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Publication numberUS3628492 A
Publication typeGrant
Publication dateDec 21, 1971
Filing dateOct 27, 1969
Priority dateOct 27, 1969
Publication numberUS 3628492 A, US 3628492A, US-A-3628492, US3628492 A, US3628492A
InventorsBaldwin William C, Meyer Theodore N
Original AssigneePlasmachem
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Outboard motor attachment
US 3628492 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)

Unite States Patent Inventors William C. Baldwin Anaheim; Theodore N. Meyer, Westminlster, both of Calif. App], No. 870.682 Filed Oct. 27. I969 Patented Dec. 21, 1971 Assignee Plasmachem, Inc.

Newport Beach, Calif.


U.S.Cl 115/17 1nt.Cl B63h2l/26 Field ofSearch ll5/l7,34;

[56] References Cited UNITED STATES PATENTS 1,663,253 3/1928 Hillborn 415/122 X 1,802,351 4/1931 Neumann..... 115/34 X 2,441,446 5/1948 Schmittcr 1. 416/170 X Primary Examiner-Andrew H. Farrell Attorney-John E. Wagner ABSTRACT: An auxiliary gear-reduction apparatus to be mountable to the drive shaft of an outboard motor for a boat in place of the conventional propeller, the apparatus reducing the rotational shaft velocity of the power output shaft and increasing the physical diameter of the propeller thereby increasing the area of thrust for the propeller.

PATENTEU 0:021 IHYI SHEET 1 OF 2 mm mwmw TA WA M N E R f. mm Lo LE mmMG m 2 3 PATENTEU DEB21 I971 362 5492 sum 2 [IF 2 INVENTOR. WILLIAM C. BALDWIN BY THEODORE N. MEYER Mink Fig. 2

BACKGROUND OF THE INVENTION The field of this invention relates to outboard motors for boats and specifically to an auxiliary speed-reduction mechanism for a relatively small horsepower outboard motor which is employed with the conventional planing hull of the smaller sized boats.

The use of outboard motors upon small fishing and runabout boats (rowboats, hydroplanes, etc.) is quite common. Usually such outboard motors are of a small horsepower to 9 hp.), as such horsepower ratings have been found to be quite efficient with the planing type hull of the small boat. Such small horsepower outboard motors are readily capable of propelling the planing-type hull boat up to speeds of 30 knots or greater. These small outboard motors are designed for use with a relatively small diameter propeller which is geared to rotate at velocities of between 2,500 r.p.m. and 3,500 r.p.m.

Other types of vehicles for leisure-time activity upon water, which are becoming frequently more common, are sailboats and houseboats. In both the sailboat and the houseboat, the hull is of the displacement type which substantially limits the speed of the craft as compared to the planing-type hull water vehicle. For example, many sailboats of the 25-foot length have a maximum hull speed of 6 knots.

It has been found that the use of a small outboard motor of the 5- to 9-horsepower size is quite desirable upon sailboats during instances of harbor entrance and exit of the sailboat. However, the use of a conventional small horsepower outboard motor in such instances results in the propeller of the motor effecting a substantial slippage, thereby creating a loss of propulsive efficiency as such motors are designed for the low drag of the planing hull craft and not for the large drag of the displacement hull craft. Further, the use of such conventional motors on sailboats has been found to be unsafe in an emergency situation due to an inadequate propulsive force. In cases of larger houseboats or other vessels, increased propulsive force is sometimes obtained by use of larger or multiple outboard or inboard-outboard motors up to 100 horsepower in rating. These power plants add to the speed of the vessel but the small high-speed propellers operate inefficiently and consequently use excess fuel.

As it is undesirable and rather costly to the consumer to purchase separate outboard motors for the planing hull boats and the displacement hull boats, it would be most desirable to design a separate attachment for such conventional outboard motors to be employed in place of the normal high-speed propeller which would eliminate propeller slippage and cause the motor to perform more efficiently when employed upon the high-drag displacement-type hull boat.

SUMMARY OF THE INVENTION The apparatus of this invention is designed to be employed in direct drive with the output shaft of an outboard motor upon removal of the conventional high-speed propeller of the motor. The apparatus of this invention is to employ the use of a substantially larger diameter l0 to 12 inches) propeller with the rotational velocity of the shaft being substantially reduced. The entire apparatus of this invention is designed to be easily and quickly installed upon the propeller end ofa conventional outboard motor. The apparatus of this invention specifically includes the use of a housing, the housing containing a drive connection to be adaptable to the power output shaft of the outboard motor, a drive gear being securely fixed to the drive connection and causing rotation of a larger diameter output gear, the output gear being fixed to a second shaft with a substantial larger diameter propeller being secured to the output gear.

One object of this invention is to employ the use of an auxiliary gear reduction mechanism with a conventional outboard motor to decrease output motor shaft velocity and employ a larger diameter propeller thereby decreasing propeller slippage when the motor is employed with high-drag displacement hull boats.

A further object of the apparatus of this invention is to design a gear-reduction mechanism to be installed upon the conventional outboard motor without any modifications of the outboard motor assembly other than removal of the existing propeller.

An additional object of this invention is to provide a gearreduction mechanism which will permit use of a larger diameter, standard propeller, commonly employed upon larger size outboard motors.

Another object of this invention is to provide an auxiliary gear-reduction mechanism which has a streamlined physical shape to minimize underwater drag.

BRIEF DESCRIPTION OF THE DRAWING FIG. la is a side view ofa conventional outboard motor employing the standard sized propeller;

FIG. 1b is a side view of a conventional outboard motor employing the gear-reduction mechanism of this invention;

FIG. 2 is a sectional side view of the gear-reduction mechanism of this invention as employed upon the outboard motor of FIG. lb;

FIG. 3 is an end view of the gear reduction mechanism of this invention taken along line 33 of FIG. 2;

FIG. 4 is a side view of the conventional outboard motor of FIG. lb employing the mechanism of this invention as it would be employed upon a sailboat displacement-type hull; and,

FIG. 5 is a side view of the conventional outboard motor of FIG. 1a as it would be employed upon a planing-type hull of a conventional power boat'.

DETAILED DESCRIPTION OF THE SHOWN EMBODIMENT Referring particularly to the drawings there is shown a conventional outboard motor unit 10 having a motor housing 12, a drive element housing 14' and a propeller l6. Outboard motor 10 is representative of the type of unit of the 5- to 9- horsepower size incorporating a relatively small diameter propeller 16. The outboard motor unit 10 is to be mounted to the stem 18 of a craft 20 by brackets 22.Craft 20 is depicted as a common power boat having the planing-type hull which exhibits low drag necessary to be efficiently driven by the small-sized propeller 16.

Referring particularly to the FIGS. 1b, 2 and 4, the identical motor unit 10 is shown with the elimination of propeller l6 and the substitution upon the propeller shaft 41 of the apparatus 24 of this invention.'A larger (10 to 12 inches in diameter) sized propeller 26 is shown connected to apparatus 24 thereby providing the thrust for the sailboat 28. It is to be understood that this invention is not to be limited to only a sailboat 28 as the invention would be most useful to any other type of displacement hull craft such as a houseboat, employing a similar small outboard motor or even up to horsepower or larger. In such latter cases, the low-speed propeller of this invention would be significantly larger, e.g., 18-20 inches in diameter.

Apparatus 24 comprises a fore housing 30 and an aft housing 32 held together in a fixed single-unit relationship by bolts 35. Forehousing 30 includes a cutout 34 and a lower extending fin 36. Cutout 34 cooperates with the lower extremity of the drive element housing 14 to provide a substantially con tinuous surface connection therebetween thereby decreasing drag with the water. Fin 36 is streamlined to minimize the drag with the water and provide protection for a larger propeller 26. Forehousing 30 includes a seal cavity 38 within which is retained a seal 40 to make the apparatus 24 watertight with respect to the drive element housing 14. The propeller shaft 41 of the drive element of the outboard motor unit 10 is to be connected in a power-transmitting manner to sleeve 42 by means of a pin 43 positioned in the shear pin bolt of shaft 41. Nut 45 functions to securely retain shaft 41 in position within spline 42. Washer 47 is positioned between nut 45 and spline 42. Sleeve 42 is rotatably mounted within forehousing 30 and aft housing 32 by bearings 44 and 46. Oil seal 48 extends about the sleeve 42 between the seal 40 and bearing 44.

Input reduction gear 50 issecured to sleeve 42 between bearings 44 and 46. The teeth of the gear 50 engage an output gear 52 which is secured upon a power output shaft 54. Shaft 54 is rotatably mounted upon bearings 56 and 58. An oil seal 60 surrounds shaft 54 and is securely retained within aft housing 32. Shaft 54 includes a depression 62 which is to facilitate the attachment of propeller 26. It is to be noted that the apparatus 24 is formed of the forehousing 30 and the aft housing 32 to facilitate its manufacture and assembling. Bearings 44 and 56 are mounted within forehousing 30 while bearings 46 and 58 are mounted within aft housing 32. Cavity 64 is provided within aft housing 32 to receive the nut 45 and the end of shaft 41.

To assemble the apparatus 24 and install such on the outboard motor unit 10, this procedure is followed: With the sleeve 42 mounted within forehousing 30, aft housing 32 containing output shaft 54 is placed adjacent to forehousing 30 so bolts 35 are able to retain the housings 30 and 32 together. In this position, sleeve 42 is journaled on bearings 44 and 46. Shaft 54 is journaled between bearings 56 and 58. Also, the teeth of the gears 50 and 52 are in engagement so that upon rotation of gear 50, gear 52 is rotated. It is to be noted that gear 52 is of a larger diameter than gear 50 so that output shaft 54 rotates fewer revolutions per minute than shaft 41. In actual practice, it has been found that three revolutions of shaft 54 per every five revolutions of shaft 41 is quite satisfactory for commonly used -9 horsepower motors. Other ratios of course are preferred, ranging between l.2:l to 2.5: 1.

To position the apparatus 24 upon propeller shaft 41 of the outboard motor unit 10, the shear pin and normal propeller 16 are removed from shaft 41. The aft housing 32 is removed and the shaft 41 is then positioned within sleeve 42 until it extends through the forehousing 30. Nut 45 is then installed and tightened upon shaft 41. To keep the entire apparatus 24 from rotating upon rotation of shaft 41, torque arms 66 are fixed to fin 36 and extend to each side of drive element 14 in a snugfitting manner. Upon installation of propeller 26 upon shaft nna 54, the apparatus 24 is now ready to effect a reduction of the velocity of shaft 41 but providingmaximum thrust efficiency through large propeller 26. Simple removal of the apparatus 24 and reinstallation of the conventional propeller in a matter of minutes returns the motor to its original propulsive configuration.

The foregoing is representative of illustrative embodiments of this invention and is not to be construed as limiting. It is recognized that one skilled in the art can, through minor modification of the structure, produce a device different in certain details and respects but not departing from the true spirit and scope of this invention. This invention therefore is not limited by the embodiments shown above but rather than by the prior art and the following claims.

We claim:

l. A speed-reducing assembly for marine motors adapted to be driven by the propeller shaft of an existing motor comprismg:

a body assembly including an opening for receiving the propeller shaft of a motor;

reduction gear means within the body assembly;

an output shaft;

means coupling a motor propeller shaft inserted in the opening to the reduction gear;

means coupling the reduction gear to the output shaft; and

means for securing the body assembly to the motor, the exterior of the body assembly being contoured to substantially form a continuation of the motor frame assembly in the region of the propeller shaft;

wherein said speed-reducing assembly is capable of transmitting power from the motor to the output shaft at reduced speed.

2. The combination in accordance with claim 1 wherein said assembly includes an enlarged body portion joining the enlarged drive element portion of an outboard motor and said body assembly also including a fin portion constituting an extension of a tin portion of snch r no t or

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1663253 *Dec 24, 1926Mar 20, 1928 of milwaukee
US1802351 *Apr 12, 1930Apr 28, 1931Gustav NeumannPropeller attachment for boats
US2441446 *Dec 23, 1944May 11, 1948Falk CorpFan drive
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4099478 *Sep 4, 1975Jul 11, 1978Brunswick CorporationHigh thrust trolling motor
US4565532 *Feb 18, 1981Jan 21, 1986Kaama Marine Engineering, Inc.Stern drive
US4728308 *Dec 28, 1983Mar 1, 1988Kaama Marine Engineering, Inc.Stern drive
US4775342 *Dec 2, 1983Oct 4, 1988Kaama Marine Engineering, Inc.Stern drive
US4981452 *Apr 20, 1988Jan 1, 1991Yamaha Hatsudoki Kabushiki KaishaSurface drive outboard with improved transmission
US6921305 *Mar 14, 2003Jul 26, 2005Brian ProvostOutboard motor
US7662005Jul 16, 2007Feb 16, 2010Brian ProvostOutboard motor with reverse shift
US7871302Mar 23, 2009Jan 18, 2011Brian ProvostOutboard motor with reverse shift
U.S. Classification440/75
International ClassificationB63H20/00, B63H20/02
Cooperative ClassificationB63H21/28
European ClassificationB63H21/28