Hydraulically powered marine propulsion tilting system with automatic let-down assembly

Claim 2

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly connected to said member for vertical swinging movement relative thereto, a hydraulic cylinder-piston assembly connected to said member and to said propulsion assembly and including a tilt cylinder having opposed first and second ends, a piston reciprocable in said tilt cylinder, and a piston rod connected to said piston and extending from said second end of said tilt cylinder, and means communicating between said first and second ends of said tilt cylinder and including means operative for temporarily affording fluid flow from said first end of said tilt cylinder to said second end of said tilt cylinder in response to the generation of relatively high pressure adjacent said second end of said tilt cylinder occuring incident to the striking of an underwater obstacle.

Claim 3

A marine propulsion device in accordance with claim 1 wherein said means for temporarily affording fluid flow from said first end of said tilt cylinder to said second end of said tilt cylinder comprises a first valve communicating between said first end of said tilt cylinder and said second end of said tilt cylinder, said first valve being biased to releasably prevent fluid flow therethrough from said first end of said tilt cylinder, a second valve communicating with said second end of said tilt cylinder and biased to releasably prevent fluid flow therethrough from said second end of said tilt cylinder, and means operative in response to fluid flow through said second valve for temporarily opening said first valve to afford fluid flow from said first end of said tilt cylinder to said second end of said tilt cylinder.

Claim 4

A marine propulsion device in accordance with claim 2 wherein said means for temporarily opening said first valve comprises a let-down valve housing having a first end communicating with said second valve and a second end communicating with said first valve, a piston reciprocable in said let-down valve housing between a first position adjacent to said first end of said let-down valve housing and a second position spaced from said first position in the direction away from said first end of said let-down housing, means on said piston operable when said piston is in said second position to open said first valve against the bias thereof, and bypass means affording restricted fluid flow from one side of said piston to the other, whereby application of pressure fluid to said first end of said let-down valve housing from said second valve displaces said piston from said first position to said second position to open said first valve so as to permit fluid flow from said first end of said tilt cylinder, through said first valve, through a part of said let-down valve housing, and to said second end of said tilt cylinder and whereby said piston will return from said second position to said first position in response to fluid flow through said restricted bypass means from said first end to said second end of said let-down valve housing.

Claim 5

A marine propulsion device in accordance with claim 2 wherein said first valve communicates with said second end of said tilt cylinder through conduit means including valve means preventing flow from said second end of said tilt cylinder to said first valve.

Claim 6

A marine propulsion device in accordance with claim 4 wherein said conduit means includes a reservoir between said first valve and said valve means.

Claim 7

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed first and second ends, pressure fluid supply and control means including a control valve housing having first and second ends, first conduit means communicating between said first end of said tilt cylinder and said first end of said control valve housing and including a first valve preventing fluid flow from said first end of said control valve housing to said first end of said tilt cylinder and releasably preventing fluid flow from said first end of said tilt cylinder to said first end of said control valve housing, and second conduit means communicating between said first end of said tilt cylinder and said first end of said control valve housing and including a second valve preventing fluid flow from said first end of said tilt cylinder to said first end of said control valve housing and releasably preventing fluid flow from said first end of said control valve housing to said first end of said tilt cylinder, and a normally closed third valve located between said first end of said control valve housing and said first conduit means and arranged to releasably prevent fluid flow therethrough to and from said first end of said control valve housing.

Claim 8

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed first and second ends, pressure fluid supply and control means including a control valve housing having first and second ends, first conduit means communicating between said first end of said tilt cylinder and said first end of said control valve housing and including a first valve preventing fluid flow from said first end of said control valve housing to said first end of said tilt cylinder and releasably preventing fluid flow from said first end of said tilt cylinder to said first end of said control valve housing, and second conduit means communicating between said first end of said tilt cylinder and said first end of said control valve housing and including a second valve preventing fluid flow from said first end of said tilt cylinder to said first end of said control valve housing and releasably preventing fluid flow from said first end of said control valve housing to said first end of said tilt cylinder, and a normally closed third valve located between said first end of said control valve housing and said first conduit means and arranged to releasably prevent fluid flow therethrough to and from said first end of said control valve housing.

Claim 9

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed first and second ends, a trim hydraulic cylinder-piston assembly including a trim cylinder fixed relative to one of said member and said propulsion assembly, having opposed first and second ends, and having therein a reciprocably movable trim piston having a piston rod extending through said second end of said trim cylinder and adapted for releasable engagement with the other of said member and said propulsion assembly, pressure fluid supply and control means, first conduit means communicating between said first end of said tilt cylinder and said pressure fluid supply and control means and including a first valve preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder and releasably preventing fluid flow from said first end of said tilt cylinder to said pressure fluid supply and control means, second conduit means communicating between said first end of said tilt cylinder and said pressure fluid supply and control means and including a second valve preventing flow from said first end of said tilt cylinder to said pressure fluid supply and control means and releasably preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder, and third conduit means communicating between said first end of said trim cylinder and said first conduit means intermediate said pressure fluid supply and control means and said first valve.

Claim 10

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed first and second ends, a trim hydraulic cylinder-piston assembly including a trim cylinder fixed relative to one of said member and said propulsion assembly, having opposed first and second ends, and having therein a reciprocably movable trim piston having a piston rod extending through said second end of said trim cylinder and adapted for releasable engagement with the other of said member and said propulsion assembly, pressure fluid supply and control means, first conduit means communicating between said first end of said tilt cylinder and said pressure fluid supply and control means and including a first valve preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder and releasably preventing fluid flow from said first end of said tilt cylinder to said pressure fluid supply and control means, second conduit means communicating between said first end of said tilt cylinder and said pressure fluid supply and control means and including a second valve preventing flow from said first end of said tilt cylinder to said pressure fluid supply and control means and releasably preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder, and third conduit means communicating between said first end of said trim cylinder and said first conduit means intermediate said pressure fluid supply and control means and said first valve.

Claim 11

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed first and second ends, a trim hydraulic cylinder-piston assembly including a trim cylinder fixed relative to one of said member and said propulsion assembly, having opposed first and second ends, and having therein a reciprocably movable trim piston having a piston rod extending through said second end of said trim cylinder and adapted for releasable engagement with the other of said member and said propulsion assembly, pressure fluid supply and control means including a control valve housing having first and second ends, first conduit means communicating between said first end of said tilt cylinder and said first end of said control valve housing and including a first valve preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder and releasably preventing fluid flow from said first end of said tilt cylinder to said first end of said control valve housing, second conduit means communicating between said first end of said tilt cylinder and said first end of said control valve housing and including a second valve preventing flow from said first end of said tilt cylinder to said first end of said control valve housing and releasably preventing fluid flow from said first end of said control valve housing to said first end of said tilt cylinder, third conduit means communicating between said first end of said trim cylinder and said first end of said control valve housing, a normally closed third valve located between said first end of said control valve housing and said first and third conduit means and arranged to releasably prevent fluid flow therethrough to and from said first end of said control valve housing, and a normally closed fourth valve communicating between said second end of said control valve housing and said second end of said tilt cylinder and said second end of said trim cylinder and arranged to releasably prevent flow therethrough to and from said second end of said control valve housing.

Claim 12

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed first and second ends, a trim hydraulic cylinder-piston assembly including a trim cylinder fixed relative to one of said member and said propulsion assembly, having opposed first and second ends, and having therein a reciprocably movable trim piston having a piston rod extending through said second end of said trim cylinder and adapted for releasable engagement with the other of said member and said propulsion assembly, pressure fluid supply and control means including a control valve housing having first and second ends, first conduit means communicating between said first end of said tilt cylinder and said first end of said control valve housing and including a first valve preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder and releasably preventing fluid flow from said first end of said tilt cylinder to said first end of said control valve housing, second conduit means communicating between said first end of said tilt cylinder and said first end of said control valve housing and including a second valve preventing flow from said first end of said tilt cylinder to said first end of said control valve housing and releasably preventing fluid flow from said first end of said control valve housing to said first end of said tilt cylinder, third conduit means communicating between said first end of said trim cylinder and said first end of said control valve housing, a normally closed third valve located between said first end of said control valve housing and said first and third conduit means and arranged to releasably prevent fluid flow therethrough to and from said first end of said control valve housing, and a normally closed fourth valve communicating between said second end of said control valve housing and said second end of said tilt cylinder and said second end of said trim cylinder and arranged to releasably prevent flow therethrough to and from said second end of said control valve housing.

Claim 13

A marine propulsion device in accordance with claim 8 wherein said pressure fluid supply and control means further comprises means for supplying pressure fluid selectively to adjacent said first and second ends of said control valve housing, a piston located in said control valve housing and movable relative to a centered position located midway between said first and second ends of said control valve housing, a first end position located adjacent to said first end of said control valve housing and affording communication between said fluid supply means and said third valve, and a second end position located adjacent to said second end of said control valve housing and affording communication between said fluid supply means and said fourth valve, means on said piston opening said third valve when said piston is in said first end position, and means on said piston opening said fourth valve when said piston is in said second end position.

Claim 14

A marine propulsion device in accordance with claim 8 and further including a reservoir and wherein said fourth valve includes means biasing said fourth valve toward the normally closed condition, and further including a fifth valve which is normally closed and which communicates with said second end of said control valve housing and with said reservoir, said fifth valve including means biasing said fifth valve toward the normally closed condition, said biasing means of said fifth valve having greater resistance than said biasing means of said fourth valve.

Claim 15

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed first and second ends, pressure fluid supply and control means, first conduit means communicating between said first end of said tilt cylinder and said pressure fluid supply and control means and including a first valve preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder and releasably preventing fluid flow from said first end of said tilt cylinder to said pressure fluid supply and control means, second conduit means communicating between said first end of said tilt cylinder and said pressure fluid supply and control means and including a second valve preventing flow from said first end of said tilt cylinder to said pressure fluid supply and control means and releasably preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder, and a normally closed relief valve communicating between said second conduit means and a sump and arranged to afford fluid flow from said second conduit means in the event of a pressure therein above a predetermined level.

Claim 16

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed first and second ends, pressure fluid supply and control means, first conduit means communicating between said first end of said tilt cylinder and said pressure fluid supply and control means and including a first valve preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder and releasably preventing fluid flow from said first end of said tilt cylinder to said pressure fluid supply and control means, second conduit means communicating between said first end of said tilt cylinder and said pressure fluid supply and control means and including a second valve preventing flow from said first end of said tilt cylinder to said pressure fluid supply and control means and releasably preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder, and a normally closed relief valve communicating between said second conduit means and a sump and arranged to afford fluid flow from said second conduit means in the event of a pressure therein above a predetermined level.

Claim 17

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed first and second ends, pressure fluid supply and control means, first conduit means communicating between said first end of said tilt cylinder and said pressure fluid supply and control means and including a first valve preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder and releasably preventing fluid flow from said first end of said tilt cylinder to said pressure fluid supply and control means, second conduit means communicating between said first end of said tilt cylinder and said pressure fluid supply and control means and including a second valve preventing flow from said first end of said tilt cylinder to said pressure fluid supply and control means and releasably preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder, and additional conduit means communicating between said first and second ends of said tilt cylinder and including means operative for temporarily affording fluid flow from said first end of said tilt cylinder to said second end of said tilt cylinder to permit downswing of said propulsion assembly in response to the previous generation of relatively high pressure adjacent said second end of said tilt cylinder occurring incident to the striking of an underwater obstacle.

Claim 18

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed first and second ends, pressure fluid supply and control means, first conduit means communicating between said first end of said tilt cylinder and said pressure fluid supply and control means and including a first valve preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder and releasably preventing fluid flow from said first end of said tilt cylinder to said pressure fluid supply and control means, second conduit means communicating between said first end of said tilt cylinder and said pressure fluid supply and control means and including a second valve preventing flow from said first end of said tilt cylinder to said pressure fluid supply and control means and releasably preventing fluid flow from said pressure fluid supply and control means to said first end of said tilt cylinder, and additional conduit means communicating between said first and second ends of said tilt cylinder and including means operative for temporarily affording fluid flow from said first end of said tilt cylinder to said second end of said tilt cylinder to permit downswing of said propulsion assembly in response to the previous generation of relatively high pressure adjacent said second end of said tilt cylinder occurring incident to the striking of an underwater obstacle.

Claim 19

A marine propulsion device in accordance with claim 12 wherein said means for temporarily affording fluid flow from said first end of said tilt cylinder to said second end of said tilt cylinder comprises a by-pass valve communicating between said first end of said tilt cylinder and said second end of said tilt cylinder, said by-pass valve being biased to releasably prevent fluid flow therethrough from said first end of said tilt cylinder, an actuating valve communicating with said second end of said tilt cylinder and biased to releasably prevent fluid flow therethrough from said second end of said tilt cylinder, and means operative in response to fluid flow through said actuating valve for temporarily opening said by-pass valve to afford fluid flow from said first end of said tilt cylinder to said second end of said tilt cylinder.

Claim 20

A marine propulsion device in accordance with claim 13 wherein said means for temporarily opening said by-pass valve comprises a let-down valve housing having a first end communicating with said actuating valve and a second end communicating with said by-pass valve, a piston reciprocable in said let-down valve housing between a first position adjacent to said first end of said let-down valve housing and a second position spaced from said first position in the direction away from said first end of said let-down valve housing, means on said piston operable when said piston is in said second position to open said by-pass valve against the bias thereof, and by-pass means affording restricted fluid flow from one side of said piston to the other, whereby application of pressure fluid to said first end of said let-down valve housing from said actuating valve displaces said piston from said first position to said second position to open said by-pass valve so as to permit fluid flow from said first end of said tilt cylinder, through said by-pass valve, through a part of said let-down valve housing, and to said second end of said tilt cylinder and whereby said piston will return from said second position to said first position in response to fluid flow through said restricted bypass means from said first end to said second end of said let-down valve housing.

Claim 21

A marine propulsion device in accordance with claim 13 wherein said by-pass valve communicates with said second end of said tilt cylinder through conduit means including valve means preventing flow from said second end of said tilt cylinder to said by-pass valve.

Claim 22

A marine propulsion device in accordance with claim 15 wherein said conduit means includes a reservoir between said by-pass valve and said valve means.

Claim 23

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed ends, a control valve adapted to communicate with a source of pressure fluid, first conduit means communicating between one of said ends of said tilt cylinder and said control valve and including a first valve preventing fluid flow from said control valve to said one end of said tilt cylinder and releasably preventing fluid flow from said one end of said tilt cylinder to said control valve, and second conduit means communicating between said one end of said tilt cylinder and said control valve and including a second valve preventing fluid flow from said one end of said tilt cylinder to said control valve and releasably preventing fluid flow from said control valve to said one end of said tilt cylinder, and a normally closed third valve located between said control valve and said first conduit means and arranged to releasably prevent fluid flow through said first conduit means to said control valve independently of said second valve.

Claim 24

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed ends, a control valve adapted to communicate with a source of pressure fluid, first conduit means communicating between one of said ends of said tilt cylinder and said control valve and including a first valve preventing fluid flow from said control valve to said one end of said tilt cylinder and releasably preventing fluid flow from said one end of said tilt cylinder to said control valve, and second conduit means communicating between said one end of said tilt cylinder and said control valve and including a second valve preventing fluid flow from said one end of said tilt cylinder to said control valve and releasably preventing fluid flow from said control valve to said one end of said tilt cylinder, and a normally closed third valve located between said control valve and said first conduit means and arranged to releasably prevent fluid flow through said first conduit means to said control valve independently of said second valve.

Claim 25

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed ends, a trim hydraulic cylinder-piston assembly including a trim cylinder fixed relative to one of said member and said propulsion assembly, having opposed first and second ends, and having therein a reciprocably movable trim piston having a piston rod extending through said second end of said trim cylinder and adapted for releasable engagement with the other of said member and said propulsion assembly, a control valve adapted to communicate with a source of pressure fluid, first conduit means communicating between one of said ends of said tilt cylinder and said control valve and including a first valve preventing fluid flow from said control valve to said one end of said tilt cylinder and releasably preventing fluid flow from said one end of said tilt cylinder to said control valve, second conduit means communicating between said one end of said tilt cylinder and said control valve and including a second valve preventing flow from said one end of said tilt cylinder to said control valve and releasably preventing fluid flow from said control valve to said one end of said tilt cylinder, and third conduit means communicating between said first end of said trim cylinder and said control valve.

Claim 26

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed ends, a trim hydraulic cylinder-piston assembly including a trim cylinder fixed relative to one of said member and said propulsion assembly, having opposed first and second ends, and having therein a reciprocably movable trim piston having a piston rod extending through said second end of said trim cylinder and adapted for releasable engagement with the other of said member and said propulsion assembly, a control valve adapted to communicate with a source of pressure fluid, first conduit means communicating between one of said ends of said tilt cylinder and said control valve and including a first valve preventing fluid flow from said control valve to said one end of said tilt cylinder and releasably preventing fluid flow from said one end of said tilt cylinder to said control valve, second conduit means communicating between said one end of said tilt cylinder and said control valve and including a second valve preventing flow from said one end of said tilt cylinder to said control valve and releasably preventing fluid flow from said control valve to said one end of said tilt cylinder, and third conduit means communicating between said first end of said trim cylinder and said control valve.

Claim 27

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed ends, a trim hydraulic cylinder-piston assembly including a trim cylinder fixed relative to one of said member and said propulsion assembly, having opposed first and second ends, and having therein a reciprocably movable trim piston having a piston rod extending through said second end of said trim cylinder and adapted for releasable engagement with the other of said member and said propulsion assembly, a control valve housing adapted to communicate with a source of pressure fluid and having first and second ends, first conduit means communicating between one of said ends of said tilt cylinder and said first end of said control valve housing and including a first valve preventing fluid flow from said control valve housing to said one end of said tilt cylinder and releasably preventing fluid flow from said one end of said tilt cylinder to said control valve housing, second conduit means communicating between said one end of said tilt cylinder and said first end of said control valve housing and including a second valve preventing flow from said one end of said tilt cylinder to said control valve housing and releasably preventing fluid flow from said control valve housing to said one end of said tilt cylinder, third conduit means communicating between said one end of said trim cylinder and said first end of said control valve housing, a normally closed third valve connected between said first end of said control valve housing and said first and third conduit means and arranged to releasably prevent fluid flow therethrough to and from said control valve housing, and a normally closed fourth valve connected between said second end of said control valve housing and the other of said ends of said tilt cylinder and said second end of said trim cylinder and arranged to releasably prevent flow therethrough to and from said control valve housing.

Claim 28

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed ends, a trim hydraulic cylinder-piston assembly including a trim cylinder fixed relative to one of said member and said propulsion assembly, having opposed first and second ends, and having therein a reciprocably movable trim piston having a piston rod extending through said second end of said trim cylinder and adapted for releasable engagement with the other of said member and said propulsion assembly, a control valve housing adapted to communicate with a source of pressure fluid and having first and second ends, first conduit means communicating between one of said ends of said tilt cylinder and said first end of said control valve housing and including a first valve preventing fluid flow from said control valve housing to said one end of said tilt cylinder and releasably preventing fluid flow from said one end of said tilt cylinder to said control valve housing, second conduit means communicating between said one end of said tilt cylinder and said first end of said control valve housing and including a second valve preventing flow from said one end of said tilt cylinder to said control valve housing and releasably preventing fluid flow from said control valve housing to said one end of said tilt cylinder, third conduit means communicating between said one end of said trim cylinder and said first end of said control valve housing, a normally closed third valve connected between said first end of said control valve housing and said first and third conduit means and arranged to releasably prevent fluid flow therethrough to and from said control valve housing, and a normally closed fourth valve connected between said second end of said control valve housing and the other of said ends of said tilt cylinder and said second end of said trim cylinder and arranged to releasably prevent flow therethrough to and from said control valve housing.

Claim 29

A marine propulsion device in accordance with claim 19 further comprising means for supplying pressure fluid selectively to adjacent said first and second ends of said control valve housing, a piston located in said control valve housing and movable relative to a centered position located midway between said first and second ends of said control valve housing, a first end position located adjacent to said first end of said control valve housing, and a second end position located adjacent to said second end of said control valve housing, means on said piston opening said third valve when said piston is in said first end position, and means in said piston opening said fourth valve when said piston is in said second end position.

Claim 30

A marine propulsion device in accordance with claim 20 and further including a reservoir and wherein said fourth valve includes means biasing said fourth valve toward the normally closed condition, and further including a fifth valve which is normally closed and which communicates with said second end of said control valve housing and with said reservoir, said fifth valve including means biasing said fifth valve toward the normally closed condition, said biasing means of said fifth valve having greater resistance than said biasing means of said fourth valve.

Claim 31

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed ends, a control valve adapted to communicate with a source of pressure fluid, first conduit means communicating between one of said ends of said tilt cylinder and said control valve and including a first valve preventing fluid flow from said control valve to said one end of said tilt cylinder and releasably preventing fluid flow from said one end of said tilt cylinder to said control valve, second conduit means communicating between said one end of said tilt cylinder and said control valve and including a second valve preventing flow from said one end of said tilt cylinder to said control valve and releasably preventing fluid flow from said control valve to said one end of said tilt cylinder, and a normally closed relief valve communicating between said second conduit means and a sump and arranged to afford fluid flow from said second conduit means in the event of a pressure therein above a predetermined level.

Claim 32

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed ends, a control valve adapted to communicate with a source of pressure fluid, first conduit means communicating between one of said ends of said tilt cylinder and said control valve and including a first valve preventing fluid flow from said control valve to said one end of said tilt cylinder and releasably preventing fluid flow from said one end of said tilt cylinder to said control valve, second conduit means communicating between said one end of said tilt cylinder and said control valve and including a second valve preventing flow from said one end of said tilt cylinder to said control valve and releasably preventing fluid flow from said control valve to said one end of said tilt cylinder, and a normally closed relief valve communicating between said second conduit means and a sump and arranged to afford fluid flow from said second conduit means in the event of a pressure therein above a predetermined level.

Claim 33

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed first and second ends, a control valve adapted to communicate with a source of pressure fluid, first conduit means communicating between said first end of said tilt cylinder and said control valve and including a first valve preventing fluid flow from said control valve to said first end of said tilt cylinder and releasably preventing fluid flow from said first end of said tilt cylinder to said control valve, second conduit means communicating between said first end of said tilt cylinder and said control valve and including a second valve preventing flow from said first end of said tilt cylinder to said control valve and releasably preventing fluid flow from said control valve to said first end of said tilt cylinder, and additional conduit means exterior of said tilt cylinder and communicating between said first and second ends of said tilt cylinder and including means operative for temporarily affording fluid flow from said first end of said tilt cylinder to said second end of said tilt cylinder to permit downswing of said propulsion assembly in response to the previous generation of relatively high pressure adjacent said second end of said tilt cylinder occurring incident to the striking of an underwater obstacle.

Claim 34

A marine propulsion device including a member adapted to be attached to a boat hull, a propulsion assembly pivotally connected to said member for vertical swinging movement when said member is attached to the boat hull, a tilt hydraulic cylinder-piston assembly connected between said member and said propulsion assembly and including a tilt cylinder having opposed first and second ends, a control valve adapted to communicate with a source of pressure fluid, first conduit means communicating between said first end of said tilt cylinder and said control valve and including a first valve preventing fluid flow from said control valve to said first end of said tilt cylinder and releasably preventing fluid flow from said first end of said tilt cylinder to said control valve, second conduit means communicating between said first end of said tilt cylinder and said control valve and including a second valve preventing flow from said first end of said tilt cylinder to said control valve and releasably preventing fluid flow from said control valve to said first end of said tilt cylinder, and additional conduit means exterior of said tilt cylinder and communicating between said first and second ends of said tilt cylinder and including means operative for temporarily affording fluid flow from said first end of said tilt cylinder to said second end of said tilt cylinder to permit downswing of said propulsion assembly in response to the previous generation of relatively high pressure adjacent said second end of said tilt cylinder occurring incident to the striking of an underwater obstacle.

Claim 35

A marine propulsion device in accordance with claim 23 wherein said means for temporarily affording fluid flow from said first end of said tilt cylinder to said second end of said tilt cylinder comprises a by-pass valve communicating between said first end of said tilt cylinder and said second end of said tilt cylinder, said by-pass valve being biased to releasably prevent fluid flow therethrough from said first end of said tilt cylinder, an actuating valve communicating with said second end of said tilt cylinder and biased to releasably prevent fluid flow therethrough from said second end of said tilt cylinder, and means operative in response to fluid flow through said actuating valve for temporarily opening said by-pass valve to afford fluid flow from said first end of said tilt cylinder to said second end of said tilt cylinder.

Claim 36

A marine propulsion device in accordance with claim 24 wherein said means for temporarily opening said by-pass valve comprises a let-down valve housing having a first end communicating with said actuating valve and a second end communicating with said by-pass valve, a piston reciprocable in said let-down valve housing between a first position adjacent to said first end of said let-down valve housing and a second position spaced from said first position in the direction away from said first end of said let-down valve housing, means on said piston operable when said piston is in said second position to open said by-pass valve against the bias thereof, and bypass means affording restricted fluid flow from one side of said piston to the other, whereby application of pressure fluid to said first end of said let-down valve housing from said actuating valve displaces said piston from said first position to said second position to open said by-pass valve so as to permit fluid flow from said first end of said tilt cylinder, through said by-pass valve, through a part of said let-down valve housing, and to said second end of said tilt cylinder and whereby said piston will return from said second position to said first position in response to fluid flow through said restricted bypass means from said first end to said second end of said let-down valve housing.

Claim 37

A marine propulsion device in accordance with claim 24 wherein said by-pass valve communicates with said second end of said tilt cylinder through conduit means including valve means preventing flow from said second end of said tilt cylinder to said by-pass valve.

Claim 38

A marine propulsion device in accordance with claim 26 wherein said conduit means includes a reservoir between said by-pass valve and said valve means.