US3831399A

US3831399A - Drive shaft configuration for a high voltage antenna tuning mechanism

Info

Publication number: US3831399A
Application number: US00330926A
Authority: US
Inventors: C Majkrzak; S Sladowski
Original assignee: Deutsche ITT Industries GmbH
Current assignee: TDK Micronas GmbH; ITT Inc
Priority date: 1973-02-09
Filing date: 1973-02-09
Publication date: 1974-08-27
Anticipated expiration: 1991-08-27
Also published as: NL7401727A

Abstract

There is disclosed dielectric material drive shaft constructions designed for use particularly in high electric-field potential environments such as in driven tuning mechanism of a high voltage helical transmitting antenna, which shaft constructions are capable of maintaining operation under unusually high mechanical loads requiring both rotational and axial movement. A plurality of elongated common-stock pieces of layered epoxy or siliconbonded fiberglass are shaped cross-sectionally to be united predeterminably into a unitary form via longitudinally running bonds of epoxy adhesive. The unitary form cross-section is a ''''soft'''' polygon, for example a rounded-off triangle or square, wherein the individual pieces are so arranged as to have the interlaminar shear planes of the layered dielectric material substantially perpendicular to the direction of the force of the applied loads. To provide a shaft surface which resists wear, prevents surface contamination, and has nontracking properties most beneficial in preventing arcing and creepage in extremely high potential electric gradient environments, a sleeve or jacket of teflon is provided about the shaft''s outer surface. In cases where shafts loads are excessive, the shaft construction may include a multiplicity of strong dielectric pins driven thru the unitary structure, each across a successive interfacing epoxy bond, to form a helical pin configuration which resist interlaminar shear loads and provides additional strength to these bonds.

Description

[451 Aug. 27, 1974 DRIVE SHAFT CONFIGURATION FOR A HIGH VOLTAGE ANTENNA TUNING MECHANISM [75] Inventors: Charles P. Majkrzak, Nutley;

Stephen F. X. Sladowski, Bayonne, both of NJ.

[73] Assignee: International Telephone and Telegraph Corporation, Nutley, NJ.

[22] Filed: Feb. 9, 1973 [21] Appl. No.: 330,926

[52] US. Cl. 64/1 R, 64/2 R, 1'74/D1G. 1,

343/895 [51] Int. Cl. Fl6c 1/00 [58] Field of Search 64/l R, -1 S, 2R, 23; l74/DIG. -l, DIG. 4; 343/895 [56] References Cited UNITED STATES PATENTS 2,763,003 9/1956 Harris 343/895 2,997,529 8/1961 Fink l74/DIG. 4 3,213,254 10/1965 Strom l74/D1G. 1 3,296,826 1/1967 Van DeGraff. 64/1 R 3,357,205 12/1967 l-loltkamp 64/] R 3,683,393 8/1972 Self 343/895 3,737,910 6/1973 Francis et al. 343/895 Primary Examiner-Samuel Scott Assistant Examiner-Randall Heald Attorney, Agent, or Firm-John T. OHalloran; Menotti J. Lombardi, Jr.

I II I) RADOME 8*;

[57]v ABSTRACT There is disclosed dielectric material drive shaft constructions designed for use particularly in high electric-field potential environments 'such as in driven tuning mechanism of a high voltage helical transmitting antenna, which shaft constructions are capable of maintaining operation under unusually high mechanical loads requiring both rotational and axial movement. A plurality of elongated common-stock pieces of layered epoxy or silicon-bonded fiberglass are shaped cro'ss-sectionally to be united predeterminably into a unitary form via longitudinally running bonds of epoxy adhesive. The unitary form cross-section is a soft polygon, for example a rounded-off triangle or square, wherein the individual pieces are so arranged as to have the interlaminar shear planes of the layered dielectric material substantially perpendicular to the direction of the force of the applied loads. To provide a shaft surface which resists wear, prevents surface contamination, and has nontracking properties most beneficial in preventing arcing and creepage in extremely high potential electric gradient environments, a sleeve or jacket of teflon is provided about the shafts outer surface. In cases where shafts loads are excessive, the shaft construction may include a multiplicity of strong dielectric pins driven thru the unitary structure, each across a successive interfacing epoxy bond, to form a helical pin configuration which resist interlaminar shear loads and provides additional strength to these bonds.

l3 Claim, 10 Drawing Figures BRUSH 6 COIL FOR/1 4 Sl-IOR rmq ARRANGEMENT 5 DRIVE SHAFT I PATENTED nuczmu SHEET 1 OF 3 W SHOR rl/vq RRANCEME/VT 5 DR/ v5 SHAFT I RADOME a 5HOR Tuv BRUSH 6 COIL FORM 4 Qfi ,g

D/RE C T/O/V OF L AMI/VA 77 ON loc WWW PATENTEB AUG 2 1 m4 SNEEI 3 OF 3 v 1 -DRIVE'SIIAFT CONFIGURATION FOR A HIGH VOLTAGE :ANTENNA'TUNING MECHANISM BACKGROUND or THE INVENTION This invention relates to high voltage antenna tuning arrangements, and more particularly to the drive shaft construction and'arrangement for tuning apparatus in high voltage antenna environments.

Antennas requiring a special drive shaft construction fortuning purposes may be of the high power transmitting type in the '2 to3O mhz range for shipboard and submarine useand comprisedprimarilyof the tunable inductive/capacitive:type; thatis, an inductive helix in series withand physically arranged :end-to-end with-a capacitive cylinder. Such antennas are disclosed in copending U.S. applications Ser. No. 324,607 filed Jan. 18, 1973 and Ser. No. 329,792 filed Feb. 5, 1973, the disclosures of which applications, in so far as they are pertinent to the present disclosure and, invention, are

incorporated herein by reference.

The tuning arrangement is, by design, a driven metal tube with one" end contacting the helix internally through an assembly of graphite brushes, the other end similarly contacting the cylinder internally, and a-multi plicity of .predetermina-bly spaced graphite brushes alternately contacting both the helix and the cylinder as required in its travel over the tuning range. This'tuning element is motor-driven by a spline shaft that not only imparts rotation to the tuning element so thatthe brushes slide alonga' helix turnbut also permits an axial movement of the tuningelement within the helix so .as to permit the brushes to follow the pitch of the helix turn. Aseriesof grooved rollers engaged onto the helix and mounted upon the tuning element imparts the proper axial movement to the tuning element. lt is this spline"shaft that is the object of this disclosure.

Since the spline shaft is rotated axially within the helix, it is subject to intense r.f, electric fields, which precludes the use of metallic drive shafts. The drive shaft must, therefore, be of dielectric materiaL-and of course, with acceptable physical properties to transmit the imposed rotation loads within its environment.

It is, therefore, an object of this invention to provide a novel driven shaft of construction capable of satisfac torily performing under the environmental conditions above-mentioned, and particularly the conditions wherein exceptionally short radiators are employed within transmitting antenna configurations of very high power rating. ln transmitting antennas of lower power rating or of reasonably tall radiators where the potential gradient along the helix is mild, the use of epoxybonded fiberglass is permitted. In transmitting antennas of higher power rating and/or of exceptionally short radiators where the potential gradient along the helix is steep, the use of silicone-bonded fiberglass is necessary. The dielectric properties that determine the choice of material are its dielectric constant and its power factor, the product of which is its loss factor;.this

latter factor is a measureof the power loss within the substance. This loss of power, of course, decreases the antennass efi'iciency and shows up as heat in the driven shaft, which can destroy it. It can be shown that the epoxy-bondedfibe'rglass will absorb ten times the electrical energy as will silicone-bonded fiberglass under the same conditions.

Since the drive-shaft'is one that'imparts axial movement to the tuning (shorting tube) .assembly as well as rotation, sliding necessarily occursat the interface. The

choice and configuration of material atthisinterface minimizing electrical stress concentration and associated steep voltage gradients particularly in an antenna tuning arrangement of the type described above.

It is a further object to provide a drive shaft construction and arrangement-which minimizes the'transfer of potentially harmful contaminants onto the shaft face.

It is another object of this invention to provide such a drive, shaft construction which even if creepage should occur along its face due to outside considerations, the surface material is of the type which is capable of repairing itself and thus in effect erase the creepage path immediately following a discharge.

In the practical sense, creepage resistance of'various materialsis determined by standard test procedures that measure surface resistance to electrical flow and the time for complete surface breakdown of the substances under predetermined conditions. By way of'example:

Surface Surface Material Resistivity Arc Resistance Epoxy-Bonded Fiberglass lxlO ohms 100 secs Silicone-Bonded Fiberglass IXIO ohms I90 secs Teflon (Fluorocarbon 'Resin) lXl0"ohms over 300 secs Finally, to completely grasp the significance of this disclosure, it is importantalso to compare certain important physical properties of the laminated materials concerned herein, namely directional strength and interlaminar strength.

Flexural Bonding Material Strength Strength Epoxy-Bonded Fiberglass 60,000 psi 2600 lb Silicone-Bonded Fiberglass 27,000 psi 900 lb in the past, where silicone-bonded fiberglass was necessary for electrical reasons, the required shaft strength was obtained by orienting the glass fibers to adequately of silicones, a source of supply for such a shaft con- SUMMARY OF THE INVENTION According to the broader aspects of this invention there is provided a driveshaft comprising a rod-like structure having a rounded polygonal cross-section and composed of a material from the class of epoxy-bonded fiberglass or silicone-bonded fiberglass, and having disposed about the exterior thereof a layer of teflon.

Also there is provided a drive shaft comprising a unitary structure made up of a plurality of elongated members mounted together in symmetrical arrangement about a longitudinal center axis, said members being composed of layered dielectric material from the class of dielectric materials which include epoxy-bondedfiberglass and silicone-bonded fiberglass, wherein each member has a longitudinally running principal plane of FIG. 4B schematically illustrates in end view the cross section of another embodiment of the drive shaft according to the invention; and

FIG. 5 is a perspective view of the drive shaft complete with a teflon sleeve according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a drive shaft 1 constructed in accordance with this invention is shown situate in a contemplated very high voltage and space restricted environment. This contemplated environment comprises the mast of a submarine having a radome.2 of dielectric material enclosing among other things a transmitting antenna. The antenna as hereinbefore described is of thetunable inductance/capacitance type, wherein the symmetry parallelly running with the layersthereof and epoxy-bonded fiberglass, in which the unitary arrangement of the pieces is such that the loads on the drive shaft are directed across rather than along the interlaminar shear planes.

Another majorfeature of the invention is a staggered arrangement of pins of strong dielectric material driven successively in helical formation through the epoxy bonds securing the three-piece construction.

BRIEF DESCRIPTION OF TI-IEDRAWINGS The above-mentioned and other objects and features of this invention will be more clearly understood from the following description taken in conjunction with the accompanying drawings, in which:

FIG. I is a fragmentary, partial-sectional side view helix (inductive) portion 3 is provided within a dielectric coilform structure 4.

Riding the shaft 1 is a tunable short arrangements of which only'the lower half is shown. By the tuning of drive shaft 1, the short 5 revolvingly remains in contact with a particular turn of the helix 3 via-a shorting brush 6, while simultaneously also being displaced vertically within the helix. The other end of short 5 (not shown) is in contact with the cylindrical (capacitive) portion of the antenna, via another shorting brush, thus providing a variable inductance/capacitance ratio relative to the position of the shorting arrangement.

The lower or drive portion 5a of shorting arrangement 5 is provided with a soft or rounded-off triangular aperture which corresponds to the rounded triangular cross-section of shaft 1, as may be better seen in FIGS. 4A and 5. It is to be noted that the shorting brushes 6 used in thearrangement 5 may conventionally be constructed of graphite. Moreover, the fit of end 5a of shorting arrangement 5 is intended to be close enough with shaft 1 so as to provide efficient schematically illustrating the novel drive shaft in an ex- FIG. 3A schematicallly illustrates the staggered arrangement of pins incorporated in the shaft according to the invention for combating shear forces;

FIGS. 3B-3D illustrate in enlarged cross-sectional views the drive shaft according to the invention taken at IIB, IIC and IID respectively of FIG. 3A, and showing the helical sequential arrangement formed by the pins in the triangular bonded shaft structure;

FIG. 4A schematically illustrates in end view the cross-section of the drive shaft in finished form as milled from the arrangement according to FIG. 2B;

operation, and which, therefore, results in more or less continual circumferential contact with the latter as the short moves vertically up or down. In view of this rubbing contact, together with the normal wearing of the graphitev brushes, there tends to occur a buildup of graphite-particles and other impurities on the surface of the shaft 1 which creates potential flash or creepage paths along the surface thereof which could result in the destruction of the equipment. A solution for this problem is provided by surrounding the shaft in a teflon sleeve or coating, which will be more clearly disclosed hereinafter.

As the splined shaft 1 is axially arranged within the helix according the the example arrangement of FIG. I, it experiences intense RF fields, thus making it impractical to use metallic drive shafts. Therefore, faced with the condition that drive shaft construction must be of dielectric material, the choice thereof together with shaft design must provide sufficiently acceptable physical properties to enable a continual transmission of imposed rotation loads within its environment.

Lower power antennas or antennas having tall radiators have comparatively mild potential gradients to contend with. In these instances epoxy-bonded fiberglass may be used as the dielectric drive shaft material. However, in instances where the drive shaft will be subjected to much steeper potential gradients, such as tors, silicone-bonded fiberglass material is required, the

Silicone-Bonded Fiberglass justification for which may be seen from differences in properties of the two materials as indicated in thetables given hereinbefo're. Another comparison between the two materials may be derived from the following Referring now to FIG. 2A, there is illustrated in end view an elongated piece of silicone-bonded fiberglasstaken from commercially available stock. This piece has been cut so as to possess in cross-section substantially .the pentagonal shape of home plate in baseball. The fiberglass stock is layered'or laminated, with the parallel layers or laminations 10a of the stock 10 being themselves parallel to the pair of parallel sides 10b of the pentagon, and also parallel to the bisector of the obtuse anglev vertex 10c of the pentagon. A line drawn parallel to the base side 10d of piece-10 and tangent to the vertex 100 forms with the two angled equallength sides l0e angles 0, preferably 30. The length of side 10d is 2,, preferably one inch stock and the distance between vertex 10c and base side 10d is 1 The shape of the elongated piece 10 defines a principal axis of symmetry which from a cross-sectional point of view bisects base side 10d and obtuse angle 10c.

Three pieces of the type shown in FIG. 2A are placed together longitudinallyto form an unitary piece 9, as shown in FIG. 2B, by way of firm bonds 12 of epoxy adhesive, running the entire length of the pieces 10. The union of the three pieces 10 is accomplished by placing the respective vertices 10c thereof together at 13, wherein by virtue of the angular shape of sides 10c of each of the pieces 10 as defined by 0, these sides match up to each other to form three basic interfaces 14 running the entire length ofthe elongated pieces 10. To be noted is the fact that each'one ofthe bonded interfaces 14 is parallel to the laminations of a respective oppositely arranged one of the pieces 10. I

FIG. 3A is illustrative of a schematic side view of the unitary structure 9 depicted in end view in FIG. 2A, wherein a series of pins composed of dielectric material such as silicone-bonded fiberglass are driven through the'unitary structure 9at spaced intervals and in a simulated helical orientation as may be better seen in FIGS. 3B-3D. FIGS. 3B-3D are enlarged crosssectional views of the unitary structure 9 in FIG. 3A taken respectively at IIB, IIC and IID thereof. As such, the pins 15 in FIGS. 3B-3D relate to successive pin positions X Y and Z, of FIG. 3A.

- For convenience and clarity the three pieces 10 forming the unitary structure 9 are labeled A, .B and C in FIGS. 3B3D to demonstrate the successive helical staggering of the pins 15 around and along the structure 9. As shown, pin position X,, which is depicted in FIG. 3B, relates to a pin 15 being driven across the epoxy bond 12 at the interface 14between pieces A and B. Likewise. FIG. 3C depicts the pin position Y, wherein a pin 15 is driven through the epoxy bond 12 at the interface 14 between pieces A and C. Similarly, FIG. 3D demonstrates the pin position 2,, whereinv a pin 15 is driven through the bond between pieces B and C The X position is a repeatof FIG. 3B, the Y position a repeat of FIG. 3C, and so on, thus forming a helical orientation of pins. It is to be understood that this pinned version of drive shaft disclosed in FIGS. 3A-3D is not required in all uses, the epoxy bonds 12 at the various interfaces 14 themselves being sufficiently strong for normal contemplated shear loads. The pinned version represents a drive shaft construction for use with abnormally high torqueloads.

The description thus far has indicated that in the pinned embodiment the pins were driven through the bonds. However, any suitable means of providing the pins 15 in their intended orientation may be used; for example drilling holes having the proper orientation may be drilled through the shaft and the pins 15 placed therein, preferably maintained via epoxy adhesive. It is preferable also, though not intended to be a limit to this invention, to assemble the pins 15 into the structure before final milling to achieve the rounded triangular cross-sectional shape depicted in FIG. 4.

- Referring to FIG. 4, there is depicted in dashed lines the outline of unitary structure 9, havingbeen milled down to the desired final softtriangularshape 18 according to the invention. This final shape is defined in part by a predetermined length L of aline 19 running between any one of the rounded vertices 18a and the center 18b of the side 18b opposite that vertex. Further definition may be derived via the combination of an extension 19a of this line 19 beyond the vertex 18a, together with extensions 17 of the sides of triangle 18 that make up the vertex 18a, forming a pair of angles 0, also in this case 30.

To be particularly noted in FIG. 4 is. the fact that the loads to be placed on the shaft, as represented by arrows 21,-are, by way of the orientation of the individual pieces 10'. making up the triangular cross-sectional shape of the shaft, oriented at almost right angles with the lamination planes 10a of the individual pieces 10. Because of this the possibility of delamination due to shaft loading is virtually nil. Moreover, by the orientation of .thepieces 10 and their respective laminations, delamination as a result of the milling operation to achieve the final rounded-off triangular shape crosssection will not occur.

It is to be understood that this invention is not to be limited in any way by the fact that the pieces 10 in the example description above are pentagonal in shape. These pieces 10 could for example be originally four sided as evidenced by the dotted lines 22 in FIG. 4. The most important consideration is that the individual pieces 10 be shaped to form close interfaces with each other to permit a uniform bond to be created therebetween.

In accordance with this, the arrangement of FIG. 4B is possible, wherein a substantially rectangular (square) construction is depicted. The basic orientation and construction method of the individual elongated pieces, relative to each other and relative to their respective laminations, is the same as for the triangular shaft construction described above. In this case, however, the individual elongated pieces are substantially square in cross-section and together form a composite or unitary square construction. Here, as is the case with the triangular construction, the shaft loads are substantially perpendicular (applied across) the laminations as indicated by the arrows in FIG. 4B. A sequential helical pin arrangement may also be incorporated into the square construction. As indicated hereinbefore, how- .ever, by virtue of the fact that the orientation of glass fibers of the individual pieces making up the composite structure is such as to prevent applied loads from coinciding directly with weak shear planes, there is permitted the fabrication of a drive shaft with relatively common techniques from readily available stocked materials without the need for the pin arrangements in all cases of normal loads.

Since the trend in more recent developments has been towards physicallyv shorter antennas, which, in turn, entails steeper voltage gradients, the reliability of the drive shaft should then be, at least, maintained, if not increased. The means for maintaining and increasing performance in this regard according to the invention is to apply a nonporous jacket or coating of teflon on the shaft to increase its surface resistivity and its surface are resistance. We have experimentally accomplished this for example by applying an off-the-shelf shrinkable teflon tubing over the shaft. Teflon has a dielectric constant of 2.1 and a dissipation factor of .0004 which'produces a loss factor of .0008 (negligible power adsorption in this application). It displays a very acceptable static-friction coefficient of .08 and dynamic-friction coefficient of .10 at a PV of 8,000. lts surface not only helps prevent the formation of surface contamination, but also provides a non-tracking property (alluded to hereinbefore) since carbonized conducting paths are not generated during arcing with teflon.

The drive shafthas to be low loss to prevent adsorp: tion of the energy from the field of the helix. This is one major reason why silicone-bonded fiberglass is chosen as the basic shaft material in high power rated or short ened radiator antenna arrangements. Teflon, as indicated above, also has very favorable properties in this regard. However, the silicone tends to pick up impurities from the constant sliding contact with the tuning element, which impurities contribute to tracking and creepage. With a teflon sleeve, however, there is presented a surface more slippery than silicone which tends to prevent clinging by impurities. Moreover, even if sufficient particles become collected onto teflon sleeve to give rise to an arcing condition, teflon confines an arc to a track on the outer surface thereof, thus avoiding carnage to the shaft itself. By its self-healing'property, teflon successfully resists surface damage from the continual sliding contact with the tuning element and robs possible secondary arcs of any less-resistive surface tracks which in the case of other materials would have resulted from carbonization from the initial arcing condition. Thus, in the unlikely case that creepage does occur along the teflon sleeve 20 due to outside considerations, there results no permanent damage to the shaft.

To be noted in FIG. is a metallic end member la mounted to the shaft 1. It is permissible to use a metallic member here inasmuch as it is positioned at all times well away from the steep gradients and high fields associative to the radiating portion of the antenna arrangements. I a

There has been disclosed herein dielectric material drive shaft constructions designed for use particularly in high field potential environments such as a helically driven tuning mechanism of a high voltage transmitting antenna, which shaft constructions are capable of maintaining operation-under unusually high mechanical loads requiring both rotational and axial movement. A plurality of elongated common-stock pieces of layered epoxy or silicone-bonded fiberglass are shaped crosssectionally tobe united predeterminably into a unitary form via longitudinally running bonds of epoxy adhesive. The unitary form cross-section is a soft polygon, for example a rounded-off triangle or square, wherein the individual pieces are so arranged as to have the shear planes of the layered dielectric material substantially perpendicular to the direction of the force of the applied loads. To provide a shaft surfacewhich resists wear, prevents surface contamination, and has nontracking properties most beneficial in preventing arcing and creepage in extremely high potential gradient environments, a sleeve or jacket of teflon is provided about the shafts outer surface. In cases where shafts loads are excessive, the shaft construction may, include a multiplicity of strong dielectric pins driven thru the unitary structure, each across a successive interfacing epoxy bond, to form a helical pin configuration which provides additional strength to these bonds.

It is to be understood that the foregoing description of specific examples of this invention is made by way of example only and is not-to be considered as limiting on the scope of this invention as set forth in the objects and features thereof and in the accompanying claims.

What is claimed is: l. A drive shaft comprising a rodlike structure having a rounded polygonal cross-section and composed of a material selected from the group consisting of epoxybonde d fiberglass and silicone-bonded fiberglass, and having disposed about the exterior thereof a layer of fluorocarbon resin; and wherein the drive shaft is a unitary structure comprised of a plurality of elongated members bonded together and symmetrically arranged about a longitudinal center axis, each of said members being of layered construction, and wherein each member has a longitudinally running principal plane of symmetry in parallel with the layers thereof and is arranged such that said principal plane of symmetry includes said longitudinal center axis.

2. The arrangement of claim 1 further including a plurality of predeterminably spaced apart dielectric pins arranged to extend through the drive shaft, each pin extending across at least one of the bonded interfaces between said members which is different from the respective interfaces associated with the adjacent pins, wherein the arrangement of said pins taken together simulates a helical form.

3. The arrangement of claim 2 wherein said pins extend through the drive shaft in substantially perpendicular orientation relative to the center axis.

4. The arrangement of claim 1 wherein the drive shaftis substantially triangular in cross-section.

5. The arrangement of claim 1 wherein the drive shaft is substantially square in cross-section.

6. The arrangement of claim 2 wherein said layer of fluorocarbon resin is a sleeve of fluorocarbon resin shrink tubing.

7. A drive shaft comprising a unitary structure made up of a plurality of elongated members mounted together in symmetrical arrangement about a longitudinal center axis, said members being composed of layered dielectric material from the class of dielectric materials which include epoxy-bonded fiberglass and silicone-bonded fiberglass, wherein each member has a longitudinally running principal plane of symmetry parallelly running with the layers thereof and is arranged such that said principal plate of symmetry includes said longitudinal center axis.

8. The arrangement of claim 8 further including a layer of fluorocarbon resin disposed about the exterior of the drive shaft.

9. The arrangement of claim 7 wherein the drive shaft has a substantially triangular cross-section and each said member interfaces with and is bonded to each of the other members.

10. The arrangement of claim 7 wherein the drive shaft has a substantially square cross-section in which each member is also substantially square shaped in cross-section.

11. The arrangement of claim 7 wherein the longitudinally running edges of the drive shaft are rounded for minimizing potential gradients in a field of high electric potential. I

12. The arrangement of claim 7 further including a plurality of predeterminably spaced apart dielectric pins arranged to extend through the drive shaft, each pin extending across at least one of the bonded interfaces between said members which is different from the respective interfaces associated with the adjacent pins, wherein the arrangement of said pins taken together simulates a helical form.

13. A drive shaft comprising a plurality of elongated members arranged to be symmetrically mounted in side-to-side communication with each other about a longitudinal center axis to form a unitary rod-like configuration of rounded polygonal cross-section, each of said plurality of members being composed of a plurality of longitudinally running planar layers of one of the materials selected from the group consisting of epoxygonded fiberglass and siliconebonded fiberglass,

wherein the arrangement of said members is such that the planar layers thereof extend substantially perpendicular to the direction of the force loads applied to the drive shaft.

Claims

2. The arrangement of claim 1 further including a plurality of predeterminably spaced apart dielectric pins arranged to extend through the drive shaft, each pin extending across at least one of the bonded interfaces between said members which is different from the respective interfaces associated with the adjacent pins, wherein the arrangement of said pins taken together simulates a helical form.
3. The arrangement of claim 2 wherein said pins extend through the drive shaft in substantially perpendicular orientation relative to the center axis.
4. The arrangement of claim 1 wherein the drive shaft is substantially triangular in cross-section.
5. The arrangement of claim 1 wherein the drive shaft is substantially square in cross-section.
6. The arrangement of claim 2 wherein said layer of fluorocarbon resin is a sleeve of fluorocarbon resin shrink tubing.
7. A drive shaft comprising a unitary structure made up of a plurality of elongated members mounted together in symmetrical arrangement about a longitudinal center axis, said members being composed of layered dielectric material from the class of dielectric materials which include epoxy-bonded fiberglass and silicone-bonded fiberglass, wherein each member has a longitudinally running principal plane of symmetry parallelly running with the layers thereof and is arranged such that said principal plate of symmetry includes said longitudinal center axis.
8. The arrangement of claim 8 further including a layer of fluorocarbon resin disposed about the exterior of the drive shaft.
9. The arrangement of claim 7 wherein the drive shaft has a substantially triangular cross-section and each said member interfaces with and is bonded to each of the other members.
10. The arrangement of claim 7 wherein the drive shaft has a substantially square cross-section in which each member is also substantially square shaped in cross-section.
11. The arrangement of claim 7 wherein the longitudinally running edges of the drive shaft are rounded for minimizing potential gradients in a field of high electric potential.
12. The arrangement of claim 7 further including a plurality of predeterminably spaced apart dielectric pins arranged to extend through the drive shaft, each pin extending across at least one of the bonded interfaces between said members which is different from the respective interfaces associated with the adjacent pins, wherein the arrangement of said pins taken together simulates a helical form.
13. A drive shaft comprising a plurality of elongated members arranged to be symmetrically mounted in side-to-side communication with each other about a longitudinal center axis to form a unitary rod-like configuration of rounded polygonal cross-section, each of said plurality of members being composed of a plurality of longitudinally running planar layers of one of the materials selected from the group consisting of epoxy-gonded fiberglass and silicone-bonded fiberglass, wherein the arrangement of said members is such that the planar layers thereof extend substantially perpendicular to the direction of the force loads applied to the drive shaft.