US3581702A

US3581702A - Trim and tilt mechanism for outboard propulsion unit

Info

Publication number: US3581702A
Application number: US845363A
Authority: US
Inventors: Theodore J Moberg
Original assignee: Chrysler Corp
Current assignee: Old Carco LLC
Priority date: 1969-07-28
Filing date: 1969-07-28
Publication date: 1971-06-01
Anticipated expiration: 1988-06-01

Abstract

A trim and tilt mechanism for an outboard motor comprising a short stroke hydraulic cylinder acting against the outboard motor at a relatively long moment arm to accomplish trimming of the motor against the resistance of the propeller thrust, and a long stroke hydraulic cylinder acting at a relatively short moment arm to accomplish rapid upward tilting movement of the unit to its fully raised position.

Description

United States Patent 1 1 3,581,702

[72] Inventor Theodore J. Moberg [56] References Cited UNITED STATES PATENTS gmfi ig 2.930.730 5/1960 Patty. .lr. 115/41(Xl [45] Patented Jude 1971 2.997.014 8/1961 Puckett 115/17 [73] Assignee Chrysler Corporation 3.191.573 6/1965 HlXOl'l 115/41 Highland Park Mich 3.406.652 10/1968 MettetaLJr. 115/41 3.460.505 8/1969 Thoene 115/17 3,250,240 5/1966 Ziegler 115/17 Primary Examiner-Milt0n Buchler Assistant Examiner-Carl A. Rutledge Attorney-Harness, Talburtt & Baldwin [54] TRIM AND TILT MECHAMSM FOR OUTBOARD ABSTRACT: A trim and tilt mechanism for an outboard P S motor comprising a short stroke hydraulic cylinder acting 1 rawmg against the outboard motor at a relatively long moment arm to [52] US. Cl 115/41 accomplish trimming of the motor against the resistance of the [51] Int. Cl B63h 5/12 propeller thrust, and a long stroke hydraulic cylinder acting at [50] Field of Search 115/41,41 a relatively short moment arm to accomplish rapid upward HT. 17 tilting movement of the unit to its fully raised position.

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TRIM AND TILT MECHANISM FOR OUTBOARD PROPULSION UNIT BACKGROUND OF INVENTION This invention relates to power lift devices for outboard propulsion units and, more particularly, to a combined trim and tilt mechanism for outboard propulsion units. Outboard propulsion units are arranged to pivot upward about a generally horizontal axis between a working position in which the propeller is in the water and a raised position in which the propeller is out of the water. The first or lower portion of this movement in which the propeller remains in the water and merely undergoes an adjustment in its angle or trim may be referred to as the tirm" portion of its upward pivotal movement and the subsequent portion of this movement in which the propeller is moved clear of the water and pivoted upwardly to its fully raised position may be referred to as the tilt portionof the upward pivotal movement. The problems and requirements of moving an outboard propulsion unit through the trim portion of its upward lifting movement are distinctly different from the problems and requirements of moving the unit through the tilt portion of its upward pivotal movement. Many lift mechanisms have been proposed and/or are presently available for outboard propulsion units but none of these prior art units completely recognizes and successfully copes with all of the unique problems and requirements of the two distinct ranges of upward pivotal movement.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a combined trim and tilt mechanism for outboard propulsion units.

A more specific object is to provide a combined trim and tilt mechanism for outboard propulsion units which recognizes and satisfies all of the performance requirements unique to the distinct stages of upward pivotal movement of the unit.

According to one feature of the present invention, the motor lift means for the propulsion unit operates to move the unit at a relatively slow angular speed through the trim range, whereby to allow fine adjustment of the trim of the propeller, and at a relatively fast angular speed through the tilt range whereby to allow the unit to be quickly moved to its fully raised position.

According to a further feature, the motor lift means acts on the propulsion unit through a relatively long moment arm during movement through the trim range, whereby to successfully overcome the high propeller thrust load during forward movement of the boat, and acts on the propulsion unit through a relatively short moment arm during movement through the tilt range, whereby to provide a large amount of upward angular movement of the unit for each increment of movement of the motor lift means.

According to another feature of the invention, the motor lift means comprises fluid motor means, and means are provided for selectively varying the effective working area of the fluid motor means as the propulsion unit is pivoted about its axis.

In the disclosed embodiment, a short stroke. hydraulic cylinder is positioned to act against the propulsion unit at a location remote from the axis of pivotal movement of the unit, whereby to develop a high force acting through a long moment arm, and a long stroke hydraulic cylinder is positioned to act against the propulsion unit at a location relatively close to the pivot axis, whereby to provide a long tilt stroke acting through a short moment arm to provide rapid angular movement of the unit to its fully raised position.

Other features and advantages of the invention will be apparent from the detailed description of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS The preferred embodiment of the invention is illustrated in the accompanying drawings, in which:

FIG. 1 is a partially fragmentary view of auboat equipped with an outboard propulsion unit employing a trim and tilt mechanism according to the invention;

FIG. 2 is a cross-sectional view taken on line 2-2 of FIG. 1;

FIGS. 3 and 4 are partially schematic views showing moved positions of the outboard propulsion unit; and

FIG. 5 is a fragmentary view looking in the direction of the arrow 5 in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The outboard propulsion unit seen in the drawings is of the outboard motor type; that is, an outboard propulsion unit in which the power source for the unit is disposed outboard of the vessel to be propelled. Although the invention is described in detail with reference to an outboard motor, it will be understood that the trim and tilt mechanism of the invention is equally applicable to outboard propulsion units of the stem drive or inboard-outboard type in which the power source is located inboard of the vessel to be propelled.

The outboard motor 10 seen in the drawings includes a cowl 12 housing an engine (not shown), a hollow drive shaft housing 14 enclosing a drive shaft (not shown), an anticavitation plate 16, a gear housing or lower unit 18, and a propeller 20. A swivel pin 22 is carried at the forward edge of drive shaft housing 14. Outboard motor 10 is shown in the drawings mounted on a boat 24 having a transom 26. Motor 10 is removably mounted on transom 26 by a pair of

stem brackets

28, 30 and a swivel bracket 32. The near stern bracket 28 is removed in FIGS. 3 and 4 for clarity of illustration.

Stem brackets

28, 30 are C-shaped in cross section and are held in a clamped position over transom 26 by clamp screws 34 having screw plates 36 engaging the inboard face 38 of transom 26; clamp screws 34 are turned by screw handles 40.

Stern brackets

28, 30 are mounted on transom 26 in transversely spaced relation with a pivot shaft 42 extending between and interconnecting the spaced brackets.

Swivel bracket 32 is generally of inverted L configuration and includes a forwardly extending leg portion 43 terminating in a horizontal journal portion 44 joumaled on pivot shaft 42, and a downwardly extending leg portion 45 including a central journal portion 46 journaling motor swivel pin 22. Swivel bracket 32 also includes sidewalls 47 which reinforce

leg portions

43, 45. The near sidewall 47 is removed in FIGS. 1, 3 and 4 for clarity of illustration.

The described bracket arrangement enables outboard motor 10 to pivot with swivel bracket 32 upwardly about the axis of pivot shaft 42, or swivel independently of swivel bracket 32 about the axis of swivel pin 22.

Outboard motor 10 is provided with a combination trim and tilt mechanism consisting of a trim cylinder 48, a tilt cylinder 50, a pressure fluid source 52, and a control device 54.

Trim cylinder 48 is a relatively large bore, relatively short stroke hydraulic cylinder of the double acting or two-way type. The tubular outer shell or casing 48a of trim cylinder 48 is rigidly secured to a mounting member 56 and member 56 is rigidly secured to the outboard face 58 of transom 26. Alternatively, mounting plate 56 may be attached to, or'fonned integrally with,

stern brackets

28, 30. The free end 481) of the piston rod 48c of trim cylinder 48 has bearing engagement with the forward face 60a of a block 60 formed as an integral forward extension of the lower end of swivel pin journal portion 46 of swivel bracket 32. Trim cylinder 48 will be seen to be arranged to extend generally normal to a line passing through the axis of shaft 42 and through piston rod tip 48c so that its line of action is generally in direct opposition to the line of action of the thrust force generated by propeller 20 during forward movement of the boat. Trim cylinder 48 may, for example, have a bore of 2.00 inches and a stroke of 1.75.

Tilt cylinder 50 is a relatively small bore, relatively long stroke hydraulic cylinder of the double acting or two-way type. The lower end of the tubular outer shell of casing 501: of tilt cylinder 50 is pivotally connected to the lower end of stem bracket 30 by a pivot pin 61. The free or upper end 50b of the piston rod 500 of tilt cylinder 50 is pivotally connected by a pivot pin 62 to 3 lug 63 formed as a forward extension of theupper end of the swivel bracket sidewall 47 adjacent stern bracket 30. Tilt cylinder 50 may be provided with a pair of op' positely oriented relief valves (not shown, but of known form) in its piston so that pressure fluid may flow through one relief valve from the lower to the upper end of the cylinder in the event that the fluid pressure in the lower end of the cylinder builds up to a predetermined value, or may flow in the reverse direction through the other relief valve if pressure in the upper end of the cylinder becomes excessive. Tilt cylinder 50 may, for example, have a bore of 1.38 inches, and a stroke of 3.30 inches and may be of the type available from Eltra Corporation ofToledo, Ohio as Part No. 105275.

Pressure fluid source 52 comprises a motor-pump unit consisting of a reversible constant speed electric motor 64 driving a reversible positive displacement pump 65 of the type including a built-in sump. Pump 65 is designed to deliver a substantially constant volume of fluid under the constant speed drive of motor 64 with the pressure of the delivered fluid varying with variations in the load placed on the pump. Motor 64 and pump 65 may be mounted on a plate 66 secured to the starboard face of the outboard portion of stem bracket 28.

Motorpump unit

64, 65 may, for example, by of the type available from Eltra Corporation of Toledo, Ohio as Part No. 104208.

A hydraulic conduit 68 connects with pump port 650 and divides into conduits 68a, 68b communicating, respectively, with the forward end of trim cylinder 48 and the lower end of tilt cylinder 50. Another hydraulic conduit 70 connects with pump port 65b and is divided into conduits 70a, 70b communicating, respectively, with the rearward end of trim cylinder 48 and the upper end of tilt cylinder 50.

Control device 54 is preferably positioned forwardly in the boat adjacent the operator's seat and consists of a switching unit of known form. Switching unit 54 includes pushbuttons 54a and 54b. Pushbutton 54a, when depressed, establishes electrical communication between storage battery 72 and motor 64 in a sense to drive motor 64 and pump 65 in a direction to supply pressure fluid through conduit 68 and establish a fluid return path through conduit 70. Pushbutton 54b, when depressed, establishes an electrical circuit of opposite polarity to motor 64 to drive pump 65 in a direction to supply pressure fluid through conduit 70 and establish a return path through conduit 68.

OPERATION OF THE PREFERRED EMBODIMENT Outboard motor unit will normally be in the down position of FIG. 1 during operation. If the operator desires to vary the trim" of the motor, button 54a may be depressed; this actuates pump 65 in a sense to simultaneously extend may thus readily move the outboard motor within the small range 48 and 50 and pivot motor 10 about axis 42. The work load during this trimming movement of the outboard motor is borne almost entirely by the trim cylinder; the trim cylinder is able to move the outboard motor readily, however, even during conditions of high propeller thrust occurring during rapid forward movement of the boat, since the working area of the trim cylinder is large thereby allowing the cylinder to generate a large force with a relatively low fluid pressure, and the moment arm of the trim cylinder is relatively long. Trim cylinder 48 of working positions between the solid line full down position of FIG. 1 and the full trim position of FIG. 3. This working range of Him position is shown bracketed in FIG. 1. During this movement within the trim range, the pressure fluid output of pump 65 is split between large bore trim cylinder 48 and small bore trim cylinder 50 so that the extension of these cylinders is relatively slow and positive, thereby allowing fine calibration or adjustment of the outboard motor within the trim range. As the outboard motor reaches its full trim position, trim cylinder 48 runs out of stroke so that any further upward tilting movement of the outboard motor must be accomplished solely by tilt cylinder 50. As tilt cylinder 50 is extended beyond the full trim position, the outboard motor is moved through the off-plane positions seen in FIG. 1 (in which the propeller is still in the water but is beyond the full trim position) and then upwardly out of the water toward the full tilt position of FIG. 4. Since tilt cylinder 50 is connected to the swivel bracket at a location much closer to tilt axis 42 than the point of bearing engagement of trim cylinder 48 with the swivel bracket, the tilt cylinder is able to move the propeller through a relatively large tilt are as the tilt cylinder is extended. Further, since the entire output of pump 65 is now being delivered to relatively small bore cylinder 50, this cylinder extends relatively rapidly so that the movement of the outboard motor unit within the off-plane and tilt range is relatively rapid as compared to its deliberate, finely adjustable movement within the trim range. The speed of angular movement of the outboard motor unit within the off-plane and tilt range is also augmented by the short moment arm of the tilt cylinder which has the effect of producing a relatively large angular movement of the propeller for each increment of extension of the tilt cylinder. The pressure developed in the fluid circuit during movement of the motor unit through its offplane and tilt ranges will depend on the load encountered. The circuit pressure in any event will have to increase as the trim cylinder runs out of stroke and the tilt cylinder takes over the movement of the outboard motor unit, since the effective working area of the fluid motor means being supplied by the pump is now significantly decreased, thereby requiring a higher circuit pressure to develop a given lifting force, and since the moment arm through which this force is being applied is now significantly shortened, thereby requiring a larger force to counterbalance and movingly overcome the gravity weight load of the unit and/or the thrust force developed by the propeller. With the propeller positioned by tilt cylinder 50 in any of its off-plane positions, the outboard motor unit may be operated under low power in shallow water situations, such as beaching, without risking harm to the lower end of the outboard unit. If a high propeller thrust force is being developed as the motor unit moves into its off-plane range from its trim range, the circuit pressure may quickly build up to the pressure setting of the relief valves in the piston of the tilt cylinder in which event the tilt cylinder will short circuit itself through one of the relief valves and the outboard motor unit will refuse to pivot upwardly beyond its full trim position. Barring this extreme conditions, however, the circuit pressure will increase as the tilt cylinder takes over to a value to overcome the gravity and/or thrust load of the unit and the outboard motor unit will be moved upwardly through the off-plane and tilt positions at a significantly increased angular speed as compared to the relatively slow angular speed at which it was moved within the trim range. cylinder in the event that excessive propeller thrust is generated with the propeller in one of its off-plane positions; this bypassing action allows the cylinder to contract to return the motor to its full trim position where the trim cylinder picks up and successfully resists the propeller thrust to prevent further downward pivotal movement of the motor. The relief valve arrangement in the tilt cylinder also functions to bypass fluid from the upper to the lower end of the tilt cylinder in the event that the lower end of the outboard motor unit strikes an obstacle, thereby allowing the outboard unit to pivot upwardly about pin 42 to prevent damage to the outboard unit. Since pump 65 is of the positive displacement type in the particular embodiment disclosed, motor 10 will hold in any pivotal position to which it is moved either within the lower trim range, the off-plane range or the upper tilt range.

The motor may be moved downwardly (or counterclockwise as viewed in FIG, 1) from any position ofpivotal adjustment by depressing button 54b. Downward movement of the unit is accomplished in a positive manner by the delivery of pressure fluid to the outer end of trim cylinder 48 and the upper end of tilt cylinder 50 and the exhausting of fluid from the lower end of the cylinder 50 and the inner end of trim cylinder 48. Trim cylinder 50 retracts first; tilt cylinder 48 remaining extended until contacted by the outboard motor.

The invention trim and tilt mechanism will be seen to provide a simple, unitary system which may be readily applied to any outboard propulsion unit and which when thus applied, provides a positive, strong and finely adjustable movement of the propulsion unit in the trim range while providing a rapid, expedient movement of the unit in its tilt range.

While a preferred embodiment of the invention has been illustrated and described in detail, it will be apparent that various changes and modifications may be made in the proposed embodiment without departing from the scope or spirit of the invention.

lclaim:

1. In an outboard marine propulsion unit adapted to be positioned rearwardly of the transom of the boat to be propelled in a normally downwardly oriented position with the propeller at the lower end of the unit disposed in wetted position below the water line, and being pivotally movable relative to said transom about a generally horizontal axis upwardly through a range of wetted trim positions and thereafter through a range of tilt positions in which the propeller is raised out of the water, the improvement comprising a combined trim and tilt means including motor means connected to said propulsion unit for pivotally moving the latter upwardly about said axis, operative during the movement of said unit through said trim range to move said unit at a relatively slow angular speed and operative during the movement of said unit through said tilt range to move said unit at a relatively fast angular speed.

2. In an outboard marine propulsion unit adapted to be positioned rearwardly of the transom of the boat to be propelled in a normally downwardly oriented position with the propeller at the lower end of the unit disposed in wetted position below the water line, and being pivotally movable relative to said transom about a generally horizontal axis upwardly through a range of wetted trim positions and thereafter through a range of tilt positions in which the propeller is raised out of the water, the improvement comprising combined trim and tilt means including motor means operative during the upward movement of said unit through said trim range to apply a pivoting force to said unit having a relatively long moment arm and operative during the upward movement of said unit through said tilt range to apply a pivoting force to said unit having a relatively short moment arm.

3. An outboard propulsion system according to claim 2 wherein said motor means includes A. first motor means operative during said trim range movement and acting through said relatively long moment arm; and

B. second motor means operative during said tilt range movement and acting through said relatively short moment arm.

4. In an outboard marine propulsion unit adapted to be positioned rearwardly of the transom of the boat to be propelled and being pivotally movable relative to said transom about a generally horizontal axis between a working position in which the propeller at the lower end of the propulsion unit is disposed below the water line to provide propulsion for the boat and a raised position in which the propeller is raised out of the water, the improvement comprising a trim and tilt mechanism for said propulsion unit including A. fluid motor means connected to said propulsion unit for pivotally moving the latter about said axis;

B. a source of pressure fluid;

C. means for delivering pressure fluid from said source to said motor means; and

D. means for varying the effective working area of said fluid motor means as said propulsion unit is moved about said axis by said fluid motor means.

5. An outboard propulsion unit according to claim 4 wherein A. said motor means includes first and second fluid motors;

and

B. said delivery means includes means for routing pressure fluid to said first motor means during the initial portion of the upward movement of said unit from said working position and routing pressure fluid to said second motor means during the subsequent portion of said upward movement.

6. An outboard propulsion unit according to claim 5 wherein:

C. said delivery means is operative to route pressure fluid to both of said motor means during said initial movement portion and is operative to route pressure fluid only to said second motor means during said subsequent movement portion.

7. An outboard propulsion unit according to claim 5 wherein:

C. said first motor means has a relatively large working area and said second motor means has a relatively small working area.

8. An outboard propulsion unit according to claim 5 wherein C. said first motor means acts on said propulsion unit through a relatively long moment arm and said second motor means acts through a relatively short moment arm.

9. In an outboard marine propulsion unit adapted to be positioned rearwardly of the transom of the boat to be propelled and being pivotally movable relative to said transom about a generally horizontal axis between a working position in which the propeller at the lower end of the propulsion unit is disposed below the water line to provide propulsion for the boat and a raised position in which the propeller is raised out of the water, the improvement comprising a trim and tilt mechanism for said propulsion unit including A. a relatively short stroke hydraulic trim cylinder having engagement at one end with said transom or with a member rigid with said transom and having engagement at its other end with said propulsion unit or with a member pivotally movable about said axis with said unit, said trim cylinder having a stroke only long enough to move said propulsion unit from its working position to an intermediate angular position between said working position and said raised position; and

B. a relatively long stroke hydraulic tilt cylinder having engagement at one end with said transom or with a member rigid with said transom and having engagement at its other end with said propulsion unit or with a member pivotally movable about said axis with said unit, said tilt cylinder having a stroke long enough to pivotally move said propulsion unit from intermediate position to said raised position.

10. An outboard propulsion unit according to claim 9 wherein E. the line of action of said relatively short stroke cylinder with said propulsion unit in said working position is angularly displaced from the line of action of said relatively long stroke cylinder.

11. In an outboard marine propulsion unit adaptedto be positioned rearwardly of the transom of the boat to be propelled and being pivotally movable relative to said transom about a generally horizontal axis between a working position in which the propeller at the lower end of the propulsion unit is disposed below the water line to provide propulsion for the board and a raised position in which the propeller is raised out of the water; the improvement comprising a trim and tilt mechanism for said propulsion unit including A. a first hydraulic cylinder having engagement at one end with said transom or with a member rigid with said transom and having engagement at its other end with said propulsion unit or with a member pivotally movable about said axis with said unit;

B. a second hydraulic cylinder having engagement at one end with said transom or with a member rigid with said transom and having engagement at its other end with said propulsion unit or with a member pivotally movable about said axis with said unit, the line of action of said first cylinder with said propulsion unit in said working position being angularly displaced from the line of action of said second cylinder with said propulsion unit in said working position.

l2. An outboard propulsion unit according to claim 11 wherein D. said first cylinder is a relatively short stroke trim cylinder and said second cylinder is a relatively long stroke tilt cylinder.

13. An outboard propulsion unit according to claim 12 wherein E. the line of action of said trim cylinder with said propulsion unit in its working position is closer to the horizontal than the line of action of said tilt cylinder.

14. An outboard propulsion unit according to claim 13 wherein F. the line of action of said trim cylinder with said propulsion unit in its working position is generally horizontal; and

G. the line of action of said tilt cylinder with said propulsion unit in its working position is generally vertical.

15. In an outboard marine propulsion unit adapted to be positioned rearwardly of the transom of the boat to be propelled and being pivotally movable relative to said transom about a generally horizontal axis between a small angular range of working positions in which the propeller at the lower end of the propulsion unit is disposed below the water line to provide propulsion for the boat and a raised position in which the propeller is raised out of the water, the improvement comprising a trim and tilt mechanism for said propulsion unit including A. a relatively short stroke hydraulic trim cylinder connected at one end to said transom or to a member rigid with said transom and bearing at its other end against a surface (n said propulsion unit or on a member pivotally movable about said axis with said unit, said trim cylinder having a stroke only long enough to move said propulsion unit within said small angular range of working positions and having a line of action generally opposing the line of action of the thrust force generated by said propeller so as to enable the cylinder to effectively overcome the propeller thrust when thus trimming the propulsion unit; and

B. a relatively long stroke hydraulic tilt cylinder connected at one end to said transom or to a member rigid with said transom and connected at its other end to said propulsion unit or with a member pivotally movable about said axis with said unit, the connection of said tilt cylinder to said propulsion unit being located closer to said pivot axis than the point of bearing engagement of said trim cylinder with said propulsion unit so as to maximize the tilting action of said tilt cylinder and enable it to move said propulsion unit all the way to its raised position.

16. An outboard marine propulsion unit according to claim 15 and further including C. a source of pressure fluid; and

D. means for routing pressure fluid simultaneously to said trim and tilt cylinders from said pressure fluid source to effect conjoint extension of said cylinders during the initial portion of the upward pivotal movement of said propulsion unit and thereafter, after said trim cylinder has reached the end of its stroke, to effect further extension of said tilt cylinder to move said propulsion unit surface away from said trim cylinder other end and move said propulsion unit to its raised position.

Disclaimer 3,581,702.The0do're J. Moberg, Hartford, Wis. TRIM AND TILT MECHA- NISM FOR OUTBOARD PROPULSION UNIT. Patent dated June 1, 1971. Disclaimer filed Feb. 10, 1972, by the assignee, Chrysler Corporation. Hereby enters this disclaimer to claims 1 through 16, inclusive, of said patent.

[Ofiicz'al Gazette July 25, 1972.]

Claims

3. An outboard propulsion system according to claim 2 wherein said motor means includes A. first motor means operative during said trim range movement and acting through said relatively long moment arm; and B. second motor means operative during said tilt range movement and acting through said relatively short moment arm.

4. In an outboard marine propulsion unit adapted to be positioned rearwardly of the transom of the boat to be propelled and being pivotally movable relative to said transom about a generally horizontal axis between a working position in which the propeller at the lower end of the propulsion unit is disposed below the water line to provide propulsion for the boat and a raised position in which the propeller is raised out of the water, the improvement comprising a trim and tilt mechanism for said propulsion unit including A. fluid motor means connected to said propulsion unit for pivotally moving the latter about said axis; B. a source of pressure fluid; C. means for delivering pressure fluid from said source to said motor means; and D. means for varying the effective working area of said fluid motor means as said propulsion unit is moved about said axis by said fluid motor means.

5. An outboard propulsion unit according to claim 4 wherein A. said motor means includes first and second fluid motors; and B. said delivery means includes means for routing pressure fluid to said first motor means during the initial portion of the upward movement of said unit from said working position and routing pressure fluid to said second motor means during the subsequent portion of said upward movement.

6. An outboard propulsion unit according to claim 5 wherein: C. said delivery means is operative to route pressure fluid to both of said motor means during said initial movement portion and is operative to route pressure fluid only to said second motor means during said subsequent movement portion.

7. An outboard propulsion unit according to claim 5 wherein: C. said first motor means has a relatively large working area and said second motor means has a relatively small working area.

9. In an outboard marine propulsion unit adapted to be positioned rearwardly of the transom of the boat to be propelled and being pivotally movable relative to said transom about a generally horizontal axis between a working position in which the propeller at the lower end of the propulsion unit is disposed below the water line to provide propulsion for the boat and a raised position in which the propeller is raised out of the water, the improvement comprising a trim and tilt mechanism for said propulsion unit including A. a relatively short stroke hydraulic trim cylinder having engagement at one end with said transom or with a member rigid with said transom and having engagement at its other end with said propulsion unit or with a member pivotally movable about said axis with said unit, said trim cylinder having a stroke only long enough to move said propulsion unit from its working position to an intermediate angular position between said working position and said raised position; and B. a relatively long stroke hydraulic tilt cylinder having engagement at one end with said transom or with a member rigid with said transom and having engagement at its other end with said propulsion unit or with a member pivotally movable about said axis witH said unit, said tilt cylinder having a stroke long enough to pivotally move said propulsion unit from intermediate position to said raised position.

11. In an outboard marine propulsion unit adapted to be positioned rearwardly of the transom of the boat to be propelled and being pivotally movable relative to said transom about a generally horizontal axis between a working position in which the propeller at the lower end of the propulsion unit is disposed below the water line to provide propulsion for the board and a raised position in which the propeller is raised out of the water; the improvement comprising a trim and tilt mechanism for said propulsion unit including A. a first hydraulic cylinder having engagement at one end with said transom or with a member rigid with said transom and having engagement at its other end with said propulsion unit or with a member pivotally movable about said axis with said unit; B. a second hydraulic cylinder having engagement at one end with said transom or with a member rigid with said transom and having engagement at its other end with said propulsion unit or with a member pivotally movable about said axis with said unit, the line of action of said first cylinder with said propulsion unit in said working position being angularly displaced from the line of action of said second cylinder with said propulsion unit in said working position.

12. An outboard propulsion unit according to claim 11 wherein D. said first cylinder is a relatively short stroke trim cylinder and said second cylinder is a relatively long stroke tilt cylinder.

14. An outboard propulsion unit according to claim 13 wherein F. the line of action of said trim cylinder with said propulsion unit in its working position is generally horizontal; and G. the line of action of said tilt cylinder with said propulsion unit in its working position is generally vertical.

15. In an outboard marine propulsion unit adapted to be positioned rearwardly of the transom of the boat to be propelled and being pivotally movable relative to said transom about a generally horizontal axis between a small angular range of working positions in which the propeller at the lower end of the propulsion unit is disposed below the water line to provide propulsion for the boat and a raised position in which the propeller is raised out of the water, the improvement comprising a trim and tilt mechanism for said propulsion unit including A. a relatively short stroke hydraulic trim cylinder connected at one end to said transom or to a member rigid with said transom and bearing at its other end against a surface on said propulsion unit or on a member pivotally movable about said axis with said unit, said trim cylinder having a stroke only long enough to move said propulsion unit within said small angular range of working positions and having a line of action generally opposing the line of action of the thrust force generated by said propeller so as to enable the cylinder to effectively overcome the propeller thrust when thus trimming the propulsion unit; and B. a relatively long stroke hydraulic tilt cylinder connected at one end to said transom or to a member rigid with said transom and connected at its other end to said propulsion unit or with a member pivotally movable about said axis with said unit, the connection of said tilt cylinder to said propulsion unit being located closer to said pivot axis than the point of bearing engagement of saiD trim cylinder with said propulsion unit so as to maximize the tilting action of said tilt cylinder and enable it to move said propulsion unit all the way to its raised position.

16. An outboard marine propulsion unit according to claim 15 and further including C. a source of pressure fluid; and D. means for routing pressure fluid simultaneously to said trim and tilt cylinders from said pressure fluid source to effect conjoint extension of said cylinders during the initial portion of the upward pivotal movement of said propulsion unit and thereafter, after said trim cylinder has reached the end of its stroke, to effect further extension of said tilt cylinder to move said propulsion unit surface away from said trim cylinder other end and move said propulsion unit to its raised position.