at a time because of the blockout members 290 and 292. However, a subsequent operation of an unlatched button will release any previously latched button.
The telescopic button switch disclosed herein may be formed of a variety of materials. Plastic is satisfactory, as it is inexpensive and readily moldable. Some metallic materials may also be satisfactory. However, it is important to electrically insulate the terminals and shoes from the button. Switches of the type shown herein may be extremely small, for example as small as one-half inch in diameter. The switches may be used in multiples, or they may be used individually. When used in multiples, they may form a keyboard, with each switch having a given number of contacts. The switches may be single-pole double throw, double-pole double-throw, or any other switch configuration conventionally used in electrical wiring. In some configurations, a blockout arrangement may be utilized such that only one switch button at a time can be depressed. The switches may be push-to-latch, push-to-unlatch, or they may be merely momentary switches. The switches may be arranged in such a configuration that the depression of one switch in a series or array or multiple of switches will release all other switches in the series.
Whereas the preferred form the invention has been shown and described herein, it should be realized that there may be many modifications, alterations and substitutions thereto.
1. A telescopic button switch including a base, a button telescopically mounted on the base, spring means normally urging said button away from the base, stop means limiting movement of said button, including at least one interior groove on said button and an outwardly extending projection on the base, said projection being positioned to move within said groove, opposite ends of said groove limiting movement of said projection therewithin, a slanted surface on a lower portion of said button, in alignment with said groove, a mating slanted surface on said base projection such that said slanted surfaces force a portion of said button outwardly during downward movement thereof, electrical terminals mounted on the base, and electrical contact shoes mounted on the button and positioned for sliding contact with said electrical terminals.
2. A telescopic button switch including a hollow base, a ho]- low button telescopically mounted on the base, spring means normally urging said button away from the base, grooves on opposite sides of the inside of said button, said grooves being of limited length and width, projections on opposite sides of the base ofa size and shape to fit within said grooves and limit reciprocal movement of the button on the base, a separate lens mounted in the button, said lens having downwardly extending legs with projections thereon positioned to fit within the grooves on the button to hold the lens within the button, electrical terminals mounted on the base, and electrical contact shoes mounted on the button and positioned for sliding contact with said electrical terminals.
3. A telescopic button switch including a base, a hollow button telescopically mounted on the base, stop means limiting movement of said button, a plurality of grooves in the interior surface of said button, a plurality of rails on the exterior surface of said base, said rails being positioned within said grooves to stabilize said button as it moves up and down on the base, electrical terminals mounted on the base, and electrical contact shoes mounted on the button and positioned for sliding contact with said electrical terminals.
4. The structure of claim 3 further characterized in that said electrical contact shoes have spaced sides positioned to straddle said terminals when in contact therewith.
5. The switch of claim 4 further characterized in that said spaced sides extend generally perpendicular to the path of shoe movement.
6. The switch of claim 4 further characterized in that said spaced sides extend generally parallel to the path of shoe movement.
7. A telescopic button switch including a base, a button telescopically mounted on the base, spring means normally urging said button away from the base, stop means limiting movement of said button, electrical terminals mounted on the base, electrical contact shoes mounted on the button and positioned for sliding contact with said electrical terminals, a support for mounting said base, and cooperating means on the base and support for providing alignment of the base on the support including an opening in the support in alignment with the base and of a size to receive said terminals, a plurality of apertures adjacent said support opening, and a plurality of feet extending downwardly from the base, said feet and apertures being so arranged that said base may be seated in only one way upon said su port.
8. T e structure of claim 7 further characterized in that said alignment means includes a plurality of upwardly-extending ridges arranged to be positioned about the exterior of the base as it seats upon the support.