US3888203A

US3888203A - Stern drive for boats

Info

Publication number: US3888203A
Application number: US455998A
Authority: US
Inventors: Lawrence L Lohse
Original assignee: KIEKHAEFER AEROMARINE MOTORS Inc
Current assignee: KIEKHAEFER AEROMARINE MOTORS Inc
Priority date: 1974-03-29
Filing date: 1974-03-29
Publication date: 1975-06-10
Anticipated expiration: 1992-06-10
Also published as: JPS5650893A; JPS50132686A; JPS5650892A; JPS5650894A; JPS5649796B2; SE400067B; CA1022804A; JPS5651959B2; SE7503655L

Abstract

Two hydraulic cylinders, one on each side of the stern drive and disposed between the tilt housing and the dirigible unit, steer the latter on the axis of the vertical drive shaft. The tilt housing is carried by lateral trunnions rotatable in bearings of the transom mounting on a transverse axis generally passing near the center of the universal joint in the horizontal drive shaft which extends through the transom. A trim adjustment and power tilt cylinder is disposed between the tilt housing and the transom mounting. The dirigible unit is suspended by the vertical drive shaft from an upper gear housing which in turn is removably secured to the tilt housing. The vertical drive shaft is protected from thrust and impact stresses by a steering support tube constituting a part of the dirigible unit and surrounding the shaft within a sleeve of the upper gear housing.

Description

United States Patent Lohse June 10, 1975 1 1 STERN DRIVE FOR BOATS Primary ExaminerTrygve M. Blix Assislam Examiner-Jesus D. Sotelo {75] lnvemor' lfi Lohse Fond du Attorney, Agent, or FirmAndrus, Sceales, Starke &

Sawall [73] Assignee: Kiekhaefer Aeromarine Motors.

on 57 ABSTRACT [22] Filed: Mar. 29, 1974 [52] U.S. Cl. 115/41 HT; 115/35 [51] Int. Cl B63h 5/12 [58] Field of Search 115/34 R, 34 A, 35, 37, 115/41 R, 41 HT [56] References Cited UNITED STATES PATENTS 2,961,988 11/1960 Wood 115/41 R 2,979,019 4/1961 Leavitt et a1 115/34 R 3.1 36,282 6/1964 Alexander, Jr. 115/35 3,181,495 5/1965 Kiekhaefer 115/34 R 3,202,125 8/1965 Morse 115/35 3,605,677 9/1971 Bergstedt.... 115/35 3,654,889 4/1972 Bergstedt 115/35 Two hydraulic cylinders, one on each side of the stern drive and disposed between the tilt housing and the dirigible unit, steer the latter on the axis of the vertical drive shaft. The tilt housing is carried by lateral trunnions rotatable in bearings of the transom mounting on a transverse axis generally passing near the center of the universal joint in the horizontal drive shaft which extends through the transom. A trim adjustment and power tilt cylinder is disposed between the tilt housing and the transom mounting. The dirigible unit is suspended by the vertical drive shaft from an upper gear housing which in turn is removably secured to the tilt housing. The vertical drive shaft is protected from thrust and impact stresses by a steering support tube constituting a part of the dirigible unit and surrounding the shaft within a sleeve of the upper gear housing.

23 Claims, 8 Drawing Figures PATENTEDJUH l 0 m5 888203 I ILL! 1 AC Du Cu O PATENTEDJUN 10 I975 wig/A STERN DRIVE FOR BOATS BACKGROUND OF THE INVENTION This invention relates to a stern drive for boats.

Heretofore, stern drives employing a double universal joint providing an extensible horizontal drive shaft through the boat transom have been constructed with both the tilt axis and the steering axis passing substantially through the center of the effective universal joint.

Such a construction, particularly where it simulates a gimbal ring. requires very heavy expensive parts to withstand the forces involved.

SUMMARY OF THE INVENTION In carrying out the present invention, the steering axis coincides with the vertical drive shaft axis substantially to the rear of the universal joint. and at least some of the same bearing assemblies are utilized for supporting the vertical drive shaft and also the dirigible propulsion unit in the upper gear housing.

The horizontal transverse tilt axis generally passes through or just above the center of the double universal joint in the horizontal drive shaft and a single trim hydraulic power cylinder is disposed between the tilt housing and the transom.

Thus, the steering and the trim or tilt mechanism are fully operative independently of each other with separate parts for each whereby the forces can be taken care of more adequately.

The stern drive is constructed with a parting line that permits the mounting plate with the tilt mechanism, horizontal drive shaft and steering control mechanism to be installed on the transom by the boat manufacturer, and to which the outer vertical drive shaft assembly and underwater unit may be readily attached by the customer.

The vertical drive shaft is mounted in roller bearings, the upper of which is operative in the upper gear housing and a lower of which is operative in the lower unit with the nut at the upper end of the shaft pre-loading the bearings for both the shaft and for steering purposes. Additional needle bearings support the lower unit in the upper gear housing, and a frictionless hearing is disposed in a generally horizontal abutment plane between the lower unit and the upper gear housing to take the axial pre-loading thrust referred to.

The inboard engine exhaust is conducted through a channel on the mounting plate to be discharged rearwardly therefrom through an opening or openings above the level of the anti-cavitation plate.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate the preferred embodiment of the invention as presently contemplated by the inventor.

In the drawings:

FIG. I is a vertical longitudinal section of the stern drive unit shown as attached to the transom of a boat;

FIG. 2 is a vertical transverse section of the drive unit taken on line 22 of FIG. coincident of the vertical drive shaft axis;

FIG. 3 is a detail section taken on line 3-3 of FIG. 1 and showing the tilt trunnion and bellows construction;

FIG. 4 is a vertical section of the mounting plate taken on line 4-4 of FIG. 3 and showing one of exhaust passages;

FIG. is a rear elevation of the boat assembly unit comprising the mounting plate and the tilt housing;

FIG. 6 is a section taken on line 66 of FIG. 1 and showing the steering and trim mechanism in top plan 5 view with parts broken away and sectioned;

FIG. 7 is a diagram showing the hydraulic circuit for operating the steering mechanism; and

FIG. 8 is a diagram showing the hydraulic circuit for operating the trim cylinder.

DESCRIPTION OF THE PREFERRED EMBODIMENT The stern drive of the present invention. as illustrated in the accompanying drawings, comprises in general a boat mounting assembly and a drive assembly 2.

The boat mounting assembly 1 comprises an outer mounting plate 3 adapted to be secured to the rear transom 4 of a boat and to be sealed thereagainst to close the opening 5 in the transom.

The engine 6 is mounted inboard of the boat with its transmission 7 carried directly by the outer mounting plate 3.

The boat mounting assembly 1 additionally comprises a tilt housing 8 which is carried by mounting plate 3 to pivot upon a horizontal transverse tilt axis 9 by means of trunnions 10 disposed in bearings ll ofthe mounting plate.

A hydraulically operated trim cylinder I2 is pivotally secured to tilt housing 8 on a transverse axis 13 parallel to tilt axis 9.

The outer end of the piston rod 14 for piston 15 operative in cylinder 12 is pivotally secured to mounting plate 3 in a recess therein extending through transom opening 5 with the pivot 16 disposed inboard of the boat and parallel to tilt axis 9.

The tilt housing 8 carries a hydraulic steering mechanism 17 adapted to be connected to the dirigible part of the drive assembly 2 for steering the latter.

Various hydraulic steering mechanisms 17 may be employed, that shown and preferred, comprising a pair of cylinders 18 each having a plunger 19 and extending rearwardly on opposite sides of the tilt housing 8.

The plungers I9 are secured to the tilt housing 8 by suitable universal ball and socket connections 20 each having a retainer plate 21 therefor.

The mounting plate 3 has an opening 22 therethrough for receiving the horizontal drive shaft 23 extending rearwardly from transmission 7 with a double universal joint 24 therein and with the free rear end of the shaft splined as at 25 for connection to the drive assembly 2.

A bellows 26 surrounds the universal joint 24 with its outer end sealed to the tilt housing 8 and its inner end 5 sealed to mounting plate 3.

A bellows type seal 27 surrounds shaft 23 and is disposed between mounting plate 3 and the housing of transmission 7 to protect the universal joint 24 from bilge water and compensate for changes in volume within bellows 26 upon tilt movement of housing 8.

The transmission 7 is carried by side posts 28 extending upwardly from the inwardly projecting portion 29 of mounting plate 3 which surrounds the recess containing pivot 16.

The exhaust from engine 6 is conducted by suitable conduit 30 to openings 31 in the mounting plate 3 on either side of the same beneath trunnions I0 and from which openings 31 of the exhaust is discharged rearwardly of the boat.

The mounting assembly I described above may be secured to the boat by the boat manufacturer, and thus shipped as an integral part of the boat.

For this purpose. a removable protective covering, not shown. may be secured over the rear face of the mounting assembly 1 for shipment purposes to protect the splined end of shaft 23 and the rear ends of steering mechanism 17.

The drive assembly 2 may be shipped as a separate unit to protect the same from possible damage, and can be readily secured to the mounting assembly I by the dealer or other purchaser without requiring any adjustments.

The drive assembly 2 comprises the upper gear hous ing 32 and the dirigible unit or lower gear housing 33.

The upper gear housing 32 comprises a casting which encloses the upper bevel gear shaft 34 and which de pends downwardly along the face of the tilt housing 8 with a vertical sleeve 35 for receiving the upper end of the vertical drive shaft 36 and an intermediate steering support tube 37.

The upper bevel gear shaft 34 is hollow and splined on the inside to receive the splined end 25 of drive shaft 23 to effect a driving connection therebetween and at the same time provide for the necessary extension when the tilt housing and drive assembly 2 tilt upwardly on tilt axis 9.

The shaft 34 is mounted in tapered roller bearings 38 at the opposite ends thereof with the construction providing for turning the shaft end to end.

A bevel gear 39 has a shank supporting shaft 34 in one of the bearings 38, and is splined upon the shaft for assembly purposes.

The bevel gear 39 meshes with a bevel gear 40 on the upper end ofthe vertical drive shaft 36 to drive the latter.

The direction of rotation of vertical drive shaft 36 can be changed by turning shaft 34 end to end whereby the beveled gear 39 will engage the opposite side of beveled gear 40, as may be desirable to cancel out the engine torque reaction on the vertical dirigible units when employing dual drives side by side on the same boat. For this purpose the dual drives will have their dirigible units connected by a cross link 41 to maintain steering synchronization.

A seal 42 is disposed between the outer end of shaft 34 and the housing 32 to prevent leakage of oil from the housing through the open tubular shaft during shipment and also during operation of the drive.

Likewise, a seal 43 is disposed between the inner end of shaft 34 and the bearing retainer cap 44 secured to housing 32, to prevent leakage of oil from the housing during shipment and also during operation of the drive.

A neoprene gasket 45 is disposed between upper gear housing 32 and tilt housing 8 to prevent water from entering the region ofthe universal joint 24 inside bellows 26.

The vertical drive shaft 36 is splined to bevel gear 40 and supported therein by lock nut 46 threaded onto the upper end of the shaft in a recess in the gear.

The bevel gear 40 is supported in housing 32 by the tapered roller bearing 47 at the upper end of sleeve 35.

The vertical drive shaft 36 is mounted within a sleeve 48 of the lower dirigible unit 33 by means of a set of straight roller bearings 49 at the lower end and the tapered roller bearings 50 near the center of the shaft.

The tapered

bearings

47 and 50 are opposed to each other in thrust and the nut 46 determines the prc-load thereof. For this purpose a needle thrust bearing assembly 51 is disposed between a flange 52 on the steering support tube 37 and the lower end of sleeve 35.

A suitable bellcville spring washer 53 is disposed hencath nut 46 to maintain the preload of

bearings

47 and 50.

The vertical steering support tube 37 is rotatably disposed within sleeve 35 by means of upper and lower needle bearings 54.

The dirigible unit 33 has an upper face to which the steering housing 55 is secured by bolts 56, with steering support tube flange 52 clamped therebetween.

The lower end of dirigible unit 33 constitutes the lower gear case 57 and skeg 58.

The lower gear case 57 contains the propeller drive shaft 59 mounted in suitable tapered roller bearings 60 therein. Shaft 59 extends rearwardly from gear case 57 through the seals 61 and carries the propeller 62 for the drive.

To complete the propeller drive connection. bevel gear 63 on the lower end of vertical drive shaft 36 meshes with a bevel gear 64 fixed on propeller shaft 59.

The

shafts

34, 36 and 59, and the bevel gears 39, 40, 63 and 64 along with

corresponding bearings

38, 47, 49, 50, 60 and the

bearings

51 and 54 all operate in a closed oil chamber within the upper gear housing 32 and the lower gear housing or dirigible unit 33, and which chamber is maintained filled with oil at all times to a level corresponding to the position of the axis of shaft 34. For this purpose, a seal 65 surrounds sleeve 35 between it and the steering housing 55 to prevent leakage of oil between the two housings.

The top of upper gear housing 32 has an access opening with a sealed removable cover 66 therefor generally co-axial with shaft 36 to provide for machining the inside of the housing and for assembly of gear 40 and nut 46 upon the shaft.

The bellows 26 is protected by suitable overlapping of telescoping portions 67 of

tilt housings

8 and 68 of mounting plate 3 curved concentric to tilt axis 9.

The steering housing 55 has an abutment ring 69 on each side of the unit and through which the corresponding steering cylinders 18 extend. The two power cylinders 18 have the combined function of a single double acting power cylinder.

Each cylinder 18 has a spherically shaped ring 70 thereon adapted to abut rearwardly against and into a socket in abutment ring 69 of a generally complemental spherical segment shape.

Hydraulic pressures are maintained in the cylinders 18 bearing against the ends of the corresponding plungers 19 therein to effect a balance of forces maintaining the dirigible unit 33 in any steering position of rotation on the vertical steering axis which in the illustration coincides with the axis of shaft 36.

As shown in FIG. 7, operation of the cylinders 18 is effected by a power steering assist system comprising a source 71 of pressure fluid an orbitrol helm or valve unit 72 and suitable locking valves 73 and 74.

The pressure fluid source 71 comprises a sump 75. a gear pump 76 driven by engine 6 and having its inlet connected to the sump. a pressure conduit 77 leading from the pump discharge outlet to locking valve 73,

and a pressure relief valve 78 in conduit 77 and which returns fluid from the conduit to the sump when the system is fully pressurized.

The orbitrol unit 72 may he of the type marketed by the Fluid Power Division of Eaton Corporation under the trademark Char-Lynn and illustrated generally in Reissue Pat. No. 25.126 granted Feb. 20. 1962 and in Reissue Pat. No. 25.291 granted Dec. 4. I962.

Locking valve 73 receives fluid from conduit 77 and transmits it to orbitrol control unit 72 through passage 79 and which unit 72 then returns the fluid through passage 80 to valve 73 and from thence to the sump 75 through return conduit 81.

The orbitrol unit 72 is Connected to the locking valve 74 by two

conduits

82 and 83, and locking valve 74 is in turn connected to the left hand steering cylinder 18 by conduit 84 and to the right hand steering cylinder 18 by conduit 85.

The locking valve 74 comprises a housing having a central longitudinal bore 86 therein with a plug 87 closing each end of the bore.

An axial passage 88 in the inner end of each plug 87 leads to a lateral passage 89 which is connected to the

corresponding conduit

84 or 85.

A spring biased check valve 90 is disposed axially of each plug to effect closure of the corresponding axial passage 88 therein.

Conduits

82 and 83 connect with the opposite ends of the bore 86 and are isolated by a valve plunger 91 disposed centrally of the bore.

The plunger 91 carries a pilot pin 92 extending axially therefrom and loosely operative in the corresponding passage 88 to unseat the check valve 90 therein when the plunger moves in the corresponding direction in response to a pressure differential in

conduits

82 and 83.

When the steering wheel 93 is turned to the right, it thus effects an increase in fluid pressure in line 82 which then actuates plunger 91 to the left in FIG. 7 and admits pressure fluid through the right hand passage 88 unseating the corresponding check valve 90 and expanding the left hand or port cylinder 18 to turn unit 33 in a direction steering the boat to the right.

At the same time movement of plunger 91 to the left effects unseating of the left hand check valve 90 by the corresponding pilot pin 92 thereby allowing the right hand or starboard cylinder 18 to contract and the fluid therein to flow out through conduit 85 and the corresponding lateral passage 89 and axial passage 88 to bore 86 and thence through conduit 83 to the orbitrol control unit 72.

Conversely rotation of steering wheel 93 to the left effects an increase in fluid pressure in line 83 which then actuates plunger 91 to the right in FIG. 7 and admits pressure fluid through the left hand passage 88 unseating the corresponding check valve 90 and expand ing the right hand or starboard cylinder 18 to turn unit 33 in a direction steering the boat to the left.

At the same time movement of plunger 91 to the right effects unseating of the right hand check valve 90 by corresponding pilot pin 92 thereby allowing the left hand or port cylinder 18 to contract and the fluid therein to flow out through conduit 84 and the corresponding lateral passage 89 and axial passage 88 to bore 86 and thence through conduit 82 back to the orbitrol control unit 72.

Orbitrol control unit 72 is directly operated by manual turning of the steering wheel 93 disposed at a convenient place in the boat for the operator.

Whenever unit 72 is being actuated by steering wheel 5 93. the flow of fluid through unit 72 between

passages

79 and 80 becomes modified to effect a pressure differential between

conduits

82 and 83.

Whenever steering wheel 93 is stationary, the orbi trol unit 72 tends to block the flow 0f fluid therethrough between

conduits

82 and 83. At the same time. locking valve 74 is neutralized and locks the fluid in the corresponding cylinders 18 to thereby prevent turning of unit 33 by external forces upon the unit.

In the event ofa failure of pressure in conduit 77. the locking valve 73 in effect disconnects orbitrol control unit 72 from the fluid pressure source 71, and manual steering by turning of wheel 93 is effected by transfer of pressure fluid between

conduits

82 and 83 depending upon the direction of steering wheel rotation to effect a corresponding expansion and contraction of the port and starboard cylinders 18 and steering of the boat.

The locking valve 73 serves to retain the fluid in the orbitrol control system during the manual steering just described. Additionally when the fluid pressure source 71 is operative to supply fluid under pressure through locking valve 73 and conduit 79 to the orbitrol unit 72. fluid in the control system is continually replenished to compensate for leakage of fluid from the orbitrol unit back through passage 80 and locking valve 73.

Referring to FIG. 8, the trim cylinder 12 is connected at its opposite ends by

conduits

94 and 95, respectively to a source 96 of power fluid.

The fluid source 96 basically comprises a reversible motor driven gear pump 97 connected to receive hydraulic fluid from a reservoir 98 in either direction of operation.

For this purpose, passage 99 supplies fluid from reservoir 98 to pump 97 when the latter operates in a direction to effect outward and upward tilt of tilt housing 8, and passage 100 supplies fluid from reservoir 98 to pump 97 when the latter operates in a direction to effect downward and inward movement of tilt housing 8.

Each

passage

99 and 100 has a floating ball check valve 101 therein to prevent fluid being discharged by pump 97 from flowing directly to the reservoir 98.

The pump 97 discharges fluid received from passage 99 into the up-line conduit 94 through a check valve 102 which maintains the pressure in the up-line conduit 94 when the pump 97 is stopped.

The pump 97 discharges fluid received from passage 100 into the down-line conduit 95 through a check valve 103 which maintains the pressure in the downline conduit 95 when the pump 97 is stopped.

When the up-line conduit 94 is pressurized by pump 97, the cylinder chamber 104 on the front side of the piston becomes pressurized and the piston is forced outwardly of the cylinder to extend the latter and effect an upward tilting of the tilt housing 8 and drive assembly 2 on tilt axis 9. At the same time. fluid in cylinder chamber 105 on the back side of piston 15 is forced out through down-line conduit 95 and passage 106 to reservoir 98.

The passage [06 has a variable resistant spring biased ball check valve 107 which allows fluid to pass at low velocities but checks the flow when a predetermined high velocity is reached.

Between valve 107 and reservoir 98, the passage 106 has an adjustable pressure relief check valve 108 for the purpose of maintaining a predetermined pressure on the back side of piston to prevent trail-out and also provide the necessary transfer of thrust of the propeller during reverse rotation of it.

When the down-line conduit 95 is pressurized by pump 97, the cylinder chamber 105 becomes pressurized to force the piston 15 inwardly of the cylinder 12 thereby contracting the latter and effecting a down ward tilt movement of housing 8 and drive assembly 2 on tilt axis 9. At the same time, fluid in cylinder chamber 104 is forced out through up-line conduit 94 and check valve 102 to passage 100 leading to the inlet of pump 97. For this purpose check valve 102 is forced open by a pilot plunger 109 actuated by fluid pressure from the discharge side of pump 97.

An adjustable pressure relief valve 110 by-passcs check valve 101 in passage 100 to relieve the excess pressure in cylinder chamber 104 at the end of the piston stroke when the drive assembly 2 has been raised to its highest tilt position and before pump 97 is stopped.

An adjustable pressure relief valve 111 connects upline conduit 94 to reservoir 98 and is normally set to open at a high pressure to protect the system from possible external overload forces.

The piston 15 has a plurality of circumferentially spaced spring biased check valves 112 to prevent flow of fluid through the piston from chamber 104 to chamber 105. and to allow a restricted flow of fluid through the piston from chamber 105 to chamber 104 in the event chamber 105 becomes excessively pressurized by external forces sufficient to substantially close check valve 107.

Lateral forces on the drive assembly 2 are transmitted to the tilt housing 8 and supported by the thrust washers 113 encircling the base of the trunnions 10 between the tilt housing 8 and the transom plate 3 at the upper end of the housing as shown in FIG. 3, and by the vertical side surfaces 114 of connections at the lower end of housing 8 bearing against complementary rearwardly extending vertical guide surfaces 115 of the transom plate 3 as shown in FIG. 6.

As shown also in FIGv 6, the upper gear housing 32 is constructed to provide stops 116 disposed on either side to be engaged by the corresponding steering abutment rings 69 to limit the angular displacement of dirigible unit 33 for steering purposes.

In the construction illustrated, the steering or dirigible unit 33 is entirely suspended from upper gear housing 32 by means ofthe vertical drive shaft 36. Thus, the same bearings generally serve to support the shaft 36 and also the dirigible unit 33. The assembly of the drive assembly 2 is thereby made lighter and more compact, and the assembly and disassembly thereof is facilitated.

The low mounting of the stern drive on the boat transom and the relative short angular tilt movement limited by the dimensions of the trim cylinder 12 and its location relative to tilt axis 9 generally prevents the propeller 62 from reaching an inoperative position upon upward tilting of the unit.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. A stern drive for boats comprising a boat mounting assembly adapted to be secured to the transom of a boat and to provide a drive connection from an inboard engine; and a drive assembly removably secured to said boat mounting assembly and comprising a substantially vertical drive shaft having means connecting the same to said drive connection; an underwater dirigible unit suspended solely by said drive shaft, a propeller carried by said unit and operatively connected to be driven by said shaft, said boat mounting assembly comprising a transom plate and a tilt housing pivotally secured to said transom plate on a transverse axis with adjustable trim and power tilt mechanism therebetween, and said drive assembly being rcmovably secured to said tilt housing to tilt therewith. and a double universal joint in said drive connection and substantially coincident to said transverse axis.

2. The construction of claim 1 in which said boat mounting assembly comprises an exhaust discharge passage therethrough adapted to be connected to receive the exhaust from said inboard engine and to discharge the same rcarwardly of the transom independent of said drive assembly.

3. The construction of claim 1 and hydraulic means connecting said transom plate and tilt housing at a predetermined radial distance from said transverse axis to constitute said trim mechanism and control the trim position of the drive assembly relative to the boat.

4. The construction of claim 3 in which said hydraulic means comprises a power cylinder with a piston therein and means to pressurize said cylinder on either side of said piston. said last named means providing the transfer of thrust from said drive assembly to the boat for either direction of drive of the boat without need for mechanical interlocks.

5. The construction of claim 1 in which said boat mounting assembly comprises a transom plate and a tilt housing pivoted to said transom plate on a horizontal transverse axis; said drive connection comprises a generally horizontal drive shaft extending through said transom plate and having its outer end disposed to tilt with said tilt housing; universal joint means in said shaft with the center thereof disposed near to said tilt axis, beliows means between said transom plate and said tilt housing to enclose said universal joint means and an expandable bellows type seal between said transom plate and the engine and enclosing the inner end of said drive connection, said seal serving to protect said universal means from bilge water and prevent undue deformation of said first named bellows.

6. The construction of claim 1 and hydraulic means disposed between said tilt housing and said dirigible unit to control the steering of said dirigible unit upon the axis of said drive shaft.

7. The construction of claim 6 in which said hydraulic means comprises a source of fluid pressure, fluid power means disposed to move said dirigible unit to a predetermined set angular position, and an orbitrol helm selectively transmitting pressure fluid from said source to said power means.

8. The construction of claim 6 in which said hydraulic means comprises a double acting power cylinder means, and abutment means on said dirigible unit universally interengaging with said hydraulic means.

9. The construction of claim 8 in which said hydraulic means comprises a power cylinder disposed on each side of said drive assembly, and means to selectively 9 pressurize said cylinders to effect steering of said dirigi ble unit.

10. The construction of claim 8 in which said hydrauhe means is carried by said tilt housing to provide for steering of said dirigible unit independently of the tilting of said tilt housing.

ll. The construction of claim 9 in which said hydraulic means is carried by said tilt housing to provide for steering of said dirigible unit independently of the tilt position of said tilt housing.

12. An outboard stern drive for boats comprising a boat mounting assembly adapted to be secured to the transom of a boat and to provide a drive connection from an inboard engine, said drive connection being carried by the engine and comprising a shaft having a splined pilot outer end extending outwardly of the face of said mounting assembly; and a drive assembly carried by said mounting assembly and comprising an upper gear housing, a tubular beveled gear shaft mounted in end bearings in said housing and disposed to receive the splined pilot end of said extending shaft substantially in the central region of the tubular shaft, beveled gears connecting said tubular gear shaft and a vertical drive shaft in said upper gear housing, said housing constituting an oil chamber for running said gears and said bearings in oil, and means external of said bearings and sealing said chamber between said housing and said tubular gear shaft at the opposite ends of the latter to retain the oil in said chamber.

13. An outboard stern drive for boats, comprising an upper gear housing, a horizontal tubular gear shaft in said housing adapted to be connected to an inboard engine to drive the same, a vertical drive shaft depending from said housing with said tubular shaft extending across the upper end of said vertical drive shaft, a bevel gear, and bearing means at opposite ends of said tubular shaft in said housing and spaced equally from the axis of said vertical shaft, said tubular shaft being adapted for displacement bodily end for-end in said bearing means to dispose said first named bevel gear selectively on opposite sides of said second bevel gear to effect reversal in the direction of rotation ofsaid vertical drive shaft.

14. The construction of claim 13 for each of two paired stern drives disposed side by side on the same transom, and in which said tubular shaft and the beveled gear thereon for one stern drive is disposed to drive its corresponding vertical drive shaft in a direction opposite to the drive of the vertical drive shaft for the companion stern drive, a dirigible drive unit having an underwater propeller for each stern drive connected to be driven by the corresponding vertical shaft, and a link between said dirigible units of said stern drives to counteract torque reactions produced by the opposite rotation of said vertical drive shafts.

[5. In a stern drive for boats, an upper gear housing, having a downwardly depending vertical drive shaft and a dirigible lower propulsion unit carried by said shaft, said upper gear housing having a depending vertical sleeve, and said propulsion unit having an upwardly extending steering support tube operatively supported by hearings in said sleeve. said sleeve and said support tube being generally coaxial with said vertical drive shaft. a thrust bearing supporting said vertical drive shaft upon the upper end of said sleeve, a thrust bearing supporting said steering support tube on a shoulder of said vertical drive shaft, means to prc-load said thrust hearings in opposition to each other, and anti-friction bearing means between said dirigible unit and said upper gear housing to accommodate said pre load.

16. In a stern drive for boats having a dirigible propulsion unit and means for mounting the same upon the transom of a boat, hydraulic steering means for said propulsion unit comprising a power cylinder means disposed on each side of said dirigible unit and carried by said mounting means, abutment means on said dirigible unit universally interengaging with said hydraulic means and means to selectively pressurize said cylinders to effect steering of said unit,

17. The construction of claim 16 in which said hydraulic steering means comprises a source of fluid pressure, and an orbitrol helm selectively transmitting pressure fluid from said source to said power cylinder means.

18. in a stern drive for boats, a drive shaft connected to be driven by an inboard engine and extending rearwardly of the transom with a splined pilot outer end, an upper gear housing mounted rearwardly of the boat transom, an underwater propulsion unit having a generally vertical drive shaft extending upwardly into said upper gear housing, a tubular bevel gear shaft mounted in bearings in said housing and disposed selectively to receive the splined pilot end of said extending shaft therein from either end, bevel gears connecting said tubular gear shaft and said vertical drive shaft in said upper gear housing, said housing constituting an oil chamber for running said gears in oil, and means sealing said chamber between said housing and said tubular gear shaft at the opposite ends of the latter to retain the oil in said chamber.

19. In a stern drive for boats, an upper gear housing adapted to be mounted rearwardly of a boat transom, a drive connection from an inboard engine and having a splined pilot end extending into said gear housing, a tubular gear shaft in said housing disposed to receive said pilot end of said drive connection and to be driven thereby, a generally vertical drive shaft extending upwardly into said gear housing beneath said tubular shaft with their axes substantially intersecting, a bevel gear on the upper end of said vertical shaft, a bevel gear on said tubular shaft meshing with said first named bevel gear to drive the latter, and bearing means at opposite ends of said tubular shaft in said housing, said tubular shaft being adapted for displacement bodily end-forend in said bearing means to dispose said second named bevel gear selectively on opposite sides of said first named bevel gear to effect reversal in the direction of rotation of said vertical drive shaft.

20. The construction of claim 19 and a dirigible lower propulsion unit suspended from said gear housing and adapted to steer upon a steering axis coincident with the axis of said vertical drive shaft.

21. The construction of claim 20 for each of two paired stern drives disposed side by side on the same transom, and in which said tubular shaft and the beveled gear thereon for one stern drive is disposed to drive its corresponding vertical drive shaft in a direction opposite to the drive of the vertical drive shaft for the companion stern drive, and a link between said dirigible units of said stern drives to counteract torque reactions produced by the rotation of said vertical drive shafts.

22. In a stern drive for boats, 21 transom plate, a tilt housing pivoted to said transom plate on a horizontal transverse axis. a drive connection comprising a generally horizontal drive shaft extending from an inboard engine freely through said transom plate and having its outer end disposed to tilt with said tilt housing, universal joint means in said shaft with the center thereof disposed near to said tilt axis, bellows means between said transom plate and said tilt housing to enclose said universal joint means, and an expandable bellows type seal between said transom plate and the engine and enclosing the inner end of said drive connection. said seal serving to protect said universal means from bilge water and prevent undue deformation of said first named bellows.

23. In a stern drive for boats mounting means adapted to be secured to the transom ofa boat and having a tilt housing pivotally carried thereby on a transverse horizontal tilt axis, a dirigible propulsion unit suspended from said tilt housing to turn on a substantially vertical steering axis, and hydraulic steering means for said propulsion unit comprising a power cylinder on each side of said unit and carried by said tilt housing, abutment means on said dirigible unit engaged by said power cylinders, and means to selectively pressurize said power cylinders to effect steering movement of said propulsion unit independently of the tilt position of said tilt housing.

Claims

1. A stern drive for boats comprising a boat mounting assembly adapted to be secured to the transom of a boat and to provide a drive connection from an inboard engine; and a drive assembly removably secured to said boat mounting assembly and comprising a substantially vertical drive shaft having means connecting the same to said drive connection; an underwater dirigible unit suspended solely by said drive shaft, a propeller carried by said unit and operatively connected to be driven by said shaft, said boat mounting assembly comprising a transom plate and a tilt housing pivotally secured to said transom plate on a transverse axis with adjustable trim and power tilt mechanism therebetween, and said drive assembly being removably secured to said tilt housing to tilt therewith, and a double universal joint in said drive connection and substantially coincident to said transverse axis.

2. The construction of claim 1 in which said boat mounting assembly comprises an exhaust discharge passage therethrough adapted to be connected to receive the exhaust from said inboard engine and to discharge the same rearwardly of the transom independent of said drive assembly.

4. The construction of claim 3 in which said hydraulic means comprises a power cylinder with a piston therein and means to pressurize said cylinder on either side of said piston, said last named means providing the transfer of thrust from said drive assembly to the boat for either direction of drive of the boat without need for mechanical interlocks.

5. The construction of claim 1 in which said boat mounting assembly comprises a transom plate and a tilt housing pivoted to said transom plate on a horizontal transverse axis; said drive connection comprises a generally horizontal drive shaft extending through said transom plate and having its outer end disposed to tilt with said tilt housing; universal joint means in said shaft with the center thereof disposed near to said tilt axis, bellows means between said transom plate and said tilt housing to enclose said universal joint means and an expandable bellows type seal between said transom plate and the engine and enclosing the inner end of said drive connection, said seal serving to protect said universal means from bilge water and prevent undue deformation of said first named bellows.

9. The construction of claim 8 in which said hydraulic means comprises a power cylinder disposed on each side of said drive assembly, and means to selectively pressurize said cylinders to effect steering of said dirigible unit.

10. The construction of claim 8 in which said hydraulic means is carRied by said tilt housing to provide for steering of said dirigible unit independently of the tilting of said tilt housing.

11. The construction of claim 9 in which said hydraulic means is carried by said tilt housing to provide for steering of said dirigible unit independently of the tilt position of said tilt housing.

13. An outboard stern drive for boats, comprising an upper gear housing, a horizontal tubular gear shaft in said housing adapted to be connected to an inboard engine to drive the same, a vertical drive shaft depending from said housing with said tubular shaft extending across the upper end of said vertical drive shaft, a bevel gear, and bearing means at opposite ends of said tubular shaft in said housing and spaced equally from the axis of said vertical shaft, said tubular shaft being adapted for displacement bodily end-for-end in said bearing means to dispose said first named bevel gear selectively on opposite sides of said second bevel gear to effect reversal in the direction of rotation of said vertical drive shaft.

15. In a stern drive for boats, an upper gear housing, having a downwardly depending vertical drive shaft and a dirigible lower propulsion unit carried by said shaft, said upper gear housing having a depending vertical sleeve, and said propulsion unit having an upwardly extending steering support tube operatively supported by bearings in said sleeve, said sleeve and said support tube being generally coaxial with said vertical drive shaft, a thrust bearing supporting said vertical drive shaft upon the upper end of said sleeve, a thrust bearing supporting said steering support tube on a shoulder of said vertical drive shaft, means to pre-load said thrust bearings in opposition to each other, and anti-friction bearing means between said dirigible unit and said upper gear housing to accommodate said pre-load.

16. In a stern drive for boats having a dirigible propulsion unit and means for mounting the same upon the transom of a boat, hydraulic steering means for said propulsion unit comprising a power cylinder means disposed on each side of said dirigible unit and carried by said mounting means, abutment means on said dirigible unit universally interengaging with said hydraulic means and means to selectively pressurize said cylinders to effect steering of said unit.

19. In a stern drive for boats, an upper gear housing adapted to be mounted rearwardly of a boat transom, a drive connection from an inboard engine and having a splined pilot end extending into said gear housing, a tubular gear shaft in said housing disposed to receive said pilot end of said drive connection and to be driven thereby, a generally vertical drive shaft extending upwardly into said gear housing beneath said tubular shaft with their axes substantially intersecting, a bevel gear on the upper end of said vertical shaft, a bevel gear on said tubular shaft meshing with said first named bevel gear to drive the latter, and bearing means at opposite ends of said tubular shaft in said housing, said tubular shaft being adapted for displacement bodily end-for-end in said bearing means to dispose said second named bevel gear selectively on opposite sides of said first named bevel gear to effect reversal in the direction of rotation of said vertical drive shaft.

22. In a stern drive for boats, a transom plate, a tilt housing pivoted to said transom plate on a horizontal transverse axis, a drive connection comprising a generally horizontal drive shaft extending from an inboard engine freely through said transom plate and having its outer end disposed to tilt with said tilt housing, universal joint means in said shaft with the center thereof disposed near to said tilt axis, bellows means between said transom plate and said tilt housing to enclose said universal joint means, and an expandable bellows type seal between said transom plate and the engine and enclosing the inner end of said drive connection, said seal serving to protect said universal means from bilge water and prevent undue deformation of said first named bellows.

23. In a stern drive for boats, mounting means adapted to be secured to the transom of a boat and having a tilt housing pivotally carried thereby on a transverse horizontal tilt axis, a dirigible propulsion unit suspended from said tilt housing to turn on a substantially vertical steering axis, and hydraulic steering means for said propulsion unit comprising a power cylinder on each side of said unit and carried by said tilt housing, abutment means on said dirigible unit engaged by said power cylinders, and means to selectively pressurize said power cylInders to effect steering movement of said propulsion unit independently of the tilt position of said tilt housing.