US 3307634 A
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March 7, 1967 o. L. BIHLMIRE 3,307,634
HUB CONSTRUCTION FOR BOAT PROPELLERS Filed Jan. 17, 1966 United States Patent 3,307,634 HUB CONSTRUCTION FOR BOAT PROPELLERS Otto L. Bihlmire, 115 W. Pendle St., South Bend, Ind. 46637 Filed Jan. 17, 1966, Ser. No. 521,125 Claims. (Cl. 170-160.54)
My invention relates to boat propellers, and more particularly to the hubs thereof. A frequent hazard in the operation of boat propellers is the impact of the propeller with an underwater obstruction, such as a reef, sand bar, projecting rock or root. When a propeller blade of metal or other rigid material strikes such an obstruction, one' possibility is that the blade may break or crack; another is that it will transmit the shock to the motor drive and cause injury to the same. Yieldable blades have been used in order to avoid the situation just described. Thus, the impact of such a blade with an unyielding obstruction is that the blade will either bend or break off. In either case the boat drive will become unbalanced and jerky. A still further effort has been made to conserve the propeller and boat drive, that is, by locating :a yieldable element in the hub of the propeller. Thus, a rubber bushing, bonded to the metal or other material of the propeller hub was incorporated in the same. In this case, when the propeller struck an immovable obstruction, the bushing in the hub would yield, protecting the blades and drive gear from injury. When such an incident occurs the propeller will stop, but its center drive will continue, breaking up and pulverizing the rubber bushing. Now, should the boat be backed away from the obstruction, the shaft drive would continue, but without turning effect on the propeller, The boat would thus be stranded, and the use of oars or the hands required in order to bring the boat to a landing facility. Moreover, where the water is rough, the boat may capsize with loss of life.
In view of the above situation, it is one object of the present invention to employ a yieldable element in a propeller hub in a manner to restore the hold by the power drive on the propeller after the latter has been freed from an obstruction, in order that the propeller may continue to turn and keep the boat in motion.
A further object is to mount a yieldable bushing in a propeller hub with means to restore the effectiveness of the bushing after it has been disrupted, and render it sufficiently firm to transmit the power drive to the propeller.
Another object is to construct the propeller hub with automatic clutch or take-up means, effective to pack the hub bushing into the firm state necessary to transmit the power drive as stated.
A better understanding of the invention may be gained by reference to the accompanying drawing, in which:
FIG. 1 is a view of the improved propeller as mounted on a drive shaft, and from the rear;
FIG. 2 is an enlarged longitudinal section of the hub portion of the propeller, with parts in elevation;
FIG. 3 is a section on the line 33 of FIG. 2; and
FIG. 4 is a duplication of the center portion of FIG. 3, showing a modification.
Referring specifically to the drawing, denotes the drive shaft, 11 the hub, and 12 the blades of the boat propeller. The hub and blades are preferably molded in one piece from hard plastic material with a flexible factor in the blades, so that these may yield to minor obstructions.
The propeller is assembled by receiving a massive sleeve 15 inside its hub. At the front end-when the propeller is installed behind a boat-the sleeve 15 has a conventional screw thread 15b suitable for receiving a nut 16, the latter having notches 16a in its front end for the appliation of a spanner wrench to turn the nut. Before its Patented Mar. 7, 1967 rear end the sleeve is again threadedas indicated at 15cbut in the opposite direction, the thread being known as a left-hand one. A nut 17 of the corresponding type, but smaller than the nut 16, is provided for mounting on the thread 15c, and has notches 17a in its rear end like the nut 16. The middle part of the sleeve is hexagonal in cross-section, and the main form thereof has a series of longitudinally-directed grooves 15a.
The hub of the propeller has an axial opening whose frontal portion is indicated at 11a and so positioned when the propeller is mounted behind a boat. The portion 114 recedes with a conical cavity 11b in rearward direction to form a rearwardly-facing annular shoulder near the end of the hub; and the rear portion lid 11d of the opening meets the shoulder from the rear. The wall of the hub cavity 11b has a series of longitudinal ribs He in circular sequence.
The yieldable bushing for the hub 11which may be of rubber or the tough plastic substance known as neopreneis shown at 20. The form of the bushing is conical to conform with that of the hub cavity 11b; and the periphery of the bushing is grooved at 20a to conform with the series of cavity ribs He. The interior of the main form of the bushing has a series of longitudinallydirected ribs 201: conforming to the grooves 15a of the sleeve 15. However, the sleeve and bushing may be joined sufiiciently without the need of the co-acting ribs 20b and grooves 15a, and such a modification is illustrated in FIG. 4. The propeller is assembled by first mounting the nut 16 on the sleeve from the front, and sliding the bushing on the sleeve from the rear until the bushing meets the nut 16 as a backing. The position of the nut 16 is where it may be adjusted back or forth if desired until its position is considered permanent. The hexagonal fit between the sleeve and the bushing engages these parts for joint rotation; and the internal ribs 20b of the bushing procure a keyed relation with the grooves 15a in the sleeve. Also, broad surface contact is present between the bushing and the larger-sized nut 16. The sleeve with the bushing mounted as stated is now inserted into the hub cavity 11b in a manner to project the rear end of the sleeve through the rear opening portion 11d as shown in FIG. 2. A yieldable washer 22 is now inserted in the said rear opening portion to seat against the shoulder 11c of the bushing, the washer followed by mounting and advancing the rear nut 17 on the thread of the sleeve. This action will cause the frontal nut 16 to seat the bushing snugly in the hub in a manner to transmit a rotary drive from the sleeve to the hub; and the degree to which the bushing is compressed is regulated by adjusting the rear nut 17. When the internal parts have been assembled with the hub as stated, the propeller is ready for mounting on the shaft 10 as shown in FIG. 2; and it is made fast thereon by a shear pin 15d.
The threading function of the nuts 16 and 17 will now be explained. As previously mentioned, the front end of the sleeve 15 has a regular or right-hand thread; and the rear nut 17 may be advanced against the washer 22 to make the hub bear against the bushing with compressing effect; and the nut 16 may also be adjusted to locate the bushing properly for this purpose. The shaft 10 is designed to rotate in counterclockwise direction as seen from the rear, in which event any further tendency of the rear nut 17 to turn will cause it to over-run the sleeve and advance against the bushing because of the left-hand thread on the rear end of the sleeve, increasing the compression of the bushing.
As will now be evident, the motion of the drive shaft will be transmitted by the bushing to the propeller to operate the boat under normal conditions; and this will prevail despite minor obstructions because of the yielding of the propeller blades to by-pass them, as mentioned before. However, in case an unyielding obstruction is encountered the propeller is stopped, but the bushing will yield to the driving force of the shaft to save the motor and drive gearing from shock or injury. This action has a disruptive effect on the surface portion of the bushing, so thatwhen the boat is pushed or backed away from the obstructionthe bushing Will have a reduced or minimal sub-stance for driving the propeller. However, the nut 17 may be advanced manually with added compressing and packing effect on the bushing as stated before, so that the bushing will become sufficiently solidified to resume its function as a clutch and procure the normal operation of the propeller. Or, if it is not practicable to advance the nut 17 manually, a quick speed-up of the engine will have an advancing effect on the nut to again engage the clutch.
In conclusion, it will be apparent that the bushing in the novel hub construction does not have to be bonded or otherwise mounted permanently on the hub of the propeller. The latter is complete as a unit when assembled with its internal parts, and therefore in readiness to be mounted on a shaft of the proper size whenever needed. Further, the clutch will not require the services of a repair man in case the propeller becomes loosened from the shaft because of striking a major obstruction during its travel, as the simple manual take up of the nut 17 or the quick acceleration of the engine will -re-pack the yieldable substance of the bushing and solidify the same to a sufficient degree for transmitting the shaft drive to the propeller. A facility is thus provided which enables the occupants of a boat to procure a quick restoration of its drive by merely backing the boat away from the obstruction and imparting either of the adjustments mentioned, so that the boat may proceed on its course and avoid the hazards of being stranded or capsizing in a rough sea.
1. A marine propeller drive shaft clutch comprising in combination with the propeller hub:
(a) the hub having an axial opening therethrough the normally forward end portion of which is tapered inwardly;
(b) a sleeve within and longitudinally of the axial opening;
(c) an elastomeric bushing on an intermediate portion of the sleeve within said tapered end portion of the axial opening in juxtaposed and bearing engagement with the adjacent hub walls;
(d) a nut threadedly engaged with the normally forward end portion of the sleeve, received within said opening .for adjustable bearing engagement with and on the adjacent end of said bushing, and,
(e) a second nut threadedly engaged on the opposite end portion of said sleeve, received within said opening for adjustable bearing engagement with and on the remaining and adjacent end of the hub.
2. The structure of claim 1 further characterized in that said one end portion of the opening is formed with an inwardly tapering wall and the bushing is of inwardly tapering form and size substantially corresponding to said one end portion of the opening.
3. The structure of claim 1 further characterized in that said one end portion of the opening is for-med with an inwardly tapering conical wall, and the form of the bushing substantially corresponds in shape and size to that of the one end portion of the opening.
4. The structure of claim 1 further characterized in that the normally forward portion of the hub axial opening is of inwardly tapering conical shape, and the form of the bushing is of shape and size substantially corresponding to that of said forward portion of the opening, and further characterized in that the threadson the normally forward end portion of the sleeve are of the left-hand type whereby to cause the first mentioned nut to overrun the shaft when said shaft is given an accelerated rotative impulse and render the adjustability of the nut automatic.
5. A marine propeller drive shaft clutch comprising in combination with the propeller hub:
(a) the hub having an axial opening therethrough, the
intermediate portion of which is tapered toward the normally rearward end of the hub, thickening and reinforcing the hub walls intermediately of the opopening for adjustable bearing engagement with and on the adjacent end of said bushing, and,
(e) a second nut threadedly engaged on the opposite end portion of said sleeve received within said opening for adjustable bearing engagement with and on said internal shoulder of the hub.
References Cited by the Examiner UNITED STATES PATENTS 1,493,066 5/1924 Caldwell et a1. 170-16054 2,543,396 2/1951 Wolff l-135.75 2,569,144 9/1951 Benson l35.75 3,047,074 7/1962 Rielag 170160.54 3,224,509 12/1965 Thompson l70l60.5
MARTIN P. SCHWADRON, Primary Examiner. EVERETTE A. POWELL, .TR., Examiner.
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