AU629328B2 - Feathering propeller with a manually adjustable pitch - Google Patents

Description

rC OPI DATE 22/10/90 APPLN- ID 53311

PCT

AOJP DATE 29, ER PCT/IT90/00030 COOPERATION TREATY(PC T COOPERATION TREATY (PCT) INTERNATIONAL APPLICATION I1 (51) International Patent Classification 5 B63H 3/02, 3/12 (11) International Publication Number: (43) International Publication Date: WO 90/11221 4 October 1990 (04 10.90)

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(21) International Application Number: (22) International Filing Date: Priority data: 83614 A/89 21 March 83630 A/89 14 July 1l PCT/IT90/00030 19 Mar,;i 1990 (19.03.90) S1989 (21,03.89) 989 (14,07.89' (74) Agents: PELLEGRI, Alberto et al.; SocietA Italiana Brevetti Via Cavour, 9, 1-21100 Varese (IT).

(81) Designated States: AT (European patent), AU, BE (Earopean patent), BR, CA, CH (European patent), DE (European patent), DK (European patent), ES (European patent), FI, FR (European patent), GB (European patent), IT (European patent), JP, LU (European patent), NL (European patent), NO, SE (European patent), US, Published With international search report, (71) Applicant (for all designated States except US): MARINE PROPELLER CONSTRUZIONI ELICHE A PASSO VARIABILE [IT/IT]; Via C. Battisti, 35, 1- 21058 Solbiate Olona (IT).

(72) Inventor; and Inventor/Applicant (for US only) BERGHELLA, Rocco [IT/IT; Via C. Battisti, 35, 1-21058 Solbiate Olona (IT), (54)Title: FEATHERING PROPELLER WITH A MANUALLY ADJUSTABLE PITCH (57) Abstract Pitch adjustment in a feathering propeller em. Sc ploying a planet gear on- gagement between a pinion 17 7 1 hub keyed on the drive 7 13 6 shaft and planet pinions at the base of the blades of the propeller which 1 are rotatably mounted through holes of the wall of 21 a hub's easing may be easily perform-d manually 22 by registering the relative 2angular position of a second portion of casing in respect to a first portion (6) of the casing housing the 17 16 7 19 a planet gear. The registration of the pitch takes place by parting said second portion of casing from said first portion against the resistance of a push-back spring (17) for a distance sufficient to disengage a coupling (12-13) between said second portion and said first portion of the casing or said pinion.

hub rotating said second portion so disengaged in respect to the first portion of the casing before releasing the pull causing again the engagement of the two portions in a modified relative angular position. In this way the stop means for the tra.

vel of a dragging sector solidly connected to the hub of the propeller, which are substantially formed on the internal wall of said second portion of the casing, change their relative angular position about the sector thus modifying the limit orientation assumed by the blades when the drive shaft is rotated. Resilient elements are used between abatment surfaces for preventing deformation thereof.

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i i i i i illY11Pii- WO 90/11221 PC'/1T90/00030 FEATHERING PROPELLER WITH A MANUALLY ADJUSTABLE PITCH BACKGROUND OF THE INVENTION The present invention relates to a feathering propeller the pitch of which can be manually adjusted and which is particularly suited for sailing-boats.

The use of feathering propellers in sailing-boats for reducing drag when the boat is moving under sail is common.

On the other hand, in order to achieve the maximum efficiency in motor-driven motion, the propeller should be designed in function of the mechanical characteristics of the engine used (torque and power characteristics in function of the r.p.m. and of the engine's efficiency) as well as of the hydrodynamic characteristics of the boat's hull.

An effective answer to these problems is given by the socalled variable pitch propellers, i.e. propellers wherein the orientation of the blades when the propeller i3 driven by the engine may be adjusted, obviously within certain limits, to particular characteristics and/or conditions of use.

There is a category of commercially available propellers known as variable pitch, feathering propellers which fit in particular the needs of auxiliary engine propulsion systems .for sailing-boats.

These known propellers commonly comprise a pinion-hub keyed by means of a conical key joint on a rotary drive shaft, said pinion-hub having a coaxial conical gear, at least two and more preferably three propeller blades, each having a conical planet pinion at the base thereof meshing with said conical gear of the pinion-hub, 0s1=ejournalled through a hub's casing free to rotate about the hub through a limited arc of circumference. Each blade is free to rotate about the axis of "hce.?Aconical pinion base in a planet-wise manner around said conical gear of the pinion-hub two opposite angles (starting from a neutral position of the blade whereat the faces of the blade are substantially parallel to the axis of the propeller shaft) presettable by stop means, under the hydraulic forces caused, respectively, .I/v\by the rotation in a forward drive sense and in a reverse i. WO 90/11221 PCT/IT90/00030 2 drive sense of the drive shaft. These stops determine the pitch of the propeller in the two senses of rotation. The potr or casing is formed by sectors joined together by means of tangential stud screws and houses the pinion-hub and the planet pinions of the blades, which are journalled through holes of the casing formed along the coupling faces of the sectors which form the casing. The latter may rotate about said pinion-hub through either of said two opposite angles, from said neutral position of the blades, together with a planet-wise rotation of the blades around said pinion-hub and about their own axis. The two opposite angles of rotation are preset by stop means which may be formed by a radially extending tooth or sector solidly connected to said casing cooperating with a radially extending tooth or sector solidly connected to the body of said pinion-hub so as to determine by abutment of one tooth with the other stops for both senses of relative rotation.

Propellers of this type are described in US patents No.

4,047,841 and No. 4,140.434. In these known propellers the pitch could not be modified but through a complete disassembly of the propeller, thus requiring hoisting the boat and of the water for changing the pitch. In a prior Italian patent application No. 83647 A/87, filed on August 11, 1987, assigned to the present applicant, a feathering propeller with a pitch adjustable without grounding the boat and without disassembling the propeller is described. The propeller disclosed in this prior application made use of a thimble meshing with an extremity of the body of said pinionhub and held engaged therewith by a spring abutting against a closing flange of the casing of the propeller through which flange was mounted an ogive-shaped terminal having a central hole through which a stem solidly connected to said thimble could pass through and emerge from the apex of the ogive terminal. By means of a suitable key this stem could be pulled out in order to disengage said thimble from said pinion-hub and re-engage the thimble on the pinion-hub after having varied their relative angular position, thus changing the pitch of the propeller.

9 Also this propeller, though having advantages in respect Lu WO 90/11221 PCU/Mr99/4030 3 to the previously known propellers, has the drawback of being necessarily disassembled in order to be mounted and dismantled from the drive shaft of the boat and moreover it is necessary to use a key for adjusting the pitch. Moreover as the other propeller of the prior art, the propeller generates a relativelyhigh level of vibrations which fact is imputable in a large measure to the way the blades are journally mounted through the casing, whereby the flexural forces are borne by the tangential stud screws used for joining together the sectors which form the casing, moreover at start-up and reversal of the sense of rotation of the propeller, the casing dragging teeth, by ramming one against the other over said stop surfaces, generate a strong banging noise and a rapid wear of the abutment surfaces of said stops.

OBJECTIVES AND SUMMARY OF THE INVENTION A main objective of the invention is to provide a feathering propeller, the pitch of which can be adjusted without requiring disassembly of the propeller and wherein the propeller may be mounted and dismantled from the drive shaft of the boat without the need for disassembling the propeller and wherein the blades are journally mounted through the wall of the hub's casing of the propeller in a way that prevents or substantially reduces the generation of vibrations.

ct \z.csEc c f r~ee\ ^tA*oocwewC: A further objective of the invention is to provide a propeller wherein the ramming of one abutment stop surface against another is resiliently.dampened.

In accordance withAthe present invention these objectives are reached by means of a propeller wherein the blades which terminate with a conical gear, planetarily engaging .with the pinion-hub's conical gear, are no longer journally held into cylindrical sockets formed by joining together two adjacent /sectors o the casing, but on the contrary each blade is solidly connected to the cylindrical stem of the respective conical pinion passing through a hole of the wall of the respective\sector of the casing. In this way the flexural forces acting on the blade are borne by the body of the I I WO 90/11221 PCY/rr9O/OOO3O 4 respective sector and are better distributed over the assembled casing than in propellers of the prior art. The use of precision machined conical pinions and not, as customary, of pinions directly machined on the integral cast body of the blade, permits to reduce clearances further and improves the vibration characteristics of the propeller.

SThe device for manually changing the pitch of the propeller without requiring tools is implemented by "segmenting" the hub's casing along the axis thereof, into a first portion rotatable in respect to the pinion-hub of the propeller and provided with holes through which rotatably pass the stems of the planet pinions of the blades of the propeller, and a second portion which is internally provided with stops for the relative angular travel of an engagement tooth or sector solidly connected to the pinion-hub in order to provide angularly spaced stops to a relative free rotation of the pinion-hub in respect to the hub's casing and viceversa. The second portion of the casing may be telescopically pulled away from the first portion of casing against the resistance of a push-back spring by a distance sufficient to disangage said second portion from said first portion of casing or from '~Ve ortion-s vQ said pinion-hub. -h4Awe mesh together through an adjustable relative angular position coupling and he pull on the second portion of the casing may be v~elissedafter having rotated it relatively to the first portion of the casing for re-engaging it with the latter, having so changed the angles set by said Stops. SrT ar\ \e, \design position of the second portion of the casing respect to the first portion containing the planet gear assembly of the feathering blades is reversible. The essentially tubular second segment of the casing, telescopically meshing with the first portion of the casing and provided with the engagement stops cooperating with the engagement tooth or sector solidly connected to the pinionhub of the propellerj may be formed on the side facing the drive shaft or toward an ogive-shaped terminal of the casing itself. In the first case the abutting surface for the.pushback spring may be provided by a tubular flange mechanically Sounted on the end of the pinion-hub body toward the drive shaft. In the second case, the ogive-shaped terminal itself, which can be connected to the rear end of the pinion-hub body of the propeller, houses the push-back spring which keeps the two other portions of the casing meshed together.

According to et further alternative embodiment of the propeller of the invention, a pitch adjustment thimble meshing with the pinion-hub is tubularly extended and solidly connected to the ogive-shaped terminal of the propeller which may be manually pulled back by a distance sufficient to distngage the thimble from the pinion-hub in order to rotate it and re-engage it in a varied relative angular position for changing the pitch. The ogive-shaped terminal is further provided with a removable cap in order to gain access and unscrew a locking nut from a threaded end of the drive shaft, thus allowing the propeller to be dismantled from (and mounted to) the drive shaft without disassembling it.

Moreover the wear of the abutment surfaces of the stops and of the engagement tooth is substantially eliminated by resiliently mounting said stops on the internal wall of one of the sectors forming the hub's casing in order to dampen the ramming together of the abutment surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS The different aspects and advantages of the propeller of the present invention will become more evident through the following detalled description of several preferred embodiments, shown in the appended drawings, wherein: 25 Fig. 1 is an exploded view of a propeller of the invention according to a first embodiment; Pig. 2 is a partial cross-sectional view of the propeller of Fig. 1; Fig. 3 is a partial schematic sectional view of a propeller according to a different embodiment of the invention; and Fig. 4 is a partial schematic scletional view of a propeller of the invention according to another alternative embodiment.

~LIA

4 920624,gjrndat 123,niarine~let,5 WO 90/11221 PCT/T90/00030 6-- DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment is shown in Figures 1 and 2. The propeller comprises a pinion-hub I. The pinion-hub 1 has a conical seat with a key (the latter is not shown in the figures) for receiving the conical end 20 of a drive shaft 2 having a threaded end 21 on which a locking ring nut 22, provided with a socket, e.g. an hexagonal socket 23, for receiving a tightening key, is tightened. The pinion-hub 1 has a conical gear 3, preferably with straight teeth, with which the conical pinions 5, at the base of as many blades 4, of the propeller planetarily mesh. Preferably the propeller has three blades, meshing at an interval of: 1200 on the circumference of the conical gear 3 of the pinion-hub 1.

The blades are journally mounted through holes 6a, 6a', of as many sectors or portions 6, of casing which are joined together by means of tangential stud bolts 19 to form a hollow casing housing the planet gear.

Each blade is pre-assembled on its respective sector of casing. To this end, each blade is provided with a cylindrical seat 4a formed at the base of the blade casting and a threaded blind hole 4b, coaxial with said cylindrical seat 4a and extending inside the body of the blade beyond the bottom of the seat 4a. The respective planet pinion 5 of the blade is provided with a bored cylindrical stem 5a which fits through the hole 6a of the respective sector of the casing and inside the seat 4a formed in the base portion of the blade 4. A stud screw 5c passes through the pinion 5, the stem 5a and tightens in the threaded hole 4b extending inside the body of the blade 4. Suit-ble setscrews Sd may be used for preventing loosening of the assembly.

The flexural forces acting on the blade are transmitted to the body of the relative sector of the casing and distributed uniformly on the tangential stud bolts 19. This readily improves the noise and vibratory characteristics of the impeller. Moreover the use of separate planet gears, on the stem of which are mounted the blades of the propeller, permits a more rational and precise machining of the gear for reducing clearances and further improving noise and vibratory WO 90/11221 PCT/MO9/00030 -7characteristics of the assembly.

Rotation is transmitted by the pinion-hub 1 to the casing supporting the blades which is f ormed by the union of the sectors 6, 6' by means of at least a tooth or circular sector 8 projecting from the external cylindrical wall of a thimble 11, which has an external broaching 13 meshing with an internal broaching 12 present on the end portion of the pinion-hub 1. The dragging tooth 8 cooperates with a circular sector or tooth 7' extending for a certain arc length and projecting from the internal wall of one of the sectors of the casing. According to a feature of the propeller of the invention, this cooperating sector 7' is in the form of a separate insert piece having the shape of a sector of a circular ring with a rectangular or trapezoidal cross section and which is housed in a rectangular or trapezoidal cross section seat or groove 7a formed on the internal wall of one (61) of the sectors forming the casing. Both ends of the ring sector 7' have the inner portion, protruding out of the seat formed in the casing, extended circumferentially so as to create two spaces or seats underneath, respectively 7c and 7d, into which resilient inserts 7e and 7f of rubber (or calibrated springs) fit. The ring sectors 7' and the resilient inserts 7e and 7f are set into the seat 7a and are laterally held in place by the coupling surface of the adjacent sectors of casing' (6 and 6' ).if a rectangular cross section ring sector 7' is used, a retaining screw may be 4sed, the stem and head of which may fit through a ledged slotted bole purposely made through the thickness of the ring sector for preventing it from falling out of the seat 7a.

As it may be easily understood by looking at the figures, the circular sector or tooth 8, solidly connected to the pinionhub 1, when the latter rotates, eventually abuts against the stop surface of the relative end of the ring sector 71 protruding out of the seat 7a and which is solidly connected to the hub's casing formed by the sectors 6, 6' and 6''0 The tooth 8 thus drags in rotation the casing and the blades 4, 4' and which, by being individually engaged through the coki~cal planet gear with the conical gear 3 of the pinion-hub 1, will have meanwhile reached a certain limit orientation by WO 90/11221 pcf/MT9/00030 -8having rotated about the axis of their pinion and planetarily about the hub's axis, thus determining the pitch. Similarly, by inverting the sense of rotation of the drive shaft 2 (e.g.

reverse gear) Che two drag teeth 7' and 8 will abut one against the other with their opposite end surfaces after the planet gear will have rotated by a certain angle thus reversing the orientation of the blades in respect to the axis of the propeller.

Therefore the orientation of the blades in respect to the propeller's axis under forward and reverse gear is determined by the relative angular position of the two circular sectors or teeth 7' and 8 for a certain relative assembly angle of meshing of the blade's pinions on the pinion-hub conical gear 3.

When the shaft 2 is stopped, e.g. when the boat is moving under sail, the blades 4, 4 and 4 under the ef fect of the hydraulic pressures caused by the dragging of the blades through the water, are free to rotate about their own axis, by "rolling" with their planet pinion around the conical gear 3 of the pinion-hub 1. Therefore the blades yield under the pressure by orienting themselve~s so -is to reduce the drag resistance. in this way, 1.0. by feathering under the hydraulic drag pressure, the propeller blades assume a "flattened" position, i.e. with their major surfaces substantially parallel to the axis of the propeller, corresponding to a mid position in respect to the two limit orientations assumed by the blades, i.e. under forward and reverse driving of the propeller's shaft. These limit orientations of the blades are determined by the relative angular position of the two circular sectors 7' and 8, as seen before.

4Upon the starting of engine propulsion of the boat and upon each reversal of rotation, the pinion-hub 1 rotates the thimble 11 and the blades 4, about the axis of their respective planet pinion 5, until the relative end of the circular sector 8 abuts against the relative end of the circular sector 7' inserted in the seat 7a' thus dragging into rotation the casing and the blades so oriented. The ramming together of the two ends of the circular sectors 8 and 7' is dampened by either one or the other, of the two re- WO 90/11221 pcr/IT90/0003 9silient inserts 7e and 7f, In this manner the intensity of the rammings is reduced and the abutment surfaces are less subject to deformation and the propeller becomes less noisy.

According to another aspect of the invention, the thimble 11 is essentially tubular and has an internal diameter sufficiently large for allowing the passage through the thimble of the locking nut 22 of the pinion-hub 1 on the conical end of the drive shaft 2. The locking nut 22 tightens on the threaded end 21 of the shaft. The tubular thimble 11 is threaded at one end lla and passes through the central hole of a flange 9a which is fixed by stud screws 9b .to the end faces of the sectors 6, of the hub's casing of the propeller. On the threaded end lla of the thimble 11, a first tubular, truncated, ogive piece 9c is screwed and locked by means of setscrews 9d. An ogive shaped cap 9e is screwed into the threaded hole of the truncated ogive piece 9c, thus completing the ogive terminal of the propeller. A spring 17 is inserted over the tubular thimble 11 and abuts compressively against the internal surface of the flange 9a and keeps the thimble 11 engaged through the broached joint 12-13 with the pinion-hub 1.

The propeller may be dismantled and mounted on the drive shaft without disassembling it. To do this it is sufficient to unscrew the cap 9e and to insert a key to engage the socket-head seat 23 on the locking nut 22 and to unscrew the latter completely thus freeing the propeller from the drive shaft.

The pitch may be varied without disassembling the propeller and without any tool. For varying the pitch it is sufficient to manually pull the portion of the casing (7) represented by the ogive terminal, formed by the truncated ogive piece 9c and by the cap 9e, against the resistance of the push-back spring 17 until disengaging the thimble 11, which is connected to the ogive terminal 7, from engagement with the pinion-hub 1 and to rotate the pulled out ogive by a certain angle before releasing the pull and letting the thimble 11 engage again with the pinion-hub 1 in a changed relative angular position. The minimum increment of variation will be unit.Arily determined by the pitch of said external WO 90/11221 PCr/rr9O/00030 10 and internal broachings 12 and 13, telescopically meshing together.

The external surface of the ogive terminal may be conveniently provided with grasps indentations tangential grooves for facilitating the pulling action..

The pitch adjustment operation is extremely simple and rapid and may be performed by a short immersion.

Pitch adjustment may be facilitated by means of a scale or reference marks engraved along the adjacent external rims of the flange 9a and of the truncated ogive piece 9c.

Normally the construction material will be marine bronze with the exception of the ogive cap 9e, which will be preferably made of ziric or of another metal more electropositive than bronze in order to sacrificially protect the bronze from corrosion.

The interior of the hub's casing may be susbtantially sealed for more effectively retaining a water resistant lubricating grease by employing suitable sealing rings (0-ring) and gaskets of "Viton" between coupling surfaces of the various components which form the propeller and which enclose the doriLbed mechanisms.

In the embodiment depicted in Fig. 3, the propeller comprises a hub 1, keyed by means of the key 2' on the drive shaft 2. The coupling is locked by the locking nut 22 screwed on a threaded end 21 of the driva shaf t and tightened on an elastic washer 22a. The locking nut is conveniently provided with a socket 23 for a tightening key. The hub I has a tubular extension la, the outer vtrface of 'which is broached has longitudinal paral'el teeth It, cut thereon). over this externally broached sur.Lace of the hub extension a first conical gear 3 may be heat-set or locked by means of suitable setscrews. On this conical gear 3 mesh the planet pinions of the blades 4 of the pr'opeller. The planet p~inion 5 of each blade has an internally bored stem 5a which fits in a housing formed at the base of the blade and the assembly is mechanically connected by means of a stud screw 5c passing through the central bore of the stem 5a of the planet pinion and screwing inside a threaded hole formed inside the body of the blade 4. Each stem 5a rotatably passes trough a hole formed WO 90/11221 PCT/O9/09030 11 through the wall of a respective sector of the h;b0's casing 6 which is formed by joining together a number of sectors by means of tangential stud bolts 19. The end facing the ogive terminal of the propeller of this first portion of casing 6 has a reduced-diameter tubular extension 6c, the external cylindrical surface of which has an external broaching 12. This first portion 6 of the casing is essentially rotatable in respect to the hub 1 keyed on the drive shaft 2.

The hub's casing comprises an essentially tubular second portion 7, which telescopically meshes by means of an internal broaching with said reduced-diameter externally broached extension 6c of the first portion of the casing. This second portion 7 of the casing has the internal wall provided with 'a seat circularly extending for a certain arc of circumference (or equivalently with two angularly spaced stops) in order to provide two circumferentially spaced stop surfaces for a dragging tooth or sector 8 which is essentially connected to the tubular extension la of the hub 1. Upon rotation of the drive shaft 2 and of the hub 1, each blade of the propeller rotates about the axis of its planet pinion 5 meshing with the conical gear 3 of the hub 1, until the rotation of the hub brings one end of the sector 8 to abut against one or the other of said stop surfaces present on the internal wall of the tubular portion 7 of the casing. At this point the casing, formed by the two portions 6 and 7 telescopically meshing together by means of the joint 12-13, is dragged into rotation and with it are the blades of the propeller in the limit orientation which they have assumed and which determines the pitch of the propeller.

The telescopic meshing between the two portions of casing 6 and 7 is maintained by a push-back spring 17 which is compressed between a terminal face of the tubular portion 7 of the casing and a stop ring 9a held by means of a Seeger ring 10 on the external surface of the end of the extension la of the hub. The spring 17 is housed inside a cavity defined by an ogive terminal 9 whi(h may be screwed on or otherwise fixed to the end of the hub extension la, As shown in Fig. 3, the terminal part 14 or base of the ogive terminal 9 may be conveniently machined in order to telescopically fit WO 90/11221 pT19/03 -12 over the end of the tubular portion 7 ef the casing.

The tubular portion 7 of the casing may be pulled manually toward the ogive terminal of the casing in opposition to the force exerted by the spring 17 for a distance sufficient to disengage the external broaching 13 from the internal broaching 12 on the end of the portion 6 of the casing and rotated relatively to the latter thus modifying the re& tive angular position of the stop surfaces present on the ternal I surf ace of the tubular portion 7 of the casing in respect to the sector 8 and to the whole planet-gear assemnbly, thus altering the pitch of the propeller.

I Again the pulling out and rotation of the tubular portion 7 of the casing may be facilitated by forming suitalble grip indentations (not shown in the figures) on the external surface of it.

A further embodiment is depicted in Fig. 4.

For brevity's sake, the same functional parts of the propeller are indicated in Fig. 4 by the same numbers used in Fig. 3 for indicating identical or functionally equivalent parts and a repeated description is doemed unnecessary.

Tn the embodiment of Fig. 4, the propeller's hub 1 has not the cylindrical extension toward the ogive terminal of the propeller as in the previously described embodiments and the dragging tooth or sector 8 is formed directly on the external surface of the hub 1 by machining. In 'this case also the conical gear 3 of the hub may be obtained by machining the end portion of the hub 1.

The ogive terminal 9 is in this case directly screwed on a th~readed end of the first portion 6 of the hub's casing.

The second tubular portion 7 of the casing telescopically meshes by means of an internal broaching 13 with an external broaching 12 formed over the external surface of a reduceddiameter end of the first portion 6 of the ca sing facing toward the drive shaft 2 and the second portion 7 is held engaged. thereon by the push-back spring 17.

Similarly to whpt described before in relation to Fig. 3, on the internal wall of the portion 7 of the casing there are e stop surfaces (not shown in the figure) circumferentially separated by a. certain arc of circumference and which m~iy WO 90/11221 pcr/IT90/0003e -13 be formed as in the case shown in Fig. 3, by machining a seat 7a extending for a certain arc of circumference and capable of accommodating the travel of a dragging tooth or sector 8 integral with the hub 1 of the propeller and which is free to rotate from one end to the opposite end of the seat 7a.

The push-back spring 17 abuts against the surface of a flange body 15 which may be screwed on a threaded end of the hub 1 toward the drive shaft 2. The flange body 15 is provided with a tubular extension 16 which telescopically fits over a purposely reduced-diameter end 18 of the second portion 7 of the casing.

Also in this embodiment the tubular portion 7 may be pulled out of engagement through the joint 12-13 with the portion 6 of the casing and rotated relatively to the latter and to the hub 1 by manually grasping the outer surface thereof and pulling it in opposition to the spring 17 in order to modify the pitch of the propeller.

The stated objectives are fully met by the propellers of the invention. Moreover the two alternative embodiments depicted in Figures 3 and 4 have the additional advantage of requiring a minimum number of parts and are exceptionally i suited for propellers of small and medium Of course suitable refei'ence marks may be engraved on the external surfaces of the two portions 6 and 7 of the casing, along the perimeter of their respective coupling faces, for facilitating pitch adjustment. Furthermore "0-ring" seals may be employed for sealing the interior of the casing housing the described mechanisms for a better retention of a water resistant lubricating grease.

Also in the two last embodiments depicted in Figures 3 and 4, resilient inserts will be preferentially used on abutment surfaces of the dragging tooth or sector 8 and/or on abutment stop surfaces of thi seat within which the sector 8 travels.

Claims (8)

1. A device for varying the pitch of a feathering propeller without dismantling the propeller, utilizing a planetary gear arrangement between the propeller's blades and a hub thereof adapted to be keyed in use to a drive shaft of the propeller, for determining a free rotation of said blades about their respective axis through an angle of relative rotation between a casing about the hub and the hub, said casing having holes through which said blades are journally mounted and said angle being set by stop means v hich determines the limit orientations respectively assumed by the blades under the two opposite conditions of hydraulic forces acting on them in forward and reverse senses of rotation of the drive shaft, characterized by the fact that said casing is formed by at least two portions telescopically meshed one 15 with the other; a first portion of the casing is essentially rotatable about said hub and is provided with said holes through which the blades are journally mounted; a second portion of the casing is provided on an internal surface of the casing with two circumferentially spaced abutment stop surfaces to confine the 20 travel of a dragging tooth or sector which is disposed between the stop surfaces and is rigidly connected to said hub; said second portion of the casing being capable of being pulled telescopically away from said first portion of casing against the resistance of a push-back spring for a distance sufficient to disengage a telescopically meshing 25 joint formed by an external broaching present on a reduced-diameter end of one of said two portions of the casing and an intern,,J broaching on said other portion of the casing, rotated relatively to said first portion of the casing and released for re-engaging of the two portions of the casing in a different relative angular position, thus changing the relative angular position of said stop surfaces with respect to said tooth or sector and thus changing the pitch df. the propeller by a minimum unitary increment which is determined by the pitch of said telescopically meshing together external and internal broachings. 920625,gjndat 123,arincet,14 15

2. The device according to claim 1, wherein said second portion of the casing telescopically couples with said fin;t portion of the casing from the side of the propeller at which the drive shaft is located in use, and can be telescopically pulled out of engagement with said first portion of the casing by pulling it axially toward the drive shaft in the opposition to a push-back spring retained by a tubular flange body mounted on the end of said hub, which hub is keyed on the end of said drive shaft, said flange body having a tubular extension housing said push-back spring and telescopically accommodating a reduced-diameter tubular end of said second portion of the casing.

3. The device according to claim 1, wherein said second portion of the casing telescopically couples with said first portion of the casing from the side of the propeller opposite to that at which the drive shaft is located in use and may be pulled out of engagement with said first portion of the casing by pulling it axially against the resistance of a push-back spring which is retained •by an ogive-shaped terminal of the casing mounted on a threaded tubular extension of said hub.

4. The device according to claim 1, wherein grip indentations are formed on the external surface of said second portion of the casing for manually exerting said pulling action followed by said rotation action for modifying the pitch of the propeller. S.i* 2

5, The device according to claim 1, wherein reference marks are engraved on the external surfaces of said two portions of the casing, at adjacent edges of the external surfaces, for facilitating pitch adjustment.

6. A variable pitch feathering propeller for sailing boats comprising a pinion-hub permanently keyed on an end of a drive shaft and locked thereon by a locking nut screwed on a threaded end of the shaft and having a coaxial conical gear; at least two blades each having a conical pinion end planetarily engaged 920624,gindatL123,marine.Ict tS -16- with said conical gear of said pinion-hub, each of said blades being free to rotate about the axis of its pinion end and around said conical gear of said pinion-hub starting from a neutral position of the blade in which the blades major surfaces are substantially parallel to the drive shaft's axis, through two opposite angles to respective liit positions set by stop means, when urged by the hydraulic forces caused, respectively, by the rotation in a forward and in a reverse sense of said drive shaft, whereby to determine the pitch of the propeller in the two senses of rotation, said blades further being rotatable around said conical gear from either of said two limit positions toward said neutral position when urged by the hydraulic forces caused by the drag forces when the propeller is dragged through water; a casing which is formed of at least two portions joined together and encloses said pinion-hub and said conical pinion ends of said blades, said casing being free to iotate about said pinion-hub within said two opposite i 15 angles which are set by said stop means, at least a first tooth or sector solidly connected to said casing and a second tooth or sector solidly connected to said pinion-hub, cooperating with each other for determining said stop means in the O two senses of rotation of the blades around their own axis and planetarily around said pinion-hub and for dragging into rotation said casing and -aid blades under the action of the drive shaft; I. ";said second tooth or sector being formed on the external cylindrical surface of a thimble having a broached tubular end meshing with a broached cylindrical end of said pinion-hub in a relative angular position therebetween which determines a certain pitch of the propeller, S. 25 characterized by the fact that each of said casing portions has a cylindrical hole and each blade is preassembled on a respective said casing portion by means of said conical pinion end having a bored stem rotatably held in said hole and rigidly fitted into a seat formed at the base of the blade by means of a stud screw passing through the central bore of said pinion and screwed inside a threaded hole extending from said seat inside the body of the blade; A said thimble is tubular and the end opposite to said broached end is 920624,gjndat.123,marine.let,16 r 17 connected to a first truncated portion of an ogive-shaped terminal of the casing by passing through an annular flange connected to an end face of said casing, a push-back spring fitting over said tubular thimble and abutting compressively against the internal surface of said annular flange to keep said thimble engaged with said pinion-hub; a threaded ogive-shaped cap is screwed into a central threaded hole of said first truncated ogive portion; the pitch being variable by pulling said ogive-shaped terminal formed by said first truncated portion and by said cap against the resistance of said spring until said thimble is disengaged from said pinion-hub, rotating by a certain angle the pulled-out ogive terminal and releasing the latter for re-engaging the thimble on the pinion-hub in a varied relative angular position; and the propeller being dismantleable from said drive shaft by unscrewing said cap, inserting a key, unscrewing said locking nut, and freeing the propeller 15 from the drive shaft.

7. The propeller according to claim 6, wherein said first tooth or sector solidly connected to said casing is formed by a ring sector insert having a rectangular or trapezoidal cross section, housed in an arcuate seat present on the internal wall of one of said portions composing said casing and confined therein by means of resilient dampening end inserts restrained by the coupling surfaces of two said casing portions adjacent thereto.

8. The propeller according to claim 7 wherein said resilient inserts are 25 blocks of rubber held at the two ends of said arcuate seat under respective extensions of said ring sector insert salient in respect to the surface of said internal wall. Dated this 24th day of June 1992 MARINE PROPELLER s.r.l. By its Patent Attorneys Davies Collison Cave 920624,gjndat 123,marinet,17