US2263942A - Turbine pedestal - Google Patents

Description

NOV. 25, 1941. R, c ALLEN 2,263,942

I TURBINEA PEDES TAL Filed Aug. 2, 1939 2 Sheets-Sheet l hlix'A r E@ Il Nov. 25, 1941. R. c. ALLEN TURBINE PEDESTAL 2 Sheets-Sheet 2 Filed Aug. 2, 1939 Patented Nov. 25, 1941 UNITED STATES PATENT OFFICE TUEBINE PED-ESTAL Application August 2, 1939, Serial No. 287,896 13 claims. I(C1. 30s- 59) This invention relates in general to a supporting structure for rotary machines and more particularly to a structure for supporting machines of this type which will eliminate destructive distortion and vibration caused by expansion and contraction of the stationary and rotary elements.

It is impractical to design and construct a rotary machine subjected to substantial changes in temperature, such as a steam turbine, having stationary and rotary elements which will expand or contract to the same extent and at the same rate. Unequal conditions of expansion and contraction of the stationary and rotary elements produce distortion and relative movement between these elements. Such conditions subject a rotary machine to serious damage as the relative movement between the stationary and rotary elements has been suflicient in some instances to cause these elements to contact. Moreover, distortion produces abnormal stresses which in some instances have caused the elements to fail. Consequently, a supporting structure for machines of this type and particularly for the high pressure or inlet end of a steam turbine must be operable to permit the stationary and rotary elements to expand and contract freely and to move relative to one another without subjecting the machine to the serious damage above mentioned.

In this connection, it has heretofore been the 1 practice (l) to slidably mount the bearing pedestal on a rigid support or sole plate and to support the adjacent end of the casing on the slidably mounted bearing pedestal or (2) to slidably mount both the bearing pedestal and the adjacent end of the casing on a rigid support or sole plate and to connect the pedestal and casing in xed longitudinal relation or (3) to slidably mount the bearing pedestal on a rigid support or sole plate, to support the adjacent end of the casing on either the pedestal or sole plate by means of flexible struts, and to connect the pedestal and casing in fixed longitudinal relation. The first case, although satisfactory for relatively small machines, produces too much friction between the pedestal and the sole plate in the case of large machines and, as a result movement of the machine tends to tilt the pedestal causing in some instances vibration of a destructive nature.

The second and third caseseliminate the tilting i' 'e eect on the bearing pedestal and the vibration caused thereby, but machines thus supported also tend to vibrate excessively which is attributed to the decrease in friction between the bearing pedestal and the sole plate and to the fact that the I means slidably mounting and guiding the pedestal for the main bearing invariably possesses some looseness which permits a slight degree of lateral movement.

Therefore, a primary object of this invention is to provide an improved supporting structure for rotary machines which will eliminate the above mentioned diiculties Another object of this invention is to provide an improved supporting structure for rotary machines which will permit the stationary and rotary elements to expand and contract freely and to move relative to one another without damaging the machine.

Another object of this invention is to provide an improved supporting structure for steam turbines which'will not transmit motion resulting from distortion or unequal expansion or contraction to the bearing structure which supports the.

rotor.

Still another object of this invention is to provide an improved supporting structure for rotary machines which will permit the main bearing supporting the rotor to be flXedly secured to eliminate vibrationv and which will permit simultaneous longitudinal movement of the thrust bearing forr the rotor and the'adjacent end of the casing. Afurther object of this invention is to provide an improved'supporting structure for rotary machines which Awill enclose and support the main and thrust bearings in a` sealed vchamber 'to thereby facilitate lubrication of the support for the movable thrust bearing.

An additional object of this invention is to provide an improved supporting structure for rotary machines embodying means for effecting simultaneous longitudinal adjustment of the rotor and thrust bearing with respect to the casing and the fixed main bearing supporting the rotor.

The inventionaccordingly consists of features of construction, combinations of elements, and arrangement of parts as more fully pointed out in the appended claims and in the detailed description in which: l

Fig. 1 is a diagrammatic side View partly in section of the inlet end of a steam turbine and a supporting structure .embodying the invention;

Fig. 2 is a plan view showing the casing support and rotor bearing structure with the covermember removed and with the connection between the thrust bearing andcasing partly in section;

Fig. 3 is a partial side elevation showing in greater detailthe manner in which the casing is supported by the pedestal structure:

Fig. 4 is a sectional view taken on line IV-IV of Fig. 2; and

Fig. is a partial plan View of a modified connection between the thrust bearing pedestal and casing with parts broken away to show the details of construction.

The invention, reference being had to Fig. 1, is shown as applied to the inlet end of a steam turbine I having a casing 2 and a spindle or rotor 3. The low pressure end of the casing which is not shown is of course supported by a foundation with the corresponding end of the rotor 3 mounted in an ordinary bearing in the usual manner. 'I'he inlet end of the casing 2 and of the rotor 3 are supportedby a member 4, which as shown in Figs. 1-4, comprises a hollow base portion 6 and a hollow cover portion 1 coacting to enclose and support the shaft portion of the rotor which extends outwardly beyond the inlet end of the casing 2. The exterior of the base 6 is provided with a pair of laterally spaced portions 8 as shown in Fig. 3 which are adapted to slidably support the adjacent end of the casing 2. The portions 8 are each bored cr otherwise provided with a vertically extendingand Vinternally threaded recess 9 and the adjacent end ofV the casing 2 and preferably the bottom portion thereof isprovided with lugs II arranged to slidably support the inlet end of the `casing 2 on the portions 8 of the base 6. The lugs II, which are preferably formed integral with the casing 2, each has a bore I2 which is in coaxial alnement with the bore of recess 9 in the supporting portion 8 when the lugs I I and the portions 8 are disposed in their proper cooperative relationship. The diameter of the bores I2, particularV attention `being directed to Fig. 3, is greater than that of the bores 9 and a positioning screw I3 havingl a smooth shank portion of less diameter than the bore I2 and an externally threaded bottom portion of reduced diameter` conforming with the diameter of the bore 9 extends through each of the bores I2 in the lugs II and into threaded engagement with the recess 9- in each'of the coacting supporting portions 8. 'I'he function of the screw I3 is to position and limit the movement of the casing 2 withV respect to the supporting structure 4. Thebottom portion of the casing 2 is provided withan axially `extending and vertically slotted guide member'I4 and a similarly arranged guide lug I6 on the base 6 has its free end disposed within the slot in the ,guide member I4 to maintain the 'casing centralized with respect to the rotor axis. The base 6 which is rigidly secured to a suitable foundation by means of bolts I1 is provided with an inwardly extending drilled and tapped flange I8 adapted to coact with a similar ,flange I9 on the cover 1 for the purpose of securing the cover to the base to form a sealed chamber. Any suitable means such as cap screws (not shown) may be used to rigidly secure the cover to the base.

The interior of the base 6, particular reference being had to Figs. l, 2 and 4, is provided with an integral web structure20 xedly mounting a spherical seating or shell 2| which in turn mounts the main bearing 22 rotatably supporting thefshaft portion of the rotor at the inlet end of the turbine. The cover-1 is provided with a web structure 23j arranged to coact with the web structure 28 ofthe base 6A and with the spherical seating or shell. 2I to aid in flxedly mounting the main bearing 22; A portion of the rear side wall of the base 6 and of the cover 1 are cut away to form an opening 24 providing access to the interior of the supporting structure 4 adu jacent the end of the rotor shaft. A removable 4cover plate 26 normally seals the opening 24.

A portion of the side wall of the base adjacent the end of the rotor shaft is provided with inwardly and outwardly extending bosses 21 and 28 respectively. The bosses 21 and 28 are drilled for the passage of cap screws therethrough and a cage 29 supporting a lubricating pump 3I and the pump drive shaft 32 is secured to the inner face of the boss 21 by means of cap screws 33. 'Ille top portion of the boss 21 merges with the flange I8 and the adjacent side surface of the cage 29 is provided with a laterally extending flange 34 which engages the top portion of the boss 21 to aid in positioning the cage 29 on the boss 21. One or more suitable sealing gaskets 36 may be disposed between the boss 21 and the coacting surfacesI on the cage 29. The pump drive shaft 32 is rotatably supported in cage 29 by means of vertically spaced bearings 31 and 38 and a gear 39, which meshes with a worm gear 4I on the rotor shaft, is secured to the shaft 32 intermediate the bearings 31 and 38. The pump 3I' is positioned to be submerged in th'e lubricant contained in the bottom of the base 6 and the lubricant which enters the pump through an inlet port (not shown) is discharged under pressure through a `delivery duct 42 formed in part in the cage 29 and in part in the bosses 21 and 28 as shown in Fig. 4. The cover 1 is provided with an opening 43 for adjusting the bearing 38 and this opening is sealed by a hollow cap member 44 only a portion of which is shown. The cap member 44 is removably secured to the cover 1 in any suitable manner. A

The sides of the flange I8 intermediate the main bearing 22 and the outer end of the casing are provided with oppositely disposed reinforced portions 46 which extend inwardly beyond the flange I9 on the cover 1 as shown in Fig. 4 for slidably supporting a thrust bearing yoke or pedestal 41. The yoke 41 comprises a hollow body portion 48 having laterally extending projections 49 adapted to slidably mount the body portion on the reinforced supporting portions 46 of the flange I8, a depending reinforcing flange 53, and a hollow cover portion 5I secured to the body portion 48 by means of cap screws 52 and defining therewith a housing enclosing and supporting the thrust bearing 54. The thrust bearing 54 comprises a thrust collar 56, cooperable bearing plates or shoes 51, a cylindrical housing 58 enclosing the thrust collar 56 and the bearing plates 51 and having at one end an inwardly extending flange 59 cooperating with the rotor shaft and at its opposite end an outwardly extending flange 6I, and an annular end plate 62 which engages the flange 6I on the housing 58 and the adjacent face of the bearing plate 51. Cap screws 63 extend through the end plate 62 and the flange 6I of the housing 58 and into the yoke 41 and ilxedly secure the yoke 41 and the thrust bearing 54 together for simultaneous movement.

A sleeve 64 surrounds the rotor shaft with its inner end abutting the adjacent face of the thrust collar 56 and its opposite end engaging the side of the worm gear 4I. The gear 4I is secured to the rotor shaft in any suitable manner such as by a nut 66. The opposite face of the thrust collar 56 abuts a shoulder 61 on the rotor shaft in the usual manner. Consequently, the thrust bearing and yoke and the rotor shaft are connected 'for simultaneous longitudinal movement and such movement may be effected by the application of a suitable force to either the rotor shaft or the thrust bearing yoke. The thrust bearing yoke 41 may be guided for longitudinal movement by making the inner edges of the iiange|9 on cover 1 of the supporting structure 4 coact with the adjacent edges of the supporting projections 49. However, in order to reduce friction, it is preferable to provide clearance between the adjacent edges of the projections 49 and the ange |9 and to prevent lateral movement of the yoke 41 by the use of adjustable means such as the screws 68. Vertical movement of the yoke 41 may also be prevented in a similar manner by the use of vertically adjustable screws 69 extending through bosses 1| formed on the interior surface of the cover 1. The screws 68 and 69 may be correctly positioned by means of shim washers 12.

The 'supporting projections 49 on the yoke 41 are oppositely disposed with respect to th'e supporting lugs on the casing 2 and the projections 49 and the lugs are provided with recesses 13 and 14 respectively. The recesses 14 in the lugs are opposite and in substantial coaxial alinement with the recesses 13 in the Vprojection 49. The wall of the supporting structure 4 intermediate the projections 49 and the lugs is provided with openings 16 formed in part in the base 6 and in part in the cover 1 which are in substantial axial alinement with the opposed pairs of the recesses 13 and 14. As best shown in Fig. 2, a member 11 having an outwardly disposed spherical seating surface 18 is disposed at the inner end of each of the recesses 13 and 14. The axially alined pairs of projections 49 and lugs are connected together by rigid tie rods 19 extending through the alined opening 16 in the supporting structure 4 and having bulbed ends 8| adapted to engage the spherical seating surfaces 18 in the recesses 13 and 14. The bulbed ends 8| of rods 19 are secured in engagement with the seating surface 18 in each of the recesses 13 and 14 by means of a pair of complementary members 82 disposed in each of the recesses 13 and 14 to form a cylinder spacedly surrounding the rod 19 and having an inner spherical seating surface 83 engaging the bulbed end 8|. The complementary members 82 are rigidly secured to the projections 49 and lugs by any suitable means suchI as the cap screws 84. A suitable sealing means 85 adapted topermit a slight lateral movement of the rod 19 is removably secured about the openings 16 and coacts with the rods 19 to prevent the escape of lubricant and the entrance of foreign material.

Lubricant is delivered by the pump 3| through the duct 42 and the pipe 86 to the main bearings 22 from which it drains to the bottom portion of the hollow base 6. In this connection, it shouldV be understood that although no means are shown for conducting lubricant to the thrust bearing 54, this bearing is also lubricated in the usual manner. Some of the lubricant escaping from the bearings 22 and 54 onto the rotor shaft is thrown by centrifugal action into contact with the interior side walls of th'e supporting structure 4 in proximity to the supporting ange portions 46 for the yoke projections 49. Consequently, lubricant is continuously supplied to the supports for the yoke 41 and the friction between relatively movable parts is reduced to a minimum. However, it should be obvious that instead of relying on an arrangement in which lubricant escaping from the bearings is indirectly delivered to the sirable to provide a construction for effecting an axial movement of the spindle with respect` to the casing in order to vary the axial clearance between the stationary and moving parts. A modied construction for accomplishing the result is shown in Fig. 5. In this construction eachof the supporting projections 49 on the yoke 41 is provided with a cylindrical bore 81 extendingl therethrough which is in substantial axial aline-- ment with the recess 14 in the opposed lug' Il on the casing 2. Disposed within the bore 81 is a' cylindrical member 88 having a coaxial and internally threaded bore 89 and an annular outward extending flange 9| which is drilled and is adapted to coact with that side ofv the projection 49 remote from the lug for rigidly securing the member88 to the yoke 41. Any suitable securing means such as the cap screws 92 may be employed. There is also disposed within' the bore 81 a member 93 having a cylindrical enlargement 94 at one end slidably engaging the surfaces of the bore 81 and a reduced portion 96 which extends through the bore 89 in the mem.- ber 88. The enlarged portion 94 presents a spherical seating surface 91 adapted to receive the bulbed end 8| of the rod 19. A pair of 'com--r plementary cap members 98 which form a spherical seating surface 99 adapted to engage andV retain vthe bulbed end 8| vof the rod 19in engagement with the seating surface 91 are secured to the enlarged portion 94 in any suitable manner such as by cap screws |00. The reduced por` tion 96 of members 93 is in threaded engagement with the members 88 and since the memv bers 88 are xedly secured to the supporting projections 49 and since the enlarged portion 94 of member 93 is held against axial movement by the engagement of the rods 19 with the casing 2 simultaneous rotation of members 93 will result in an axial movement of the yoke 41. The rotor 3 and the yoke 41 as previously described are arranged for simultaneous longitudinal movement in either direction and therefore it should be obvious that rotation of the members 93 will effect simultaneous axial movement of both the yoke 41 and the rotor 3. A worm gear |0| is secured to the free end of the reduced portion 98A of each member 93 and this gear together with a collar |02 which is also secured to the reduced portion 96 in spaced relation to the gear |0I coact with the opposite ends of the members 88 to limit the axial movement of the yoke 41 in either direction. A transverse shaft |03 rotatably mounted in bearings |94 in the base portion 6 is provided with an operating hand wheel |05 and with worms |01 which mesh with the worm gears` |0| on the members 93 for rotating same.

The previously described support for the inlet end of the casing 2 and the connection between the casing'2 and the yoke 41 for the thrust bearing'54 permits a slight lateral movement of the casing 2 withk respect to the axis of the machine and with respect to the yoke 41. However, rods 19 connect the casing 2 and the yoke 41 for 7simultaneous longitudinal movement and since the bearing and rotor are connectedior simultaneous longitudinal movement either` direc-l tion, ai movement or the casing slides the rotor or spindle shaft axially in the main bearing 22: thereby maintaining at all times a. desired: axial relationship between the casing and. rotor parts. Stated differently, there can be no rte-,latineV axial movement of the casing and rotor except iorthe adjustment obtained by the manipulation. of the. adjustable connection described in the preceding' paragraph. The friction between the rotate ing spindle shaft and the lubricated main bearingV 22' and between the supporting' projecions $9 for the yoke 41 and' the supporting ange portions 45 of the base member 6` is relatively small and as a result longitudinal movement oi the-casing and rotor does not tend to tilt the supporting structure 4 and neither does. such movement subject the supporting structure to excessive stresses. Moreover, since the main, bearing is iixedly mounted in a substantially' rigidv supporting structure 4 which in turn; isxedly secured to a suitable foundation, vibration of! the machine attributable to the supporting structure is reduced to a minimum.

A machine support embodying thev invention'. contemplates a construction in which the main bearing supporting the rotor is rlxedly` mounted in. a substantially rigid support, the thrust bearing and the adjacent end of themachine casing are. slidably mounted on the same or on different substantially rigid' supportingl members for longitudinal'movement'the thrust bearing and rotor areA connected for simultaneous longitudinal movement in either' direction, and the casing and thrust bearing are connectedA for simultaneous longitudinal movement. The invention isv obviously applicable to all types ci rotary machines and although it is of particular impor-y tanceV in connection with steam: turbines, it should be borne in mind that the particular details of construction shown and described in connection with the application of the inventionv to a steam turbine are merely illustrative. Consequently, it should be understood that it is not desired to limit the invention to the particular feaures of construction herein shown and' described as various modifications Within the scope of the appended claims may occur to persons skilled in the art.

It is claimed and desired to secure by Letters Patent:

1. A supporting structure for a machine having a rotor, a casing enclosing said rotor, and separate main and thrust bearings for the rotor comprising means xedly supporting the main bearing, means supporting the thrust bearing and the adjacent end ofv the rotor casing for 1ongitudinal movement with respect to the axis of the machine and with respect to said supporting means, and means connecting the adjacent end of the rotor casing with the thrust bearing so that expansion of the rotor casing effects a simultaneous movement of the thrust bearing.

2'. A supporting structure for a machine having a rotor, a casing enclosing said rotor, and separate main and thrust bearings for the rotor comprising means xedly supporting the main bearing, means supporting the thrust bearing and the adjacent end of the rotor casing for longitudinal movement with respect to the axis of the machine and with respect to said supporting means, means connecting the thrust bearing with. the rotor for simultaneous longitudinal movement in either direction, andY means connecting aaeaaea the adjacent end or the rotor casing with the thrust bearing so that' expansion of the' rotor casing effects a simultaneous movement of the thrust bearing'.

3. A supporting structure permitting expansion and contraction of the rotor and rotor casing of a machineY having main and thrust bearings for the rotor` comprising a support, a main bearing iXedl-y mounted on said support, a thrust bearing slid'ablyl mounted on said support for longitudinal movement with respect to thel axis of the machine, means-'slidably mounting the adjacent end of the rotor casing on said support for'movement both laterally and longitudinallyv with respect to the: axis of thel machine, and means permitting lateral movement oir the rotor casing withrespect to the axis of the machine operatively' connecting the adjacent end of the rotor casing and the thrust bearingv so that eX- pansion of the rotor casing eiiects` a simultaneous longitudinal movement of thethrust` bearing.

4. In a rotarymachine combination, a sup-- porting structure permitting' expansion and con-` traction of the machine' casing and of the rotor disposed therein comprising means defining a hollow and substantially rigid member cooper"- ating with the rotorand casing to. enclose one end of the rotor and to sli'dably support the adjacent end or the mach-ine.. casing, said hollow member :having disposed therein a xed main bearing supporting the rotor; a. thrust bearing operatively engaging the rotor and a. support for the thrust bearing movable longitudinally with respect to the axis. of' the machine andA with respect of said member, and means connecting the adjacent end od the machine casing and; the support for the thrust-bearing so that expansion or the machine casing effects a simultaneous longitudinal movement of" the thrust. bearing.

5. In a rotary machine combination, a sup.- porting structure permitting expansion and contraction; of.' the machine casing and'v oi' the rotor disposed therein comprising means defining a hollow and; substantiallyrigid member cooperating with the rotor and easing to. enclose one end of the rotor and to slidably support the adjacent end oi'` the machine casing, said hollow member havingI disposed therein a xed main bearing supporting the rotor, a thrust'bearing operatively l engaging the rotor and a support fory the thrust bearingl movable longitudinally with respect to the axis of the machine and with respectto said member and positioned to receive lubricant from one of said bearings, means operative to deliver a lubricant to said bearings, and means connecting the adjacent end' of the machine casing and the support for the thrust bearing so that ex'- pansion of the machine casing eliects a simultaneous longitudinal movement of the thrust bearing; 4

6. In a rotary machine combination, a supporting structure permitting expansion and" contractionV of they machine casing and of the rotor disposed therein comprising means defining a hollow and substantially rigid member cooperating with the rotor and casing to enclose one end of the rotor and to slidably support the adjacent end of the machine casing, said hollow member being adapted to contain a lubricant and having disposed therein a fixed main bearing supporting the rotor, a thrustbearing, a support for the thrust bearing movable longitudinally with respect to the axis ofthe machine and with respect to said member and positioned to receive lubricant escaping from one of saidbearings, and a lubricant feeding means operative to deliver lubricant from the bottom portion of the hollow member to one of said bearings, and means connecting the adjacent endofthemachine casing and the support for the thrust bearing so that expansion of the machine casing elects a simultaneous longitudinal movement of the thrust bearing.

7. A pedestal construction for rotary machines adapted to enclose and support one end of the rotor and to slidably support the adjacent end of the machine casing comprising means defining a hollow and substantially rigid member having spaced exterior portions arranged to slidably support the casing and interiorly disposed bearing means providing a xed main bearing for supporting the rotor and la thrust bearing movable longitudinally with respect to the axis of the rotor, and means connected with the thrust bearing and extending exteriorly of the hollow member and adapted to connect the machine casing with the thrust bearing so that expansion of the machine casing effects a simultaneous longitudinal movement of the thrust bearing.

8. A supporting structure for a machine having a rotor, a casing enclosing said rotor, and main and thrust bearings for the rotor comprising means xedly supporting the main bearing, means supporting the thrust bearing and the adjacent end of the rotor casing for longitudinal movement with respect to the axis of the machine and with respect to said supporting means, means connecting the thrust bearing with the rotor for simultaneous longitudinal movement in either direction, means connecting the adjacent end of the rotor casing with the thrust bearing so that expansion of the rotor casing effects a simultaneous longitudinal movement of the thrust bearing, and means operable to eilect a limited axial adjustment of the thrust bearing and rotor with respect to said rotor casing.A

9. A supporting structure for a machine having a rotor, a casing enclosing said rotor, and main and thrust bearings for the rotor comprising means xedly supporting the main bearing, a stationary means supporting the thrust bearing for longitudinalvmovement with respect to the axis of the machine, means connecting the thrust bearing with the rotor for simultaneous longitudinal movement in either direction, a stationary means supporting the adjacent end of the rotor casing for movement both laterally and longitudinally with respect to the axis of the machine, means permitting lateral movement of the rotor casing with respect to the thrust bearing operatively connecting the adjacent end of the rotor casing with the thrust bearing so that expansion of the rotor casing effects a simultaneous longitudinal movement Vof the thrust bearing, and means operable to elect a limited axial adjustment of the thrust bearing and rotor with respect to said rotor casing.

10. A supporting structure for a machine having a rotor, a casing enclosing said rotor, and separate main and thrust bearings for the rotor comprising means xedly supporting the main bearing, a stationary means supporting the thrust bearing for longitudinal movement with respect to the axis of the machine, a stationary means supporting the end of the rotor casing adjacent said thrust bearing for movement both laterally and longitudinally with respect to the axis of the machine, and means connecting said end of the rotor casing with the thrust bearing so that expansion of the rotor casing effects a simultaneous longitudinal movement of the thrust bearing.

11. A supporting structure for a machine having a rotor, a casing enclosing said rotor, and separate main and thrust bearings for the rotor comprising means lixedly supporting the main bearing, a stationary means supporting the thrust bearing for longitudinal movement with respect to the axis o the machine, a stationary means supporting the end of the rotor casing adjacent said thrust bearing for movement both laterally and longitudinally with respect to the axis of the machine, and means permitting lateral movement of the rotor casing with respect to the axis of the machine operatively connecting said end of the rotor casing with the thrust bearing" so that expansion of the rotor casing effects a simultaneous longitudinal movement of thethrust bearing.

12. A supporting structure permitting expansion and contraction of the rotor and rotor casing of a machine having separate main and thrust bearings for the rotor comprising a rigid support, a main bearing fixedly mounted on said support, a thrust bearing slidably mounted on said support for longitudinal movement with respect to the axis of the machine, means slidably mounting the end of the rotor casing which is adjacent said thrust bearing on said support, and means connecting said end of the rotor casing with the thrust bearing so that expansion of the rotor casing effects a simultaneous longitudinal movement of the thrust bearing.

13. A pedestal construction for rotary machines adapted to permit expansion and contraction of the machine casing and of the rotor disposed therein comprising a stationary and substantially rigid supporting member, means on said member slidably supporting one end of the machine casing, a main bearing flxedly secured on said member for supporting one end of the rotor, a rotor thrust bearing slidably mounted on said member for longitudinal movement with respect to the axis of the machine, and means connecting said thrust bearing with said one end of the machine casing so that expansion of the machine casing eiects a simultaneous longitudinal movement of the thrust bearing and rotor.

ROBERT C. ALLEN.

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