High performance stern drive unit

Disclosed herein is a marine propulsion device comprising a bracket adapted to be fixed to a boat transom and having an upper portion and a lower portion, a propulsion leg including a rotatably mounted propeller, a first ball joint universally connecting the propulsion leg and the lower bracket portion, a hydraulic cylinder-piston assembly having first and second ends, a pivot connecting the first end of the hydraulic cylinder-piston assembly to the propulsion leg about an axis which is generally horizontal when the bracket is boat mounted, a second ball joint universally connecting the second end of the hydraulic cylinder-piston assembly to the upper bracket portion, and a drive train adapted to be connected to a prime mover, extending through the bracket and the propulsion leg, and drivingly connected to the propeller.

BACKGROUND OF THE INVENTION 
The invention relates generally to marine propulsion devices, and more 
particularly, to stern drive units. 
Still more particularly, the invention relates to arrangements for mounting 
a propulsion leg from the transom of a boat so as to enable steering 
movement of the propulsion leg and vertical tilting movement of the 
propulsion leg for the purpose or trimming the propulsion leg to maximize 
propulsion efficiency. 
Attention is directed to the following U.S. Pat. Nos.: Wanzer 2,755,766 
Issued July 24, 1956, Hansson et al 3,003,311 Issued Oct. 31, 1961, 
Shimanckas 3,183,880 Issued May 18, 1965, MacDonald et al 3,368,517 Issued 
Feb. 13, 1968, Wynne 3,376,842 Issued Apr. 9, 1968, Warburton 3,403,655 
Issued Oct. 1, 1968, Strang 3,841,257 Issued Oct. 15, 1974, Lohse 
3,888,203 Issued June 10, 1975, Adams, et al 3,933,116 Issued Jan. 20, 
1976. 
SUMMARY OF THE INVENTION 
The invention provides a marine propulsion device comprising a bracket 
adapted to be fixed to a boat transom and having an upper portion and a 
lower portion, a propulsion leg including a rotatably mounted propeller, a 
first universal coupling connecting the propulsion leg and one of the 
bracket portions, an extensible and contractable rigid link having first 
and second ends, means pivotally connecting the first end of the rigid 
link to the propulsion leg about an axis which is generally horizontal 
when the bracket is boat mounted, a second universal coupling connecting 
the second end of the rigid link to the other of the bracket portions, and 
a drive train adapted to be connected to a prime mover, extending through 
the bracket and the propulsion leg, and drivingly connected to the 
propeller. 
In one embodiment of the invention, the first universal coupling is 
connected to the lower bracket portion and the second universal coupling 
is connected to the upper bracket portion. 
In one embodiment of the invention, the bracket includes, between the upper 
and lower portions, a sleeve portion, the propulsion leg includes, below 
the means pivotally connecting the propulsion unit to the rigid link and 
above the first universal coupling, a forwardly opening sleeve portion in 
alignment with the sleeve portion of the bracket, a flexible annular 
member extends between the sleeve portions of the bracket and the 
propulsion leg, and the drive train extends through the sleeve bracket 
portion, through the flexible annular member, and through the sleeve 
portion of the propulsion leg. 
In one embodiment of the invention, the first and second universal 
couplings comprise ball joints. 
In one embodiment of the invention, the first and second universal 
couplings are located in a common vertical plane extending through the 
axis of the sleeve portions and the steering axis extends in the vertical 
plane and through the center of the universal couplings in upwardly and 
forwardly inclined relation. 
In one embodiment of the invention, the rigid link comprises a hydraulic 
cylinder-piston assembly. 
In one embodiment of the invention, the hydraulic cylinder-piston assembly 
and the propulsion leg include surfaces affording relative movement 
therebetween while accommodating transmission of side thrust from the 
propulsion leg to the hydraulic cylinder-piston assembly. 
In one embodiment of the invention, the hydraulic cylinder-piston assembly 
is extended when the propulsion leg is in the normal running position. 
Other features and advantages of the embodiments of the invention will 
become known by reference to the following general description, claims and 
appended drawings.

Before explaining one embodiment of the invention in detail, it is to be 
understood that the invention is not limited in its application to the 
details of construction and the arrangement of components set forth in the 
following description or illustrated in the drawings. The invention is 
capable of other embodiments and of being practiced and carried out in 
various ways. Also, it is to be understood that the phraseology and 
terminology employed herein is for the purpose of description and should 
not be regarded as limiting. 
GENERAL DESCRIPTION 
Shown in the drawings is a marine propulsion device which is mounted on a 
boat hull 11 including a transom 13 and which is generally in the form of 
a stern drive unit 15 including boat mounted prime mover or engine 17 
(shown schematically) and a propulsion leg 19 which rotatively supports a 
propeller 21 and which is supported from the transom 13 for pivotal 
tilting and steering movements. 
The propulsion leg 19 is supported from the transom 13 by means including a 
transom bracket 25 which is fixed by any suitable means on the transom 13 
and which includes a lower portion 27 having a slightly upwardly and 
rearwardly inclined mounting ear 29, together with an upper portion 31 
having a generally horizontally and rearwardly extending mounting ear 33, 
and a central portion 35 joining the upper and lower portions 31 and 27 
and including a sleeve portion 37 which is preferably generally 
cylindrical and which has a fore and aft generally horizontal axis 39. As 
shown, the lower mounting ear 29 extends rearwardly further than the upper 
mounting ear 33. 
The propulsion leg 19 includes a central part having a mounting arm 45 
which inclines forwardly and downwardly and, adjacent the upper end 
thereof, a transverse generally horizontal pivot pin 47, together with a 
sleeve portion 49 which is loated intermediate the pivot pin 47 and the 
mounting arm 45, which is forwardly open, which is preferably cylindrical, 
and which has an axis 51 which is generally coincident with the axis 39 of 
the sleeve portion 37 of the transom bracket 25. 
Connected to and extending between the sleeve portions 37 and 49 of the 
transom bracket 25 and the propulsion leg 19 is a flexible tube or boot 55 
which is of accordian configuration and which can be constructed of rubber 
or rubberlike material. 
Means are provided for tiltably and steerably connecting the propulsion leg 
19 to the transom bracket 25. While various constructions can be employed, 
in the disclosed construction, such means includes an extendible and 
contractible rigid link. While various arrangements can be employed, in 
the illustrated construction, such rigid link comprises a hydraulic 
cylinder-piston assembly 57 which extends at least in part, in a recess 59 
in the upper end of the propulsion leg 19 and which is pivotally 
connected, at its rearward end 61, to the pivot pin 47 adjacent the upper 
end of the propulsion leg 19. 
The end 63 of the hydraulic cylinder-piston assembly 57 includes a 
forwardly extending mounting arm 65 which is connected to the upper 
rearwardly extending mounting ear 33 of the transom bracket 25 by a first 
or upper universal coupling 71 accommodating pivotal movement of the 
propulsion leg 19 relative to the transom bracket 25 in both the 
horizontal and vertical planes to provide for both steering of the 
propulsion leg 19 and for trim adjustment of the propulsion leg 19. While 
various arrangements can be employed, in the illustrated construction, the 
upper universal coupling 71 comprises a spherical socket 73 formed in the 
mounting arm 65 of the hydraulic cylinder-piston assembly and a ball 75 
which is movably received in the socket 73 and which extends from a stud 
77 fixed to the upper mounting ear 33 extending from the transom bracket 
25. 
Still further in addition, the means for tiltably and steerably connecting 
the propulsion leg 19 to the transom bracket 25 comprises a second or 
lower universal coupling 81 connecting the mounting arm 45 of the 
propulsion leg 19 and the lower mounting ear 29 of the transom bracket 25. 
While various arrangements can be employed, in the illustrated 
construction, such lower universal coupling 81 includes a spherical socket 
83 formed in the mounting arm 45 of the propulsion leg 19 and a ball 85 
which is movably received in the socket 83 and which extends from a stud 
87 fixed to the lower mounting ear 29 at a point rearwardly of the 
location of the fixation of the upper ball 75 of the upper universal 
coupling 71. 
In is noted that, as a result of the construction just described, the 
propulsion leg steering axis 91 passes through the centers of the balls 75 
and 85 and slightly inclines upwardly and forwardly. Tilting occurs about 
a transverse tilt axis extending through the center of the lower ball 85. 
The hydraulic cylinder-piston assembly 57 also serves as means for tiltably 
displacing the propulsion leg 19 relative to the transom bracket 25 about 
the tilt axis so as to enable trimming of the propulsion leg 19 relative 
to the boat 11 to maximize propulsion efficiency. 
When the propulsion leg 19 is in the normal running position, the hydraulic 
cylinder-piston assembly 57 is extended. Any suitable means can be 
connected to the hydraulic cylinder-piston assembly 57 for selectively 
supplying pressure fluid thereto so as to contract and expand the 
hydraulic cylinder-piston assembly 57 and thereby adjust the trim position 
of the propulsion leg 19. In the disclosed construction, a hydraulic pump 
93 is schematically shown located inboard of the transom 13 and connected 
to the opposite ends of the hydraulic cylinder-piston assembly 57 by a 
pair of hydraulic conduits 95. 
Any suitable means (not shown) can be employed for effecting steering 
movement of a propulsion leg 19 about the steering axis 91. 
Also included in the disclosed construction is a drive train 101 which 
drivingly connects the propeller 21 with the engine 17. More specifically, 
the drive train 101 includes an output shaft 103 which can extend from the 
engine 17, or if desired, from an inboard reversing or speed transmission 
(not shown), and which is connected to a double universal joint and 
extensible shaft assembly 111 which extends through the transom 13 and 
through the sleeve portion 37 of the transom bracket 25, through the boot 
or tube 55, and through the sleeve portion 49 of the propulsion leg 19. 
Use of the double universal joint and extensible shaft assembly 111 
affords continuity of power delivery from the engine 17 to the propeller 
21 notwithstanding trimming and steering movements of the propulsion leg 
19 relative to the transom bracket 25. More specifically, the double 
universal joint and extensible shaft assembly 111 includes a first 
universal joint 113 connected to the output shaft 103, which first 
universal joint 113, in turn, is connected to a first stub shaft 115 
telescopically splined to a second stub shaft 117 which, in turn, is 
connected through a second universal joint 119 to a shaft 121 supported by 
bearings 123 and 125 in the propulsion leg 19. 
Within the propulsion leg, the drive train 101 also includes a vertical 
drive shaft 127 which, at its upper end, is connected by a bevel gear set 
131 to the shaft 121 and which, at its lower end, is connected by a bevel 
gear set 133 to a shaft 135 carrying the propeller 21. 
The propulsion leg 19 also includes a water pump 141 which is driven by a 
shaft 143 connected by a bevel gear set 145 to the propeller shaft 135 and 
which includes suitable inlet and discharge conduits (not shown). 
Alternatively, as shown in FIG. 2, the upper ball 75 may be mounted 
directly to the sleeve portion 37 of the transom bracket 25. In addition, 
the recess 59 previously referred to can be formed in a bracket or member 
151 which is suitably attached to the upper part of the propulsion leg 19. 
In addition, the hydraulic cylinder-piston assembly 57 can be formed so as 
to include a cylinder 161 fabricated such that the external side surfaces 
163 thereof mate closely with the fore and aft internal side surfaces 165 
of the recess 59 so as to permit movement of the cylinder 161 in the fore 
and aft direction relative to the recess 59 while, at the same time, 
affording transmission of side thrust from the propulsion leg 17 to the 
hydraulic cylinder-piston assembly 57. 
Various of the features of the invention are set forth in the following 
claims.