US2395861A

US2395861A - Transmission line joint

Info

Publication number: US2395861A
Application number: US397771A
Authority: US
Inventors: Cyrus H Fraser
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-06-12
Filing date: 1941-06-12
Publication date: 1946-03-05
Anticipated expiration: 1963-03-05

Description

March 5, 1946. c FRASER TRANSMISSION LINE JOINT Filed June 12, 1941 5 Sheets-Sheet 1 INVENTOR Cyrus 17 Fraser ATTORNEY March 5, 1946. c. H. FRASER 2,395,861

TRANSMISSION LINE JOINT f Filed June 12, 1941 s Sheets-Shet 2 mvE/vron N Cyrus H fi-aser n'r'rannsr a March 5, 1946'. c. H. FRASER TRANSMISSION LINE JOINT Filed June 12, 1941 5 Sheets-Sheet 3 HWmTl INVENTOR Gyras f7 Fi'aser BY Arromvsr Patented Mar. 5, 1946 UNITED STATES PATENT OFFICE.

TRANSMISSION LINE JOINT Cyrus H. Fraser, Washington, D. 0.

Application June 12, 1941, Serial No. 397,771 18 Claims. (c1. 174-21) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) This invention relates to a joint to be used in a radio transmission line between two sections of the line, one of which must be rotated with respect to the other.

Radio transmission lines are used to conduct power from a radio transmitter or from an antenna to a receiver. The transmission line is composed of an outer tubular conductor and an inner conductor with air or another dielectric between them. Usually the inner conductor is from about 1%" to 1" in diameter and the outer conductor from A" to 3" in outside diameter. The inner conductor is suspended within the outer conductor andcentered by insulators usually of the ceramic type, which are fastened at regular intervals along the inner conductor.

Such transmission lines are usually filled with a gas under a pressure of from 10 to 20 pounds above atmosphere in order to prevent moisture from reaching the insulators on the inner conductor and destroying their insulating value. For several years there has been a need for a transmission line connection to an antenna which would allow the antenna to be rotated without appreciable loss of gas from the line over a period of several months. Such a connection to a rotating antenna must be so constructed that it will not introduce an impedance irregularity in the flow of radio frequency power to and from the antenna. In order to prevent the occurrence of such an irregularity the joining-means between the stationary and rotating parts of the transmission line must avoid the use of fittings which would have the efiect of causing a discontinuity in the size and spacing of the inner and outer conductors of the transmission line.

An impedance irregularity as discussed above results in a loss of power and becomes increasingly important as the frequency of the radio transmission increases.

'It is an object of this invention to provide a joint which will allow relative rotation between sections of a transmission line with allowing any appreciable escape of gas from the line over a period of several months. It is a further object of the invention to provide such a Joint which will not create a change in the impedance char- 7 gether with the accompanying drawings, in which:

Fig. 1 is a view partly in section taken along the axis of a transmission line and showing a joint embodying the invention;

Fig. 2 is a view similar to Fig. 1 showing the arrangement for maintaining a supply oi oil in the joint;

Fig. 3 is a view similar to Fig. 1 showing a second embodiment of the invention employing a single seal;

Fig.4 is a view similar to Fig. 1 showing a third embodiment of the invention making use of concentric oil chambers;

Fig. 5 is similar to Fig. 1 showing an embodimentof the invention adapted for use with horizontally extending transmission lines;

Fig. 6 is a view similar to Fig. 1 showing another embodiment of the invention-in which the seals of Fig. 1 have been replaced by packing;

Fig. 7 is a view similar to Fig. 1 showing another embodiment of the invention illustrating the use of a seal of a difierent type than that shown in Fig.1; and

Fig. 8 is a side view of an enlarged portion of the outer conductor.

In the embodiment shown in Figs. 1 and 2 relerence numeral i indicates the outer conductor of a transmission line having a concentric inner conductor 2 spaced from the outer conductor by means of a plurality of ceramic insulators .3. The space between the conductors is intended to be supplied with a gas at a pressure, for example, from 10 to 20 pounds above atmospheric. The outer conductor is shown as split into two sections at 4, the upper end of the lower section being of slitted construction resulting in a provision of a plurality of fingers 5 lnto'which the lower end of the upper section is inserted. The inner conductor is provided with a similar Joint at 6 having a plurality of fingers I. The complete joint of the inner conductor is shown on Fig. 2. The material of the conductors is of a springy nature which enables the fingers 5 and I to snugly grip the opposed section while still allowing rotation between sections.

The sealing means for this joint is contained in a housing 8 which surrounds the transmission line and is provided with a sleeve 9 snugly fitting the outer conductor of the transmission line and extending above the joint 4. The upper end of this sleeve is connected in a gas-tight manner to the lower end of the upper section of the outer conductor as shown at Hi. This connection may be soldered Q1 welded. S u y fitting amn d't lower section of the outer conductor is a sleeve H of some material, such as stainless steel, which will take a high polish and provide rigidity. The lower end or this sleeve is also connected in a gas-tight manner to the outer conductor by soldering or similar means of connection as shown in i2. (This sleeve extends upwardly inside the housing 8 and is provided with a pair of stepped bearing surfaces I3 and i4 upon which rotate oilless bearings |5 and I6 which form a part of the housing 8. As an additional safeguard against inadequate bearing lubrication, oil chambers l1 and i8 are provided in the housing 8 behind these bearings in order to provide the bearing metal with a constant supply of oil. Ducts are provided for filling these reservoirs, which ducts are normally closed in a gas-tight manner by means of threaded plugs l9 and 20.

The housing 8 is divided into 3 sections, 2|, 22 and 23, sections 2| and 23 containing the oil reservoirs I1 and |8 respectively, and the section 22 being a hollow cylindrical member which is secured to sections 2| and 23 by

lag bolts

24 and 25. The walls of section 22 are spaced from the sleeve H to provide an oil chamber 26. At each end of this chamber is secured in a gas-tight manner by flanges formed on abutting sections of the housing, a

soft steel ring

21 or 28 in which is imbedded a

bronze ring

29 or 30. Against one face of each of these rings is held a ring of hard steel 3| or 32. These steel rings are held against the respective bronze rings by means of a spiral spring 33 which surrounds the transmission line and has its ends abutting against a pair of

housings

34 and 35 in which are contained synthetic

rubber gasket rings

36 and 31. The

rings

36 and 31 are L-shaped in cross-section, having one portion snugly fitting the sleeve H and the other portion abutting the hard steel rings 3| or 32. The abutting faces of sealing rings 29, 3| and 30, 32 are lapped to optical flats. The chamber 26 is kept completely filled with oil. The frictional contact of

rings

36 and 31 with sleeve II is such that

housings

34 and 35 and the rings which they enclose will partake of the movements of sleeve II and there will be no loss of gas between the

rings

36 and 31 and the surface of sleeve II,

This type of joint is adapted for use in a vertical position. When so used the level of the oil in chamber 26 will always be below the level of the break in the transmission line which will prevent oil from entering the transmission line. In order to avoid any conduction of oil between the upper portion of the lower section of the line and the surrounding sleeve 9, the outer diameter of the outer conductor is reduced over an area including the lower portions of the fingers 5 as shown at 15 in Fig. 8.

In Fig. 2 is shown the means for filling the reservoir 26. It consists of a boss 38 formed on part 23 of the housing and having a chamber 39 therein, A filling duct 40 is normally sealed by means ofa-threaded plug 4|. Extending from near the top of this chamber down into the reservoir 26 is a pipe 42 which acts as an air vent to permit the escape of air from reservoir 26 when it is being filled with oil. A duct 43 extends from the bottom of the chamber 39 into the reservoir 28 for the passage of oil therethrough. Only the lower part of duct 43 is shown in dotted lines in Fig. 2, the upper portion being located behind pipe 42. A plastic window 44 is shown provided for the purpose of rendering visible the level of the oil in chamber 39.

In this embodiment of the invention the hous ing 8 is constructed to rotate with the upper section of the transmission line which leads to the antenna. It is shown in Fig. 1 as being supported by a member 45 which is also part of the rotating structure. The friction of the

synthetic rubber rings

36, 31 is such that these rings, the spring 33 and the hard steel rings 3|, 32 will all rotate with sleeve so that relative movement occurs between

rings

39 and 32 and between rings 29 and 3|.

Any leakage of gas between the two conductors of the transmission line must proceed from the fingers 5 downwardly between the sleeve H and the bearing ring l6, thence along the sleeve II and out into chamber 26 by way of the abutting surfaces of rings 38 and 32, Any leakage of gas which takes place into reservoir 26 serves to increase the pressure on the oil in that reservoir until the pressure on the oil is equal to the pressure in the transmission line, at which time no further leakage into reservoir 26 will occur.

Leakage of gas from chamber 26 can be completely stopped at all its gasket joints, Any leakage of gas out of the chamber must then occur by passage of gas between the abutting faces of rings 29 and 3| to the surface of sleeve II and thence out between the surface of sleeve II and the bearing sleeve I5. Experience has shown, however, that over a period of several months no leakage of gas whatsoever will occur.

Another embodiment of the invention is shown in Fig. 3 wherein the h using 8 remains stationary while the upper section of the transmission line rotates with respect thereto. In this embodiment a sleeve 46 terminates above the lower end of the upper section of the outer conductor and is connected thereto by a gas-tight means such as solder shown at 41. The sleeve extends downwardly past the joint, finally terminating at 14 within the lower part of housing 8. The upper part of sleeve 46 is supported in a packed joint formed at the upper end of housing 8. Immediately beneath this joint it is rotatively supported by means of a ball bearing assembly 5|). Beneath this assembly a flange" is formed on the sleeve and the sleeve is then continued downwardly with a uniform diameter until near its lower end where its diameter is reduced to form a shoulder indicated at 5|. Beneath the shoulder 5| the lower end of the sleeve is supported by means of an oilless bearing 52. While bearing 56 has been shown as a roller bearing and 52 as an oilless bearing, it should be understood that the type of bearing used is not material to the invention. Just above the shoulder portion 5| of the sleeve 46 is secured a. ring 53 preferably of bronze, this ring being held in place against rotation by flange 54 formed on a portion of the housing 8. A gasket 16 extending across the entire width of the side wall of housing 8 and the flange 54, together with a gasket 98 beneath the ring 53, aid in holding the ring against rotation and prevent gas leakage beneath the ring and out through housing 8 at this point. Bearing against the bronze ring 53 is a sealing assembly of the same type as shown in Figs. 1 and 2 composed of a hard steel ring packed with a synthetic rubber ring and a spring. It should be understood that where sealing assemblies of this type are mentioned that the materials, bronze and steel, are mentioned only by way of illustration. Such seals are conventional and the materials usually employed are bronze and steel, the purpose being to provide one hard and one soft bearing surface. It is not material which of the rings is bronze and which is flange 68. The reservoir 26 is filled with oil as in Figs. 1 and 2. The lower end of the housing 8 is secured by a gas-tight means such as soldering .to the lower stationary portion of the conductor as shown at 66. h

In operation the housing 8. the lower section of the transmission line and ring 63 remain stationary. The upper section of the transmission line together with sleeve 86 and the sealing assemblies consisting of spring 88 and the rubber and steel rings rotate together. Any sas leaking from the joint in the transmission line must pass downwardly beneath sleeve 46, out at its lower end 14, back over its outer surface under bearing ring 62, thence under ring 68 and out into chamber 26 throughthe seal. To leak from the chamber 26 the gas must pass upwardly through the packed Joint at the upper end of housing 8. Oil obviously cannot'leak into the interior of the transmission line either in this embodiment or in that shown in Figs. 1 and 2, since the oil level is at all times below the joint.

The embodiment shown in Fig. 4 is somewhat similar to that of Fig. 3 but employs a pair of concentric oil reservoirs and a pair of concentric seals. A sleeve 66 is secured to the lower end of the upper section of the outer conductor by means of a gas-tight seal shown at 61. It extends downwardly over the transmission on line joint and terminates just inside the lower end of the housing 8 as in Fig. 3 at point 58. The upper portion of the sleeve is supported in a packed joint formed in the upper part of housing 8 and beneath this joint is supported by ball bearing assembly 68. Beneath the ball bearing assembly 68 the diameter of the sleeve increases at a shoulder 66 and below this'point it flares out into a wide flange 6| having dependent therefrom, a skirted portion 62, the flange extending beyond the skirt. The housing is divided into three parts, the lowermost of which is numbered 63. Overlying part 66 and extending between sleeve 56 and the walls of housing 8 is a steel ring 66 which is held down against rotation with respect to housing 8 by means of a flange 61. formed on the inner walls of housing 8. A gasket 64 forms a gas-tight seal between the lower surfaces of the side walls of housing 8 and the ring 66 and .the upper surface of part 68. A pair of spaced, annular, upwardly extending flanges 66 and 11 are formed on ring 66 and against the fiat upper surface of each of these flanges is pressed 3. seal assemblylsuch as shown in Figs. 1 and 2 described above, consisting of a spring pressing against a housing containing a rubber ring and a steel ring, the upper ends of the springs of these assemblies being pressed against the flange 6|. The rubber ring of the assembly' which cooperates with flange 11 fits snugly against the outer surface of skirt 62 while the corresponding rubber ring cooperating with flange 66 is pressed against the outer surface of sleeve 66. The skirt 62 together with the seal carried thereon and flange 11 divide the interior of housing8 into 2 chambers, the inner one marked 68 and the outer 68. Chamber 68 is filled with oil through a fllling hole shown Any gas leaking out of the transmission line must travel downwardly of the sleeve 66 through its lower end68 and from thence up between sleeve 66 and bearing 13, then out into chamber 68 by way of the seal cooperating with flange 66,

from thence into chamber 68 by way of the seal cooperating with flange 1] and out through the packed joint surrounding the upper end of sleeve 66. As in the preceding embodiments, oil cannot leak ,into the interior of the transmission line, since its level never rises above the joint. In this embodiment the housing 8 is stationary while the sleeve 66 and the sealing means carried thereby revolve'with the upper section of the transmission line.

Fig. 5 shows an embodiment of the invention adapted for use with a horizontally extending transmission line, It employs a housing 8 of the same general type as used in the preceding embodiments which is secured in a gas-tight manner at 86 to the left hand or rotating end of the transmission line. A sleeve 6| is shown fitted over the right hand or stationary and of the e transmission line and secured thereto ina gasa thick cylinder 81, the inner diameter of which is enlarged by a shoulder 86 near its left hand end. Bolted to the shoulder 88 is an annular disc '88 having imbedded near its central edge a bronze ring 86. Abutting against the bronze rings 86 and 86 are a pair of seals of the type shown in Figs. 1 and 2 which are forced against

rings

86 and 86 by means of a spiral spring in a manner described in Fig. 1. This arrangement provides a large diametered chamber 81 to the left of disc 68. Secured to the sleeve 8| within this chamber are a pair of oil throwing discs 8| and 82. The reservoir to the right of disc 88, marked 88, is kept completely filled with oil in the previously described manner through oil hole 84 which is normally sealed in a gas-tight manner by means of plug 86.

In this embodiment the housing 8 rotates with the left hand section 'of the transmission line while the right hand section of the transmission line together with sleeve 8| and the seals carried thereby remain stationary. However, the right hand section may be rotated while the left hand section remains stationary, if desired. Any gas leaking from the transmission line must pass to the right between the outside of sleeve 8| and the bearing 86, thence by way of the seal cooperating with ring 86 into the chamber 88 and from there by way of the seal cooperating with ring 86 it must pass out of chamber 88 and thence between sleeve 8| and bearing 68 to the outside of the housing. Any oil which may succeed in passing by oil thrower discs 8| and 82 and be thrown to the walls of chamber 81, in the bottom of which sealed by plug 16 while chamber 68 is fllled through fllling hole shown sealed by plug 1|. Air

vents 18 and 18 are provided. The lower end of housing 8 is secured in a gas-tight manner to it will accumulate. A drain hole closed gas-tight by plug 86 is provided for draining this chamber.

The embodiment illustrated in Fig. 6 is similar to that in, 8s. 1 and 2 with the exception that in this embodiment packed joints have been substituted for the seals shown in Figs. 1 and 2. The

housing 8 has an upwardly extending portion I66 which fits snugly over the Joint in the transmissionline and the upper end of which is sealedina gas-tight manner to theupper or rotating section of the transmission line at IOI. A sleeve I02 is fitted over the lower or stationary section of the transmission line near the Joint, and this is provided with two stepped bearing portion I03 and I04 which are supported for rotation by bearings I05 and I06. The portion I of housing 0 carries a dependent skirt I 01 having an internal diameter greater than that of the external diameter of portion I02 of the sleeve. Within the annular space formed between the skirt and sleeve are fitted packing means I00 which are compressed by means of a thimble I09 threaded into the lower end of the skirt. A similar skirt extends downwardly from the lower portion of housin 0 and packing I I0 is compressed within this skirt by means of thimbl III. The interior of housing 0 surrounding the upper skirt I0I comprises a chamber I I2 which is kept filled with oil by means of an oil filling duct I I 3 normally closed in a gastight manner by means of plug H4. The lower end of sleeve I04 is secured in a gas-tight manner by means of plug H4. The lower end of sleeve I04 is secured in a gas-tight manner to the lower portion of the transmission line as indicated at Any gas leaking from the transmission line must pass downwardly over the exterior of the sleeve between the portion I03 and bearing I05 and thence between the portion I02 and the packing I00 into chamber I I 2 from where it must pass between portion I04 and bearing I06 and then downwardly between portion I04 and packing I II to the outside of housing 0.

Many other sealing arrangement involving packing and embodying the invention may be resorted to. For example, resilient means may be interposed between the packing material I00 and H0 and their respective thimbles I09 and III. Another possible construction is the reversal of the lower skirt and the replacement of thimbles I09 and III by a common resilient means acting on both sets of packings.

In Fig. '7 is shown an embodiment of the invention employing a type of seal which varies somewhat from those previouslydiscussed. A sleeve I20 is secured in a gas-tight manner to one sec tion of the transmission line as shown at I2I. The ends of the sleeve are supported by bearings I22 and I23. The housing 0 is divided into three portions, the uppermost portion of which carries a ring I20 of synthetic rubber or similar material in which is imbedded a bronze ring I24. The central portion of the sleeve has secured immovably thereto as by solderin or welding, a ring I25 of hard steel. The ring may, if desired, be an integral part of the sleeve, formed by machining processes. The lowermost section of housing 0 has imbedded therein a bronze ring I26 against which is forced the hard steel ring of a spring pressed seal assembly such as was described in connection with Figs. 1 and 2. The upper end of the spring of this assembly abuts against ring I25. The lower end of housing 8 is secured in a gas-tight manner to the lower section of the transmission line as shown at I21. The upper end of the spring of the seal assembly bears against ring I25 and tends to force upwardly this ring together with sleeve I20 and the left hand section of the transmission line, thu maintaining a seal between ring I25 and I24. At the same time the spring also maintains a seal with respect to ring I20. Any gas escaping from the transmission line must pass upwardly between the sleeve and the bearing I23 and thence out into the oil filled central chamber I20 of housing 0 by way of the seal cooperating with ring I20 and from there by way of the seal between ring I24 and I2! between the bearing I22 and the sleeve to the outside of housing 0. The position of the break in the transmission line above the oil level of chamber I20 prevents leakage of oil into the line.

While a reinforcing sleeve has been shown in each of the illustrated embodiments of the invention, such a sleeve is necessary only in certain types of Joints. In those types illustrated by Figs. 1, 5, 6 and 7, the sleeve may be dispensed with if the outer conductor is made strong enough and of proper material and configuration to do the work assigned to the sleeve in the joints illustrated by these figures. These changes in the dimensions and thickness of the outer conductor will not cause an impedance irregularity if the inner diameter and configuration of the conductor is not altered.

While these Joints have been described with particular reference to radio transmission lines, it is obvious that they are applicable wherever it is desired to prevent the escape of fluid around a rotating shaft or pipe passing through a bearing. The invention may be used, for example, to prevent the passage of a liquid between a shaft and a bearing in which it turns. An instance of such a usewould be to prevent the entry of sea water around the propeller shaft of a boat. Applicant has disclosed several embodiments of the invention and doubtless many changes in proportions, material and arrangement are possible without exceeding the scope of the invention. For example, packing may be substituted for the other types of seals shown. It is to be understood in this connection that the invention is to be considered as limited only by the scope and limitations of the appended claims.

The invention described herein may be manufactured and/or used by or for the Government of the United States of .America for governmental purpose without the payment of any royalties thereon or therefor.

I claim:

1. Means for preventing the escape of, gas under pressure from the interior of a radio transmission line having two sections mounted for rotation relative to each other, without interfering with said rotation, said means comprising a housing surrounding the adjacent ends of said section, means forming an integral gas-impervious connection between said housing and one of said sections around the entire periphery of said section, a reinforcing sleeve of bearing material fitted snugly around and integrally connected.

to the other of said sections in a gas-impervious manner around the entire periphery of said section, a pair of bearing means carried by said housing, each of said bearing means surrounding a portion of said sleeve, said housing being so shaped as to form a gas-tight chamber around said sleeve intermediate said bearings, ring means carried at each end of said chamber in gas-tight relation to the walls thereof, each of said ring means fitting snugly around said sleeve and having a fiat bearing surface, a pair of ringlike sealing means fitted around said sleeve between said ring means, each of said sealing means having a flat surface mating with one of said first-mentioned flat surfaces, resilient means carried by said sealing means and snugly fitting around said sleeve whereby to prevent passage of gas between said sealing means and said sleeve and to cause said sealing means to rotate with said sleeve, means urging each of said sealing means against one of said ring means until the said flat surface carried by said sealing means is forcefully pressed against the said mating surface of said ring means and a body of lubricating fluid substantially completely filling said chamber.

2. A means for preventing the escape of gas under pressure from the interior of a radio transmission line having two sections joined for rotation relative to each other, without interfering with said rotation, said means comprising a housing s shaped as to form a closed chamber enclosing a portion of one of said sections and having endwalls forming bearings for the rotation of said section therein, a portion of said housing extending from one of said bearings across said joint and being integrally secured to the other of said sections in a gas-impervious manner around the entire periphery thereof, and means sealing said chamber against passage of gas under pressure thereinto by way of the one of said bearings nearest said joint, said means including a gas-impervious extension of the end wall of said housing nearest said joint, and means en circling said one of said sections in a gas-impervious manner and in non-rotating relation thereto, said extension and said last named means having mating surfaces, meanspressing said mating surfaces together over an area completely encircling said one of said sections, and a body of lubricating fluid substantially completely filling said chamber.

3. Means for preventing the escape of gas under pressure from the interior of a. radio transmission line having two sections mounted for rotation relative to each other, without interfering with said rotation, said means comprising a housing surrounding the adjacent ends of said sections, means forming an integral gas-impervious connection between said housing and one of said sections around the entire periphery of said housing extending from one, of said bearings across said joint and being integrally secured to the other of said sections in a gas-impervious ber.

5. A means for preventing the escape of gas under pressure from the interior of a radio transmission line having two sections joined for rotation relative to each other, without interfering with said rotation, said means comprising a. stifl'- ening sleeve of bearing material fitting over the adjacent ends of said sections, means forming an integral gas-impervious connection between said sleeve and one of said sections, a housing shaped to form a chamber surrounding a portion of said sleeve, and having end walls in which said i a gas-tight chamber enclosing a portion of the other of said sections and having bearing means in its opposite walls in which said section rotates, a ring means carried at each end of said chamber forming an annular gas-tight extension of said chamber walls, each of said ring means fitting snugly around said section and having a fiat bearing surface, a pair of ring-like sealing means fitted around said section between said ring means, each of said sealing means havin a fiat surface mating with one of said first-mentioned flat surfaces, resilient means carried by said sealing means and snugly fitting about said other of said sections whereby to prevent passage of gas between it and said section and to cause said sealing means to rotate with said section, means urging each of said sealing means against one of said ring means until the said fiat surface carried by said sealing means is forcefully pressed against the said mating surface of said ring means, and a body of lubricating fluid completely filling said chamber.

4. A means for preventing the escape of gas under pressure from the interior of a radio transmission line having two sections joined for rotation relative to each other, without interfering with said rotation, said means comprising a sleeve is journalled for rotation relativeto said housing, the end wall of said housing farthest from said connection being extended into engagement with the periphery of the other of said sections, means forming an integral gas-impervious connection between said endwall and said section completely encircling said section and sealing means formed between said end wall and said sleeve, said sealing means comprising a ringshaped member in gas-impervious relation to said end wall, said ring-shaped member having a bearing surface, a sealing member encircling said sleeve in a gas-impervious manner and in non-rotative relation thereto, said sealing member having a bearing surface mating with said first-mentioned bearing surface, an abutment formed on said sleeve and spaced from said sealing member, resilient means surrounding said sleeve between saidabutment and said sealing member and tending to press said bearing surfaces tightly together over an area completely encircling said sleeve, a cylindrical skirt extending from said abutment in the direction of said housing so shaped as ,to iform a closed chamber enclosing a portion of one of said sections and end wall, a sealing'means similar to said firstmentioned sealing means between said skirt and said end wall, said abutment extending beyond the periphery of said skirt, and resilient means surrounding said skirt between said abutment and said sealing means in the same manner as first-mentioned resilient means, and a body of lubricating fluid substantially completely filling said chamber both inside-and outside of said skirt.

6. A means for preventing the escape of as under pressure from the interior of a radio transmission line having two sections joined for rotation relative to each other, without interfering with said rotation, said means comprising a stiffening sleeve of bearing material fitting over the adjacent ends of said sections, means forming an integral gas-impervious connection between said sleeve and one of said sections, a housing shaped to form a chamber surrounding a portion of said sleeve, and having end walls in which said sleeve is journalled for rotation relative to said housing, the end'wallof said housing farthest from said connection being extended into engagement nection between said end wall and said sectionaround the entire periphery of said section and sealing means formed between said end wall and said sleeve, said sealing means comprising a ringshaped member in gas-impervious relation to said end wall, said ring-shaped member having a bearing surface, a sealing member, encircling said sleeve I l a gas-impervious manner and in nonrotative relation thereto, said sealing member having a bearing surface mating with said firstmentioned bearing surface, an abutment formed on said sleeve and spaced from said sealing member, resilient means surrounding said sleeve between said abutment and said sealing member and tending to press said bearing surfaces tightly together over an area completely encircling said sleeve, and a body of lubricating fluid substantially completely filling said chamber.

I. A means for preventing the escape of gas under pressure from the interior of a radio transmission line having two sections Joined for rotation relative to each other, without interfering with said rotation,.said means comprising a stiffening sleeve of bearing material fittingover the adjacent ends of said sections, means forming an integral gas-impervious connection between said sleeve and one of said sections, a housing shaped to form a chamber surrounding a portion of said sleeve, and having end walls in which said sleeve is journalled for rotation relative to said housing, the end wall of said housing farthest from said connection being extended into engagement with the periphery of the other of said sections,'means forming an integral gas-impervious connection between said end wall and said section'around the entire periphery of said section and sealing means formed between one of said end walls and said sleeve, said sealing means comprising a gasimpervious extension of said one of said end walls and a sealing member encircling said sleeve in a gas-tight manner and in non-rotative relation thereto, said sealing member and said sealing means having cooperating surfaces, means forcefully pressing said surface together over an area completely encircling said sleeve and a body of lubricating fluid substantially completely filling said chamber.

8. A means for preventing the escape of gas under pressure from the interior of a radio transmission line having two sections joined for rotation relative to each other, without interfering with said rotation, said means comprising a housing shaped to form a chamber surrounding 9. Portion of one of said sections and having end walls in which said section is journalled for rotation relative thereto, the end wall of said housing nearest said joint being extended into engagement with the periphery of the other of said sections, means forming an integral gas-impervious connection between said end wall and said sections around the entire periphery of said section and sealing means formed between one of said end walls and said one of said sections, said sealing means comprising a ring of resilient material imbedded in said one of said end walls and sur rounding said section, a ring of bearing material imbedded in said resilient ring and having a bearing face, a ring-shaped member of bearing mate-- -rial secured to said section in an integral nonrotativ'e manner and having a bearing surface mating with said first-mentioned bearing surface, an abutment carried by said sleeve and spaced from said ring-shaped member, resilient means surrounding said sleeve between said abutment and said ring-shaped member and tending to press said bearing surfaces tightly together and a body of lubricating flu! substantially completely filling said chamber.

9. A means for preventing the escape of gas under pressure from the interior of a radio transmission line having two sections joined for rotation relative to each other, without interfering with said rotation, said means comprising a. housing shaped to form a chamber surrounding a portion of one of said sections and having end walls in which said section is journalled for rotation relative thereto, the end wall of said housing nearest said joint being extended into engagement with the periphery of the other of said sections, means forming an integral gas-impervious connection between said end wall and said section around the entire periphery of said section and sealing means formed between one of said end walls and said one of said sections. said sealing means comprising a ring of resilient material imbedded in said one of said end walls and surrounding said section, a ring of bearing material imbedded in said resilient ring and having a bearing face, a sealing member encircling said section in a gas-tight manner and in nonrotative relation thereto, and having a bearing surface mating with said bearing face, means forcefully pressing said bearing surface and sold bearing face together and a body of lubricating fluid substantially completely filling said chamber.

10. Means for preventing the escape of fluid under pressure from the interior of a hollow cylindrical member composed of two sections joined together for relative rotation, comprising means joined to one of said sections in a fluid-tight manner around the periphery thereof and extending across said joint to form a wall having an opening in which the other of said sections is journaled, means forming a fluid-tight chamber around a portion of said member on the side of said wall from which said fluid would normally escape, said chamber forming means comprising a portion of said wall, means for preventing entry of said fluid into said chamber, said means comprising a packing means carried by said wall. means for preventing escape of any fluid which might leak into said chamber, said means comprising packing means carried by the portion of the wall of said chamber surrounding said member as it leaves said chamber, said portion of said chamber wall forming a bearing for said member and a body of lubricating fluid substantially completely filling said chamber, said body of lubricating fluid being only under such pressure as may build up in said chamber due to leakage. of said fluid thereinto, said chamber being so dimensioned and located as to accommodate all of 'said lubricating fluid below the level of said joint.

11. Means for preventing the escape of fluid under pressure from the interior of a hollow cylindrical member composed of two sections joined together for relative rotation, comprising means joined to one of said sections in a fluid-tight manner around the periphery thereof and extending across said joint to form a wall having an opening in which the other of said sections is journaled, means forming a fluid-tight chamber around a portion of said member on the side of said wall from which said fluid would normally escape, said chamber forming means comprising a portion of said wall, a sealing means for preventing entry of said fluid into said chamber, said sealing means comprising a pair of means having cooperating surfaces in slidin contact over an area completely encircling said member, means pressing said surfaces forcefully together, one of said pair of means being carried in fluid tight non-rotating relation to the. periphery of said member and the other having the same relation to said wall, a similar sealing means for preventing escape of any fluid which might leak into said chamber, said last named sealing means being located inside said chamber and in fluidtlght relation to the portion of the wall of said chamber surrounding said member as it leaves said chamber, and a body of lubricating fluid substantially fllling said chamber, said body of lubricating fluid being only under such pressure as may build up in said chamber due to leakage of said fluid thereinto, said chamber being so dimensioned and located as to. accommodate all,

of said lubricating fluid below the level of said joint.

12. Means for preventing the escape of fluid under pressure from the interior of a hollow cy lindrical member composed of two sections joined together for relative rotation, comprising means joined to one of said sections in'a fluid-tight manner around the periphery thereof and extending across said jointto form a wall having an opening in which the other of said sections is journaled, means forming a fluid-tight chamber enclosing a section of said member on the side of said wall from which said fluid would normally escape, said chamber forming means comprising a portion of said wall, a sealing means for preventing entry or said fluid into said chamber, said sealing means comprising a pair of means, one of which isr carried in fluid-tight non-rotating relation to the periphery of said member and he other having t e same relation to said wall, each of said pair of means having a surface completely encircling said member and having a configuration conforming tothat of the other of said surfaces, means pressing said surfaces together in an area of contact completely encircling said member, and a body of lubricating fluid substantially completely filling said chamber, said body of lubricating fluid being only under such pressure as may build up in said chamber due to leakage of said fluid thereinto, said chamber being so dimensioned and located as to accommodate all of said lubricating fluid below the level of said joint.

13. Means for preventing the escape of fluid under pressure from the interior of a hollow cylindrical member composed of two sections joined together for relative rotation, comprising means joined to one of said sections in a fluid-tight manner around the periphery thereof and extending across said joint to form a wall havin an opening in which the other of said sections is journaled, means forming a fluid-tight chamber around a portion of said member on the side of said wall from which said fluid would normally escape, a sealing means for preventing the escape of any fluid which might leak into said chamber, said sealing means comprising a pair of means,

A 7 said surfaces, means pressing said surfaces together in an area of contact completely encircling said member, and .a body of lubricating fluid substantially completely filling said chamber, said body of lubricating fluid being only under such pressure as may build up in said chamber due to leakage of said fluid thereinto, said chamber being so dimensioned and located as to accommodate all of said lubricating fluid below the level of said joint.

a 14. Means for preventing the escape of gas under pressure from the interior of a radio transmission line having two sections joined for rotation relative to each other, without interfering with said rotation, said means comprising a housing enclosing said Joint and having two parts mounted for rotation relative to each other, each of said parts being a gas-tight extension of a different one of said sections and extending around the complete circumference thereof, each of said parts presenting a surface completely enone of which is carried in fluid tight non-rotat- 7 ing relation to the periphery of said member and the other having the same relation to that portion, of said chamber forming means which surrounds said member as it leaves said chamber, I

circling said transmission line for cooperation with the corresponding surface on the other of said parts, and means acting on said parts to prevent the passage of gas between said surfaces, said means including a body of lubricating fluid substantially completely fllling said housing, said body of lubricating fluid being only under such pressure as may build up in said housing due to leakage of said gas thereinto, said housing being so formed and dimensioned as to accommodate belowthe level of said joint all the lubricating fluid which may leak through between said surfaces toward said joint within a predetermined time.

15. Means for preventing the escape of gas under pressure from the interior of a radio transmission line having two sections joined for rotation relative to each other, without interfering with said rotation, said means comprising a housing enclosing said joint, said housing comprising a gas-impervious extension of one of said sections completely enclosing said joint and presenting a surface completely encircling the other of said sections for cooperation therewith, and means sealing the space between said surface and said other of said sections against the passage of gas therethrough, said means including a body of lubricating fluid substantially completely filling said housing, said body of lubricating fluid being only under such pressure as may build up in said housing due to leakage of said gas thereinto, said housing being so formed and dimensioned as to accommodate below the level of said jointall the lubricating fluid which may leak through between said surfaces toward said joint within a predetermined time.

16. Means for preventing the escape of fluid under pressure from the interior of a hollow vertical cylindrical member composed of two sections joined together for relative rotation, comprising a sleeve integrally secured in a fluid-tight manner about the periphery of the upper of said sections near said joint, said sleeve extending downwardly in snugly fitting relation over a portion of said lower section, a housing integrally secured in a fluid-tight manner about. the periphery of the lower of said sections beneath said sleeve and enclosing a portion of said sleeve, a bearing for said sleeve formed in each of the upper and lower ends of said housing, means forming a pair of fluid retaining rotatable seals between said sleeve and said housing, saidseals defining a chamber between said housing and said sleeve and a body of lubricating fluid substantially filling said chamber.

1'7. Means Ior preventing the escape of fluid under pressure irom the interior of a hollow cylindrical member composed of two sections Joined together for relative rotation, comprising a sleeve integrally secured in a gas-tight manner about the periphery of one oi said sections near said joint, said sleeve extending across said Joint in snugly fitting relation over a portion of the other of said sections, a housing integrally secured in a fluid-tight about the periphery 0! said other section beyond said sleeve and enclosing a portion of said sleeve, a bearing for said sleeve formed in each end of said housing, means forming a pair of fluid-retaining rotatable seals between sleeve and said housing, said seals cleaning a chamber: between said housing and.

sleeve body of lubricating fluid subssantially filling said chamber.

18. Means for preventing the escape of gas under pressure from the int rior 0! a hollow cylindrical member composed of two sections Joined together for relative rotation, comprising a housing integrally secured in a fluid-tight manner about the periphery of one of said sections, ex-- tending across said joint and there being formed into a closed chamber having fluid impervious walls and surrounding a portion of the other of said sections, fluid-tight sealing means sealing the space between the periphery of said other section and the walls of said chamber where s lu section enters and leaves said chamber, a bearing means for said section carried by said housing and located between said sealing means, and a body of lubricating fluid substantially filling said chamber.

CYRUS H. FRASER.