US3219261A

US3219261A - Cross-flow fan rotor support means

Info

Publication number: US3219261A
Application number: US423454A
Authority: US
Inventors: Laing Nikolaus
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-11-17
Filing date: 1965-01-05
Publication date: 1965-11-23
Anticipated expiration: 1982-11-23
Also published as: GB943766A; GB943765A; DE1403059A1

Description

Nov. 23, 1965 N1 LAING 3,219,261

CROSS-FLOW FAN ROTOR SUPPORT MEAN S Original Filed Nov. 17, 1959 2 Sheets-S heet 1 m 4 FIG]. HMJWMHHHJHHIHH /4 \i 1 l "w 4 /0 E INVENTOR Nikol us Loing BYy M, 141/6 4%M ATTO RNEYS Nov. 23, 1965 N. LAING 3,219,261

CROSS-FLOW FAN ROTOR SUPPORT MEANS Original Filed Nov. 17, 1959 2 Sheets-Sheet 2 w /22- w w w FIG. 5.

INVENTOR Nikola s Luing 8! x/MII W, ZAAI ATTORNEYS United States Patent 3,219,261 CROSSJFLOW FAN ROTOR SUPPORT MEANS Nikolaus Laing, 7I4l Aldingen B, Stuttgart, Germany Continuation of application Ser. No. 353,596, Nov. 17,

195?. This application Lian. 5, i965, Ser. No. 423,454 Claims priority, application Germany, Nov. 17, 1958,

26 Glaims. (Cl. 230-117) This application is a continuation of my copending application Serial No. 853,596 filed Nov. 17, 1959.

This invention relates to fans of the cross-flow type, that is, fans having a bladed cylindrical rotor and guide means co-operating therewith on rotation of the rotor in a predetermined direction to set up a flow of air from an inlet side of the rotor through the path of the rotating blades of the rotor to the interior of the rotor and thence again through the path of the rotating blades to an outlet side of the rotor.

Various forms of cross-flow fans have been proposed since the end of the last century. The available documents suggest that for the most part these proposals envisage fans of large capacity and fans which moreover require close tolerances between the rotor and guide means for their successful operation: in many cases the fans require guide means within the rotor. Obviously, fans of this sort can only be made by the classic engineering techniques by which fine tolerances can be obtained but since the units are large these techniques would be called for anyway and cannot be regarded as adding unnecessarily to the manufacturing costs: crossflow fans having fine tolerances could only be made in very small sizes by scientific instrument techniques at prohibitive expense. Other cross-flow fans have been proposed having a new principle of design of a cross-flow fan wherein rotor and guide means cooperate to set up and stabilize a vortex of Rankine type which is eccentric to the rotor axis: in this fan the rotor defines an interior space clear of interior guides, and preferably wholly unobstructed, and the guide means are external of the rotor and with advantage well spaced therefrom. This form of cross-flow fan is particularly suited to manufacture in fractional horsepower sizes by quantity production methods, since successful operation of the fan is independent of fine or closely maintained tolerances.

One advantage of the cross-flow fan lies in the fact that the rotor length is limited only by mechanical considerations of rotor strength and support, since the flow takes place in planes substantially transverse to the rotor axis and flow in any elementary portion of the length will be generally similar to flow in any other such portion. By contrast, the axial fan can only deliver an air stream of annular shape, and in the centrifugal fan, since flow enters from one end, the rotor length cannot usefully exceed about 0.6 multiplied by the rotor diameter.

In a cross-flow fan the length of the rotor will determine how it is supported. If the rotor is short conventional centrifugal fan practice can be adopted and the rotor over-hung-mounted on the end of a drive shaft. However if the rotor is long the rotor requires to be supported at both ends. In quantity production slight misalignments of bearings and slight errors in axial positioning of the various parts cannot readily be eliminated: nevertheless such misalignments must in general impose a severe braking torque on a fractional horsepower motor or even stall it altogether. Misalignments and positioning deviations may arise not only in manufacture. A fan which is constructed of light sheet metal may for example suffer distortion due to defective packing, rough transport, or to being dropped in use.

The main object of the invention is to provide, in a cross-flow fan of fractional horsepower size, means for 3,219,261 Patented Nov. 23, 1965 supporting and driving a long rotor, which means are adapted to economic manufacture by quantity production methods and will nevertheles be reliable in operation and impose no substantial braking torques despite minor misalignments of rotor and support means, errors of axial positioning and other deviations from the designed condition of the fan.

The invention accordingly provides a cross-flow fan as above defined, and with the rotor clear of obstruction and the guide means spaced exteriorly thereof. A frac tional horsepower motor is provided to drive the rotor, and one end of the rotor is mounted on an end of the motor shaft through the intermediary of a first flexible portion which is capable of substantial universal movement free of braking torque and preferably also is itself the sole means which transmits drive from the motor to the rotor. This flexible portion is conveniently an elastomeric bushing frictionally gripping the shaft and engaged in a hole provided by the rotor end member. However the flexible portion may also be a member of elastic material providing a plurality of spokes, the central part of this member being mounted on the shaft and the ends of the spokes being connected to the rotor end member. The other end of the rotor is journal-mounted by a stub-shaft element and co-operating bearing element. Either one such element is connected to the other rotor end member and the other element is connected to the stationary support means by a second flexible portion, or one such element is connected to the support means and the other is connected through the flexible portion to the rotor, the flexible portion in either case being capable of substantial universal movement without imposing a braking torque on the motor. The second flexible portion may be an elastomeric member having a web-like area, the central part of such member carrying one of said elements and the periphery being secured to the support means. Alternatively, the flexible element may be a member providing spokes, arranged as described for the driven end of the rotor. The flexible element may also be a diaphragm on the end of the rotor. The aim of the design will always be to enable some misalignment of the rotor without substantially braking the motor, and to facilitate production: as regards the latter, the invention provides inter alia a fan unit permitting manual assembly through the inlet opening.

The invention will be further described with reference to the accompanying somewhat diagrammatic drawings showing certain embodiments of the invention by way of example. In the drawings:

FIGURE 1 is a transverse section of a fan heater showing one form of cross-flow fan in which the invention may be incorporated;

FIGURE 2 is a longitudinal section, partly cut away, of the FIGURE 1 fan heater;

FIGURE 3 is a longitudinal section, partly cut away, of a rotor, motor and adjacent sectioning parts of a crossflow fan such as shown in FIGURES 1 and 2, showing one preferred way of rotatably mounting the rotor to accommodate minor misalignments and variation of axial spacing;

FIGURE 4 is a longitudinal section of one end of a rotor such as might be used in the cross-flow fan of FIG- URES 1 and 2, showing another way of supporting the rotor to accommodate manufacturing inaccuracies;

FIGURE 5 is a section similar to FIGURE 4 but showing yet another way of accommodating rotor misalignment; and

FIGURE 6 is an end view of the FIGURE 5 rotor.

Referring to the drawings, the fan heater illustrated in FIGURES 1 and 2 thereof comprises a casing 1 enclosing a cross-flow fan unit comprising a rotatably mounted cylindrical bladed rotor 2 and a pair of

guide walls

3, 4 interconnected by parallel and

walls

5, 6, all these

walls

3, 4, 5, 6 being held spaced from the interior of the casing. The casing 1 has end walls 7 8, and top and

bottom walls

9, 10, a vertical left hand wall 11 (as viewed in FIGURES l and 2) and an upwardly and outwardly sloping right hand wall 12: a sloping wall portion 13 joins the lower edge of the wall 11 to the bottom wall while the top wall 9 slopes down at the right hand side to join the upper edge of the wall 12; in any horizontal cross-section the casing has a rectangular outline. An air inlet 14 to the casing 1 is provided over adjacent areas of the side wall 11 and top wall 9 which lie opposite the rotor 2. An air outlet 15 is provided over an area of the side wall 12 opposite the rotor 2. Curved

vanes

16, 17 extend longitudinally across inlet and

outlet

14, 15 to prevent manual contact respectively with the rotor 2 and with heater means to be described.

The casing 1 provides on the inside of the end wall '7 an inwardly-opening recess 18 snugly receiving and locating a fractional horsepower electric motor 19 the shaft 20 of which supports one end of the rotor 2 and drives it in the direction of the arrow 21. At the bottom of the recess 18 the end wall 7 is perforated at 22 for access of cooling air to the motor 19.

The

guide walls

3, 4 which extend the length of the rotor 2, each have a main guide portion 25, 26 and an

outlet guide portion

27, 28. The main guide portions 25, 26 of the guide walls face each other across the rotor 2 and are spaced therefrom an appreciable distance at their lines of nearest approach thereto, designated 30, 31 which define a nearly 180 arc of air entry to the rotor. In the example shown, the main guide portion converges with the rotor in the direction of rotor rotation shown by the arrow 21. The

outlet guide portions

27, 28 of the guide walls 3, t are straight and diverge in the direction of flow to form a diffuser 32, discharging directly towards the outlet 15. The main guide and outlet portions 25, 27 of the guide wall 3 meet in a nose 33 and define thereat an angle of just over a right angle. The main guide and

outlet portions

26, 28 of the wall 4 merge in a smooth surface diverging steadily from the line 31 of nearest approach to the rotor. The wall 3 includes a lead-in portion 34- guiding air to the rotor 2. The edges of the

guide Walls

3, 4 terminate in spaced relation to the casing 1 adjacent the inlet 14 and outlet 15.

In operation, the rotor 2 and

guide walls

3, 4 co-operate to set up vortex having, adjacent the wall 3, a generally cylindrical core parallel to and eccentric of the rotor axis and interpenetrating the rotor blades. This vortex core is a rotating body of air and the outermost, and fastest, stream tube thereof is diagrammatically indicated at V in FIGURE 1. By reason of the vortex a flow of air is set up through the casing which passes from the inlet 14, twice through the path of the rotating blades of the rotor 2, through the diffuser 32 and out through the outlet 15. The vortex causes the air to travel through the rotor 2 along lines which are curved about the vortex core V, the greater part of the throughput being concentrated in the more strongly curved and faster flow lines adjacent the core. Thus because of the vortex the air is turned through the angle subtended at the rotor by the outlet 15 and that part of the inlet 14 through which the air chiefly passes, and this turning of the air is unaccompanied by the losses which would occur if it had been accomplished in bent ducting.

An electric heating element 36, comprising a plurality of resistance wires 37 held in castellated insulating support 38, is mounted within the diffuser 32 between the guide walls Fraud 4. The wires 37 may be closer together adjacent the wall 3 where the flow is faster.

The guide wall 3 is, as already mentioned, spaced from the interior of the casing 1. The space 40 defined between the wall 3 and the casing enables air which has passed through the rotor 2 to return to the entry are thereof, in

case the inlet 14 or outlet 15 should be blocked. The inlet 14 extends over a part of this space 10, so that in normal operation there is always some air flow through it from the inlet 14 to the rotor. Within the space 4t), and in the air flow just mentioned, there is mounted a thermostat 41 connected electrically with the heater element 36. By adjustment of the thermostat 41 the heater element 36 can be cut in and out as required to maintain a desired temperature in a room in which the fan heater is placed, and will be quick in responding to temperature change by reason of the air flow over it from the inlet 14 to the rotor 2. If the inlet 14 or outlet 15 is blocked while the heater element 36 is in circuit, the recirculating flow of heated air through the space 40 will immediately cause the thermostat 41 to cut out the heater element. This arrangement thus obviates the need for a separate safety switch to cut out the element 36 on overheating.

FIGURES 1 and 2 do not show the specific means by which the rotor 2 is rotatably mounted. One form of such means is illustrated in FIGURE 3; parts shown in FIGURE 3 which are similar to those of FIGURES l and 2 are designated by the same reference numerals and will not need further description.

The rotor 2 comprises a series of blades 190 extending parallel to the rotor axis and arranged in a ring thereabout to define an unobstructed interior space, the blades 1% being mounted on rotor end members 101, 102 of sheet material and generally of disc formation. The driven rotor end member 101 is coupled to the shaft 20 of the drive motor 19 by a drive connection 103, and the end member 1% at the non-driven end of the rotor 2 is rotatably mounted from the stationary end wall 6 of the fan.

The drive connection 193 comprises a flexible ring or bushing 105 preferably made of soft rubber and having a central portion of reduced thickness which engages a portion 106 of reduced diameter on the shaft 29 of the drive motor 19. The ring 105 has a grooved periphery 1118 which grips the opposite faces adjacent an aperture M9 in the rotor end support member 101. Lugs 111 integral with the ring 165 and projecting therefrom are arranged to engage a pin 112 secured to the shaft 20 to rotate the rotor 2 upon rotation of the shaft. To reduce the axial length of the rotor the end support disc 11 is inwardly dished.

By providing sufiicient frictional engagement between the ring 1115 and the portion 1% of reduced diameter on the shaft 211 the lug 111 and pin 112 can be dispensed with.

The supporting means 1% for the other end of the rotor 2 comprises a stub shaft 114 rigidly secured to the rotor end member 1112 a flexible generally conical diaphragm 116 secured at its thickened periphery by means of rivets 117 to the wall 6 and a bearing 119 secured to the central portion of the diaphragm 116, the stub shaft 114 being journalled in the bearing 119. The central portion of the rotor end member 1112 is inwardly dished at 120 and the stub shaft 114 is secured to this dished portion, which accommodates most of the axial length of the diaphragm 116, stub shaft 114 and bearing 119 thus reducing the distance between the end of the rotor 2 and the mounting plate 6. The diaphragm 116 is, in this embodiment, made of rubber with the central portion of increased thickness at 121, this central portion having a recess 122 into Which the bearing 119 is fitted. A cylindrical bore 123 of the bearing 119 receives the stub shaft 114, which has a spherical depression for receiving a ball 124 located in the closed end of the bore 123 to provide and end limit stop for the shaft 114.

The ring or bushing 1% and the diaphragm 116 are both capable of accommodating substantial universal movement without imposing braking torques, and thus minor misalignments of rotor 2, drive shaft 20 and end wall 6 will not interfere with the proper operation of the fan. Moreover, both the diaphragm 116 and the ring or bushing 15particularly when the lugs 111 and pin 112.

are omitted-can accommodate also appreciable variation in the axial spacing of the parts. The diaphragm 116 can also compensate for a minor degree of eccentricity or misalignment of the stub shaft 114 relative to the true axis of the rotor. Thus the rotor 2 is mounted in a manner whereby even substantial inaccuracies of manufacture, such as may occur in economic quantity production, do not affect the successful operation of the fan.

Moreover, it will be seen that the rotor mounting arrangement described permits the rotor to be assembled within the guide wall structure by simple manual manipulation after insertion of the rotor through the wide opening between the guide walls 3, d on their inlet side.

FIGURE 4 shows a further mounting arrangement for the non-driven end of the rotor 2. Here the rotor end member 102 carries a flexible diaphragm 138 secured thereto at its edges as shown diagrammatically at 131 and mounting a stub shaft 132 at its central portion, the stub shaft being journalled in a bearing (not shown in FIGURE 4) which may be fixed to the end wall 6 (see FIGURE 2) of the fan unit. It will be appreciated that minor misalignments of the stub shaft 132 relative to the true axis of the rotor of the guide wall 6 will be accommodated by flexure of the diaphragm 139. The diaphragm may be made of metal or a flexible plastics material.

FIGURES 5 and 6 show a mounting arrangement suitable for use at either end of the rotor 2 and comprising a member 135', which may be of spring steel or flexible plastics, and which provides three arcuate spokes 13d radiating from a central hub 137. The outer ends of the spokes 136 are secured, as for example by screws 138 to projections on the rotor end member here designated 139. The hub 137 may be connected, at the driven end of the rotor, to the motor drive shaft 2%; at the non-driven end, it may be located and journal upon a fixed stub shaft. In either case, the arrangement accommodates manufacturing inaccuracies by fiexure of the spokes 136.

The stub-shaft and bearing elements of the various embodiments may of course be inverted in position: their function is simply to provide a journal mounting at the non-driven end of the rotor. The rubber diaphragm or other flexible member, located between one such element and the fixed support or between that element and the rotor end member, provides a substantial degree of universal movement of the journal mounting above referred to:

I claim:

1. A cross-flow fan comprising stationary support means, an electric motor rigid with the support means and having a drive shaft, a bladed cylindrical rotor having end members, a first flexible portion connected to one end of the drive shaft and to one rotor end member, the first flexible portion providing support for said one end of the rotor which support is capable of substantial universal movement free of braking torque, and journal mounting means at the other end of the rotor comprising a stub shaft element and a bearing element therefor, a second flexible portion connected to one of said elements and interposed with the journal mounting means between the stationary support means and the end member at the other end of the rotor to provide support therefor capable of substantial universal movement free of braking torque, and guide walls rigid with the stationary support means and extending the length of the rotor in spaced relation externally thereto the guide walls and rotor cooperating on rotation thereof to induce a flow of air from one side of the rotor through the path of the rotating blades to the interior of the rotor and thence again through the path of the blades to another side of the rotor.

2. A fan as claimed in claim 1, wherein said first flexible portion is an elastomeric bushing.

3. A fan as claimed in claim 2, wherein said bushing frictionally embraces the drive shaft.

4. A fan as claimed in claim 3, wherein the bushing engages in a groove in the shaft.

5. A fan as claimed in claim 3, wherein said bushing frictionally grips said one end member.

6. A fan as claimed in claim 3, wherein said bushing is compressed in a hole provided by said end member.

'7. A fan as claimed in claim 3, wherein said end member has a disc-like portion with a central hole and said bushing is received in the hole and frictionally grips the periphery thereof.

8. A fan as claimed in claim 7, wherein the bushing is exteriorly grooved and said one member is engaged in the groove.

9. A fan as claimed in claim 1, wherein said second flexible portion is an elastomeric member providing an annular web like portion.

18'. A fan as claimed in claim 9, wherein said elastomeric member is connected between one of said stubshaft and bearing element and said stationary support means, and the other of said elements is connected to the rotor end member.

11. A fan as claimed in claim 1%, wherein said bearing element is located in a central recess in the elastomeric member and the rotor end member is inwardly dished to at least partly accommodate the axial length of the hearing member.

12. A fan as claimed in claim 1, wherein said second flexible portion is a diaphragm connected between one of said stub-shaft and bearing elements and said rotor end member, the other of said elements being mounted on the stationary support means.

13. A fan as claimed in claim 1, wherein said first flexible portion is a member providing a bushing surrounding the shaft and a plurality of spokes whose inner ends are integral with the bushing and whose outer ends are connected to the rotor end member.

14-. A fan as claimed in claim 1, wherein said second flexible portion is a member having an inner axially disposed part connected by said stub-shaft and bearing elements to the stationary support means and plurality of spokes whose inner ends are integral with the inner part and whose outer ends are connected to the rotor end member.

15. A cross-flow fan comprising stationary support means, an electric motor rigid with the support means and having a drive shaft, a bladed cylindrical rotor having end members one of which has recess-providing means, an elastomeric bushing surrounding one end of the drive shaft and engaged in the recess in said one end member, a stub-shaft element at the other end of the rotor, a bearing element journalling the stub-shaft element, and an elastic member having a central portion secured to one of said elements and a surrounding web-like portion secured remote from the central portion to said stationary support means, the other of said elements being connected to the other rotor end member, said bushing and said web-like portion of the elastic member rotatably supporting the rotor and each providing for substantial universal movement of the respective end member relative to the support means, and guide walls rigid with the stationary support means and extending the length of the rotor in spaced relation externally thereto the guide walls and rotor cooperating on rotation thereof to induce a flow of air from one side of the rotor through the path of the rotating blades to the interior of the rotor and thence again through the path of the blades to another side of the rotor.

16. A fan as claimed in claim 15, wherein the bushing itself transmits drive between the drive shaft and said one rotor end member.

17. A cross flow fan comprising a guide wall structure including first and second guide walls joined by end walls and an electric motor rigid with one end wall and having a drive shaft, a bladed cylindrical rotor having end members, a drive connection between the drive shaft and one rotor end member, journal mounting means at the other end member of the rotor comprising a stub shaft element and a bearing element therefor, flexible means interposed with said journal mounting between the other end wall and the other rotor end member, the first and second guide walls extending the length of the rotor in spaced relation exteriorly thereof and defining an inlet wider than the rotor diameter and an outlet, and the guide walls cooperating with the rotor on rotation thereof to induce a flow of air from the inlet through the path of the rotating blades of the rotor to the interior thereof and thence again through the path of the rotating blades to the outlet, the drive connection being a push fit on the shaft and the stub shaft and bearing elements being relatively telescopable and the drive connection and flexible means being capable of substantial universal movement whereby the rotor is capable of assembly by manual manipulation through the inlet.

18. A flow machine comprising a cylindrical bladed rotor, a mounting for the rotor, means to guide fluid twice through the blades of the rotor in a direction transverse to the rotor axis, supporting means for rotatably supporting the rotor at one end from the mounting and for supplying drive thereto at the other end only, the supporting means including, at the one end of the rotor, a unitary member providing flexible spokes the spokes being secured to the rotor remote from the rotor axis and carrying an element journal-connected to the rotor mounting for rotation about a fixed axis.

19. A flow machine as claimed in claim 18, wherein said axially disposed element is a bushing.

20. A flow machine comprising a cylindrical bladed rotor, a mounting for the rotor, means to guide fluid twice through the blades of the rotor in a direction transverse to the rotor axis, supporting means for supporting the rotor at one end from the mounting, a drive connection at the other end of the rotor; said rotor supporting means including a stub shaft member, a bearing member journalling said stub shaft member, and an elastic connecting element secured at its outer periphery to said rotor mounting and having an inner portion in frictional retaining engagement about said bearing member, the stub shaft member being fixed to said rotor.

21. A flow machine as claimed in claim including end location means acting between the stub shaft member and the bearing member.

22. A flow machine as claimed in claim 21 wherein the end location means comprises a ball acting between a closed end of the bearing member and the end of the stub shaft member.

23. A flow machine as claimed in claim 20 wherein the rotor has an end wall which has a central inwardly dished portion carrying said stub shaft member, and wherein said connecting element projects into the dished end wall portion.

4. A flow machine comprising a cylindrical bladed rotor, a motor having a shaft driving the rotor, means to guide fluid twice through the blades of the rotor in a direction transverse to the rotor axis, and a drive connection connecting the rotor and the motor shaft and permitting at least some universal movement and providing both drive to the rotor and support for the end of it; said drive connection comprising a flexible ring embracing the shaft of said motor, a disc in one end of the rotor having a central aperture within which said ring is supported, said ring having a peripheral groove therein, the side walls of said peripheral groove and the opposite faces of said disc adjacent said aperture being in frictional engagement to provide the connection between the ring and the rotor.

25'. A flow machine comprising a cylindrical bladed rotor, a mounting for the rotor, means to guide fluid twice through the blades of the rotor on rotation thereof in a direction transverse to the rotor axis, means for rotatably supporting the rotor upon the mounting at both ends thereof and for driving the rotor, said supporting and driving means including a rigid rotor end wall presenting an axial opening, an axially located shaft member extending into said opening, and an elastometric element pushfitted into the opening about the shaft and frictionally retained in assembled position by the compression between the rotor end wall and shaft.

26. In a cross-flow machine as claimed in claim 24, said shaft having a portion of reduced diameter, said ring engaging said reduced portion.

References Cited by the Examiner UNITED STATES PATENTS 1,679,890 8/1928 Baldwin 308-143 1,684,773 9/1928 Marks 230-1345 1,823,579 9/1931 Anderson 257-137 1,885,046 10/1932 Bennett 308-26 1,889,588 11/1932 Anderson 230- 1,920,952 8/1933 Anderson 230-125 1,991,280 2/1935 Hynes 219-391 2,131,484 9/1938 Ringwald 219-391 2,458,268 1/1949 Hinds 219-391 2,479,571 8/1949 Hewitt 219-3913 2,820,880 1/1958 Huntsinger et al. 219-391 2,942,773 6/1960 Eek 230-125 2,968,436 1/1961 Coester 230-125 FOREIGN PATENTS 19,354 12/1929 Australia. 783,574 9/1957 Great Britain.

LAURENCE V. EFNER, Primary Examiner.

Claims

1. A CROSS-FLOW FAN COMPRISING STATIONARY SUPPORT MEANS, AN ELECTRIC MOTOR RIGID WITH THE SUPPORT MEANS AND HAVING A DRIVE SHAFT, A BLADED CYLINDRICAL ROTOR HAVING END MEMBERS, A FIRST FLEXIBLE PORTION CONNECTED TO ONE END OF THE DRIVE SHAFT AND TO ONE ROTOR END MEMBER, THE FIRST FLEXIBLE PORTION PROVIDING SUPPORT FOR SAID ONE END OF THE ROTOR WHICH SUPPORT IS CAPABLE OF SUBSTANTIAL UNIVERSAL MOVEMENT FREE OF BRAKING TORQUE, AND JOURNAL MOUNTING MEANS AT THE OTHER END OF THE ROTOR COMPRISING A STUB SHAFT ELEMENT AND A BEARING ELEMENT THEREFOR, A SECOND FLEXIBLE PORTION CONNECTED TO ONE OF SAID ELEMENTS AND INTERPOSED WITH THE JOURNAL MOUNTING MEANS BETWEEN THE STATIONARY SUPPORT MEANS AND THE END MEMBER AT THE OTHER END OF THE ROTOR TO PROVIDE SUPPORT THEREFOR CAPABLE OF SUBSTANTIAL UNIVERSAL MOVEMENT FREE OF BRAKING TORQUE, AND GUIDE WALLS RIGID WITH THE STATIONARY SUPPORT MEANS