US2101985A - Electrical condenser - Google Patents

Description

Dec. 14, 1937. 5 5 CRAMER 2,101,985

ELECTRI CAL CONDENS ER Filed May 9.I 1934 5 Sheets-Sheet l "1 J Aff 7 ffm f3 5 Z5@ {wh/7; unlunl'nn 74, 9/ j /n` if@ f7" ff je ZZ- 4 hmmag 5 INVENTOR Z55/Ord I l" mer' Dec. 14, 1937. s s CRAMER 2,101,985

ELECTRICAL CONDENSE Dec. 14, 1937. Y s, s CRAMER 2,101,985

ELECTRICAL CONDENSER Filed May 9, 1954 5 Sheets-Sheet 3 INVENTOR 4% .5gg/y ,5f gam/n BY /f I Dec. 14, 1937. s s CRAMER 2,101,985

ELECTRICAL CONDENS ER insu/21 Dec. 14,1937. s. s. CRAMER 'y ELECTRICAL coNDENsER Filed lay 9, 1934 5 Sheets-5118?l 5 INVENTOR ATTORNEY Patented Dec. 14, 193']A PATENT OFFICE z.1o1,9s ELECTRICAL coNDENsEn stanley s. Cramer, Haddon Heights, N. J., as-

signor to Radio Condenser Company, Camden,

Application May 9, 1934, Serial No. 724,688

23 Claims.

This invention relates to improvements in electrical condensers, particularly of the variable type, such as are used in tunable circuits of radio receiving sets.

Because of the present-day practice of making smaller radio receiving sets, smaller umts, including tuning condensers, must be used in their construction. To reduce the size of the condenser and still have sufcient capacity for the tunable circuits, the plates must be brought closer together, which means that greater care must be -used in the assembly of the stator and rotor groups of plates, else the warping stresses brought about in the manufacturing processes will prevent accurate centering of the stator and rotor plates, and more time must then be. spent in getting these plates into accurate alignment.

Such small condensers have thus become precision instruments because the capacity settings must be stable and the condensers must be capable of withstanding the strains and stresses applied to them without affecting the capacity settings, because present-day practice allows only a small tolerance in the variations of the capacity of one condenser of a gang with respect to another. This tolerance is on the order of 1 to 1.5 mmfd. While it is customary at the present time to provide the outer plates of a condenser unit so that they may be ilexed at different points to compensate for cer- '30 tain variations in the condensers, including the circuit with which they are connected, the design of the condenser must be one to give great rigidity. It is one of the objects of my present invention to produce a condenser which is relatively small and of light weight as compared with previous designs of the same capacity, but one which will stand the various abuses without drifting oi the capacity. At the same time, it is a further object to provide a construction which can be carried 40 out at an even lower cost..

Another object of my invention is to provide a construction in which the parts are so arranged as to facilitate the accessibility sothat the assembly operations may be quickly and carefully performed.

In the last few years it has been customary, in order to get rigidity and therefore stable capacity, to use an all-metal frame for carrying condensers, the frame being made from a single piece of metal, usually of steel, having shield plates between units either swedged or riveted in place between the various units of the gang; or, as an alternative, the end plates have been swedged or riveted in place between the side members of the frame in the same manner as the shield plates.

This sort of construction has generally been referred to as the bath tub type of frame, but such a frame makes the gang condenser of considerable weight. To materially reduce this weight, I have discarded the shell or bath tub type of frame entirely and have made a frame having two rigid metallic end plates, preferably of steel, held together by very rigid metallic rods constructed and arranged with Ithe end plates to produce a frame structure having a torsional l0 strength much greater than the frames heretofore used. On certain tests which I have made,

I have found that the frames to be hereinafter described will stand more than twice the tor-` sional iorce than the ."bath tub type of frame 15 previously referred to, with a drifting capacity of the condenser oi' less than 1A of the amount of drift in the condensers mounted in the previously described frame.

The advantages of my new construction will 20 appear from the specification which follows. In the drawingsz.

Figure l is a plan view of a three-gang condenser, only one unit being illustrated of one form of my invention. 25

Figure 2 is a right-hand end view of Figure 1 with the rotor turned ninety degrees.

Figure 3 is a section on the line 3-3 of Figure 1.

Figure 4 is a section on the line 5 4 of Fig- 30 ure 1. f.

Figure is a view similar to Figure l, but showing a modified form of mounting the stator element.

Figure 6 is a view on the line 6 5 of Figure 5. 35

Figure '7 is a side elevation of a further modified form of three-gang condenser showing the rotor turned at an angle of ninety degrees from its zero or full capacity position. In this form, as well as in Figures 1 and 5, no trimmer condenser is illus- 40 trated.

Figure is a View of the right-hand end of the 'gang condenser shown in Figure 7.

Figure 9 is a view looking at one end of the bottom oi one of the stator units of Figure 7, 45 showing a part of the end plate and one shield plate.

Figure 10 is -a partial view on the line Iii- I0 of Figure 7.

Figure 11 is a partial view on the line il-ii 50 of Figure 7.

Figure 12 is a sectioncn the line l2-i2 of Figure 7.

`Figure 13 is a side elevation of a three-gang condenser similar to that shown in Figure 7, but 55 showing certain modified details of mounting the stators and fastening the end plates in position. v

Figure 14 is a viewl of the right-hand end of Figure 13. I

Figure 15 is a view looking at one end of the bottom of one of the stator units of Figure 13, showing a part of the end plate and one shield plate.'

Figure 16 is a partial sectional view on the line Figure 17 is a side elevation of a further form of three-gang condenser similar to that shown vin Figures 7 and 13, but with certain modified details. r A

Figure 18 is a view of the right-hand end of Figure 17.

Figure 19 is a partial view on the line I9-I9 of Figure 17. Figure 20 isa side elevation of a three-gang condenser, only two of the stator units being illustrated to show certain modied details.

Figure 21 is a partial view looking at the right-hand end of Figure 20.

Figure 22 is a view looking at the bottom of one end of the stator units shown in Figure 20, showing details of mounting the stator in the frame.

Figure 23 is a side elevation of the frame of a three-gang condenser showing further modified I which may be used.

` Figure 26 is a fragmentary view of the right.

hand end of the frame shown in Figure 25.

Figure 27 is a fragmentary end view 0 a further modifiedl construction of the condenser frame.

Figure 28 is a view looking at the bottom of Figure 27.

Figure 29. is an end view, part in sectlonand part in elevation, of a still further modified form of construction.

Figure 30 is a side view of the end of a condenser as constructed in Figure 29.

Figure 31 is a side view of one end of a modifie form of frame structure.

Figure32 is an end view of Figure 31.

Figure 33 is a side view similar to Figure 3l of a condenser frame, but of a modified form'of fastening the bars to the end bearing plates.

Figure 34 is an end view of Figure 33.

Figure 35 is a side View, partly in section, of one end of `a condenser showing a still further modiied form of fastening the bars to the end plates.

Figure 36 is an end view of Figure 35.

Figure 37 is an end view of a still further modiiled form.

Figure 38 is apart sideand part sectional view of Figure 37.

Figure 39 is a part-sectional and part-elevational view of a further modication.

Figure 40 is a partial side view of one'end of a condenser showing how the end` plates may be welded direct to the frame rods.

Referring now to the different views, I and 2 are metallic end plates, preferably of steel and of a thickness to give considerable rigidity. Each of the plates I and 2 is provided with two sets of lugs, one set, 3, being provided so that the condenser may be mounted in one angular position, while the otherl set, 6, is provided so that the condenser may be mounted in a reverse angular position as will be 'clear by reference to Figure 2. For holding the end plates land 2 in operative position, I provide two similar rods 5 and'6, preferably of steel and of a size to rigidly -width of the notch between the forked ends 3 is somewhat smaller than the diameter of the portion 9 at the base of the grooves 1. Furthermore, the depth of the grooves 1 is suchas to provide a considerable radial bearing surface for the lforked ends 8 of the plates I and 2. Thus, when the rods 5 and 6 are forced into position in the end plates I and 2, the plates are securely gripped in position'. The rods 5 a'nd 6 have additional annular grooves I to receive the forked ends of shield plates II, but the depth of these grooves i8 need not be as great as the depth of the grooves 1, but preferably the shield plates are securely gripped `by the rods when they are forced into the position shown.

The end plate I carries aball bearing race i 2 similar to that shown in my Patent/1,800,719, for

supporting one end of the rotor shaft I3, the opposite end of which is supportedI in a ball thrust bearing I4 supported by an adjusting screw I5 in the end plate 2. ,While I have indicated this type of bearing in the end plate 2, it is understood that a bearing similar to that in the end plate I may be used.

The rotor plates I 6 are carried on the shaft I3 in any satisfactory manner as by grooves within which the plates I6 are staked or otherwise held. The stator group of plates I 1 is suspended from the frame rods and 8 by a saddle I8 having forked ears I9 which tightly fit into annular grooves 20'in the rods 5 and 6. The projecting tie bar 24, as best illustrated in Figures 3 and 4.

However, it is to be understood that before the soldering operation takes place, an assembly tool has been inserted between the stator and rotor platesto properly space them an equal distance apart, all in the manner as described and claimed in Cramer application Serial No. 717,860, illed March 28, 1934 After the soldering operation is completed, the tool is removed, thereby leaving each of the stators assembled in the frame without any torsional strains thereon. L

As shown in Figures 5 and 6, the stator II of each unit condenser is fastened to the plain rods 5 and 6 in a somewhat diierent. manner from that shown in the previous iigures. When the stator plates4 I1 are attached to their tie bars 2li,

"there being one on opposite sides of each stator,

an insulator 2'I is riveted between the tie bars 24 and the shouldered portion of the plates I1. To the free end' of the insulator 2l, is fastened, as by rivets 28, a metallic support member 29 preferably in the form of a small steel plate, the opposite end'of which extends into a longitudinal slot in one of the members and 6, and is staked thereto at 30, thereby giving a suspension type of mounting for the stator somewhat different from that shown in Figure 1.

In Figures 7 to 12 inclusive, I have illustrated a modied form of condenser in which the end plates l and 2 are rectangular in shape but held together by the frame rods 5 and 6 in a manner similar to that already described, except that each of the rods 5 and 6 has a longitudinal groove 3| preferably extending throughout its length, and the material 32 of the end plates is preferably staked inwardly out of the plane of the end plate so as to absolutely prevent the rods 5 and 6 from turning. Furthermore, the insulators 33, one on each side of the stator, are positioned in the grooves 3|, being staked in position therein as more clearly shown in Figure 1l.

Each of the insulators 33 has a metallic bracket 34 fastened thereto in any satisfactory manner as by rivets 35. The bracket 34 has a pair of inwardly projectmg arms 36, one on each side of the insulator, and each arm 36 has a lip 31 extending, one toward the other, as is clearly shown in Figure 9. These lips 31 act as means for assisting in soldering the stator tie bar 24 to the bracket 34. The manner of positioning the rotor plates and stator plates with a special fixture for carrying out the soldering operation is similar to that already explained with respect to Figure 1. The bracket 34 is provided with a terminal 38 for making electrical connection to the stator. Also, it may be noted that each insulator 33 may have a tapped hole 39 to receive an adjusting screw for adjusting a trimmer plate which maybe added to each unit in a manner as will be later referred to on one of the other forms of condensers illustrated such, for example, as shown in Figure 25, wherein the trimmer plate is fastened to the shield plate It may be noted in Figure^8 that the end plates and 2 may be provided with re-enforcing ribs 40 punched either outwardly or inwardly.

In Figures `13 to 16 inclusive, each of the insulators 33 is stakedinto grooves 3| in the rods as in the form shown in Figure 7, and the rods 5 being provided in the end bearing plates to assist in the assembly of the parts. This means that the studs 50 for supporting the stator, while similar in shape to the studs 4|,. are shorter, thereby making the condenser of less width than in the form shown in Figures 13 and 14. In addition, a somewhat different style of trimmer plate 5| is used, one of these trimmer plates being indicated in position in Figure 17, it having a similar connecting lug 48 as in Figure 13. The trimmer'plate 5| is also provided with inturned fingers 52 for preventing an insulator not shown but used for separating the plate 5l from the. bar 44, from turning. Y

In some cases Where the condenser is mounted in whatv might be termed an upside-down position, the fingers 52 act as supports for this trimmerv insulator. Where no trimmer plate is used, a terminal plate 53 is provided, the same being riveted to the insulator by the end of the studs In Figure 20, the frame members and 2 are held together in the same manner; that is, by the rods 5 and 6, as has been described, but the stator group of plates, only two of which are shown, are fastened to an insulating bar 54 which extends from end to end of the condenser through shown, and at the same time, it adds a certain and 6 are attached to the end plates I and 2 inv wherein a pair of studs 4I with shoulders 42 have reduced ends which pass through the insulator 33 and also through a trimmer plate 43 for riveting the trimmer plate 43 securely to the insulator 33. The opposite ends of the studs 4I are soldered in a manner previously explained to the stator tie bar 24 as clearly indicated in Figure 15.

To provide a cooperative capacity element for the trimmer plates 43, a rectangular-shapedbar member 44 is positioned in slots in the bottom of the end bearing plates and 2, being staked in position at 45 as indicated. The bar 44 has tapped holes 46 to receive adjusting screws which pass through clearance holes 41 in the trimmer amount of stiiness to the Whole frame of the condenser. l

In this form, each of the stators is carried by a bracket 51 fastened to the bar insulator 54 in any satisfactory manner as by rivets 58, the stator being soldered to the projecting lingers 59 in the manner explained in Cramer application, Serial No. 717,860, heretofore referred to. It may be noted that the end plates i and 2 are provided with arms or brackets 66 for mounting the condenser. Similar brackets may be attached to the end bearing plates in certain of the other forms that have been described.

In Figure 23, the rods 5 and 6 are fastened to the end plates I and 2 in a manner similar to that shown in Figures 18 and 20. A metallic bar 6|., similar to the bar 55, is staked into position in slots in the end plates I and 2 and in the shield plates but in this case the bar insulator 62 does not pass through the end plates I and 2 but is held therebetween to the metal bar 6| as by rivets 63. The stator group of plates is held to the insulator 62 in the same manner as in Figure 20.

In Figures and 26, bar insulators 64, similar to 54, are used, but these bars pass through slots in the end plates and 2 and are held in position as by staking at 65. The stator group 01' plates is held to the vinsulators 64 by brackets plates 43. The screws and insulating bushings.

used in holes 41 and the trimmer plates are not shown in Figure 13, "but their function-is well understood. Each trimmer platehas an ear or lug 48 thrown outwardly therefrom for the purpose of making electrical connection to the stator.

66 which have inwardly projecting fingers somewhat similar to the iingers 59 to which the stator tie bars are soldered. The bracket 66 extends downwardly over the insulator so as to act as one In Figures 17, 18 and k19, the construction isV very similar to that shown in Figures 13 to 16 inclusive, except the frame rods 5 and 6 are moved inwardly toward the shaft, notches 49 element of a trimmer condenser, the other element being a metallic member 61 which may have a bent end folded over and fastened to the shield plate as by rivet 66. An adjusting screw 69 and insulator 10, as shown in Figure 25, are used for adjusting the position of the trimmer plate 61, it being understood that a thin insulator, such as a piece of mica, is mounted between the trim- 0f the various forms of condensers utilizing a frame having end plates held together by heavy binding rods, I prefer the construction shown in Figures 17 `to 19 inclusive, where the stator plates are suspended from the binding rods and an auxiliary metallic bar is utilized .for an element of the trimmer condensers, as well as act ing as a stiiening member for the frame.

In certain of the forms, for example in Figures 7, 13 and l'l, the shaft i3 is indicated as being hollow and having a plurality of holes it therein. These holes are utilized for certain speed-producing mechanism which forms no part of my present invention and will therefore not be further referred to herein.

In Figure 29, the end plates t, only one ofwhich is shown, are fastened together'with rods t in about the same manner as has been previously described; likewise, the insulators 33 are held to the rod d by staking them in the grooves in the rod t. The insulator 33 has holes therein to receive one or more (2 being shown) insulating bushings l5. These insulators are preferably of isolantite and may be held in the insulators @t in any satisfactory manner as by a force-nt, the hole in the insulator 3d or the portion of the bushing l5 tting in this hole being iirst treated with suitable cement.

The bushing it carries an eyelet ld, the outer ends of which are spun over at 'il to clamp a trimmer plate i8 securely in position. The free end of the trimmer plate l5 is arranged in overlapping relationship to an upstanding part 'le of the end plates i, an insulator et, preferably of mica, being used as the dielectric between the parts 19 and the trimmer plate l, the usual adjusting trimmer screw 69 and insulating bushing it being used. The stator tie bar 26 is provided with an outwardly extending lug 8l which may be punched from the tie bar 2d, or it may be made in a separate piece and soldered to the bent portion 2e of the tie bar 24 before the stator Ii is ready to be assembled in the condenser frame. In either case, after the stator has been placed in the frame the extreme end 82 pf the lug 8i is soldered across the outer face of the eyelet 16. By this construction, the soldering operation is brought to the extreme outside portion of the condenser, thereby speeding up the operation of assembly, it being understood that Vtloetator and rotor elements are positioned by a suitablexture previous to soldering as heretofore ,referred to. In some cases, the insulation pieces 33 may be dispensed with and a piece .of

steel usedin their stead, the isolantite bushing' 15 being suicient to provide the necessary insulation in mounting the stator. or stators to the frame. x l

In Figures 31 and 32 the metal of the end plate I is extruded or forced inwardly at 83 to provide a longer bearing for the rods 6, it being understood that the rods 6 have a force-llt into the end bearing plates i so that the frame produced is a rigid one. I may also spot-weld the ange or plate il artiest extruded portion 83 to the rod e, as well as spotweld the end of the rod to the plate around the line 86. In addition, the end plates may be provided with another rod e positioned at the bottom of the end plates, this extra rod being fastened to the plates in any of the ways described herein.

In Figure 33, the rod d has a reduced end portion at te force-fitted into the end plate i, having an extruded portion et the same as in Figure 3l, but in the opposite direction. The reduced end portion et may be also spot-welded around the distributed flange In Figure 35, the rod t has a reduced end portion de 'which is force-tted into the end de and the outer portion spun over the plate at di.

In Figures 37 and 38, the end of the rod d may have some other form than circular, such as a square shape 89, the outer end of the rod being spun over or welded at et.

It is to be understood that any of the previously described forms may have a rod at, the bottom of the end plates as shown in Figures Sl to 38 inclusive.

In Figure 39, the frame rods, only one oi which, 5, is shown, are rectangular inshape. The frame rods are grooved to receive insulators il@ carrying the studs di which are soldered to the tie bars at the point 26. Riveted on the outer ends oi the studs lli, against the insulators is a trimmer plate it which, however, in s case is formed upwardly into the desired shape and es:- tends into capacity position with the frame rod d, being adjusted with respect thereto by the screw te, it beingV understood that the usual insuiator is used between the trimmer plate l@ and the rod 1 In Figure d0, the frame rod d is shown as being welded to the end plate 2. The welding open-1 ation may be any of the well-known processes, such as spot, butt. or even arc welding, either ot which will securely anchor the bars and end ,dates together, without being obliged to notch or perforate the end plates to receive the ends This reduced end may be lrnuried at of the frame rods. Therefore, when I speak of l the end plates being securely anchored to the frame rods, this may be accomplished by any of the ways herein described which are broadly rey ferred to as cooperative formations.

From what has been said, it will be underst that the general object is to get, for a single unit or gang condenser, a frame that is light yet rigid, and one that is easy to make, and at the same time provide a frame that will enable the condenser elements to be mounted thereon as free from stresses as possible.

What I claim is:

1. An electrical condenser comprising at least one stator and rotor set of elements; a lightweight, high rigidity, non-warping frame for sup-porting said elements in close cooperative vpredetermined and 'non-drifting relationship, including rigid metal end bearing plates for supporting a shaft carrying the rotor plates, means for securely holding said bearing plates in nonwarpingoperative'position including a plurality of metallic rods of a material and size as dened herein and disposed at least one on each side of the shaft, said rods at their extremities and the said reduced rod portions. which latter engage ments comprise gripping surfaces of relatively large lateral area for the purposes described.

2. An electrical condenser as set forth in claim 1, further characterized in that a plurality of groups of stator Vand rotor elements are provided to form a gang condenser, at least two of said rods having additional grooves spaced between Said groups of elements, and shield plates tightly tting in said grooves similarly to said end plates.

3. An electrical condenser as set forth in claim 1, further characterized in that said rods have longitudinal grooves at least at leach end, and parts of said bearing plates being forced into said longitudinal grooves. A

4. An electrical condenser' as set forth in claim 1, further characterized in that at least two of said rods have longitudinal grooves extending for at least the major portion of the length thereof, insulators fastened in the grooves of said rods and extending away from the rods and having means attached to their opposite ends for supporting the stator element.

5. An electrical condenser at set forth in claim 1, further characterized in that at least two of said rods have longitudinal grooves extending from lend toend of the rods, parts of said end plates being forced into said grooves, insulators staked in position in said grooves and extending away from the rods, and means carried by the insulators for attaching a stator element thereto.

6. A condenser as set forth in claim 1, characterized in that the stator having tie bars is suspended from at least two of said rods by means including insulators fastened to the rods and studs having ends fastened to the insulators and their opposite ends being soldered to the tie bars.

'7. A condenser as set forth in claim l, characterized in that the stator having tie bars is suspended from at least two of said rods by means including insulators fastened to the rods and studs having collars fitting against one face of the insulator, and ends extending from the collars and riveted over on the opposite side of the insulator, the opposite ends of the studs being soldered to the stator tie bars.

8. A condenser as set forth in claim 1, characterized in that the stator having tie bars is suspended from at least two of said rods by means including insulators fastened to the rods and studs having collars fitting against one face of the insulator, and ends extending from the collars and riveted over on the opposite side of the insulator, the opposite endsv of the studs being soldered to the stator tie bars, and a `trimmer condenser plate also rivetedto at least one of the insulators by the same stud ends.

9. A condenser as set forth in claim 1, characterized in that the stator having tie bars is suspended from a plurality of said rods by means including insulators fastened to the rods and studs having collars fitting against one face of the insulator, and ends extending from the collars and riveted over on the opposite sidel of the insulator, the opposite ends of the studs being soldered to the stator tie bars, and a trimmer condenser plate also riveted to at least one of the insulators by the same stud ends, said condenser being further characterized in that metallic bars extend between and are fastened to the end bearing plates, one on each side of the condenser, the bars being positioned to act as one element of the trimmer condenser and as a frame-bracing member.

10. A condenser as set forth in claim 1, c haracterized in that the stator having tie bars is suspended from a plurality of said rods by means including insulators fastened to the rods and parts carried by the insulators -soldered to the tie bars of the stator, said parts comprising a metal plate fastened to each insulator, each plate having arms extending beyond the sides of its insulator toward the stator, each arm having a lip extending one toward the other and being soldered to the, stator tie bar on each side of the condenser.

11. A condenser as set forth in claim l, characterized in that the stator having tie bars is suspended from a plurality of said rods by means including insulators fastened to the rods and parts carried by the insulators soldered to the tie bars of the stator, said parts comprising a metal plate fastened to each insulator, each plate having arms extending beyond the sides of its insulator toward the stator, each arm having a lip extending one toward the other and being soldered to the stator tie bar on each side of the condenser, said metal plate also acting as one element of a trimmer condenser.

12. For an electrical gang condenser having a plurality of stator and rotor groups of plates, a light-weight, high-rigidity, non-warping frame including two rigid, metallic end bearing plates for the shaft carrying the rotors, said shaft and stators being held in fixed non-warping spaced relationship by a plurality of metal rods of a material and size as defined herein and disposed at least one on each side of the frame, said rods at their extremities and the end plates having cooperative formations press-fitted together in slidable gripping engagement across a portion of the rods reduced in diameter as well as on opposite sides of said end plates adjacent said reduced rod portions, which latter engagements comprise annular gripping surfaces bounded by the outside diameter of the rods.

13. A frame for an electrical condenser as set forth in claim 12 further characterized in that the frame has rigid, metallic bar members located, adjacent said rods onV each sidev of the frame and extending between and rigidly fastened to said end bearing plates.

14. A frame for an electrical condenser as set forth in claim l2 further characterized in that the frame has bar members located adjacent said rods on each side of the frame and extending between and rigidly fastened to said end bearing plates, said bar members including strips of rigid metal and insulation, the insulation strip carrying the stator plates.

15. A frame for an electrical condenser as set forth in claim 12 further characterized in that the frame has rigid, metallic bar members located adjacent said rods on each side of the frame and extending between and rigidly fastened to said end bearing plates, said bar members carrying insulation strips that support the stator plates.

16. A frame for an electrical condenser as set forth in claim 12 further characterized in that the frame has bar members located adjacent said rods and extending between and fastened to said end bearing plates, said bar members including strips of metal and insulation, the insulation strip carrying the stator plates, said insulation strip being held in slots in the end bearing plates by the metal strip.

17. A frame for an electrical condenser as set forth in claim 12 further characterized in that the frame has bar members located adjacent said rods and extending between and fastened to said end bearing plates, said bar members being a; abonnes of insulating material to which atleast the stator is attached.

18. A frame for an electrical condenser as set 'forth in claim 12 further characterized in that to hold said bars therein.

i9. An electrical condenser as set forth in claim l, further characterized in that a plurality of groups of stator and rotor elements are provided to form a gang condenser, at least two of said rods having additional grooves spaced between said groups of elements, and shield plates tightly fitting in said grooves similarly to said end plates, said rods having further additional annular grooves for receiving stator support elements. 1

20. For an electrical condenser having stator and rotor groups of plates, .a frame including two end bearing plates for the rotor shaft held in fixed spaced relationship by a plurality of metal rods of relatively large diameter disposed at least one on each side of the frame, said rods and end plates having forced/interlocking 'lts made 'integral by welding, said rods having relatively large lateral bearings at least on the inside portions of the end plates.

2l. An electrical condenser as set forth in claim l, further characterized in that at least two of said rods have longitudinal grooves extendving for at least the major portion of the length thereof, members fastened in said grooves and extending away from the rods. at least one bushing of insulating material carried by said members, said bushing having an eyelet going therethrough and a metallic arm fastened to the eyelet and to a stator element tie bar.

22. An electrical condenser as set forth in claim l, further characterized in that at least two of said rods have longitudinal grooves extending for at least the major portion of the length thereof, members fastened in said grooves and extending away from the rods; at least one bushing of insulating material carried by said members, said bushing having an eyelet going therethrough, a metallic arm fastened to the eyelet and to a stator element tie bar, further characterized in that a trimmer plate is fastened to said insulator by said eyelet.

23. For an electrical condenser having stator and rotor groups of plates, a frame including two end bearing plates for the rotor shaft held in hxed spaced relationship by a plurality of metal rods disposed at least one on each side of the frame, said rods at their extremities and the end i plates having cooperative formations such. that these parts may be permanently anchored together, further characterized in .that at ieast twoI of said rods have longitudinal grooves therein, insulators fastened in said grooves and en tending away from the rods, at least one rnetal= lic stud carried by each insulator and extending to a point near astator tie bar and soldered thereto, and a trimmer plate held to said insu lator by said stud and extending into capacity relationship with said rod, with means carried by the rod for adjusting the position of the trimmer plate with respect thereto.

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