US2436096A

US2436096A - Apparatus for testing the static balance of propeller blades

Info

Publication number: US2436096A
Application number: US487000A
Authority: US
Inventors: Leroy B Chubb
Original assignee: Avco Manufacturing Corp
Current assignee: Avco Manufacturing Corp
Priority date: 1943-05-14
Filing date: 1943-05-14
Publication date: 1948-02-17
Anticipated expiration: 1965-02-17

Description

Feb. 17, 1948.

L. B. 'CHUBB APPARATUS FOR TESTING THE STATIC BALANCE OF PROPELLER BLADES Filed May 14, 1945 3 Sheets-Sheet Fri .Feb. 17, 1948. V L.B.HUBB 2.436.096

APPARATUS FOR TESTING THE STATIC BALANCE 0F PROPELLER BLADES I Filed May 14, 1943 3 Sheets-Sheet 2 Lenqgb. (1/5116!) Feb. 17, 1948.

L. B. CHUBB APPARATUS FOR TESTING THE STATIC BALANCE OF PROPELLER BLADES Filed May 14, 1943 3 Sheets-Sheet 3 Patented Feb. 1'7, 1948 APPARATUS FOR TESTmG THE STATIC BALANCE OF PROPELLER BLADES Leroy B. Chubb, Toledo, Ohio, assignor to Avco Manufacturing Corporation, a corporation of Delaware Application May 14, 1943, Serial No. 487,000

20 Claims. 1

The invention relates to apparatus for use in making propeller blades.

In the fabrication of hollow steel propeller blades it is desirable and important for the proper performance of the blade to finish the tubular shank end of the blade, which is usually rotatably confined in a radial socket in the hub for pitch variation, according to the hanging vertical center line of the blade when it is suspended in vertical hanging balance rather than according to its physical longitudinal axis. In the fabrication of these blades in production equipment discrepancies between said axis and said hanging center line are practically unavoidable and this renders it necessary to machine the shank for its proper performance in the hub.

One object of the invention is to provide improved apparatus for measuring the variation at the tip of the blade between the physical longitudinal axis and the hanging vertical center line for use in machining the internal and external peripheries of the shank so that the axis of the shank, when installed in a hub, will be coincident with the true vertical center line of gravity or hanging vertical center line of the blade.

Another object of the invention is to provide improved apparatus for expediting the manipulation of the propeller blades for determining the variation between the physical longitudinal axis and the true hanging vertical center line.

Another object of the invention is to provide a simple, efficient and quickly attachable and detachable device for internally gripping the shank of the blade for hanging the blade on an abutment' on the flexible suspension element.

Another object of the invention is to provide a device which is adapted to gripand is quickly attachable to and detachable from the flexible suspension element such as a wire, for hanging the blade from its shank while making measurements at the tip.

Other objects of the invention will appear from the detailed description.

The invention consists in the several novel features which are hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawings:

Fig. 1 is a front elevation of apparatus embodying and for carrying out the invention.

Fig. 2 is a vertical central transverse section.

Fig. 3 is a vertical section of the device detachably secured in the shank of the blade and the detachable device for gripping the suspension 2 Wire for suspending the blade from a hanging center in the shank of the blade.

Fig. 4 is a section taken on line 4-4 of Fig. 3.

Fig. 5 is a section taken on line 55 of Fig. 3.

Fig. 6 is a section taken on line 6-6 of Fig. 3.

Fig. 7 is a plan view of parts of the device which are secured in the shank of the blade for suspension of the blade from the wire.

Fig. 8 is a section taken on line 8-8 of Fig. 5.

Fig. 9 is a vertical section of the Viewing and measuring device.

Fig. 10 is a section taken on line Ill-l 0 of Fig. 9.

Fig. 11 is a plan ofthe lens and the casing in which it is mounted.

Fig. 12 is a diagram illustrating the manner of determining the location of the hanging vertical center line at the tip of the blade from the physical longitudinal axis of the blade.

In the fabrication of the blade a the working portions of the blade are finished to airfoil contour and the shank a is rough finished. A point a is prieked in the tip at the physical longitudinal axis for use in measuring the hanging vertical center line at the tip of the blade. The blade is then elevated and suspended so it will hang in vertical balance. While hanging in vertical balance, the tip end of the blade is viewed andthe location of the hanging vertical center line is micrometrically measured from the point a These measurementsv are then used in'machining the interior andexterior peripheries-of the shank so its axis will conform to the true g. center line of the blade. The blade. is placed in a cylindrical fixture or. jig with the true hanging center line congruent with or lying along the center line in the jig. The jig is, then placed in suitable equipment so that the internal and external surfaces of the hub may be machined parallel'to the hanging center line of the blade. In assembling the blade into the jig the point a is again utilized by positioning it away from the center line of the jig according to the measurements as determined by the micrometer readings taken when the blade was in hanging balance in the hanging fixture.

The apparatus exemplifying the invention comprises, generally: a flexible element such asfa wire for suspending the blade in hanging balance; a detachable abutment device on the suspension wire on which the blade is free to hang in vertical balance; a device which is detachably secured in the bore of the shank of the propeller for suspending the blade in hanging balance from the abutment device: hoisting mechanism comprising a winding drum for the wire for raisiv ing and lowering the blade from its shank into its hanging position; a columnar supporting structure; an overhead device for gripping the wire above the blade for holding the latter in an elevated hanging position; a device controlled from floor level for operating the overhead gripping device; an optical unit for viewing from below the tip of the blade; and means for measuringthe variation between the point indicating the physical longitudinal axis and the hanging vertical center line when the blade is suspendedi hanging balance.

The supporting structure comprises a solid concrete base which is usually built on a solid foundation under the shop floor 2i; apair of concrete columns 23 built on the base 20 and spaced apart to provide between them a vertically extending space in which the propeller blade a can be suspended; a plate 22 rigidly mounted on the base 2d at convenient working level for the operator; andtI-beam 24 which rigidly connects the top of the columnszti; and a frame 25 rigidly mounted on the top ofll-beam 24 for supporting a sheave, 2!- which is journaled in. a bracket. 28' which is welded tov the top of the frame 25. A suspension wire 26 has a portion which. depends from the sheave 21 for attachment to the propeller blade. An overhead electric hoisting mechanism 279 is. mounted on the beam and comprises a drum 39 on which the wire 25 is wound to hoist the blade; connected to the freeend of the wire 25 from the floor into suspended position between the: columns 23. Rungs 19 secured in the base 20 and columns form a ladder on which an operator can climb to theupper portion of the supportingstructure.

Theabutment-device for supporting the shank end of the blade for vertical hanging balance fromthe wire Zioomprises a body or thimble 35 through which the-wire 26 passes and which is provided witha notched gripping flange or wheel 38; a conical socket 39. and an: internal screwthread 31. A gripping member 32-- comprises a stem 32 which is threaded to the screwthread 3-1 in. the thimble 36 and provided with a wheel or grip 33 at itslower end, a seriesof longitudinally extending radial slots- 35 which formcontractible jaws for gripping thewire 2G, and a conicalportion 40 fitting: inthe conical socket 39- inthethimble 3B; Thimble 36 and member-32' have acentral opening through which the wire 26- passes. In attaching the abutment device to' wire 25, the wireis threaded through thimble 36 and member 32 and the thimble 36 is then rotated around member 32 which will cause the conical socket 391 to contract the jaws on member 32- and' forcethem-into firm gripping relation with the wire. Reverse rotation of the thimble will permit thejawsonmember 32 to expand and release the. wire. The upper end of thimble 35- for suspending the blade on the hemisphericalabutment surface 41' of the thimble 36 comprises acylindricalbodyAG-which isad'apted to extend freely-into the bore of the shank of the blade and. is provided with a peripherally notched flange 41' adapted to abut against the end of theshank; a 'series of'wedges SO-Which areradially 4 slidable in slots 54 in the body 46; and an expanding sleeve 45 which extends through body 46 and comprises a cone 5| which engages and is adapted to spread the wedges 5B in the bore of the blade for internally gripping the shank. Sleeve 45 is slidable in the body 46 and is connected thereto against rotation by a: spline 49. A. nut 48 is screw-threaded to the upper end of the expanding sleeve 45, abuts against the upper face of flange 4! on body 46, and is adapted to slide thesleeve 4.5 in body 46 so that cone 5| will expand, the wedges 58 into internal gripping engagement with the bore of the blade. Spring rings 53. are adapted to contract the wedges 58 when the nut 48 is rotated on member 4| to release the wedges 58; A bearing block 42 is seated against the shouldered upper end of a socket 15 in the expanding sleeve 45 and is provided with a conical surface 43 which engages the hemispherical surface 4! on. the member 36 of the wire gripping device so that the blade and the device clamped in the blade are free to permitthe blade to hang inverticalbalance. The thimble 3.6 extends into the socket 45 in sleeve 45 blade hangs is coincident with the axis of the shank. This expansible gripping device exemplifies one which is adapted to be clamped in the bore of the blade for freely suspending the blade from the abutment device which is clamped to the wire 26, so that the blade will pass into true vertical hanging balance.

In usin the invention the shank gripping device with the bearing block 42 therein is secured in the blade while the latter is on ornear the floor and after the wire 25 has been threaded therethrough and? the abutment device has been secured on the wire. The drum 30 will then be operated bythe hoisting device 29- to wind the wire 26, on the drum. The abutment device on the wire will engage the gripping device in the shank of the blade and. elevate the blade until it is freely suspended in hanging balance with its tip a above'thebase 28 of the supporting structure.

The invention comprises device for gripping the wire 25 to support the blade in hanging balance for. the determination of the discrepancy between the physicallongitudinal axis and the hanging vertical center line of the blade. This deviceis supported? above the hanging blade by an I-beam 55 which extends between the columns 23 and is secured to angle ironsfixed t'o saidcol umns. This gripping device is ,supportedin a frame which comprises a block 56, bars. 51 welded to the top of said block, and-a bar 58 secured by screws 59to the bars 51. Theframe issupported from thev I-beam 55v by bolts 60. which extend: through block 58 and bars51 and 58. Avbearing block 6! is seated in a shouldered recess in block 56 and is provided with an upwardly facing conical bearing surface. The wire 25' between the sheave 21 and the end-on which the blade is suspended extends through' a thimble or sleeve 63. The lower end of sleeve 63 is provided with a hemisphericalbearing surface 64- which engages the conical surface 62'inthe-block'6l A stem'65 is screw-threaded at66- to the sleeve 63 and is provided with a conical lower end 61 which fits in a conical bore 68 in the sleeve 63 and with longitudinal slits 69 so that the portions between the slits constitute contractible jaws for gripping the wire. The cone 61 formed on the stem 65, fits sleeve will contract the jaws on said stem and cause them to grip the wire 26. Reverse rotation of the stem will release said jaws to permit the wire to slide through the block 6|, sleeve 63 and stem 65. Lugs I6 fixed to block 56 extend loosely into notches II in a flange on the upper end of sleeve 63 to hold said sleeve against rotation. Suflicient play of the lugs I6 in notches II is provided to permit the sleeve 63 and the stem 65 therein to tilt on the bearing block 6| so that the wire will hang truly vertical from the sleeve 69.

This cable gripping device is elevated for suspending the blade above the base 26 and mechanism is provided for operating it conveniently by an operator on the floor 2 I. This mechanism comprises a hand wheel I2 fixed to the lower end of a shaft I3 which is journaled in a bracket which is fixed to the front side of one of the standards 23; avertical shaft I4 journaled in the block 56 and bar 58 and connected by a universal joint I5 to the upper end of shaft 13; a pinion I6 keyed to shaft 14 between bar 58 and block 56; a gear 11 meshing with pinion I6 and journaled on a hollow stud I8 which is secured by a nut 19 in the bar 56; and a series of-pins 86 fixed in and depending from gear I1 and extending loosely into holes 8| in the flange 82 on the upper end of the stem 65. Holes 8| are enlarged to permit the sleeve 63 and the stem 65 to tilt. The wire 26 extends through the stud 16. Before the hoisting device is operated to wind wire 26 on the drum 36 for hoisting the blade to its elevated hanging position, the operator on the floor 2| will rotate the wheel I2 in one direction which will cause pinion I6 to rotate gear 'I'! which car ries the pins 86 and the latter will rotate the stem 65 tocause the screw-thread 66 to movethe stem 65.upwardly in the sleeve 63. This will cause the jaws on the stem 65 to spread so that the wire 26 will pass through the stem 65 and sleeve 63. When the blade has been elevated to its hanging position below the block 56, rotation of the hand wheel 12 in the opposite direction will rotate the stem 65 into the cone 98 in the sleeve 63 and jamb the jaws on said stem into firm gripping relation with the wire 26 so that the blade will be suspended at the fixed elevation desired. After the hanging center line of the blade has been determinedas hereinafter set forth, the hand wheel I2 may be again operated to release the wire 26 so that the blade can be lowered to floor level. This exemplifies means accessible from the floor for operating the device for locking the depending portion of the wire 26. Before the blade is hoisted to its hanging position a, point a is pricked in the tip on the physical longitudinal axis of the blade. When the blade is elevated and suspended the wire 26 permits it to hang in vertical balance around a vertical line extending through the center of the bearing between the sleeve 63 and the bearing block 6I. 'When the point a on the tip of the blade in hanging balance is not coincident with the hanging,

vertical center line, said point will be horizontally offset from the vertical. hanging center line in distance and direction according to the discrepancy between the vertical hanging center line and the physical longitudinal axis resulting from variations in the distribution of mass in or in the machining of the blade.

An optical device is provided for viewing the tip of the blade and micrometric means for measuring the variation between the point a which indicates the physical longitudinal axis and the hanging vertical center line at the tip of the blade while it is suspended in vertical hanging balance. This optical device is mounted over the plate 22 at convenient working level for the operator and comprises a, mounting or casing 9 I; a lens carried by a tube 96; a pinion 92 which engages rack-teeth 93 on tube 96 for focusing the lens 85'on the tip of the blade; a thumb wheel 92 for rotating pinion 92; screws 94 engaging a shoe 95 for securing tube 96 with its lens therein in its adjusted position; an upwardly and forwardly inclined tube 86 with a suitable lens and eye-piece; and housed

prisms

81 and 68 which provide for vision from tube 86 of the tip of the blade through the lens 65. The lens 85 is provided with

hair lines

96, 91 at right angles to each other which intersect in the center of lens 85 and tube 96. The optical device with the lens 85 therein is mounted for movement in planes at right angles to each other corresponding to the

lines

96, 91 so that the intersection of

lines

96, 91 may be shifted longitudinally and transversely into vertical alignment with the point a on the physical longitudinal axis of the blade.

The mounting 9| is detachably and fixedly carried by a plate I66 which is slidable horizontally and transversely under the tip of the blade in a plane parallel to the line 91 on lens 65 over a plate I65 which is slidable longitudinally on the fixed plate 22, so thatby compounding the movements of the plates I 66 and I65 the intersection of the

lines

96, 91 may be brought into vertical alignment with the point at on the tip of the blade while the latter is viewed by the operator. A screw I6! is connected to plate I65, threaded to a lug I68 which is fixed on the plate 22, and provided with a stem I6'I for turning the screw to positively shift plate I65. A screw I69 is connected to plate I66, threaded to a lug II 6 which is integral with the plate I65, and provided with a handle I69 for turning the screw to positively adjust the plate I66 over the plate I65. The position of the plate I65 on the plate 22 is indicated by a pointer III and a scale II2 fixed to plate 22. The position of the plate I66 on the plate I65 is indicated by a pointer I I3 on plate I69 and a scale II6 fixed to plate I65. These scales are marked to indicate when the mounting 9| is adjusted to vertically align the intersection of

lines

96, 91 on lens 65 with the hanging vertical center line of the blade when it is in true vertical hanging balance and also to indicate the distance which the mounting and lens are moved horizontally in directions at right angles to each other to vertically align said intersection with the point a on the tip of the blade. As a result, when the intersection of the

lines

96, 91 is shifted horizontally into vertical alignment with the point a on the tip of the blade, the coordinates X and Y, as illustrated in Fig. 12, will be measured on the scales H4, H2, respectively. In this manner the variation or discrepancy between the physical longitudinal axis and; the hanging vertical. center .line. at; the tip of: the blade. will be: accurately. determined and measured; The mounting: Si is.- provided with: albase flange-99S which is. d'etachably secured by clamping lugs 98 to plate Hill. A circular plate I01 is clamped between the flangeilill and plate. I; The-baseflange BSYis provided with a stud i0? which fits into a hole in the; plate NH and the latter is provided with a cylindrical stud I03 which fits into a corresponding.- opening in plate I00; The base flange 93'is.pr0Vided' with notches 34' which, when the clamps 98; are loosened and the flangev 99 isrotat'ed. tobring'the notches into alignment with lugs 9'8, will: permit the: mounting 9i to be removed from 'theplate m0;

The optical device is partially enclosed: in. a housing H6 which is provided with. an opening in its top for exposing the tip of theblade;

After the X and Y coordinates. have beenit-hus measured, the hand. wheel 121 is operated to release the wire. 26 and the blade is lowered. The shankgripping device is thenreleased. from the-blade and lefton. the'wire 26. The blade is then positioned in. a suitable fixture 01'. jig in accordance with the true hanging center line of the blade coincident? with or lying along the center line of the jig. This jig: is then placed: in a. suitable equipment: andxthe internal and external: surfaces: of the shank aremachined' parallel to the hanging center line of the blade. In assembling. the blade into the jig the. blade is positioned from the point a? and the center line of the jig'according to the measured coordinates X and Y as determined by. the micrometric readings taken: when the blade was" in the hanging fixture.

The invention exemplifies apparatus for expeditiously and accurately determining and measuringthe discrepancy between the physical longitudinal center line and the vertical center line of a propellerblade at its tipwhen the blade is in hanging balance for use in machining or remachining'the shank of'the blade in accordance with its: true hanging center line to facilitate-the fabrication ofpropeller blades within permissible tolerances for mounting the blade inv a. hub in accordance with the hanging vertical center line andawhichresults in reducing the tolerance range.- The invention also exemplifies: a fixture for conveniently handling'the-blade for hanging it in vertical balance; a conveniently operable device for controlling an: overhead device for grippingthe wire to support the blade in elevated position; an abutment deviceadapted to be clamped to the suspension'wire; and a, device whichis adapted to internally grip the shank ofthe blade for suspension from the abutment device on the wire;

The invention isnot to be understood as restricted'to the details set forth sincethese-may be modified within" thescope of the appended claims Without departing from the spirit and scope of theinventiom Having thus described the invention, what I claim as new and desire to secure by Letters Patentis:

1 Apparatus for use in malcing'propeller blades provided with a shank for connection to a hub: comprising; a supporting. structure; means adapted" to: be. connected to the: shank. of the bladefor suspending the blade. from; saidstructure so itis free to. hang vertically with'the tip at. its lower end; and an optical device-on: said structure for viewing the tip-of the bladefrom below; including: meansfor. measuring: the deviationbetween the. vertical:v line of; the hanging centerand: a mark on the: physical longitudinal axis at the. tip. of the blade in; difierent. angular directions.

2. Apparatustfor usein makin'gtpropellerblades provided with. a shank for: connection to a hub comprising, a. supporting. structure; means adapted to be. connected to the: shank of. the blade for suspending th8.':b1&de'. from saidstructure so it is. free to'hang vertically with' the tip at its lower: end, and; an optical device on: said structure; for viewing the tip of the blade from below including means for: moving; said device in horizontal planes in directions at right angles to each other, and means; formeasurin'g: in said planes the deviation between: the vertical lineof the. hanging: center and a mark. on the physical longitudinal axis at. the. tip of the. blade in dif, ferent angular directions.

3. Apparatus-for use. in maklng'propell'er blades provided. with a shank. for. connection: to. a hub comprising, a supporting structure means adapted to be: connected to the shank of. the blade. for suspending the blade from. said; structure so it is free. tohang vertically with the tip at its. lower. end, and; an optical device; on said structure for viewing: the tip of the; bladeafiom below comprising a lens below the. blade and provided with means movable to vertical coincidence with a. point on the tip of: the blade, an: eye-piece in ofiset relation .to the blade, prisms between the lens and the. eyeepiece, andm'eans for measuring the deviation between the vertical hanging: center line and a mark on thephysical longi tudinal axis at thetip of the blade in different angular directions,

4. Apparatusfor use in making propeller blades provided with a shank for. connection to a hub comprising, a supporting structure, means adapted to be. connected to the. shank of the blade for suspending the blade from said strumture so it is free tohang vertically with the tip at its lower end, an optical device. on saidstruc' ture for viewing the tip of the blade from below including, a lens below the blade, an eye-piece in offset relation to'the blade; prisms between the lens and theeye-piece, and amountin for the lens; eye-piece and prisms, movable in horizontal planes in directions at: righti'angles to each other to positionthe. lens. in vertical alignment with amarkedphysical center onthe tip of the blade, and means carried by said mounting for measuring in said planes the distance between the vertical line of" the hanging center and a mark on the-physical longitudinal axisat the tip of the blade.

5'; Apparatusfor usein-making propeller blades provided with a shank for connection to a hub comprising, a rigid columnar supporting structure; a. flexible suspension element for the blade carried by the structure and havinga depending end-portion, hoisting mechanism supported on the structure and connected to' said element for. raising the blade intoa freely hang,- ing position, means. on the depending portion of the element. for supporting the blade,.a device on the supporting, structure for gripping. said element to hold the blade in a predetermined hanging position, meansior. operating the. gripping device tosecure and release. said element, and means below and for determining the deviation of. amark on the physical longitudinal V .tip of the blade.

l 6. Apparatus for use in making propeller blades provided'with a shank for connection to a hub comprising, a rigid columnar supporting structure, a flexible suspension element for the blade carried by the structure and having a depending end-portion, a sheave at the top of the structure around which the element extends, elevated hoisting mechanism supported on the structure and'connected to the other end of said element for raising the blade into a freely hanging position, means on the depending portion of the element for supporting the blade, a device on the supporting structure for gripping said element to hold the blade in a predetermined hanging position, means for operating the gripping device to secure and release said element, and optical means below and for determining the deviation of a mark on the physical longitudinal axis from the vertical hanging center line at the tip of the blade.

7.' Apparatus for use in making propeller blades provided with a shank for connection to a hub comprising, a flexible element having a depending portion for a hanging connection to the shank of' the blade, a device for gripping said element to support the blade in hanging position comprising a member provided with contractible jaws for gripping said element and a body to which said member is screw-threaded and provided with means for contracting the jaws to grip the element, said body and member having a central opening through which said element passes, bearing-means for supporting said bodymember so the member and body tilt in any direction, means for holding the body against rotation, and means for rotating said member in the body.

8. Apparatus for use in making propeller blades provided with a shank for connection to a hub comprising, a flexible element having a depending portion for a hanging connection to the shank of the blade, a device for gripping said element to support the blade in hanging position comprising a member provided with contractible jaws for gripping said element and a body to which said member is screw-threaded and provided with means for contracting the jaws to grip the element, said body and member having a central opening through which said element passes, bearing-means for supporting said bodymember so the member and body are free to tilt in any direction, a stationary support for the bearing-means, means between the support and body, for holding the body against rotation while permitting it to tilt, and means for rotatin said member in the body.

9. Apparatus for use in making propeller blades provided with a shank for connection to a hub comprising, a flexible element having a depending portion fora hanging connection to the shank of the blade, 2. device for gripping said element to support the blade in hanging position comprising amember provided with contractible jaws for gripping said element and a body to which said member is screw-threaded and provided with means for contracting the jaws to grip the element, said body and member having a central opening through which said element passes, bearing-means for supporting said bodymember so the member and body are free to tilt in any direction, a stationary support for the bearing-means, means between the support and body, for holding the body against rotation, and

gearing for rotating saidmember mounted on the support, and a loose driving connection between the gearing and said member which permits said member to tilt in any .direction.

10. Apparatus for use in making propeller blades provided with a shank for connection to a hub comprising, a flexible element having a depending portion for a hanging connection to the shank of the blade, a device for gripping said element to support the blade in hanging position comprising a member provided with a screw-threaded stem having contractible jaws for gripping said element and a body member with a screw-thread for said stem and provided with means for contracting the jaws to grip the element, said stem and body having a central opening through which said element passes, bearing-means for supporting said body so the body and stem are free to tilt in any direction, means for holding the body against rotation, and means for rotating said member in the body.

11. Apparatus for use in making propeller blades provided with a shank for connection to a hub comprising, a flexible element having a'depending portion for a hanging connection to the shank of the blade, a device for gripping said element to' support the blade in hanging position comprising a member provided with contractible jaws for gripping said element and a body to which said member is screw-threaded and provided with means for contracting the jaws to grip the element, said body and member having a central opening through which the element passes, a stationary support, a bearing carried by the support which permits said body and member to tilt in any direction, means between the support and the body for holding the body against rotation while permitting such tilting movement, and gearing carried by said support for rotating said member in the body while permitting said member to tilt.

12. Apparatus for use in making propeller blades provided with a shank for connection to a hub comprising, a supporting structure including a pair of rigid columns extended upwardly from a working floor and spaced apart laterally to provide between-them space for hanging theblade, a flexible suspension element for the blade having a depending end-portion between the columns, means for detachably supporting the blade on the end of the depending portion of the element, hoisting mechanism supported on' the structure and to which the element is connected for raising the blade into hanging position between the columns, an overhead device on the supporting structure for gripping the element to suspend the blade in its hanging position, means operable from a point adjacent the floor level for operating the gripping device to release and lock said element, and meansbelow the hanging blade for measuring the variation between a mark on the physical axis and the vertical line of the hanging center at the tip of the blade.

13. Apparatus for use in making propeller blades providedwith a shank for connection to a hub comprising, a supporting structure including a pair of rigid columns extended upwardly from a working floor and spaced apart laterally to provide between them space for hanging ,the blade, an overhead guide on the structure, a flexible suspension element for the blade extending around said guide and having a free depending portion between the columns, means for detachably supporting the blade on the end of the depending portion of the element, hoisting mechainismzsupported on thesstructureand to which the element is connected for raising the blade into hanging position between. thecolumns, an over.- head device-on the supporting-structure for gripping the element to suspend the blade in its hanging position, means operable .from' a .point adjacent the floor level for operating thegripping :device to release and lock said element, and aneans below the hanging blade-for measuring the variation between a mark on the physical axis sand the vertical line of the hanging centera't the tip of :the blade.

14..Me'ans .for hangingra propeller blade with a tubular shank from arlfiexible suspension ele- :ment comprising, .a body provided with a :memberiadaptedito extend into :the shank of the propeller. a :fiange on saidbody, gripping members slida'blym'ounted insaid body for internallylgripping the'shank, a sleeve provided with means for expanding said members and slidably mounted in said :bodma nut threaded tos'aid sleeve for shiftlnglit-to expand said gripping members, :a bearing-member in the sleeve having a downwardly facing conical surfacaiafstem provided'with contractible jaws for gripping said element and a thimble 'extendingin'to the sleeve and having means atits upper end for engaging the conical surface on the bearing-member andmeans for contracting the jawsgtheithimbleiand'stem being connected :by a screw thread, the sleeve, thimble and stem :being provided with an opening through which said. element passes.

15. devicei'for supporting a propeller blade havinga tubularv shank'jrom a flexible suspension element provided :with an abutment comprising, a bodyadapted to sextend into the shank of tthexz blade elements mounted to slide radially in said.ibody i'for internally gripping the shank, a. sleeve slidably mounted in .and extending through said body and provided with means for spreading the gripping elements, a .-.nut on the sleeve for shifting the sleeve in the body, and a bearing in :the sleeve for 'tiltably supporting the device and blade from the abutment on the suspensionelement.

T16. Adevice for supportinga propeller blade having-a tubular shank from a flexible suspension Ielement provided with an abutment, comprising, abody adapted to extend into the shank V of the blade, elements mounted :to slide radially in said body for internally gripping the shank, a holdingflange-on the body on the outside of the blade, a sleeve slidablymounted in, and-extending through said body and provided with means for spreading the gripping elements, a nut .on' the sleeve for shiftin thesleeve in the body, and :a bearing in the sleeve for 'tiltably supporting the device and blade from the abutment'onthe suspension'element.

17; Means :for hanging-a propeller blade provided with atubular shank, .from a flexible suspension element so it will be free to hang'vertically, comprising: a device including means for detachably gripping said element and provided with a bearing; a device including a body insertableinto the shank of the blade, means carried by the body for internally gripping the shank, andla'bearing fixed in said-bodyas a support therefor having a bore which is .clear of the element; said bearings being separable andprovided with engaging faces for universal tilting o'i,.an'd.solelysupporting, the blade and the blade gripping device on the element gripping. device,

so that the blade will be free to hangiverticallyc 18. Means. for hanging a propeller :blade provided with a tubular shank, from a fflexible ssuspension-element so it will be free to hang vertically, comprising: adevice including means for detachably' gripping said element and provided with :a bearing; 'a device including a body in.- sortable into the shank of the blade, meanscarried by the body for internally gripping the shank, and a'bearing rfixedinthebody as .a.;supv port therefor having an opening "for clearing the element; said bearings being separable and provided withconioal and arcuate-engagingdaces for universal tilting of, .and solely-supporting, the blade and the blade gripping device :on the element gripping device so that the blade will ibe free to hang vertically.

'19. Means for hanging a propeller blade provided with a tubular'shank, from a flexible suspension element so it will be free to hang vertically, comprising: a device including means 'for detachably gripping said element and provided with a:bearing;,a device includinga tubular body .insertable into the shank of the blade, expansible jaws carried by the body for gripping-the shank, a member slidably mounted in the body for exhanding the jaws for, internally gripping the shank, and a bearing fixed in said body as -.a support therefor having a bore which is'clear :of the element; said bearings being separable .and provided with engaging faces in said member.f0r universal tilting of, and solely supporting the blade and the blade gripping device :on the :element gripping device so that the blade will:.be free to hang vertically,

20. Means for hanging a propeller blade provided with a tubular shank, from .a flexiblesuspension element so it will be free to hang vertisally, comprising: a device including means :for detachably gripping said element and provided with'a bearing; a device including'a tubular body insertable into the shank of the blade, means in the body 'for internally gripping the shank, and a bearing "having a bore which is clear 'of the element, said element gripping :member being adapted to extend into the tubular body, said bearings being disposed inthe tubularbody, and being separable andprovided with engaging faces for universal tilting of, and solely supporting the blade and the blade gripping device on the element gripping device so that the .blade will he free tohang vertically.

' LEROY B. CHUBB.

REFERENCES CITED The following references :are so'f record in the file of this patent:

I UNITED STATES PATENTS