TWO-SPEED TRANSMISSION

TRANSMISSION A DEUX VITESSES

English Abstract

ABSTRACT OF THE DISCLOSURE
Disclosed herein is a marine propusion device
incorporating a two-speed transmission including a first
drive gear which is mounted for common rotation with an
input shaft drivingly connected to an engine and which
meshes with first driven gear mounted for rotation
coaxially with a drive shaft drivingly connected to the
propeller shaft and further including a second drive gear
ratio of the first drive and driven gears. The second

Claims

The embodiments of the invention in which an
exclusive property or privilege is claimed are defined
as follows:
1. A marine propulsion device comprising an input
shaft drivingly connected to a power source, a lower unit
having a rotatably mounted drive shaft, a propeller shaft
rotatably mounted in said lower unit and carrying a pro-
peller, means drivingly connecting said drive shaft to
said propeller shaft, and a two-speed transmission drivingly
connecting said input shaft to said drive shaft and including
a first drive gear mounted for common rotation with said
input shaft, a second drive gear mounted for rotation
coaxially with and independently of said input shaft, a
first driven gear mounted for rotation coaxially with said
drive shaft and disposed in enmeshing engagement with said
first drive gear, the gear ratio of said first drive gear
to said first driven gear having a first value, a second
driven gear mounted for common rotation with said drive
shaft and disposed in enmeshing engagement with said second
drive gear, the gear ratio of said second drive gear to said
second driven gear having a second value greater than said
first value, first clutch means operable for drivingly
connecting said first drive gear to said drive shaft to
afford rotation of said drive shaft in one rotary direction
through said first drive and driven gears and to permit
rotation of said drive shaft relative to said first driven
gear when said drive shaft is rotated in said one rotary
direction at a rate of rotation greater than the rate of
rotation of said first driven gear, and second clutch means
for selectively drivingly connecting said second drive gear
to said input shaft whereby said drive shaft thereafter is
rotated in said one rotary direction, in response to rotation
13

of said input shaft, through said second drive and driven
gears and independently of said first drive and driven gears.
2. A marine propulsion device according to Claim 1
wherein said second clutch means is operable, in response
to rotation of said input shaft, to drivingly connect said
second driven gear to said input shaft when said input
shaft is rotated above a predetermined speed.
3. A marine propulsion device according to Claim 2
wherein said second clutch means comprises a centrifugal
clutch carried by said input shaft and including means
operable, in response to rotation of said second drive gear
by said second driven gear, for drivingly connecting said
second drive gear to said input shaft when the rotational
speed of said second driven gear exceeds a speed corres-
ponding to said predetermined speed.
4. A marine propulsion device according to Claim 3
wherein said centrifugal clutch includes a clutch drum
mounted for common rotation with said input shaft, a plurality
of clutch shoes, and a clutch shoe driver mounted for common
rotation with said second drive gear and for rotation indepen-
dently of said input shaft, said clutch shoe driver carrying
said clutch shoes and operable, in response to rotation of
said second drive gear, for rotatably driving said clutch
shoes so as to cause radially outward movement of said clutch
shoes from a retracted position spaced from said clutch drum
to an extended position in driving engagement with such
clutch drum.
14

5. A marine propulsion device comprising an input
shaft drivingly connected to a power source, a lower unit
including a rotatably mounted propeller shaft carrying a
propeller, first and second drive shafts rotatably mounted
in said lower unit and drivingly connected to said propeller
shaft, and a two-speed transmission drivingly connecting
said input shaft to said first and second drive shafts and
including a first drive gear mounted for common rotation
with said input shaft, a second drive gear mounted for
rotation coaxially with and independently of said input
shaft, a first driven gear mounted for rotation coaxially
with said first drive shaft and disposed in enmeshing
engagement with said first driven gear, the gear ratio of
said first drive gear to said first driven gear having a
first value, a second driven gear mounted for common rota-
tion with said first drive shaft and disposed in enmeshing
engagement with said second drive gear, the gear ratio of
said second drive gear to said second driven gear having a
second value greater than said first value, a third driven
gear mounted for rotation common with said second drive
shaft and disposed in enmeshing engagement with said second
driven gear, first clutch means operable for drivingly
connecting said first driven gear to said first drive shaft
to afford rotation of said first drive shaft in one rotary
direction through said first drive and driven gears, to
afford rotation of said second drive shaft in a rotary
direction opposite to said one direction through said first
drive and driven gears, said second driven gear, and said
third driven gear, and to permit rotation of said first
drive shaft relative to said first driven gear when said
first drive shaft is rotated in said one rotary direction at
a rate of rotation greater than the rate of rotation of said

first driven gear, and second clutch means for selectively
drivingly connecting said second drive gear to said input
shaft whereby said first drive shaft thereafter is rotated
in said one rotary direction, in response to rotation of
said input shaft, through said second drive and driven gears
and independently of said first drive and driven gears and
whereby said second drive shaft thereafter is rotated in a
rotary direction opposite to said one rotary direction, in
response to rotation of said input shaft, through said
second drive gear, said second driven gear and said third
driven gear.
6. A marine propulsion device according to Claim 5
wherein said second clutch means is operable, in response
to rotation of said input shaft, to drivingly connect said
second driven gear to said input shaft when said input
shaft is rotated above a predetermined speed.
7. A marine propulsion device according to Claim 6
wherein said second clutch means comprises a centrifugal
clutch carried by said input shaft and including means
operable, in response to rotation of said second drive
gear by said second driven gear, for drivingly connecting
said second drive gear to said input shaft when the rotational
speed of said second driven gear exceeds a speed corres-
ponding to said predetermined speed.
16

8. A marine propulsion device according to Claim 7
wherein said centrifugal clutch includes a clutch drum
mounted for common rotation with said input shaft, a
plurality of clutch shoes, and a clutch shoe driver mounted
for common rotation with said second drive gear and for
rotation independently of said input shaft, said clutch
shoe driver carrying said clutch shoes and operable, in
response to rotation of said second driver gear, for
rotatably driving said clutch shoes so as to cause radially
outward movement of said clutch shoes from a retracted posi-
tion spaced from said clutch drum to an extended position
in driving engagement with such clutch drum.
17

9. A two-speed transmission including an input shaft
adapted for connection to a power source, a drive shaft, a
first drive gear mounted for common rotation with said
input shaft, a second drive gear mounted for rotation
coaxially with and independently of said input shaft, a
first driven gear mounted for rotation coaxially with said
drive shaft and disposed in enmeshing engagement with said
first drive gear, the gear ratio of said first drive gear
to said first driven gear having a first value, a second
driven gear mounted for common rotation with said drive
shaft and disposed in enmeshing engagement with said second
drive gear, the gear ratio of said second drive gear to
second driven gear having a second value greater than said
first value, first clutch means operable for drivingly
connecting said first driven gear to said drive shaft to
afford rotation of said drive shaft in one rotary direction
through said first drive and driven gears and to permit
rotation of said drive shaft relative to said first driven
gear when said drive shaft is rotated in said one rotary
direction at a rate of rotation greater than the rate of
rotation of said first driven gear, and second clutch means
for selectively drivingly connecting said second drive
gear to said input shaft whereby said drive shaft there-
after is rotated in said one rotary direction, in response
to rotation of said input shaft, through said second drive
and driven gears and independently of said first drive and
driven gears.
18

10. A two-speed transmission according to Claim 9
wherein said second clutch means is operable, in response
to rotation of said input shaft, to drivingly connect
said second driven gear to said input shaft when said
input shaft is rotated above a predetermined speed.
11. A two-speed transmission according to Claim 10
wherein said second clutch means comprises a centrifugal
clutch carried by said input shaft and including means
operable, in response to rotation of said second drive
gear by said second driven gear, for drivingly connecting
said second drive gear to said input shaft when the
rotational speed of said second driven gear exceeds a speed
corresponding to said predetermined speed.
19

12. A two-speed transmission according to Claim 11
wherein said centrifugal clutch includes a clutch drum
mounted for common rotation with said input shaft, a
plurality of clutch shoes, and a clutch shoe driver mounted
for common rotation with said second drive gear and for
rotation independently of said input shaft, said clutch
shoe driver carrying said clutch shoes and operable, in
response to rotation of said second drive gear, for rotatably
driving said clutch shoes so as to cause radially outward
movement of said clutch shoes from a retracted position
spaced from said clutch drum to an extended position in
driving engagement with such clutch drum.

13. A marine propulsion device comprising an input
shaft drivingly connected to a power source, a lower unit
having a rotatably mounted drive shaft, a propeller shaft
rotatably mounted in said lower unit and carrying a pro-
peller, means drivingly connecting said drive shaft to
said propeller shaft, and a two-speed transmission drivingly
connecting said input shaft to said drive shaft and including
a first drive gear mounted for common rotation with said
input shaft, a second drive gear mounted for rotation.
coaxially with and independently of said input shaft, a
first driven gear mounted for rotation coaxially with said
drive shaft and disposed in enmeshing engagement with said
first drive gear, the gear ratio of said first drive gear
to said first driven gear having a first value, a second
driven gear mounted for common rotation with said drive
shaft and disposed in enmeshing engagement with said second
drive gear, the gear ratio of said second drive gear to said
second driven gear having a second value greater than said
first value, first clutch means operable for drivingly
connecting said first driven gear to said drive shaft to
afford rotation of said drive shaft in one rotary direction
through said first drive and driven gears and to permit
rotation of said drive shaft relative to said first driven
gear when said drive shaft is rotated in said one rotary
direction at a rate of rotation greater than the rate of
rotation of said first driven gear, and second clutch means
for selectively drivingly connecting said second drive gear
to said input shaft,whereby said drive shaft thereafter is
rotated in said one rotary direction, in response to rotation
21

of said input shaft, through said second drive and driven
gears and independently of said first drive and driven gears.
14. A marine propulsion device according to Claim 13
wherein said second clutch means is operable, in response
to rotation of said input shaft, to drivingly connect said
second driven gear to said input shaft when said input
shaft is rotated above a predetermined speed.
15. A marine propulsion device according to Claim 14
wherein said second clutch means comprises a centrifugal
clutch carried by said input shaft and including means
operable, in response to rotation of said second drive gear
by said second driven gear, for drivingly connectin said
second drive gear to said input shaft when the rotational
speed of said second driven gear exceeds a speed corres-
ponding to said predetermined speed.
16. A marine propulsion device according to Claim 15
wherein said centrifugal clutch includes a clutch drum
mounted for common rotation with said input shaft, a plurality
of clutch shoes, and a clutch shoe driver mounted for common
rotationwwith said second drive gear and for rotation indepen-
dently of said input shaft, said clutch shoe driver carrying
said clutch shoes and operable, in response to rotation of
said second drive gear, for rotatably driving said clutch
shoes so as to cause radially outward movement of said clutch
shoes from a retracted position spaced from said clutch drum
to an extended position in driving engagement with said
clutch drum.
22

17. A marine propulsion device comprising an input
shaft drivingly connected to a power source, a lower unit
including a rotatably mounted propeller shaft carrying a
propeller, first and second drive shafts rotatably mounted
in said lower unit and drivingly connected to said propeller
shaft, and a two-speed transmission drivingly connecting
said input shaft to said first and second drive shafts and
including a first drive gear mounted for common rotation
with said input shaft, a second drive gear mounted for
rotation coaxially with and independently of said input
shaft, a first driven gear mounted for rotation coaxially
with said first drive shaft and disposed in enmeshing
engagement with said first driven gear, the gear ratio of
said first drive gear to said first driven gear having a
first value, a second driven gear mounted for common rota-
tion with said first drive shaft and disposed in enmeshing
engagement with said second drive gear, the gear ratio of
said second drive gear to said second driven gear having a
second value greater than said first value, a third driven
gear mounted for rotation common with said second drive
shaft and disposed in enmeshing engagement with said second
driven gear, first clutch means operable for drivingly
connecting said first driven gear to said first drive shaft
to afford rotation of said first drive shaft in one rotary
direction through said first drive and driven gears, to
afford rotation of said second drive shaft in a rotary
direction opposite to said one direction through said first
drive and driven gears, said second driven gear, and said
third driven gear, and to permit rotation of said first
drive shaft relative to said first driven gear when said
first drive shaft is rotated in said one rotary direction at
a rate of rotation greater than the rate of rotation of said
23

Claim 17 continued
first driven gear, and second clutch means for selectively
drivingly connecting said second drive gear to said input
shaft whereby said first drive shaft thereafter is rotated
in said one rotary direction, in response to rotation of
said input shaft, through said second drive and driven gears
and independently of said first drive and driven gears and
whereby said second drive shaft thereafter is rotated in a
rotary direction opposite to said one rotary direction, in
response to rotation of said input shaft, through said
second drive gear, said second driven gear and said third
driven gear.
18. A marine propulsion device according to Claim 17
wherein said second clutch means is operable, in response
to rotation of said input shaft, to drivingly connect said
second driven gear to said input shaft when said input
shaft is rotated above a predetermined speed.
19. A marine propulsion device according to Claim 18
wherein said second clutch means comprises a centrifugal
clutch carried by said input shaft and including means
operable, in response to rotation of said second drive
gear by said second driven gear, for drivingly connecting
said second drive gear to said input shaft when the rotational
speed of said second driven gear exceeds a speed corres-
ponding to said predetermined speed.
24

20. A marine propulsion device according to Claim 19
wherein said centrifugal clutch includes a clutch drum
mounted for common rotation with said input shaft, a
plurality of clutch shoes, and a clutch shoe driver mounted
for common rotation with said second drive gear and for
rotation independently of said input shaft, said clutch
shoe driver carrying said clutch shoes and operable, in
response to rotation of said second driven gear, for
rotatably driving said clutch shoes so as to cause radially
outward movement of said clutch shoes from a retracted
position spaced from said clutch drum to an extended position
in driving engagement with said clutch drum.

21. A two-speed transmission including an input shaft
adapted for connection to a power source, a drive shaft, a
first drive gear mounted for common rotation with said
input shaft, a second drive gear mounted for rotation
coaxially with and independently of said input shaft, a
first driven gear mounted for rotation coaxially with said
drive shaft and disposed in enmeshing engagement with said
first drive gear, the gear ratio of said first drive gear
to said first driven gear having a first value, a second
driven gear mounted for common rotation with said drive
shaft and disposed in enmeshing engagement with said second
drive gear, the gear ratio of said second drive gear to
second driven gear having a second value greater than said
first value, first clutch means operable for drivingly
connecting said first driven gear to said drive shaft to
afford rotation of said drive shaft in one rotary direction
through said first drive and driven gears and to permit
rotation of said drive shaft relative to said first driven
gear when said drive shaft is rotated in said one rotary
direction at a rate of rotation greater than the rate of
rotation of said first driven gear, and second clutch means
for selectively drivingly connecting said second drive
gear to said input shaft whereby said drive shaft there-
after is rotated in said one rotary direction, in response
to rotation of said input shaft, through said second drive
and driven gears and independently of said first drive and
driven gears.
26

22. A two-speed transmission according to Claim 21
wherein said second clutch means is operable, in response
to rotation of said input shaft, to drivingly connect
said second driven gear to said input shaft when said
input shaft is rotated above a predetermined speed.
23. A two-speed transmission according to Claim 22
wherein said second clutch means comprises a centrifugal
clutch carried by said input shaft and including means
operable, in response to rotation of said second drive
gear by said second driven gear, for drivingly connecting
said second drive gear to said input shaft when the
rotational speed of said second driven gear exceeds a speed
corresponding to said predetermined speed.
27

24. A two-speed transmission according to Claim 23
wherein said centrifugal clutch includes a clutch drum
mounted for common rotation with said input shaft, a
plurality of clutch shoes, and a clutch shoe driver mounted
for common rotation with said second drive gear and for
rotation independently of said input shaft, said clutch
shoe driver carrying said clutch shoes and operable, in
response to rotation of said second drive gear, for rotatably
driving said clutch shoes so as to cause radially outward
movement of said clutch shoes from a retracted position
spaced from said clutch drum to an extended position in
driving engagement with said clutch drum.
28

25. A marine propulsion device comprising an
input shaft drivingly connected to a power source, a lower
unit having a rotatably mounted drive shaft, a propeller
shaft rotatably mounted in said lower unit and carrying
a propeller, means drivingly connecting said drive shaft
to said propeller shaft, and a two-speed transmission
drivingly connecting said input shaft to said drive shaft
and including a first drive gear fixed to said input shaft
for common rotation with said input shaft, a second drive
gear mounted for rotation coaxially with and independently
of said input shaft, a first driven gear mounted for
rotation coaxially with and independently of said drive
shaft and disposed in enmeshing engagement with said first
drive gear; the gear ratio of said first drive gear to said
first driven gear having a first value, a second driven
gear fixed to said drive shaft for common rotation with
said drive shaft and disposed in enmeshing engagement with
said second drive gear, the gear ratio of said second drive
gear to said second driven gear having a second value
greater than said first value, first clutch means operable
for drivingly connecting said first driven gear to said
drive shaft to afford rotation of said drive shaft in
one rotary direction through said first drive and driven
gears and to permit rotation of said drive shaft relative
to said first driven gear when said drive shaft is rotated
in said one rotary direction at a rate of rotation greater
than the rate of rotation of said first driven gear, and
second clutch means for selectively drivingly connecting
said second drive gear to said input shaft when said input
29

Claim 25 continued
shaft is rotated above a predetermined speed, said
second clutch means comprising a centrifugal clutch in-
cluding a clutch drum mounted for common rotation with said
input shaft, a plurality of clutch shoes, and a clutch shoe
driver mounted for common rotation with said second
drive gear and for rotation independently of said input
shaft, said clutch shoe driver carrying said clutch shoes
and being operable, in response to rotation of said second
drive gear, for rotatably driving said clutch shoes so
as to cause radially outward movement of said clutch shoes
from a retracted position spaced from said clutch drum
to an extended position in driving engagement with said
clutch drum.

26. A marine propulsion device comprising an
input shaft drivingly connected to a power source, a
lower unit including a rotatably mounted propeller shaft
carrying a propeller, first and second drive shafts
rotatably mounted in said lower unit and drivingly connected
to said propeller shaft, and a two-speed transmission
drivingly connecting said input shaft to said first and
second drive shafts and including a first drive gear fixed
to said input shaft for common rotation with said input
shaft, a second drive gear mounted for rotation coaxially
with and independently of said input shaft, a first driven
gear mounted for rotation coaxially with and independently
of said first drive shaft and disposed in enmeshing engage-
ment with said first driven gear, the gear ratio of said
first drive gear to said first driven gear having a first
value, a second driven gear fixed on said first drive
shaft for common rotation with said first drive shaft and
disposed in enmeshing engagement with said second drive
gear, the gear ratio of said second drive gear to said
second driven gear having a second value greater than said
first value, a third driven gear fixed for rotation in
common with said second drive shaft and disposed in enmeshing
engagement with said second driven gear, first clutch means
operable for drivingly connecting said first driven gear
to said first drive shaft to afford rotation of said first
drive shaft in one rotary direction through said first
drive and driven gears, and to permit rotation of said first
drive shaft relative to said first driven gear when said
first drive shaft is rotated in said one rotary direction
at a rate of rotation greater than the rate of rotation of
31

Claim 26 continued
said first driven gear, and second clutch means for
selectively drivingly connecting said second drive gear
to said input shaft when said input shaft is rotated above
a predetermined speed, said second clutch means comprising
a centrifugal clutch including a clutch drum mounted
for common rotation with said input shaft, a plurality
of clutch shoes, and a clutch shoe driver mounted for common
rotation with said second drive gear and for rotation in-
dependently of said input shaft, said clutch shoe driver
carrying said clutch shoes and being operable, in response
to rotation of said second drive gear, for rotatably
driving said clutch shoes so as to cause radially outward
movement of said clutch shoes from a retracted position
spaced from said clutch drum to an extended position in
driving engagement with said clutch drum.
32

27. A two-speed transmission including an input
shaft adapted for connection to a power source a drive
shaft, a first drive gear fixed to said input shaft for
common rotation with said input shaft, a second drive gear
mounted for rotation coaxially with and independently
of said input shaft, a first driven gear mounted for
rotation coaxially with and independently of said drive
shaft and disposed in enmeshing engagement with said first
drive gear, the gear ratio of said first drive gear to
said first driven gear having a first value, a second
driven gear fixed to said drive shaft for common rotation
with said drive shaft and disposed in enmeshing engagement
with said second drive gear, the gear ratio of said second
drive gear to second driven gear having a second value
greater than said first value, first clutch means operable
for drivingly connecting said first driven gear to said
drive shaft to afford rotation of said drive shaft in one
rotary direction through said first drive and driven gears
and to permit rotation of said drive shaft relative to
said first driven gear when said drive shaft is rotated
in said one rotary direction at a rate of rotation greater
than the rate of rotation of said first driven gear, and
second clutch means for selectively drivingly connecting
said second drive gear to said input shaft when said input
shaft is rotated above a predetermined speed, said second
clutch means comprising a centrifugal clutch including a
clutch drum mounted for common rotation with said input
shaft, a plurality of clutch shoes, and a clutch shoe
driver mounted for common rotation with said second drive
gear and for rotation independently of said input shaft,
33

Claim 27 continued
said clutch shoe driver carrying said clutch shoes and
being operable, in response to rotation of said second
drive gear, for rotatably driving said clutch shoes so
as to cause radially outward movement of said clutch
shoes from a retracted position spaced from said clutch
drum to an extended position in driving engagement with
said clutch drum.
34

28. A marine propulsion device comprising an input
shaft drivingly connected to a power source, a lower unit
having a rotatably mounted drive shaft, a propeller shaft
rotatably mounted in said lower unit and carrying a propeller,
means drivingly connecting said drive shaft to said propeller
shaft, and a two-speed transmission drivingly connecting
said input shaft to said drive shaft and including first
drive means for selectively drivingly connecting said input
shaft and said drive shaft and including a drive gear, a
driven gear in meshing engagement with said drive gear, and
a one-way overrunning clutch drivingly connecting said input
shaft and said drive shaft through said drive and driven gears
when the rotational speed of said input shaft is less than
a predetermined value, said first drive means having an
input-output speed ratio with a first value, and second
drive means for selectively drivingly connecting said input
shaft and said drive shaft when the rotational speed of said
input shaft is greater than said predetermined value, said
second drive means including a selectively actuatable clutch
for drivingly connecting said input shaft and said drive shaft,
said second drive means having an input-output speed ratio
with a second value greater than said first value.

29. A marine propulsion device in accordance with
Claim 28 wherein said input shaft and said drive shaft are
axially offset.
30. A marine propulsion device in accordance with
Claim 28 wherein said second drive means includes a second
drive gear and a second driven gear in meshing engagement
with said second drive gear.
31. A marine propulsion device in accordance with
Claim 28 wherein said second drive means clutch comprises a
centrifugal clutch including a drum drivingly connected
to one of said input shaft and said drive shaft and a
driver drivingly connected to the other of said input shaft
and said drive shaft and operable in response to driver
rotation above a predetermined speed to effect driving
engagement between said driver and said drum and therefore
between said input shaft and said drive shaft.
32. A marine propulsion device in accordance with
Claim 28 and further including a second drive shaft
rotatably mounted in said lower unit and drivingly connected
to said propeller shaft, and means adjacent said first
and second drive means for drivingly connecting said first
mentioned drive shaft to said second drive shaft for
transmissions of power to said propeller shaft through said
first mentioned and second drive shaft.
36

33. A marine propulsion device comprising an
input shaft drivingly connected to a power source, a
lower unit having a rotatably mounted drive shaft offset
from said input shaft, a propeller shaft rotatably mounted
in said lower unit and carrying a propeller, means drivingly
connecting said drive shaft to said propeller shaft, and a
two-speed transmission drivingly connecting said input
shaft to said drive shaft and including first drive and
driven gears in meshing engagement, the gear ratio of
said first drive gear to said first driven gear having a
first value, second drive and driven gears in meshing en-
gagement, the gear ratio of said second drive gear to
said second driven gear having a second value greater than
said first value, means fixedly connecting one of said
first drive gear to said input shaft and said first driven
gear to said drive shaft; a one-way overrunning clutch
connecting the other of said first drive gear to said
input shaft and said first driven gear to said drive shaft,
means fixedly connecting one of said second drive gear to
said input shaft and said second driven gear to said
drive shaft and a centrifugal clutch for selectively drivingly
connecting the other of said input shaft to said second drive
gear and said second driven gear to said drive shaft, said
centrifugal clutch including a drum fixed to one of said
gear and said shaft included in the other of said input
shaft which is connectable to said second drive gear and said
second driven gear which is connectable to said drive
shaft, a driver fixed to the other of said gear and said
37

Claim 33 continued
shaft included in the other of said input shaft which is
connectable to said second drive gear and said second
driven gear which is connectable to said drive shaft, and
at least one clutch shoe movably mounted on said driver
for movement into engagement with said drum.
38

34. A marine propulsion device comprising an input
shaft drivingly connected to a power source, a lower unit
having a rotatably mounted drive shaft offset from said
input shaft, a propeller shaft rotatably mounted in said
lower unit and carrying a propeller, means drivingly
connecting said drive shaft to said propeller shaft, and
a two-speed transmission drivingly connecting said input
shaft to said drive shaft and including first drive and
driven gears in meshing engagement, the gear ratio of said
first drive gear to said first driven gear having a first
value, means fixedly connecting one of said first drive gear
to said input shaft and said first driven gear to said drive
shaft, a one-way overrunning clutch connecting the other of
said first drive gear to said input shaft and said first
driven gear to said drive shaft, second drive and driven
gears in meshing engagement, the gear ratio of said second
drive gear to said second driven gear having a second value
greater than said first value, means fixedly connecting said
second driven gear to said drive shaft, and a centrifugal
clutch for selectively drivingly connecting said second drive
gear to said input shaft, said centrifugal clutch including
a drum fixed to one of said input shaft and said second
drive gear, a driver fixed to the other of said input shaft
and said second drive gear, and at least one clutch shoe
movably mounted on said driver for movement into engagement
with said drum.
39

35. A marine propulsion device comprising an
input shaft drivingly connected to a power source, a
lower unit having a rotatably mounted drive shaft offset
from said input shaft, a propeller shaft rotatably mounted
in said lower unit and carrying a propeller, means drivingly
connecting said drive shaft to said propeller shaft, and
a two-speed transmission drivingly connecting said input
shaft to said drive shaft and including first drive and
driven gears in meshing engagement, the gear ratio of said
first drive gear to said first driven gear having a first
value, second drive and driven gears in meshing engagement,
the gear ratio of said second drive gear to said second
driven gear having a second value greater than said first value,
means fixedly connecting one of said first drive gear to
said input shaft and said first driven gear to said drive
shaft, a one-way overrunning clutch connecting the other
of said first drive gear to said input shaft and said
first driven gear to said drive shaft, means fixedly
connecting said second drive gear to said input shaft,
and a ccntrifugal clutch for selectively drivingly connecting
said second driven gear to said drive shaft, said centri-
fugal clutch including a drum fixed to one of said drive
shaft and said second driven gear, a driver fixed to the
other of said drive shaft and said second driven gear,
and at least one clutch shoe movably mounted on said
driver for movement into engagement with said drum.

36. A two-speed transmission including an input shaft
adapted for connection to a power source, a drive shaft,
including first drive means for selectively drivingly
connecting said input shaft and said drive shaft and
including a drive gear, a driven gear in meshing engagement
with said drive gear, and a one-way overrunning clutch
drivingly connecting said input shaft and said drive shaft
through said drive and driven gears when the rotational speed
of said input shaft is less than a predetermined value,
said first drive means having an input-output speed ratio
with a first value, and second drive means for selectively
drivingly connecting said input shaft and said drive shaft
when the rotational speed of said input shaft is greater than
said predetermined value, said second drive means including
a selectively actuatable clutch for drivingly connecting
said input shaft and said drive shaft, said second drive
means having an input-output speed ratio with a second
value greater than said first value.
41

Description

TITLE
TWO-SPEED TRANSMISSION
INVENTOR
Charles D. Strang
BACKGROUND OF THE INVE~TION
The invention relates to transmissions and, more
particularly, to two-speed transmissions for marine pro-
pulsion devices and the like.
The thrust requirement curve (thrust vs. speed)
for planing boats propelled by an outboard motor or a
stern drive propulsion unit has a marked hump at the point
where the boat is starting to plane. The propeller
ordinarily must absorb full engine power at rated engine
r.p.m. and maximum boat speed. A conventional size
propeller normally limits the r.p.m. during this critical
time, thereby limiting the thrust developed. If the pro-
peller is designed to permit the boat to "go over the hump"
under relatively high load conditions, such as when water
skiers are being towed, it will permit the engine to run
at excessive speeds once the boat is planing and less power
is r~quired to drive the propeller.
This problem could be alleviated by using a pro-
peller having an adjustable pitch; however, many years of
development have failed to produce a practical and
efficient adjustable pitch propeller.
Also, it is desirable for propulsion units used
in racing boats to have a transmission which permits the
boat engine to rapidly turn up to a full speed when
accelerating out of a turn and then shift automatically to
facilitate full speed operation after the boat is planing.

~ 5
SU~ARY O~ T~IE INVENTION -
The invention provides a marine propulsion device
comprising an input shaft drivingly connected to a power
source, a lower unit having a rotatably mounted drive shaft,
a propeller shaft rotatably mounted in the lower unit and
carrying a propeller, means drivingly connecting the drive
shaft to the propeller shaft, and a two-speed transmission
drivingly connecting t'ne input shaft to the drive shaft and
including first drive means between the input shaft and the
drive shaft for selectively drivingly connecting the input
shaft and the drive shaft at all input speeds and including a
drive gear, a driven gear in meshing engagement with the
drive gear, and a one-way overrunning clutch drivingly
connecting the input shaft and the drive shaft through the
drive and driven gears when the rotational speed of the
input shaft is less than a predetermined value, which first
drive means has an input-output speed ratio with a first
valueJ and second drive means for selectively drivingly
connecting the input shaft and the drive shaft when the
rotational speed of the input shaft is greater than the
predetermined value, which second drive means includes a
selectively actuatable clutch for drivingly connecting the
input shat and the drive shaft, and which second drive
means has an input-output speed ratio with a second
value greater than the first value.
In accordance with one embodiment, the input
shaft and the drive shaft are axially offset.
In accordance with one embodiment, the second drive
means includes a second drive gear and a second driven gear
in meshing engagement with the second drive gear.
. ~,. .
. . .
....
, . .
': . .' ' . : ' .' :

In accordance with one embodiment, the second
drive means clutch comprises a centrifugal clutch
inc~uding a drum drivingly connected to one of the
input shaft and the drive shaft and a drive~ drivingly
connected to the other of the input shaft and the
drive shaft and operable in response to driver
rotation above a predetermined speed to effect driving
engagement between the driver and khe drum and therefore
between the input shaft and the drive shaft.
In accordance with one embodiment, the marine
propulsion device further includes a second drive shaft
rotatably mounted in the lower unit and drivingly
connected to the propeller shaft, and means adjacent
the first and second drive means for drivingly connecting
the first mentioned drive shaft to the second drive
shaft for transmissions of power to the propeller shaft
through the first mentioned and second drive shaft.
One of the principal features of the
invention is the provision of a marine propulsion
device including a simple two-speed transmission
which can be conveniently shifted to a higher
gear ratio.
Another of the principal features of the
invention is the provision of a marine propulsion
device including a two-speed transmission which is
arranged to prevent engine overspeeding at full
throttle and maximum speeds of a planing boat.

Another of the principal features of the
invention is the provision of such a marine propulsion
device including such a transmission which automatically
shifts between two different gear ratios at a
predetermined engine speed.
Other features and advantages of the
invention will become apparent upon reviewing the
fol-lowing detailed descriptiGn, the drawing, and
the appended claims.
BRI~F DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevational view,
partially broken away and partially in section,
of an outboard motor embodying various of the
features of the invention.
Fig. 2 is a side elevational view,
partially broken away and partially in section,
of another embodiment of an outboard motor
embodying various of the features of the
invention.
Before explaining preferred embodiments
of the invention in detail, it is to be understood
that the invention is not limited in its application
to the details of construction and the arrangements
of the components set forth in the following description
or iilustrated in the drawings. The invention is
capable of other embodiments and of being practiced
and carried out in various ways. Also, it should be
understood that the phraseology and terminology employed
herein is for the purposes of description and should not be
.
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~ 5
regarded as limiting.
DESCRIPTION OF THE PREFERRED E~IBODIMENTS
-
Illustrated in ~ig. 1 is a marine propulsion
device, such as an outboard motor 10, including a power
S head 12 which houses an internal combustion engine 14 and
a lower unit 16 having a gear box 18. Rotatably mounted
in the gear box 18 is a propeller shaft 20 carrying a pro-
peller 22 on the outer end. Located within the gear box 18
is a pair of facing, axially-spaced gears 24 and 26 which
are carried by and are drivingly connected to the ~ropeller
shaft 20. Extending through the lower unit 16 is a
rotatably mounted drive shaft 28 carrying a lower bevel
gear 30 which meshes with ~he gears 24 and 26. The drive
shaft 28 is drivingly connected to the engine 14 through a
two-speed transmission, designated generally by the reference
numeral 32.
The transmission 32 includes an input shaft 34
which is rotatably mounted such as by a bearing 35 and is
drivingly connected to the engine 14, a first drive gear 36
carried by and mounted for common rotation with the input
shaft 34, and a second drive gear 38 mounted for rotation
coaxially with and independently of the input shaft 34.
The transmission 32 also includes a first driven gear 40
which meshes with the first drive gear 3~ and is mounted for
rotation coaxially with the drive shaft 28 and a second
driven gear 42 which meshes with the second drive gPar 38
and is mounted for common rotation with the drive shaft 28.
For reasons explained below, the gear ratio of the second
drive gear 38 to the second driven gear 42 is greater than
the gear ratio of the first drive gear 36 to the first driven
gear 40.
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.. . , , - " , - ,
- . .. . .. : ~

The first driven gear 40 is drivingly connec~ed
to the drive shaft 28 by a suitable one-way, overrunning
clutch means 44 disposed therebetween. The one-way clutch
means 44 is constructed in the conventional manner so a
detailed description of its structural features and mode
of operation is not necessary for full understanding of
the invention. Generally, the one-way clutch means 44 is
arranged so that, in response to rotation o the first
driven gear 40 via the first drive gear 36 and the input -
shaft 34, it drives the drive shaft 28 in one rotary direc-
tion. Further, the one-way clutch means 44 is arranged so
that, when the rotational speed of the drive shaft 28 in the
one rotary direction exceeds the rotational speed of the
first drive gear 40 in the same rotary direction (i.e., when
the drive shaft 28 overruns the first driven gear 40), the
drive shaft 28 becomes free wheeling relative to the first
driven gear 40.
For example, the one-way clutch means 44 can
include teeth or lugs (not shown) which are drivingly
connected to the first driven gear 40, which are biased
into driving engagement with complementary teeth or lugs
(not shown~ provided on the drive shaft 28, and which are
disengaged from the drive shaft teeth or lugs when over-
running occurs.
Carried on the input shaft 34 is a centrifugal
clutch which is operable, in response to rotation of the in-
put shaft 34 above a predetermined speed, to drivingly
connect the second drive gear 38 to the input sha~t 34.
While various arrangements can be used, in the
specific construction illustrated, there is provided a
centrifugal clutch 46 including a clutch drum ~8 which has
a cylindrical inner surface 50 and is mounted for common
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. .
- . - .. .. . . : , . . . ............. .

rotation with the input sha~t 34. The clutch 46 also has
two or more clutch shoes 52 carried by a clutch shoe driver
54 which is drivingly connected ~o the second drive gear 38
and is mounted for rotation coaxially with and independently
of the input shaft 34. The clutch shoe driver 54 rotates
the clutch shoes 52, in response to rotation o~ the second
drive gear 38, and is arranged in a suitable manner to
cause the clutch shoes 52 to move radially between an inner
or retracted position spaced from the clutch drum 48 and an
outer or extended position in driving engagement with the
clutch drum inner surface 50 when the second drive gear 38
is rotated a~ a speed corresponding to the predetermined
input shaft speed.
The clutch shoes 52 can be constructed in any
suitable manner including an arcuate surface adapted to
drivingly engage the inner surface 50 of the clutch drum 48
when the clutch shoe driver 54 is rotated at a speed cor-
responding to the predetermined input shaft speed. Outward
movement of the clutch shoes 52 from the retracted positlon,
in absence of rotation of the clutch shoe driver above the
predetermined speed, is restrained by a suitable means
(not shown). ~:
In operation, when the input shaft 34 is being
rotated at low or moderate speeds, the drive sha~t 28, and
thus the propeller 22, is driven by the input shaft 34 via
the first drive gear 36, the first driven gear 40, and the ;:
one-way clutch means 44. The second drive gear 38 is also
being driven by the second driven gear 40 at this time but
is free wheeling relative to the input sha~t 34 because the :
clutch shoe driver 54 is being rotated at a speed less
than the predetermined speed at which the clutch shoes 52
are moved radially outwardly to the extended position.
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l~en the engine speed is increased to a point
where the clutch shoe driver 54 is rotated above the
predetermined speed, the clutch shoes 52 drivingly engage
the inner surface 50 of the clutch drum 48 to drivingly
connect the second drive gear 38 to the input shaft 34. -
The second drive gear 38 thereafter drives the second
driven gear 42.
Since the gear ratio between the second drive
gear 38 and the second driven gear 42 is greater than the
gear ratio between the first drive gear 36 and the first
driven gear 40, the drive shaft 28 is rotated at a rate
faster than the rate of rotation of the first driven gear
40, causing the one-way clutch means 44 to disengage so that
the drive shaft 28 is free wheeling reIative to the first
driven gear 40. The drive shaft 28 thereafter is driven
by the input shaft 34 via the centrifugal clutch 46, the
second drive gear 38 and the second driven gear 42.
When the engine speed is decreased to a point
where the rate of rotation of the clutch shoe driver 54 falls
below the predetermined speed, the clutch shoes 52 return
toward the retracted position (i.e., disengage ~rom the
clutch drum 48), thereby disconnecting the second drive
gear 38 from the input shaft 34 and causing a reduction in
the rate of rotation of the drive shaft 28 to a speed where
the one-way clutch means 44 re-engages. The drive shaft 28
thereafter is driven by the input shaft 34 via the first
drive gear 36, the first driven gear 40, and the one-way
clutch means 44.
With this arrangement, a relative large propeller
can be used to develop sufficient thrust to get the boat to
"go over the hump" on the thrust vs. speed curve with large
boat loads or while towing skiers and yet the engine will
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- - . . . .. . . ~ . . :

~ \
not overspeed at ~ull throttle and maximum boat speed after
the boat is planing. That is, the engine 14 can be operated
at a high speed while rotating the propeller 22 at a low
speed via the input shaft 34, the first drive gear 36,
the first driven gear 40, and the one-way clutch means 44,
to develop su~ficient power or thrust to get the boat "over
the hump." Once the boat is planing and less engine power
is required to rotate the propeller 22 at maximum speed,
the transmission 32 shi~ts, via the centrifugal clutch 46,
to the higher gear ratio provided by the second drive gear 38
and the second driven gear 42, thereby preventing the engine
14 from overspeeding at full throttle and maximum boat
speed. Thus, smaller, more economical engines can be used
for carrying heavy loads or towing water skiers, which tasks
normally require larger engines to get the boat "over the
hump" and into planing trim.
Further, the two-speed transmission 32 can be
advantageously used in propulsion units for racing boats. ~
The transmission permits the engine to rapidly turn up to ~;
higher r.p.m.'s while accelerating out of a turn and then
shifts, after the boat is planing, to facilitate top speed
operation. When a centrifugal clutch is employed as in
the embodiment illustrated in Fig. 1, this shifting is
accomplished automatically without any effort on the part
of the driver and higher lap speeds normally can be obtained
for a given engine.
Fig. 2 illustrates another embodiment of the
invention including various components which are constructed
and arranged in a manner similar to the embodiment illus- - -
trated in Fig. 1. Thus, the same reference numerals have
been assigned to common components. -
;- . . .. . , ., . . . . ~. . , . . - : . ,.

The basic difference between the marine pro-
pulsion unit 60 shown in Fig. 2 and the marine propulsion
unit 10 shown in Fig. 1 is that the former employs dual
drive shafts instead of a single drive shaft. The use of
dual drive shafts affords the use of smaller drive gears
to impart the same power to the propeller and ~hus less
frontal area for the gear case 18 and/or smaller size of
the portion of the housing enclosing the upper end of the
drive shafts.
Located within the gear box 18 and dri~ingly
connected to the propeller sha~t 20 are a pair of bevel
gears 62 which can be a unitary element as illustrated or
separate gears. Extending through the lower unit 16 is a
first rotatably mounted drive shaft 64 which is similar to
the drive shaft 28 in Fig. 1 and carries a lower bevel
gear 66 which meshes with one of the gears 62. Extending
through the lower unit 16 in parallel relationship to the
first drive shaft 64 in a second rotatably mounted drive
shaft 68 carrying a lower bevel gear 70 which meshes with
the other of the gears 62. The first and second drive
shafts 64 and 68 are drivingly connected to the engine by
a two-speed transmission 32a which is constructed and
operates in the same basic manner as the transmission 32
in Fig. 1, except that the second driven gear 42a, in addi-
tion to meshing with the second drive gear 38, also meshes
with a third driven gear 72 mounted on the upper end of the
second drive shaft 68 for common rotation therewith.
In operation, when the input shaft 34 is being
rotated at low or moderate speeds, the first drive shaft 64
is driven by the input shaft 34 via the first drive gear 36,
the first driven gear 40, and the one-way clutch means 44.
The second drive shaft 68 is driven by the input shaft 34

via the first drive gear 36, the first driven gear 40, the
one-way clutch means 44, the second driven gear 42a and the
third driven gear 72 to effect counter rotation of the drive
shafts 64 and 68 and the gears 66 and 70. The second
drive gear 38 is also being driven by the second driven gear
42a at the same time but is free wheeling relative to the
input shaft 34 because the clutch shoe driver 54 is being
rotated at a speed less than the speed at which the clutch
shoes 52 are moved radially outwardly to an extended position.
When the engine speed is increased to a point
where the clutch shoe driver 54 is rotated above the pre-
determined speed, the clutch shoes 52 engage the clutch
drum 48 to drivingly connect the second drive gear 38 to
the input shaft 34, causing the transmission 32a to shift ~ .
as described above. The drive shafts 64 and 68 thereafter
are driven by the input shaft 34 via the centrifugal clutch .
46, the second drive gear 38 and the respec~ive second :
driven gear 42a and third driven gear 72. When the engine
speed is decreased, the transmission shifts back to the
lower gear ratio as described above. :~
While a centrifugal clutch has been illustrated
and described, and generally is preferred because automatic
shifting is afforded, it is within the scope of the invention
to employ a suitable manually shiftable clutch for selectively . :~.
connecting the second driven gear 38 to the input shaft 34.
Although the two-speed transmission of ~he invention has
been described for use on an outboard motor, it should be
understood that it can be used in other marine propulsion ~
devices, such as stern drive units, and in other similar .
applications. .
Further, while the transmission has been illustrated
and described as being located in the powerhead, immediately
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below the engine and above the drive shaft and on ~he
top of the drive shaft housing, it can be located in
the lower unit above the gear box, such as in the lower
end portion of the drive shaft housing connected to
the gear box.
Various of the features of the inventlon are
set forth in the following claims:
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