U.S. patent number 3,722,455 [Application Number 05/118,134] was granted by the patent office on 1973-03-27 for hydraulic power trim and power tilt system for a marine propulsion device.
This patent grant is currently assigned to Outboard Marine Corporation. Invention is credited to Eugene C. Carpenter.
United States Patent |
3,722,455 |
Carpenter |
March 27, 1973 |
HYDRAULIC POWER TRIM AND POWER TILT SYSTEM FOR A MARINE PROPULSION
DEVICE
Abstract
Disclosed herein is an outboard motor including a first
extensible hydraulic cylinder means pivotally connected between a
transom bracket and a swivel bracket to afford power tilting and,
in response to the striking of an underwater obstacle, to afford
energy absorption, together with a second extensible hydraulic
cylinder means having an extensible part and mounted on the transom
bracket with the extensible part positioned for engagement with the
swivel bracket to afford trim adjustment. The disclosed outboard
motor also includes connection of the first and second extensible
hydraulic cylinder means in parallel relation to an electrically
operated reversible hydraulic pump and further includes an
electrically operated normally closed valve controlling
communication between the trimming hydraulic cylinder means and the
hydraulic pump independently of the communication between the
tilting hydraulic cylinder means and the hydraulic pump, together
with a tilt control switch operable to actuate the hydraulic pump,
and a trim control switch operable to actuate the hydraulic pump
and to open the normally closed valve.
Inventors: |
Carpenter; Eugene C.
(Galesburg, IL) |
Assignee: |
Outboard Marine Corporation
(Waukegan, IL)
|
Family
ID: |
22376685 |
Appl.
No.: |
05/118,134 |
Filed: |
February 23, 1971 |
Current U.S.
Class: |
440/56; 440/61H;
440/61D; 440/61R; 440/61J |
Current CPC
Class: |
B63H
20/10 (20130101); F02B 61/045 (20130101) |
Current International
Class: |
B63H
20/00 (20060101); B63H 20/10 (20060101); F02B
61/00 (20060101); F02B 61/04 (20060101); B63h
005/12 () |
Field of
Search: |
;115/41R,41HT,18
;248/4 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Buchler; Milton
Assistant Examiner: Rutledge; Carl A.
Claims
What is claimed is:
1. A marine propulsion device comprising a first bracket adapted to
be attached to a boat transom, a tiltable assembly comprising a
second bracket connected to said transom bracket for vertical
swinging movement about a horizontal axis, and a propulsion unit
connected to said second bracket for swinging movement relative to
said second bracket about an axis transverse to said horizontal
axis, a first extensible hydraulic cylinder means, means pivotally
connecting said first extensible hydraulic cylinder means to said
first bracket and to said tiltable assembly, a second extensible
hydraulic cylinder means having an extensible part, means
connecting said second extensible hydraulic cylinder means to one
of said first bracket and said tiltable assembly with said
extensible part being positioned for engagement with the other of
said first bracket and said tiltable assembly, an electrically
operated hydraulic pump, and conduit means hydraulically
communicating said first and second extensible hydraulic cylinder
means in parallel relation to said hydraulic pump and including an
electrically operated normally closed valve controlling
communication between said second extensible hydraulic cylinder
means and said hydraulic pump independently of the communication
between said first extensible hydraulic cylinder means and said
hydraulic pump.
2. A marine propulsion device in accordance with claim 1 wherein
said device is an outboard motor.
3. A marine propulsion device in accordance with claim 2 including
a pivot connecting said second bracket to said first bracket and
wherein said second hydraulic cylinder means has an axis at a
greater perpendicular distance from said pivot than the maximum
perpendicular distance from said pivot to the axis of said first
hydraulic cylinder means.
4. A marine propulsion device in accordance with claim 3 wherein
said perpendicular distance from the axis of said second hydraulic
cylinder means to said pivot is more than double the perpendicular
distance from said pivot to the axis of said first hydraulic
cylinder means.
5. A marine propulsion device in accordance with claim 2 wherein
said tiltable assembly is pivotal upwardly from a normal operating
position relative to said first bracket through an arc of at least
about 45.degree. and wherein said second hydraulic cylinder means
is disengaged from the other of said first bracket and tiltable
assembly prior to pivotal movement of said tiltable assembly from
the normal operating position through an arc of about
30.degree..
6. A marine propulsion device in accordance with claim 2 wherein
said first hydraulic cylinder means comprises a hydraulic shock
absorber including a cylinder, a piston movable in said cylinder,
and means affording hydraulic flow from one side of said piston to
the other in response to sudden upward movement of said tiltable
assembly from the normal operating running position.
7. A marine propulsion device in accordance with claim 2 wherein
said second hydraulic cylinder means comprises a cylinder fixed
rigidly relative to said first bracket, a piston movable in said
cylinder, and wherein said extensible part comprises a ram
extending fixedly from said piston and through one end of said
cylinder.
8. An outboard motor comprising a transom bracket, a second bracket
connected to said transom bracket for vertical swinging movement
about a horizontal axis and adapted to support a propulsion unit
for swinging movement relative to said second bracket about an axis
transverse to said horizontal axis, a first extensible hydraulic
cylinder means, means pivotally connecting said first extensible
hydraulic cylinder means to said transom bracket and to said second
bracket, a second extensible hydraulic cylinder means having an
extensible part, means connecting said second extensible hydraulic
cylinder means to said transom bracket with said extensible part
positioned for engagement with said second bracket, an electrically
operated hydraulic pump, conduit means hydraulically communicating
said first and second extensible hydraulic cylinder means in
parallel relation to said hydraulic pump and including an
electrically operated normally closed valve controlling
communication between said second extensible hydraulic cylinder
means and said hydraulic pump independently of the communication
between said first extensible hydraulic cylinder means and said
hydraulic pump, a tilt control switch electrically connected to
said hydraulic pump for actuating said hydraulic pump in response
to operation of said tilt control switch, and a trim control switch
electrically connected to said hydraulic pump and to said normally
closed valve for actuating said hydraulic pump and for opening said
valve in response to operation of said trim control switch.
9. An outboard motor in accordance with claim 8 wherein said
hydraulic pump is a reversible pump and includes first and second
outlet ports and wherein said conduit means connects each end of
each of said first and second extensible hydraulic cylinder means
to said outlet ports of said pump to provide for power operation in
opposing directions.
10. An outboard motor in accordance with claim 8 wherein said
transom bracket includes a series of apertures at a common radius
from said horizontal axis and further including a thrust bolt
removably received in one of said apertures and wherein said second
bracket includes a portion engageable with said thrust bolt when
permitted by the location of said extensible part.
11. A marine propulsion device in accordance with claim 1 wherein
said second extensible hydraulic cylinder means includes two
cylinders and respective pistons in each of said cylinders.
12. A marine propulsion device in accordance with claim 1 including
a trim control switch electrically connected to said hydraulic pump
and to said normally closed valve for actuating said hydraulic pump
and for opening said valve in response to operation of said trim
control sWitch.
13. A marine propulsion device in accordance with claim 1 including
a tilt control switch electrically connected to said hydraulic pump
for actuating said hydraulic pump in response to operation of said
tilt control switch, and a trim control switch electrically
connected to said hydraulic pump and to said normally closed valve
for actuating said hydraulic pump and for opening said valve in
response to operation of said trim control switch
14. A marine propulsion device in accordance with claim 1 wherein
said hydraulic pump is a reversible pump and includes first and
second outlet ports and wherein said conduit means connects each
end of each of said first and second extensible hydraulic cylinder
means to said outlet ports of said pump to provide for power
operation in opposing directions and wherein said normally closed
valve controls fluid flow to the end of saId second extensible
cylinder means opposite from said extensible part.
15. A marine propulsion device in accordance with claim 1 wherein
said first bracket includes a series of apertures at a common
radius from said horizontal axis and further including a thrust
bolt removably received in one of said apertures and wherein said
tiltable assembly includes a portion engageable with said thrust
bolt when permitted by the location of said extensible part.
16. A marine propulsion device comprising a first bracket adapted
to be attached to a boat transom, a tiltable assembly comprising a
second bracket connected to said transom bracket for vertical
swinging movement about a horizontal axis, and a propulsion unit
connected to said second bracket for swinging movement relative to
said second bracket about an axis transverse to said horizontal
axis, a first extensible hydraulic cylinder means, means pivotally
connecting said first extensible hydraulic cylinder means to said
first bracket and to said tiltable assembly, a second extensible
hydraulic cylinder means having an extensible part, means
connecting said second extensible hydraulic cylinder means to one
of said first bracket and said tiltable assembly with said
extensible part being positioned for engagement with the other of
said first bracket and said tiltable assembly, an electrically
operated hydraulic pump, and conduit means hydraulically
communicating between said pump and each of said first and second
extensible hydraulic means and including means for operating said
first extensible hydraulic cylinder means independently of said
second extensible hydraulic cylinder means.
Description
BACKGROUND OF THE INVENTION
The invention relates generally to marine propulsion devices such
as outboard motors and stern drive units which include vertically
tiltable propulsion or lower units supporting a propeller. Such
lower units are desirably trimmed relative to the boat and thereby
to the water to obtain maximum speed and safety conditions. Such
trimming effects both the relation of the boat to the water and the
angle at which the propeller generates propulsive thrust. Other
factors are involved in the "trim" of a boat as, for instance,
passenger loading and sea conditions. Thus, one particular
relationship of a propulsion unit to a boat can give good results
under one set of conditions and less satisfactory results under
another set of conditions. Furthermore, conditions can change when
underway, as for instance, if the weather or sea conditions change,
or if the distribution of passenger weight changes. Accordingly, it
is desirable to be able to adjust the trim under way.
It should also be noted that proper trim between a lower unit and a
boat is an important safety factor when under way. In this regard,
for instance, a "bow-down" condition can cause violent
uncontrollable action in swells.
In addition to trim, another factor of significance with respect to
vertically tiltable marine propulsion lower units is capability to
absorb shock incident to rearward and upward swinging occurring in
response to the striking of an underwater obstacle and the capacity
for power tilting of the propulsion unit upwardly and downwardly
relative to the trimmed running position. For example, propeller
removal is facilitated by tilting the lower unit to its fully
raised position and shallow water operation at reduced speeds is
facilitated by tilting the lower unit to a partially raised
position. Power tilting in the down or return direction also
affords return of the propulsion unit after the striking of an
underwater obstacle and after power tilting upwardly to partially
and fully raised positions.
Various arrangements have been provided in the past for
hydraulically absorbing shock or dissipating energy in response to
the striking of an underwater obstacle. In addition, various
arrangements have been employed to afford power tilting of a marine
propulsion lower unit between a running position and a partially or
fully raised or elevated position. In addition, various hydraulic
arrangements have been provided for adjusting the trim of an
outboard motor relative to a boat even when under way and to afford
energy absorption in response to striking of an underwater
obstacle. However, all the known prior arrangements were incapable,
without trim setting by the operator, of affording propulsion unit
return to the same trim position after power tilting or after
tilting in response to the striking of an underwater obstacle. The
Examiner's attention is directed to the following United States
patents: Ziegler U.S. Pat. No. 3,250,240 issued May 10, 1966;
Kiekhaefer U.S. Pat. No. 2,953,335 issued Sept. 20, 1960; North
U.S. Pat. No. 3,295,221 issued Nov. 15, 1966; North U.S. Pat. No.
3,434,449 issued Mar. 25, 1969; Woodfill U.S. Pat. No. 3,434,448
issued Mar. 25, 1969; McCormick U.S. Pat. No. 3,434,450 issued Mar.
25, 1969.
SUMMARY OF THE INVENTION
The invention provides a hydraulic system which affords power
tilting and trimming in such manner that tilting can occur without
affecting the trim setting and such that upon return tilting the
lower unit will return, without attention to trim by the operator,
to the previously set trim position.
The invention also provides a hydraulic system as set forth in the
preceding paragraph and which incorporates shock absorbing capacity
so that, upon the striking of an underwater obstacle, energy will
be dissipated and upon return tilting movement, the lower unit can
be returned to the previously set trim position.
The invention further provides for an electrically operated
hydraulic system which is selectively operable to provide either
"up" or "down" power tilting or "in" or "out" power trim
adjustments.
In accordance with the invention, there is provided, in association
with an outboard motor propulsion or lower unit or in association
with a stern drive propulsion or lower unit, a hydraulic tilt
cylinder which functions to effect power tilting and which includes
a piston provided with porting affording energy dissipation upon
upward swinging of the propulsion unit in response to the striking
of an underwater obstacle. Also in accordance with the invention,
there is provided a hydraulic trim cylinder including an extensible
ram which is engageable with a swivel bracket or other component to
adjustably establish the trim setting. Although other arrangements
are possible, in the disclosed construction, two tilt cylinders and
two trim cylinders are employed.
Also in accordance with the invention, there is provided a
hydraulic conduit and pump arrangement, as well as an electrical
control system such that a single reversible pump provides pressure
fluid under the same pressure to both the tilt and trim cylinders
in response to actuation of a trim control switch and such that,
upon actuation of a tilt control switch, hydraulic fluid is
supplied only to the tilt cylinder, thus leaving the trim cylinder
unaffected, so that upon return tilting, the swivel bracket or
other component will return to the previously established trim
position.
Also in accordance with the invention, the trim cylinders are
arranged to take advantage of a substantial moment arm with respect
to the horizontal tilt axis so that trim adjustments can be
effectively made under way and at high speeds. Thus, the trim
cylinders are several times more powerful (because of moment arm
consideration) then the tilt cylinders, notwithstanding employment
of hydraulic fluid under the same pressure conditions.
Also in accordance with the invention, the power tilt and power
trim features of the invention are employed as a supplement to the
previously employed thrust pin which functions as a safety trimming
device in case of failure of the hydraulic system.
One of the principal objects of the invention is the provision of a
hydraulic system for tilting and trimming the vertical tiltable
propulsion or lower unit of a marine propulsion device such as an
outboard motor or stern drive unit.
Another principal object of the invention is the provision of a
hydraulic system as indicated in the preceeding paragraph, which
system includes a "memory" feature", i.e., in which power tilting
can occur without affecting the trim setting and so that,
accordingly, upon downward tilting, the propulsion unit will
automatically return to the previously set trim position.
This feature is of substantial importance, as for instance, if an
underwater obstacle were struck and the propulsion unit tilts
rearwardly and upwardly, when using the construction disclosed
herein, the propulsion unit can subsequently be power operated for
return tilting movement to the pre-selected trim position with the
foreknowledge that the propulsion unit will quickly and rapidly
return to the previously set proper trim condition, thereby
avoiding any necessity on the part of the operator to attend to
trimming the propulsion unit.
Another of the principal objects of the invention is the provision
of a hydraulic power tilting and trimming system in which trimming
can be readily achieved when under way at high speeds and wherein
power tilting can be accomplished independently of trimming and
without affecting the previously set trim adjustment.
Another object of the invention is the provision of a hydraulic
power tilting and trimming system which can be readily and
economically manufactured and which will provide reliable service
over a long and useful life.
Other objects and advantages of the invention will become known by
reference to the following description and accompanying
drawings.
DRAWINGS
FIG. 1 is a fragmentary perspective view of an outboard motor
embodying various of the features of the invention.
FIG. 2 is an enlarged fragmentary side elevational view of the
outboard motor shown in FIG. 1 with the swivel bracket shown in a
first trim position.
FIG. 3 is a view similar to FIG. 2 with the swivel bracket shown in
a trim position which is angularly displaced rearwardly from the
position shown in FIG. 2.
FIG. 4 is a view similar to FIG. 2 showing the location of the
swivel bracket at the fully tilted position.
FIG. 5 is a schematic diagram of the hydraulic system incorporated
in the outboard motor shown in FIG. 1.
FIG. 6 is a schematic view of the electrical control system
incorporated in the outboard motor shown in FIG. 1.
GENERAL DESCRIPTION
Shown in FIG. 1 is a marine propulsion device in the form of a
fragmentarily illustrated outboard motor 11 which embodies various
of the features of the invention and which is shown mounted on the
transom 13 of a boat. As is conventional, the outboard motor 11
includes a clamp or transom bracket 17 which is connectable to the
boat transom 13 and which journals a horizontally extending pintle
or tilt pin 19. Carried by the pivot pin 19 is a tiltable assembly
comprising a member or swivel bracket 21 which includes provision
for rotatably mounting a king pin 23 in generally perpendicular
relation to the horizontal tilt pin 19. As is conventional, the
tiltable assembly also includes a propulsion or motor unit 27 which
is connected to the king pin 23 and which includes a power head and
a lower unit supporting a propeller, and which is steerable
relative to the swivel bracket 21, as well as tiltable with the
swivel bracket 21 relative to the transom bracket 17.
In general, the transom bracket 13 and swivel bracket 21 can be
constructed, except as otherwise noted herein, in general
accordance with the arrangement shown in the Conover U.S. Pat. No.
3,061,250 issued Oct. 30, 1962.
As is common, the transom bracket 17 includes a pair of
transversely spaced rearwardly extending wings 29 having an arcuate
series of aligned apertures 31 which extend at a common distance
from the tilt pin 19 and which are adapted to selectively receive a
thrust bolt 33 (See FIG. 2). In turn, the swivel bracket 21
includes a transversely extending concave pad 37 adapted to engage
the thrust bolt 33 and to thereby establish the trim of the motor
unit 27 relative to the boat and to the water and thereby also to
provide for transmission to the boat of propulsive thrust generated
by the propeller. Conventionally, changes in trim were achieved by
moving the thrust bolt 33 from one set of aligned apertures 31 to
another. Obviously, trim changes could not conveniently be made
under way to meet changing wind and sea conditions or changing load
conditions in the boat.
In accordance with the invention, in order to provide both power
tilting and shock absorbing features, a first extensible hydraulic
cylinder means 41 is pivotally connected between the transom
bracket 17 and the swivel bracket 21. While other arrangements are
possible, in the disclosed construction, the first hydraulic
cylinder means 41 comprises a pair of hydraulic power tilt
cylinders 43 and 47 which are essentially identically constructed
and mounted, except for being transversely spaced. Only the
cylinder 47 and its mounting will be described.
More specifically (as shown in FIG. 2), the hydraulic cylinder 47
is pivotally connected, at its lower end, to a stud 49 extending
from a lower part of the transom bracket 17 and receives a piston
51 connected to a piston rod 53 which, at its outer end, is
pivotally mounted on a stud 57 extending from an upper part of the
swivel bracket 21. As a consequence of the above described
connection, the cylinder 47 pivots slightly during pivotal movement
of the swivel bracket 21 relative to the transom bracket 17, but is
nonetheless disposed with the axis of the cylinder in a generally
upright position in generally parallel relation to the boat
transom.
In order to provide for hydraulic actuation of the tilt cylinders
43 and 47 to afford power tilting of the connected propulsion or
motor unit 27 and swivel bracket 21 in both directions between a
normal running position and a raised or elevated position which can
be angularly spaced from the running position anywhere from about
40.degree. to about 75.degree., hydraulic fittings 59 and 61 are
respectively provided at the upper and lower ends of each of the
cylinders 43 and 47 whereby to constitute each cylinder a double
acting cylinder.
In order that the hydraulic cylinder can also function as a shock
absorber in response to violent striking of an underwater object,
the piston 51 is provided with porting 63 in the form of one-way
spring controlled check valve or valves which will open to permit
restricted fluid flow, and thereby to absorb or dissipate energy,
when the pressure in the fluid above the piston 51 increases above
a predetermined value in response to attempted rearward and upward
tilting movement of the propulsion or motor unit 27 and connected
swivel bracket 21 consequent to the violent striking of an
underwater obstacle. The springs associated with the check valves
are designed to keep the check valves closed under normal cylinder
pressures produced by a reversible electric pump 71 which is
designed to be mounted remotely from the cylinders 43 and 47 and
preferably inside of the boat.
The pump 71 includes two outlet ducts or ports 73 and 77 and is
constructed and is selectively operable so that, in response to
rotation in one direction, pressure fluid is supplied to one of the
outlet ports 73 and 77 and the other outlet port is connected to a
sump or source of fluid, and in response to rotation in the
opposite direction, pressure fluid is supplied to the other outlet
port and the first mentioned port is connected to the sump or
source of pressure fluid. Such pumps 71 are well known in the art
and need not be further described.
Also in accordance with the invention, and in order to provide
power trim independently of the power tilting, i.e., to permit
power tilting without affecting the trim setting, there is provided
a second extensible hydraulic cylinder means 81 connected to the
transom bracket 17 and including an extensible ram engageable with
the swivel bracket. While other constructions can be employed, in
the disclosed construction, such second extensible hydraulic
cylinder means comprises a pair of hydraulic trim cylinders 83 and
87 which are essentially identically constructed and mounted except
for being transversely spaced. Accordingly, only the hydraulic
cylinder 87 will be described.
More particularly, the hydraulic cylinder 87 is provided as a part
of a unitary casting or member 89 which form both cylinders 83 and
87, which provide various conduits or ducts, still to be described,
and which is adapted to be mounted on the lower part of the transom
bracket 17. Carried in the cylinder 87 is a piston 91 which is
connected to an extensible part or ram 93 extending outwardly of
the cylinder 87 for abutting engagement with a cooperating pad or
ear 97 on the swivel bracket 21. The cylinder 87 is essentially
double acting and, as shown, is mounted on the transom bracket in
such manner that the ram 93 or axis of the cylinder extends at an
angle of about 60 degrees to the transom. Accordingly, the
perpendicular distance from the axis of the trim cylinders 83 and
87 to the tilt pin 19 is substantial and is several times greater
than the maximum perpendicular distance to the tilt pin 19 from the
axis of the tilt cylinders 43 and 47. In the specifically disclosed
construction, the perpendicular distance from the tilt pin 19 to
the trim cylinder axes is six times the maximum perpendicular
distance from the tilt pin 19 to the tilt cylinder axes.
Means (See FIG. 5) in the form of a hydraulic conduit system 111 is
provided for connecting the pump 71 to the cylinders 43, 47, 83,
and 87. In addition, means (See FIG. 6) in the form of an
electrical control system 113 is provided for actuating the pump 71
and controlling the hydraulic conduit system 111 so as to
selectively afford power trimming and power tilting and so as to
afford tilting of the motor unit upwardly from a selected trim
position either in response to hydraulic action or in response to
striking of an underwater obstacle and so that, upon return
tilting, the motor or propulsion unit 27 will return to the
previously pre-selected trim position.
As can be seen from FIG. 5, the trim cylinders 83 and 87 are
hydraulically connected in parallel with each other and the tilt
cylinders 43 and 47 are also hydraulically connected in parallel
with each other. As can also be seen from FIG. 5, the tilt
cylinders 43 and 47, as a group, are connected to the hydraulic
pump 71 in parallel with the connection of the trim cylinders 83
and 87, as a group, to the pump 71. More specifically, the
hydraulic conduit system 111 includes a first conduit 117 which
extends from the pump outlet port 73 and communicates with a
pressure relief valve 119, and which includes a first branch 121
connected to one end of the tilt cylinders 43 and 47, and a second
branch 123 connected to one end of the trim cylinders 83 and 87.
The hydraulic conduit system 111 also includes a second conduit 127
which extends from the pump outlet port 77 and communicates with a
pressure relief valve 129, and which includes a first branch 131
connected to the other end of the tilt cylinders 43 and 47 and a
second branch 133 connected to the other end of the trim cylinders
83 and 87.
In order to permit operation of the tilt cylinders 43 and 47
without operating the trim cylinders 83 and 87, one of the branch
conduits, i.e., in the disclosed construction, the branch conduit
133, includes a normally closed solenoid operated valve 137.
As shown in FIG. 6, the electrical control system 113 includes a
motor 139 which is included in the pump 71, as well as a tilt
control switch 141 and a trim control switch 143.
The tilt switch 141 constitutes a single pole double throw switch
operable to selectively provide for operating the pump motor 139 in
either direction. More particularly, the tilt switch 141 is
operable through respective "up" and "down" relays 147 and 149 to
provide for associated operation of the pump motor 139.
Specifically, the relays 147 and 149 are each connected to a ground
151, such as the frame of the pump motor, and are selectively
connectable through the tilt control switch 141 to a battery
153.
The pump motor 139 is connected through the relays 147 and 149 to a
pump battery 157 so that pump operation in one direction occurs in
response to energizing of the "up" relay 147 and so that pump
operation in the other direction occurs in response to energizing
of the "down" relay 149.
The trim control switch 143 comprises a double pole double throw
switch which is connected to the battery 153 and to the "up" and
"down" relays 147 and 149, as well as to a solenoid 159 operatively
associated with the normally closed valve 137, which solenoid 159
is also connected to ground 151. In operation, the trim control
switch 143 is operable to selectively provide for operation of the
pump motor 139 in either the "up" or "down" direction and to
simultaneously energize the solenoid 159 so as to open the branch
conduit 133 and to afford hydraulic flow relative to the trim
cylinders 83 and 87 so as to thereby extend or retract the rams 93
as may be desired, notwithstanding under way operation of the boat
at high speeds.
Also in operation, when the tilt control switch 141 is actuated,
hydraulic fluid is supplied to the tilt cylinders 43 and 47 to
raise or lower the propulsion or motor unit 27. However, actuation
of the tilt control switch 141 is ineffective to energize the
solenoid 159 and, accordingly, the rams 93 do not change position.
Thus, upon down tilting of the propulsion or motor unit 27
subsequent to the striking of an underwater obstacle or in response
to actuation of the tilt control switch 141, the motor unit 27 will
come to rest at the trim position previously established by the
rams 93.
Thus, it is clear, that tilting of the motor unit 27 can occur in
reference to a preselected trim position which is not disturbed as
a consequence of such tilting.
When the trim control switch 143 is actuated, hydraulic fluid is
supplied to both the tilt cylinders 43 and 47 and to the trim
cylinders 83 and 87 to cause adjustment in the position of the rams
93 and accompanying tilting of the motor unit 27. Such adjustment
of the ram position selectively establishes the desired trim.
It is noted that the moment arm or perpendicular distance to the
tilt pin 19 from the axis of the trim cylinders 83 and 87 is
several times the moment arm to the tilt pin 19 from the axis of
the tilt cylinders 43 and 47 and, as a consequence, even though all
cylinders 43, 47, 83, and 87 are subject to the same pressure, the
trim cylinders 83 and 87 are several times more effective in
displacing the motor unit 27 about the horizontal tilt axis. As a
consequence of the substantial moment arm associated with the trim
cylinders 83 and 87, the trim cylinders 83 and 87 are effective to
change the trim of the motor unit 27 even when under way under full
throttle conditions.
It should also be noted the disclosed construction continues the
use of the thrust bolt or pin 33 which serves a safety function,
limiting vertical swinging movement of the propulsion unit and
connected swivel bracket toward the transom bracket in the unlikely
event of a hydraulic failure. As a consequence, even if there is
hydraulic failure, the disclosed construction retains the
conventional capability for trim adjustment.
Various of the features of the invention are set forth in the
following claims.
* * * * *