US3073395A - Multiple pitch removable blade propeller - Google Patents

Description

1963 P. K- DUNCAN 3,073,395

MULTIPLE PITCH REMOVABLE BLADE PROPELLER Filed Dec. 12, 1960 INVENTOR.

j; By PAUL K. DUNCAN ATTORNEY iclnited gdtates 3,073,395 MULTEPLE PHQH REMQVABLE BLADE PRGPELLER Paui K. Duncan, 5211 SW. 7th St, Miami 44, Fla. Filed Dec. 32, less, Ser. No. 75,263 7 (Jlaims. (til. Fill-160.6)

This invention relate to improvements in marine propellets, and has particular reference to a multiple pitch removable blade propeller.

Marine propellers present problems with which the industry has long had to contend. In the manufacture of the propeller there is the problem of obtaining sufficient precision of balance and symmetry. Under conventional manufacturing methods it is difliculit to ob tain good dynamic balance in the masses of two or three blades on a common hub. It is also diflicult to make all the blades sufficiently identical in contour and thick mess that they will react exactly the same in the water, particularly in high speed rotation. Either lack of dynamic balance or differences in the blade reactions in the water create objectionable vibration at high speed. The high degree of accuracy necessary to eliminate such vibration normally requires considerable hand work which makes the propellers quite expensive under conventional methods.

There also exists the problem of repair of minor damage after the propeller is put into service. Small nicks and dents in the blades, for example, are often removed 7 by hammering or filing. In the former case there may be no Weight unbalance, but, nevertheless, the repaired blade can seldom be restored so perfectly that it will not present a difierent reaction in the water. In the latter case both balance and Water reaction are disturbed, making it very difiicult to eliminate vibration in the repaired propeller.

The primary object of the present invention is, therefore, to provide an improved propeller having removable blades which are precisely identical to each other so that exact balance and uniformity of water reaction are obtained in the blades of a new propeller and so that blades damaged in use can be replaced individually without replacing the whole propeller or attempting repair.

Further objects are to provide a propeller in which all the blades are derived from a single mold, to provide a propeller of the type described in which the blades may be either of cast metal or molded plastic, to provide an improved propeller blade which will draw from an injection mold, to provide a novel and improved pitch adjustment for the blades, and to provide improved means for securing the blades on the hub to facilitate pitch adjustment, removal and replacement.

The present form of construction permits the hub and blades to be made of dilferent materials, if desired. The hub would ordinarily be made of metal such as steel or bronze, while the blades may be made from a variety of materials such as plastic, die cast aluminum, zinc, pot metal, or other alloys. Each blade has a beveled circular base to fit the semicircular forward end of a dovetail slot on one side of the hub. The base is rotatable in the slot for pitch adjutment, which adjustment is positively locked by peripheral notches in the base engageable with a pin in the slot. Each blade base is secured in its hub slot by a dovetail slide lock having a semicircular end to lit the blade base. The slide locks for all the blades are secured by a ring nut on the rear end of the hub. This form of construction makes it easy to change the pitch when desired and to replace a damaged blade. The individual blades can be made so inexpensively that it is more economical to carry spare blades than to attempt repair of a damaged blade.

Patented Jan. 15, 1963 ice Additional objects and advantages will become apparent and the invention will be better understood from the following description of the preferred embodiment illustrated in the accompanying drawing. Various changes may be made, however, in thedetails of construction and arrangement of par-ts and certain features may be used without others. All such modifications within the scope of the appended claims are included in the invention.

In the drawings:

FIGURE 1 is an exploded view of a propeller embodying the features of the invention showing one blade removed from the hub;

FIGURE 2 is a side elevation view of the propeller of FIGURE 1; and

FIGURE 3 is a longitudinal sectional View on the line 3-3 of FIGURE 2.

In FIGURE 1 the propeller is seen to comprise a hub lit having a shaft bore 9 and a pair of identical blades 1'1 and 12;, each with a circular base 13. Each blade is secured to the hub by a dovetail slide lock 14, the slide locks in turn being secured by a ring nut 15. The hub may also be made to mount three or four blades if desired. I

The hub is provided with a flat chordal surface 20 for each blade. This flat surface contains a dovetail groove or slot 21 having an entrance opening at the rear end or the hub and a closed semicircular forward end 22 The sides of circular base 13 are beveled at an angle to fit the sides and end of slot 21 as shown, whereby the base will rotate in the slot to provide the desired pitch angle for the blade, the blade being rotatable through a full circ e in the slot 21. A selected pitch adjustment is retained by a plurality ofradial notches 25 in the circular base 13 which are engageable with a pin 26 in the semicircular end 22 of the slot, the pin being radial to the axis of the hub. The notches '25 provide for different forward speeds including a slow trolling speed and may include neutral and reverse positions, if desired.

Projecting from the rear end of the hub is an externally threaded boss 27 concentric with the axis of the hub and of slightly less radius than the distance from the flat bottom of slot 21 to the axis of the hub. The propeller is assembled by sliding each blade base13 into its slot 21. The top or outer side of the blade base 13 is provided with an index mark 30, and the fiat surface 20 is provided with reference marks 31 designating dilferent pitch edges. By turning the index mark 30 to a selected one of the reference marks 3-1, the blade is set at the desired pitch. Then the blade base is pushed into the end of slot 21 to engage locking pin 26 in one of the notches '25, after which the blade will no longer rotate in slot 21. Slide locks 14 are then inserted in slots 21 and ring nut 15 is applied to the boss 27.

Each slide lock has a semicircular inner end 35 beveled to the same angle as blade base 13 and clamping the half 'of the periphery of the base that is not clamped by I beveled slot end 22. The outer ends of slide locks 14 project slightly beyond the ends of slots 21 whereby the ring nut bears against the ends of slide locks in spaced relation to the end surface 32 of the hub to clamp the blade bases 13 securely in the ends of slots 21. Suitable lock means may be provided for ring nut 15, if desired.

When it is desired to change the pitch of the blades, it is necessary only to loosen the ring nut 15 so that the blade bases 13 will move rearwardly a fraction of an inch to clear locking pins 26. Then the blades may be rotated to turn the index mark 30 to a different one of the marks 31 without removing any of the parts. When a blade is to be replaced, both the ring nut and slide lock are removed as shown in FIGURE 1. It is not necessary to disturb the hub mounting on the propeller shaft.

Ring nut 15 may be withdrawn'over a nut on the end of the propeller shaft since the latter need be only of sufficient diameter to engage the end surface 36 of boss 27 within the thread diameter of the boss.

Since the blades are all made individually in the same mold, it is evident that they will be exactly identical and precisely balanced in all respects without the necessity for any hand work. The blades can be molded or. cast so inexpensively, and the blades can be changed so easily, that there is no necessity for attempting to repair a damaged blade. Thus, the present improved form of construction solves not only certain serious manufacturing problems, but also the major repair and maintenance problems for the user.

Having now described my invention and in what manner the same may be used, what I claim as new and desire to protect by Letters Patent is:

1. A propeller comprising a hub having a plurality of longitudinal slots in its outer peripheral surface, blades having circular bases rotatable in said slots for pitch adjustment, slide locks in said slots having semicircular inner ends clamping said blade bases in end portions of said slots, and a nut coaxial on said hub clamping all of said slide locks against said blade bases.

2. A propeller comprising a hub having a plurality of longitudinal slots in its outer peripheral surface, blades having circular bases rotatable in said slots for pitch adjustment, means in said slots locking said blade bases against rotation, slide locks in said slots having semicircular inner ends clamping said blade bases in end portions of said slots and a nut coaxial on said hub clamping all of said slide locks against said blade bases.

3. A propeller comprising a hub having a plurality of longitudinal surface slots with closed forward ends and open rear ends, an axial cylindrical boss on the rear end of said hub having an external screw thread, said hub having an axial bore therethrough to receive a propeller shaft, an annular end surface on said boss between said bore and said thread, propeller blades mounted in said slots, slide locks in said slots clamping said blades against said closed forward ends of the slots, and a ring nut on said boss clamping said slide locks against said blades.

4. A propeller comprising a hub having a plurality of longitudinal. dovetail slots each having a semicircular closed end and an open end, blades having beveled circular bases rotatable in said slots for pitch adjustment and fitting said semicircular ends of said slots, beveled slide locks in said slots having beveled semicircular ends fitting said blade bases, and means clamping said slide locks against said blade bases.

5. A propeller comprising a hub having a plurality of longitudinal dovetail slots each having a semicircular closed end and an open end, blades having beveled circular bases rotatable in said slots for pitch adjustment and fitting said semicircular ends of said slots, beveled slide locks in said slots having beveled semicircular ends fitting said blade bases, means locking said blade bases in rotative adjustment, and a nut on said hub clamping said slide locks against said blade bases, said blade bases be ing disengageable from said locking means for pitch adjustment when said nut is loosened.

6. A propeller comprising a hub having a plurality of longitudinal dovetail slots each having a semicircular closed end and an open end, blades having beveled and notched circular bases rotatable in said slots for pitch adjustment and fitting said semicircular ends of said slots, pins in said semicircular slot ends engaging .said base notches to lock said pitch adjustment, beveled slide locks in said slots having beveled semicircular ends fitting said blade bases, and a out on said hub clamping said slide locks against said blade bases.

7. A propeller comprising a hub having a plurality of longitudinal dovetail slots each having a semicircular closed end and an open end, blades having beveled and notched circular bases rotatable in said slots for pitch adjustment and fitting said semicircular ends of said slots, means in said slots engaging said base notches to lock said pitch adjustment, beveled slide locks in said slots having beveled semicircular ends fitting said blade bases, and a single means clamping all of said slide locks against said blade bases.

References Cited in the file of this patent UNITED STATES PATENTS 1,010,929 Loetzer Dec. 5, 1911 1,634,329 Malm July 5, 1927 1,819,728 Bough Aug. 18, 1931 2,664,961 Goede Jan. 5, 1954 2,844,207 Curley July 22, 1958 FOREIGN PATENTS 546,799 Germany Mar. 16, 1932 1,128,113 France Apr. 20, 1956

Claims (1)

1. A PROPELLER COMPRISING A HUB HAVING A PLURALITY OF LONGITUDINAL SLOTS IN ITS OUTER PERIPHERAL SURFACE, BLADES HAVING CIRCULAR BASES ROTATABLE IN SAID SLOTS FOR PITCH ADJUSTMENT, SLIDE LOCKS IN SAID SLOTS HAVING SEMICIRCULAR INNER ENDS CLAMPING SAID BLADE BASES IN END PORTIONS OF SAID SLOTS, AND A NUT COAXIAL ON SAID HUB CLAMPING ALL OF SAID SLIDE LOCKS AGAINST SAID BLADE BASES.

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