US1892899A - Elastic fluid turbine of the combined radial-axial flow type - Google Patents

Description

A. LYSHOLM Jan. 3, 1933..

ELASTIC FLUID TURBINE OF THE CbMBINED RADIAL AXIAL FLOW TYPE Filed April 18 5.929 2 Sheets-Sheer 1 m HIPHHHHHIJIIHHIJIIH HIHHHHHHHHHHH l- ,n n u 1 llllll Ill llllllll IIH LIILIF a w v. w Z 5 w 4 2 W.

lnvergtor A LYSHOLM' 1,892,899

ELASTIC FLUID TURBINE OF THE COMBINED RADIAL AXIAL FLOW TYPE Filed April 18, 1929 2 sheets-sheet 2 Jain. 3, 1933.

attorneys Patented 1.... 3, i933 UNITED STATES PA ENT OFFICE ALF L YSHOLM, OF STOCKHOLM, SWEDEN, ASSIGNOR TO AKTTEBOLAGE'I LJUNGSTRfiMS ANGTURIBIN, F 'STOCKHOLM, SWEDEN, A JOINT-STOCK COMPANY OF SWEDEN ELASTIC FLUID TURBINE or THE commnnn RAD AL-AXIAL rLow TYPE Application filed April 18, 1929, Serial No. 356,213, and in Sweden-April 21, 1928.

Steam turbines are previously known, in which the steam delivering the energy enters the center of the turbine and first passes through the turbine in the radial direction through one or more blade systems pertaining to aradial blade system, the steam beingthen conducted to the outlet of the turbine through one or more blade systems pertaining to an axial blade s stem, Particularly in turbines of the double rotary type, the moving blades pertaining to the axial blade system of the turbine have been arranged symmetrically about a central plane extending through the center of the turbine at right angles to the axis of rotation. Each such axial blade system'has been provided with two or more rows of moving blades arranged on a turbine rotor common to all moving blade rows, said turbine rotor having been made integral with the turbine rotor carrying about half the number of blade rings in the radial blade system. Inasmuch as different parts of such a turbine rotor are subjected to diiferent temperatures and since stresses in the rotor of dangerous magnitude are caused by such difi'er-, ent temperatures'in the rotor, it has been previously proposed to divide the turbine disk into a plurality of parts situated within each other, said parts having been connected with one another by means of what may be-termed articulated connections, while the outermost portion of the turbine'rotor adapted directly to carry the moving blades of the axial flow. blade system'has at the same time been 'divided into two or more approximately equal parts disposed beside each other, each part carrying only one row of moving blades in the axial blade system. These outermost parts have also been connected with each other through an articulated connection freely permitting the differeiit expansions caused by the different temperatures under which the several parts of the turbine rotor operate. Such a construction entails a number of disadvantages, however. In the first place it is rendered ex pensive from the point of view of manufacture and, secondly, the axial length of the turbine between the shaft bearings will'be excessive, particularly in large turbines, in-

asmuch as two or more parts of the turbine rotors have to be arranged axially beside each other with interconnecting articulated mem- The manner in which the above mentioned disadvantages of prior forms of turbine construction are eliminated and the nature and more specific objects of the present invention will appear more fullv in conjunction with the following description of examples of turbine structure suitable for carrying the invention into eifect.1

In the drawings forming a part of this specification; Fig. 1 shows a cross section throu h the upper half part of a steam turbine of the double rotation type; Fig. 2 shows a modification of a detail thereof; Fig. 3 is a section on line B'B in Fig. 2; and Fig. 4 shows a detail of the axial blade system.

In Fig. 1. A-A designates a plane normal to the ax's of rotation 1 of the turbine, about which plane the turbine is substantially symmetrical. 2 is a shaft with which the inner part 3 of a turbine rotor is rigidly connected in known manner. The part 3 of the turbine rotor is arranged withn a part 4, which, in turn, is situated within an outer part 5.

Thus the turbine rotor consists of the parts 3, 4 and 5. of which the inner parts 3'and 4 carry blade ringsin the radial flow blade systems Sand 9 bymeans of articulated connecions 6 and 7. According to the inventon, the outermost part 5 carries two rows of moving blades. 10 and 11 in the axial flow blade system Arranged between the blade rims 10 and 11 is a guide blade row 12 within the stationary casing 13 of the turbine or within parts united therewith. The outermost rotor part 5 also carries a radial flow blade system 15, l kewise by means of articulated connections 14. In operation, the steam enters through the inlet conduit 16 'of the turbine and flows to the central part 17 of the turbine. By means of labyrinth packings 18 and 19 of known type the steam is prevented from leaking out in large quantities between the stationary and the rotating parts of the turbine. From the space 17 the steam first passes through the inner blade system 8 of the rad'al flow blade'system. At 20, means are provided by the opening 21, the channel 22 and the conduit 22a for bleeding steam or for supplying steam, depending on the conditions under which the turbine is to operate. The steam next passes through the radial flow blade system 9. At 23, means are also provided for bleeding steam through the passage 24,

which steam is m xed in the space 25 with that steam which has passed through the labyrinth packing 18. The space 25 is preferably in communication, for instance by means of the conduit 25a, with an apparatus through which steam may be withdrawn or utilized. This apparatus may be connected with or completed to form a feed water pre-.

heater for the steam boler cooperating wiih the turbine. In order to prevent steam from the space 25 from leaking out between the rotating parts, a labyrinth packing is provided in known manner at 26. A plurality of the conduits indicated, for instance 22a and 25a, may consist of separate pipes or of passages provided in the parts of the turbine.

After the steam has passed through the blade system 9 it flows through'the radial flow blade system 15 into the space 27 where the further direction of flow of the steam is controlled by guide blades 28 arranged eradially adjacent to the blade system 15 and before the steam in the space 29 is caused to alterdirection and pass through the axial flow blade system 101211. From the outlet 30 outside the last blade'11 of the axial flow blade system the steam is conducted to a.

hereinabove'stated, to freely permit d'ifer-* ent expansions of the turb ne parts by articulated connections, thereby preventing the production of severe temperature stresses in the various parts.

The; outer turbine part 5 of the turbine rotor carrying all of the rowsof moving blades in this axial flow blade portion is reinforced at its inner part by two rings 31 and 32 which are shrunk in known manner on the element providing the disk-like portion of part 5, which element is provided with pro jections fitting into recesses in the reinforcing rings 31 and 32. These reinforcing rings are provided with holes as at 33, said holes registering with each other and with the holes in the inner rotor parts 4 and 3 when the rings are shrunk in position. Extending through these holes are bolts 34 which in the embodiment shown are cylindrical and hollow. Each bolt is provided atits inner end with a stopper 35 which cooperates with a flange on the rotating part of the labyrinth packing 18, located radially inside the bolt, to

lock the bolt in position. Thus, all rotating parts of this half-part of the turbine are guided by means of the same bolt 34.

Figs. 2 and 3 illustrate an embodiment where bolts of different lengths are'used and where the bolts themselves are of a somewhat different character. In these figures, the parts to be found in Fig. 1 have been designated as before. In the manner described in connection with Fig. 1, the rotor parts 3 and 4 are connected with the aid of long bolts 34 to the outermost rotor part 5 through the agency of the shrunk on rings 31 and 32. The bolts 34 extend, however, only through the one of the rings 31 and 32, which latter are still connected, in the planenormal to the axis of rotation, with each other by means of shorter bolts 36 threaded into holes provided between the long bolts.

The bolts described have been shown as being hollow in all of the figures of the drawings. The outer diameter of the bolts should in known manner be so great in relation to the diameter of the holes that the bolts must, when all of the parts are cold, be pressed into the holes to bear against the walls of the holes with great pressure. It is because of the resiliency due to the hollowness of the bolts that this may be done. The smaller bolts connect partsthat are rigid with respect to each other, and thus they need not be hollow.

They may be made conical and may be retained in position by the insulating plate sur-. rounding the rings 31 and 32.

In Figs. 2 and 3, the bolts have, particularly at the passage 22, a smaller diameter, in order to facilitate an elongation of the bolts, in case these should seize in the holes. Normally, however, the ring-shaped parts should be slidable on the bolts at the temperature attained during turbine operation. Figs. 2 and 3 also show that the bolts are provided with grooves or turned-out portions, in order to prevent seizing. For this reason the grooves should be filled with some suitable lubricant ensuring movement between the bolts and the elements.

V Embodiments are also conceivable where the various parts are united by a plurality of series of bolts which do not all lie in the same plane and onl extend through two or three parts situate outside each other.

Fig. 4 shows a detail of the axial blade system in a somewhat modified embodiment. Here, too, the outer part 5 is forked, each shank of the fork carrying a row of axial moving blades 10 and 11 respectively, but in distinction from the embodiment shown in Fig. 1, the blade row 10 consists of blades, the roots 10a of which have been extended and shaped in such a manner as to form a. tight ring not letting the steam through. By shaping the blades in this manner the construc tion may be made lighter, in that the axial extension of the blade rootscan be made smaller than in the case of the construction previously described, where the one blade carrying end of the part 5 extends as far as to'the profiled portion of the blade. If desired, the blades of a plurality of the axial flow blade rows may be provided with roots made in this manner, but in a blade system of the type shown good results are obtained if only the first axial flow moving blade row is made with blade roots shaped in accordance with this feature of the invention. The innermost part of each bladeroot is provided with a bead-like attachment adapted to be fitted into a slot 106 in the turbine disk.

From the foregoing description, it'will be evident that the present invention provides a rotor construction comprising an inner part rigid with the turbine shaft and a rigid outer part the weight of wh ch is carried radially inwardly in substantially a direct line to the part rigid with the turbine shaft, the path of force transmission from the outer part to the part rigid with the turbine shaft lying entirely between planes normal to-the axis of rotation of the turbine and defining the axial extent of the outer part. In other words, the weight of the rigid outer part is carried to the inner part rigid with the turbine shaft through the medium of elements which lie between the transverse planes of the axially outer face of the ring 32 and the axially inner face ofthe ring 31.

Furthermore, the form of construction d sclosed permits the placing of'a plurality of rows of axial flow blades on a single rigid outer rotor part. In large turbines of the type in question, multistage ax al flow blade systems are essential in order to take care of the steam volumes encountered without resorting to impractical designs, and in order to secure the desired power output from a turb'ne of given size, the speed of operation must I be increased considerably as compared with the speeds heretofore considered the maximum permissible with large unts of the radial flow type. In the forms of construction heretofore employed, the use of radial flow turbine units. of large size operating at .high speeds is precluded, not only because of d'stortion of certain of the weight carrying parts of the turbine rotor due to the great weight of the outer rotor parts and blade rows carried thereby, but also because of the fact that articulated construction of the prior formsof apparatus necessitates an axial length between the bearings of the turbine so great that the critical speed of the turbine shaft is reduced to a figure below that permitting the turbine to be operated safely at the rotor which in turn results in a short overhung turbine shaft the lowest critical speed of which is of relatively high value.

The invention also permits the construction of a rigid outer rotor part, the inner portion of which is of less diameter than the maximum diameted of the labyrinth packing, without sacrifice of the desired axial compactness of design. By making the radially inner portion of the rigid rotor part of relatively small d ameter the desired strength for this part may be obtained in turbines of relatively large size without the necessity of em loying parts of excessive weight.

do not claim herein the subject matter relating to the stationary guide blade structure of the turbine illustrated herein by way of example. This subject matter is disclosed and claimed in my copending appl cations Serial Nos. 356,488, and 456,014 filed April 19, 1929 frdm, which subject matter is discosed and claimed in U. S. Patent No. 1,870,212 granted August 2, 1932 on the application of. Alf

-Lysholm and Gosta L. B." Wahlsten filed March 14, 1930.

It will be evident that many changes and variations from the illustrative embodiments herein disclosed may be made without departing from the scope of the. invention as defined in the appended claims.

What I claim as new and desire to secure by Letters Patentof the United States of..-

America is: v

1. A turbine rotor for radial flow elastic fluid turbines having an axial flow blade system, comprising a number of rotary parts disposed one within the other, the outermost of" said rotary parts connected to the adjacent inner part and guided in relation thereto by means of bolts, said outermost part being formed symmetrically with respect to a plane passing through said bolts, at least two blade rings pertaining to said axial flow blade sys- 5 tern being arranged on said outermost part.

2. A turbine rotor for radial flow elastic fluid turbines having an axial flow blade system, comprising a number of rotary parts disposed one within the other and connected 1) with each other, the outermost of said rotary parts supporting at least two blade rings pertaining to said axial blade system, and reinforcing rings shunk on said outermost rotary part and united with the adjacent inner part by means of bolts.

3. A turbine rotor for radial flow elastic fluid turbines having an axial flow blade system, comprising a number of rotary parts disposed one Within the other and connected with each other, the outermost of said rotary parts supporting at least two blade rings pertaining to said axial blade system, and reinforcing rings shrunk on said outermost rotary part and united with the inner parts by means 26 of bolts.

4. A turbine rotor for radial flow elastic fluid turbines having an axial flow blade system, comprising a number of rotary parts disposed one within the other and connected with 30 each other, the outermost of said rotary parts supporting at least two blade rings pertaining to said axial blade system, and reinforcing rings shrunk on said outermost rotary part,

one of said reinforcing rings being united with the inner rotary parts by means of bolts. 5. A turbine rotor for radial flow elastic fluid turbines having an axial flow blade system, comprising a number of rotary parts disposed concentrically one within the other, the outermost of said rotary parts supporting at least two blade rings pertaining to said axial blade system, reinforcing rings shrunk on the radially innermost portion of said outermost part andextending in overlapping fashion radially inwardl of said innermost portion, and bolts of di erent length connecting the various rotary parts with each other, all of said bolts being arranged in the same radial plane, the bolts of shorter length extending only through said overlapping portions of the shrunk on rings.

6. A turbine rotor for radial flowelastic fluid turbines having an axial flow blade system, comprising a number of rotary parts disposed one within the other and connected with each other, the outermost of said rotary parts supporting at least two blade rings pertainiiig to said axial blade system, at least one of said blade rings being connected to said outermost part by means of a fluid-tight ring forming extensions of the roots of the blades in said blade ring.

7 A turbine rotor for radial flow elastic fluid turbines having an axial flow blade system, comprising a number of rotary parts disposed one within the other and connected with each other, the outermost of said rotary parts supporting at least two blade rings pertaining to said axial blade system, the roots of the blades of at least one of said blade rings being extended radially inwardly to form a fluid-tight ring, said ring being provided with bead-like attachment means, and slot means in said outermost part to receive said attachment means.

8. A turbine rotor for radial flow elastic fluid turbines having an axial blade system, comprising a number of rotary parts disposed concentrically one within the other, the outermost of said rotary parts supporting at least two blade rings pertaining to said axial blade system, reinforcing rings shrunk on the radially innermost portion of said outermost part and extending in overlapping fashion radially inwardly of said innermost portion, and hollow bolts connecting the various rotary parts with each other, all of said bolts being arranged in the same radial plane.

9. A turbine rotor for radial flow elastic fluid turbines having an axial blade system, comprising a number of rotary parts disposed one within the other and connected with each other, the outermost of said rotary parts supporting at least two blade rings pertaining to said axial blade system, reinforcing rings shrunk on said outermost rotary part, and hollow bolts uniting one of said reinforcing rings with inner rotary part-s of the rotor. I

10. A turbine disk for radial flow elastic fluid turbines having an axial blade system, comprising a number of rotary parts disposed concentrically one within the other, the outermost of said rotary parts supporting at least two blade rings pertaining to said axial flow blade system, reinforcing rings shrunk on the radially innermost portion of said outermost part. and extending in overlapping fashion radially inwardly of said innermost portion, and hollow bolts connecting the various rotary parts with each other, all of said bolts being arranged in the same radial plane.

11. A turbine rotor for radial flow elastic fluid turbines having a multistage axial flow blade system comprising an inner rotor part rigid with the turbine shaft, a rigid outer rotor part around said inner part, said outer part comprising a single disk-like portion carrying at its outer periphery a plurality of rows of moving blades of the axial flow blade system, and means providing a connection for supporting said outer part in radially movable relation with respect to said inner part along lines of force transmission situated entirely between planes normal to the axis ofj'rotation of the turbine and defining the axial extent of said outer part.

12. A tudbine rotor for radial flow elastic fluid turbines having a multistage axial flow 4 rigid with the turbine shaft, a rigid outer rotor part around said innerpart, said outer part comprising a single disk-like portion carrying at its outer periphery a plurality of rows of moving blades of the axial flow blade P system, said rows being similarly arranged axially to each side of the central plane of said disk-like portion, and means providing a connection for supporting said outer partin radially movable relation with respect to the inner part, said means being arranged'to transmit the weight of the outer part to the inner part along lines of forcetransmission situated entirely between planes normal to the axis of rotation of the turbine and defining the axial extent of said outer part.

13. A turbine rotor for radial flow elastic fluid turbines having a multistage axial flow blade system, comprising an inner rotor part rigid with the turbine shaft, a rigid outer rotor part having a single disk-like portion bifurcated at its outer periphery, each part of the bifurcation carrying a row of axial flow blades, and means providing a connection between said inner and said outer rotor part for supporting the weight of said outer parts in radially movable relation with respect to the inner part along lines of force transmission situated entirely between planes normal to the axis of rotation of the turbine and defining the axial extent of said outer art. p 14. A turbine rotor for radial flow elastic fluid turbines having a multistage axial flow blade system, comprlsingan inner rotor part rigid with the turbine shaft, a rigid outer rotor part having a single disk-like portion bifurcated at its outer periphery, the parts of the bifurcation bein located similarly'to each part of the side 0 the central plane of said disk-like portionxand each bifurcation carrying a row of axial flow blades, and meansproviding a connection for supporting the outer rotor part in radially movable relation with respect to the inner rotor part, said means being arranged to transmit the weight of the outer art inwardly to the inner part along lines of force transmission situated en: .tirely between planes normal to the axis of rotation of the turbine and defining the axial extentof said outer part.

15. A turbine rotor for radial flow elastic fluid turbines having a multistage axial flow blade system, comprising an inner rotor part rigid with the turbine shaft, a rigid outer rotorrpart having a single disk-like portion bifurcated at its outer periphery, said bifurcations beinglocated similarly to each side of the central plane of said disk-like portion and each bifurcation carrying a row of axial flow blades, and means providing a connection for supporting the outer rotor part in radially movable relation with respect to the inner rotor part, said means being arranged to transmit the weight'of the outer part inwardly to theinner part'alon lines of force transmission situated entirely etween planes normal to the axis of'rotation of. the turbine and. defining the axial extent of said outer art.

radial flow blade systemcomprising a plurality of concentrically arranged rows of radial flow blades and an axial flow. blade system comprising a plurality of rows of axial flow blades, a rotor comprising an inner part rigid with the turbine shaft, a rigid outer part having a single disk-like portion bifurcated at its outer periphery, each part of the bifurcation carrying a row of moving axial flow blades, one of the outer rows of said moving radial flow blades being carried by said disk-like portion radially inside said bifurcation, and a plurality of radially arranged bolts providin a direct connection between saidinner an outer rotor parts for supporting the weight of said outer part in radially movable relation with respect to the inner part along lines of force transmission situated entirely between planes normal to the axis of rotation of the turbine and defining the axial extent of said outer part.

17. In an elastic fluid turbine having a radial flow blade system comprising a plurality of concentrically arranged rows of of the bifurcation carrying a row of movin axial flow blades, one of the outer rows 0 said moving radial flow blades being carried by said disk-like portion radially inside said bifurcation, and a plurality of radially arranged bolts providing a direct connection between said inner and outer rotor parts for supporting the weight of said outer .part in radially movable relation with respect to the inner part along lines of force transmission situated entirely between planes normal to the axis of rotation of the turbine and defining the axial extent of said outer part.

18. A turbine rotor for radial flow elastic fluid turbinesv having an axial flow blade system comprising an inner rotor part rigid with the turbine shaft; an outer rotor part comprising a rigid radially inner portion,

a single disk-like portion rigid with respect 16. In an elastic fluid turbine having a.

bifurcated at its outer periphery, each part part in' radially movable relation with re- Y spect to the inner rotor part along lines of force transmission situated entirely between planes normal to the axis of rotation of the turbine and defining the axial extent of said outer part.

19. In an elastic fluid turbine having a radial flow system and an axial flow system comprising a plurality of rows of moving blades, a rotor comprisin an inner part rigid with the turbine sha t, an outer part situated around said inner part, said outer part being rigid and carrying a plurality of said rows of moving. blades and means comprising a plurality of bolts arranged radially between said inner and said outer parts and providing a path of force transmission for supporting the weight of said outer part, said path of force transmission being situated entirely between planes normal to the axis of rotation of the turbine and defining the axial extent of the rows of blades carried by said outer part.

20. A turbine rotor for radial flow elastic fluid turbines having an axial flow blade system comprising an inner rotor part rigid with the turbine shaft; an outer part comprising a single rigid and relatively heavy radially inner portion having substantial radial extent, a single disk-like portion rigid with respect to said inner portion and a radially outer portion com rising a plurality of blades of the axial ow blade system carried by said disk-like portion; and means com-,

prising a plurality of radially arranged bolts providing a connection between said inner and said outer parts for supporting said outer part in radially movable relation with. respect to the inner rotor part along lines of force transmission situated entirely between planes normal to the axis of rotation of the turbine and defining the axial extent of said outer part, the rojections of the axes of said bolts intersecting the radially inner portion of said outer rotor part for a substantial distance radially outwardly of said bolts.

21 A turbine rotor for radial flow elastic fluid turbines having an axial flow blade sysrotation, and means comprising a pluralityof radially arranged bolts providing a connection between said inner and said outer parts for supporting said outer part in ra dially movable relation with respect to the inner rotor nart alon lines of force transmission situated entirely between planes normal to the axis of rotation of the turbine and definin the axial extent of said outer part, 4

the pro1ections of the axes of said bolts intersecting the radially inner portion of said outer rotor part for a substantial distance radially outwardly of said bolts.

22. A turbine rotor for radial flow elastic fluid turbines having an axial flow blade system comprising an inner rotor part rigid with the turbine shaft; an outer part comprising a single rigid and relatively heavy radially inner ortion having substantial radial extent, a slngle disk-like portion rigid with respect to said inner portion and a radially outer portion comprising a bifurcation at the outer periphery of said disk-like por- 'tion, each of the parts of said bifurcation carrying a row of axial flow blades; each of said portions being substantially symmetrical axially with respect to a plane axially central of said outer rotor part and transverse to the axis of rotation, and means including radially arranged bolts providing a path of force transmission for supporting the outer rotor part in radially movable relation with respect to the inner rotor part, said path of force transmission lying entirely between planes normal to the axis of rotation and defining the axial extent-of the inner portion of said outer rotor part.

23. A turbine rotor for radial flow elastic fluid turbines having an axial flow blade system comprising an inner rotor part rigid with the turbine shaft; an outer part comprising a single rigid and relatively heavy radial y inner ortion having substantial radial extent, a single disk-like portion rigid with respect to said inner portion and a radially outer portion comprising a bifurcation at the outer periphery'of said disk-like portion, each of the parts of said bifurcation carrying a row of axial flow blades; each of said portions being substantially symmetrical axially with respect to a plane axially oentral of said outer rotor part and transverse to the axis of rotation and a plurality of radially arranged bolts providing a direct connection between said inner and said outer rotor parts for supporting said outer rotor part in radially movable relation with respect to the inner rotor part, said bolts being situated so that the axes thereof intersect the radially inner portion of said outer rotor part for a substantial distance radially outwardly of the bolts and said connection providlng a path of force transmission between said inner and said outer rotor parts situated entirely between planes normal to the axis of rotation of the turbine and defining the axial extent of said outer part.

24. In a turbine of the combined radial axial flow type, a shaft, a fixed member, a 1'0- tor, and radially extending labyrinth packing between the rotor and said fixed member,

said rotor comprising an inner part rigid with the shaft, an outer part carrying a plurality of axial fiowblades and means comprising radially extending bolts providing a connection forsupporting said outer part in radially movable relation with respect to said inner part along lines of force transmission situated entirely between planes normal to the axis of rotation of the turbine and defining the axialextent of said outer part, the inner ortion of said outer part being situated axlally to one side of said labyrinth packing and extending radially inwardly to a smaller diameter than the outer diameter of the labyrinth packing.

25. In a turbine of the combined radial axial flow type, a shaft, a fixed member, a rotor and radially extending labyrinth grackin between the rotor and said fixed mom er, sai

rotor comprising an inner part rigid with the shaft, an outer part around said inner part, said outer part comprising a rigid inner portion, aradially extending. disk-like portion rigid with respect to said inner portion and a plurality of rows of axial flow blades carried at the outer periphery of said disk-like portion, said inner portion'having a, diameter smaller than the .outer diameter of said labyrinth packing and being situated axially to one side thereof, and means comprising radially extending bolts providing a direct connection for supporting said outer rotor part in radi lly movable relation with respect to the nner rotor part along lines of force transmission situated entirely between planes normal to the axis of rotation of the turbine and defining the axial extent of said outer part.

oil

In testimony whereof I aiiix my signature.

. ALF LYSHO LM.

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