U.S. patent application number 09/894665 was filed with the patent office on 2003-01-09 for epicyclic gear system.
Invention is credited to Fox, Gerald.
Application Number | 20030008748 09/894665 |
Document ID | / |
Family ID | 25403364 |
Filed Date | 2003-01-09 |
United States Patent
Application |
20030008748 |
Kind Code |
A1 |
Fox, Gerald |
January 9, 2003 |
Epicyclic gear system
Abstract
An epicyclic gear system has a sun gear, a ring gear located
around the sun gear, and planet gears located between and engaged
with sun and ring gears. In addition, it has a carrier including a
carrier flange offset axially from the planet gears, carrier pins
projecting from the carrier flange into the planet gears, and
bearings between the planet gears and the carrier pins so that the
planet gears rotate on the pins. Each bearing includes an inner
race having tapered raceways presented away from the carrier pin,
opposing tapered raceways on the ring gear, and tapered rollers
organized in two rows between the raceways. Whereas the carrier pin
is cantilevered from the carrier flange, the inner race is
cantilevered from the carrier pin remote from the carrier flange,
and this insures that the axes about which the planet gears rotate
remain parallel to the central axis of the system.
Inventors: |
Fox, Gerald; (Massilon,
OH) |
Correspondence
Address: |
POLSTER, LIEDER, WOODRUFF & LUCCHESI
763 SOUTH NEW BALLAS ROAD
ST. LOUIS
MO
63141-8750
US
|
Family ID: |
25403364 |
Appl. No.: |
09/894665 |
Filed: |
June 28, 2001 |
Current U.S.
Class: |
475/346 |
Current CPC
Class: |
F16C 2240/84 20130101;
F16H 1/2836 20130101; F16C 27/04 20130101; F16C 2361/61 20130101;
F16C 19/386 20130101; F16C 33/586 20130101; F16C 33/605 20130101;
F16H 1/48 20130101; F16H 57/082 20130101 |
Class at
Publication: |
475/346 |
International
Class: |
F16H 057/08 |
Claims
What is claimed is:
1. An epicyclic gear system comprising: a sun gear located along a
central axis; a ring gear located around the sun gear and sharing
the central axis with the sun gear; at least one planet gear
located between and engaged with the sun and ring gears for
rotation about an offset axis, the planet gear having a raceway
that is presented toward the offset axis; and a carrier coupled to
the planet gear and including a carrier flange, a carrier pin
projecting from the flange into the planet gear, an inner race
attached to the carrier pin remote from the carrier flange and also
located within the ring gear where it has a raceway presented
outwardly away from the offset axis and toward the raceway carried
by the ring gear, and rolling elements located in a row between and
contacting the raceways on the ring gear and inner race.
2. A gear system according to claim 1 wherein the carrier pin is
cantilevered from the carrier flange, and the inner race is
cantilevered from the carrier pin at a location remote from the
carrier flange.
3. A gear system according to claim 2 wherein the inner race
includes a sleeve which surrounds, but is spaced from the carrier
pin, and an end wall connected to the sleeve at one end of the
sleeve; wherein the raceway for the inner race is on the sleeve;
and wherein the carrier pin is connected to the inner race at the
end wall of the inner race.
4. A gear system according to claim 3 wherein the end wall and the
sleeve are formed integral.
5. A gear system according to claim 4 wherein the carrier pin and
the end wall of the inner race are formed integral.
6. A gear system according to claim 3 wherein the raceway on the
planet gear is one of two outer raceways which are located oblique
to the offset axis and are inclined in opposite directions; wherein
the raceway on the inner race is one of two inner raceways that are
oriented oblique to the offset axis and inclined in opposite
directions, one of the inner raceways being located within and
inclined in the same direction as one of the outer raceways and the
other inner raceway being located within and inclined in the same
direction as the other outer raceway; and wherein the rolling
elements are arranged in two rows between the outer and inner
raceways.
7. A gear system according to claim 6 wherein the raceways are
tapered; wherein the rolling elements are tapered rollers; wherein
the sleeve of the inner race has thrust ribs at the large ends of
the tapered inner raceways; and wherein one of the thrust ribs fits
over the inner race as an initially separate component.
8. In an epicyclic gear system including a sun gear located along a
central axis, a ring gear located around the sun gear and sharing
the central axis; planet gears located between and engaged with the
sun and ring gears for rotation about offset axes that are located
around the central axis; a carrier coupled with the planet gears
and including a carrier flange offset axially from the planet
gears, carrier pins cantilevered from the carrier flange and
projected into the planet gears along the offset axes, there being
a separate carrier pin for each planet gear, an inner race
cantilevered from each carrier pin remote from the carrier flange
and located within the planet gear into which the pin projects, a
first inner raceway carried by each inner race and presented
outwardly away from the offset axes for that inner race, a first
outer raceway carried by the planet gear that is located around the
carrier pin and presented inwardly toward the offset axes and
toward the first inner raceway on the inner race; and rolling
elements located between and contacting the first raceways.
9. The combination according to claim 8 and further comprising a
second inner raceway carried by the inner race around each carrier
pin and presented outwardly away from the offset axes for that
carrier pin, a second outer raceway carried by the planet gear that
is around the carrier pin and presented inwardly toward the offset
axes and the second inner raceway; and wherein the rolling elements
are arranged in two rows, with one row being between the first
inner and outer raceways and the other row being between the second
inner and outer raceways.
10. The combination according to claim 9 wherein the raceways are
oblique to the offset axes; and wherein the first inner and outer
raceways are inclined in the same direction and the second inner
and outer raceways are inclined in the same direction, which
direction is opposite to the direction of inclination of the first
raceways, whereby the rolling elements in the row between the first
raceways will transfer thrust loads in one axial direction and the
rolling elements in the row between the second raceways will
transfer thrust loads in the opposite axial direction.
11. The combination according to claim 10 wherein the raceways are
tapered and the rolling elements are tapered rollers.
12. The combination according to claim 11 wherein the first and
second raceways taper inwardly toward each other so that the large
ends of the rollers in the row between the first raceways are
presented away from the large ends of the rollers in the row
between the second raceways.
13. The combination according to claim 12 wherein the inner race
has thrust ribs at the large ends of the inner raceways; and
wherein one of the thrust ribs is a rib ring formed as a separate
component that is installed on the inner race after the rollers are
placed between the planet gear and the inner race.
14. The combination according to claim 10 wherein inner race
includes a sleeve on which the inner raceways are located and an
end wall at one end of the sleeve; the end wall being attached
firmly to the carrier pin remote from the carrier flange with the
sleeve surrounding, but being spaced from the carrier pin.
15. In an epicyclic gear system having a central axis and a planet
gear that rotates about an offset axis that is offset radially from
the central axis, the improvement comprising: a carrier flange
located beyond one end of the planet gear, a carrier pin projecting
from the carrier flange into the planet gear such that it is
cantilevered from the carrier flange; and a bearing located between
the carrier pin and the planet gear for coupling the planet gear to
the carrier flange and enabling the planet gear to rotate about the
offset axis, the bearing including an inner race which is attached
to the carrier pin remote from the carrier flange and includes a
sleeve which surrounds the carrier pin, yet is spaced from the pin,
the sleeve having a first raceway that is presented outwardly away
from the offset axis for the planet gear, the bearing also
including a first outer raceway that is carried by the planet gear
and is presented inwardly toward the offset axis and the first
inner raceway, the bearing further including rolling elements
arranged in a row between the first inner and outer raceways.
16. The combination according to claim 15 wherein the inner race
also includes an end wall extended between the sleeve and the
carrier pin and attached firmly to the pin remote from the carrier,
whereby the inner race is cantilevered from the carrier pin.
17. The combination according to claim 15 wherein the first inner
and outer raceways are inclined in the same direction with respect
to the offset axis; wherein the inner race has a second inner
raceway that is presented outwardly away from the offset axis and
is inclined with respect to the offset axis in a direction opposite
the inclination of the first raceways, and the bearing also
includes a second outer raceway carried by the planet gear and
presented inwardly toward the second inner raceway and inclined
with respect to the offset axis in the same direction as the second
inner raceway; and wherein the rolling elements are organized in
first and second rows, the rolling elements of the first row being
between the first raceways and the rolling elements of the second
row being between the second raceways.
18. The combination according to claim 17 wherein the raceways are
tapered and the rolling elements are tapered rollers; wherein the
inner race has a thrust rib at the large end of the first inner
raceway with the rib projecting beyond the first inner raceway, the
large ends of the rollers in the first row being against the thrust
rib, and the inner race also has a mounting surface at the large
end of the second inner raceway with the mounting surface having a
diameter no greater than the diameter of the large end of the
second inner raceway, and wherein an initially separate rib ring is
located around the mounting surface on the inner race and projects
outwardly beyond the large end of the second inner raceway, the
large ends of the tapered rollers in the second row being against
the rib ring.
19. The combination according to claim 18 wherein the inner race
also includes an end wall extended between the sleeve and the
carrier pin and attached firmly to the carrier pin remote from the
carrier flange, whereby the inner race is cantilevered from the
carrier pin.
20. The combination according to claim 19 wherein the end wall and
sleeve of the inner race are integral.
21. In an epicyclic gear system having a central axis and a planet
gear offset radially from the central axis where it is located
between and engaged with other gears, the improvement comprising: a
carrier flange located beyond one end of the planet gear; a carrier
pin projecting from the carrier flange into the planet gear, the
carrier pin being offset from the central axis and cantilevered
from the carrier flange; an inner race attached to the pin remote
from the carrier flange such that the inner race is cantilevered
from the pin, the inner race having an inner raceway that is
presented outwardly away from the carrier pin; an outer raceway
carried by the planet gear and presented toward the inner raceway
on the inner race; and rolling elements located in a row between
and contacting the inner and outer raceways.
22. The combination according to claim 21 wherein the inner race
includes a sleeve which surrounds the carrier pin and carries the
inner raceway, yet is spaced from the pin, and an end wall at one
end of the sleeve, with the inner race being attached to the
carrier pin at the end wall.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] None
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] None
BACKGROUND OF THE INVENTION
[0003] This invention relates in general to gear systems and, more
particularly, to an epicyclic gear system.
[0004] The typical epicyclic or planetary gear system basically has
a sun gear provided with external teeth, a ring gear provided with
internal teeth, and several planet gears located between the sun
and ring gears and having external teeth which mesh with the teeth
on the sun and ring gears. In addition to its gears, the typical
system has a carrier to which the planet gears are coupled. Either
the sun gear, the ring gear, or the carrier is held fast, while
power is delivered to and taken from the remaining two components,
and thus power is transferred through the planetary system with a
change in angular velocity and an inverse change torque.
[0005] The sun and ring gears for all intents and purposes share
the same axis, a central axis, while the planet gears revolve about
radially offset axes that are parallel to the central axis--or at
least they should. Often the offset axes and the central axis are
not parallel, and as a consequence the planet gears skew slightly
between sun and ring gears. This causes excessive wear along the
teeth of the planet, sun and ring gears, generates friction and
heat, and renders the entire system overly noisy.
[0006] The problem certainly exists in straddle carriers. With this
type of carrier the pins on which the planet gears rotate extend
between two carrier flanges in which the pins are anchored at their
ends. The carrier experiences torsional wind up which causes one
carrier flange to rotate slightly ahead of the other flange. Not
only does this skew the pin for each of the planet gears such that
one end lies circumferentially ahead of the other, but it also
causes the leading end of the pin to dip toward the central axis
and the other end to draw away from the central axis. The end
result is a poor mesh between the planet gears and the sun and ring
gears, and of course the friction, wear and noise associated with
poorly meshed gears. To counteract this tendency, some planetary
systems rely on gears that are wider than necessary and thus offer
greater tolerance to skewing along the gear contact. But these
systems can occupy excessive space and can be quite heavy.
[0007] Other transmissions rely on a double cantilever arrangement
at the pins for their planetary gears to maintain the planet gears
and the sun and ring gears properly meshed. In this arrangement the
carrier has a single carrier flange located beyond the ends of the
planet gears, and the carrier pins project from that flange into,
and indeed through, the gears. Each carrier pin has one end
anchored in the carrier flange and its other end anchored in a
sleeve which turns back over the pin to support the planet gear.
U.S. Pat. No. 3,303,713 to R. J. Hicks shows a double cantilevered
arrangement. Often an antifriction bearing is fitted between the
sleeve and the planet gear. But antifriction bearings consume
space, making the planet gears excessively large in diameter, which
in turn makes the entire gear system too large and heavy.
SUMMARY OF THE INVENTION
[0008] The present invention resides in an epicyclic gear system
that has a sun gear, a ring gear around the sun gear and at least
one planet gear located between and engaged with the sun and ring
gears. A carrier flange is offset axially from the planet gear and
a carrier pin projects from it into the planet gear. An inner race
is attached to the carrier pin remote from the carrier flange, and
it has a raceway which is presented toward a raceway carried by the
planet gear. Rolling elements are organized in a row between the
opposed raceways to enable the planet gear to revolve about the
carrier pin. The invention also resides in a carrier and bearing
for such a gear system.
DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is an exploded perspective view of an epicyclic gear
system constructed in accordance with and embodying the present
invention;
[0010] FIG. 2 is a sectional view of the gear system at one of its
planet gears and showing the coupling between the planet gear and
the carrier; and
[0011] FIG. 3 is a sectional view of the gear system similar to the
system of FIG. 2, but showing a modified coupling.
DETAILED DESCRIPTION OF INVENTION
[0012] Referring now to the drawings, a planetary transmission A
(FIG. 1), which is actually an epicyclic gear system, has the
capacity to transmit power of considerable magnitude, given its
size and weight. In short, it has a high power density. In contrast
to some planetary transmissions, the transmission A relies on
meshing gears that are quite narrow, yet the teeth of those gears
remain properly meshed, even when transmitting substantial power
and torque. The transmission A has a central axis X of rotation
about which torque is transferred to the transmission A and
delivered from it. The transmission A basically includes a sun gear
2 having its axis coincident with the central axis X, a ring gear 4
which surrounds the sun gear 2 and shares the axis X with it, and
planet gears 6 which mesh with and rotate between the sun and ring
gears 2 and 4 about axes Y that are offset radially from, yet
parallel to, the central axis X. In addition, the transmission A
has a carrier 8 to which the planet gears 6 are coupled, and the
carrier 8 likewise shares the axis X.
[0013] Referring more specifically to the sun gear 2, it is
attached to a shaft 12 or some other supporting structure with
which it normally rotates, but it may be fixed against rotation in
some installations. The sun gear 2 has external teeth 14 which are
presented outwardly away from the axis X.
[0014] The ring gear 4 is typically fixed, and thus does not
rotate, although it may rotate in some installations. In any event,
the ring gear 4 has internal teeth 18 which are presented inwardly
toward the axis X and toward the external teeth 14 on the sun gear
2 and lie concentric with them. The ring gear 4 may be part of or
integrated into a housing for the transmission A.
[0015] An annular space exists between the sun and ring gears 2 and
4, and the planet gears 6 occupy that space. Each has external
teeth 22 which mesh with the external teeth 14 or the sun gear 2
and the internal teeth 18 on the ring gear 4. Thus, when the sun
gear 2 rotates relative to the ring gear 4 about the axis X or vice
versa, the planet gears 6 will revolve, each about its offset axis
Y that lies parallel to the central axis X. The planetary gears 6
are hollow, with each having two raceways 24 (FIG. 2) which taper
downwardly to an intervening surface 26 located midway between the
ends of the gear 6. The large ends of the raceways 24 for each
planet gear 6 open out of the ends of the gear 6.
[0016] The carrier 8 includes (FIG. 1) a carrier flange 30 to which
all of the planet gears 6 are coupled, it being offset axially
beyond corresponding ends on each of the gears 6. Normally, the
carrier 8 rotates about the axis X, although it may remain fixed in
some installations. When the carrier 6 rotates, it is usually
coupled to a shaft 32 that lies along the axis X. In addition to
the carrier flange 30, the carrier 6 has carrier pins 34 which
project from the flange 30 into the planet gears 6, their axes
generally corresponding to the axes Y of rotation for the planet
gears 6.
[0017] More specifically, the carrier flange 30 opposite each
planet gear 6 has a tapered hole 36 (FIG. 2). The carrier pins 34,
on the other hand, have tapered surfaces 38 which lead out to
threaded ends 40. The tapered surfaces 38 conform in configuration
to the tapered holes 36 in the flange 30 and indeed fit snugly into
the tapered holes 36 so that the pins 34 project from the face of
the carrier flange 30 that is presented toward the planet gears 6.
The threaded ends 40 project beyond the other face of the carrier
flange 30 where they are engaged by nuts 42 which are turned down
snugly against that face. This lodges the carrier pins 34 at their
tapered surfaces 38 firmly in the carrier flange 30. Thus, each pin
34 is, in effect, cantilevered from the carrier flange 30.
[0018] Each carrier pin 34 projects through its planet gear 6, and
at the opposite end of the gear 6, that is the end remote from the
carrier flange 30, is fitted to an inner race 46 which the planet
gear 6 also encircles. The inner race 46 has an end wall 48 and a
sleeve 50 formed integral with the end wall 48. Indeed, the sleeve
50 turns backwardly from the end wall 48 into the interior of the
gear 6 and thus encircles the carrier pin 34. The end wall contains
a bore 52 into which the end of the carrier pin 34 fits with an
interference fit. At its very end the carrier pin 34 is joined to
the end wall 48 along a weld 54. Thus, the interference fit
together with the weld 54 secure the inner race 46 firmly to the
carrier pin 34. The interior surface of the sleeve 50 is somewhat
larger than the carrier pin 34, and as a consequence the inner race
46 at its end wall 48 is cantilevered from the remote end of the
carrier pin 34.
[0019] The sleeve 50 of the inner race 46 lies within the interior
of the planet gear 6 and has two tapered raceways 56 which taper
downwardly to a separating rib 58. The raceways 56, which have
their centers along the axis Y, are presented outwardly away from
the axis Y and toward the raceways 24 on the gear 6, each raceway
56 on the inner race 46 being opposite one of the raceways 24 on
the gear 6. On the other hand, the separating rib 58 lies opposite
the intervening surface 26 of the gear 6. Each raceway 56 on the
inner race 46 tapers in the same direction as the raceway 24 toward
which it is presented on the planet gear 6. The raceway 56 closest
to the carrier flange 30 leads out to a thrust rib 60 that is
formed integral with the sleeve 50 of the inner race 26. The other
raceway 56 leads out to a cylindrical mounting surface 62 that
surrounds the end wall 48. The mounting surface 62 has a rib ring
64 fitted to it with an interference fit and further secured with a
weld 66 at its end. The rib ring 64 extends axially from the weld
66 to the large end of the tapered raceway 56, so the rib ring 64
forms another thrust rib, similar function to the rib 60 at the end
of the inner race 46 that is remote from the carrier flange 30.
[0020] The annular region between each planet gear 6 and inner race
46 that the gear 6 surrounds is occupied by rolling elements in the
form of tapered rollers 70 organized into two rows. One row lies
along the integral thrust rib 60 that is adjacent to the carrier
flange 30 and contacts the opposed raceways 24 and 56 at that end,
while the other row lies along the rib ring 64 that surrounds the
end wall 48 of the inner race 46 and contacts the raceways 24 and
56 at that end. Indeed, the tapered rollers 70 contact the raceways
24 and 56 along their tapered side faces, there being generally
line contact here. They also bear against the thrust rib 60 and rib
ring 64 at their large end faces. The thrust rib 60 and rib ring 64
prevent the rollers 70 from moving up the raceways 24 and 56 and
being expelled from the annular region between the planet gear 6
and the inner race 46. The rollers 70 of each row are on apex,
meaning that the conical envelopes in which the side faces of the
rollers 70 of a row lie will have their apices located at a common
point along the axis Y. This produces pure rolling contact between
the side faces of the rollers 70 and the raceways 24 and 56. While
the rollers 70 of each row may be separated with a cage, preferably
they are not so confined. This enables each row to contain the
maximum number of rollers 70.
[0021] The rollers 70 together with the inner race 46 and the
raceways 24 on the planet gear 6 form a double row tapered roller
bearing 72 that couples the planet gear 6 to the carrier pin 34
about which the gear 6 rotates. Indeed, the bearing 72 has the
capacity to facilitate rotation of the planet gear 6 about the axis
Y with minimal friction, while confining the gear 6 radially and
axially on the carrier pin 34. In other words, the bearing 72 takes
thrust loading in both axial directions. Moreover, the bearing 72
is set to a condition of light preload, and as a consequence no
axial or radial clearances exist within it. This enables the gear 6
to rotate on the carrier pin 34 without axial or radial free motion
and without wobbling.
[0022] The carrier pins 34 possess a measure of flexibly and indeed
will flex well within their elastic limits when torque is
transferred through the planet gears 6. The double cantilever
arrangement enables the axes Y to remain parallel to the axis X,
and hence the planet gears 6 remain properly meshed with the sun
and ring gears 2 and 4. Thus, the planet gears 6, and likewise the
sun and ring gears 2 and 4, need not be excessively wide to account
for off-center gear contact.
[0023] To assemble the carrier 8, each carrier pin 34 at its
cylindrical end is forced into the bore 52 in the carrier flange 48
of the inner race 46 for that pin 34. Then the carrier pin 34 at
its end is welded to the end wall 48, producing the weld 54.
Thereupon, the rollers 70 for the row remote from the end wall 48
are placed along the raceway 56 that leads up to the thrust rib 60,
with the large end faces of those rollers being 70 against the rib
60. Next the planet gear 6 is installed over the inner race 46 and
the row of rollers 70 on that race 46. The leading raceway 24 in
the gear 6 seats against the side faces of those tapered rollers
70. This leaves an annular void between the raceways 24 and 56 at
the opposite end planet gear 6. More rollers 70 are inserted into
this void with their small ends leading, thus creating a second row
of rollers 70 having their large ends located along the end of the
mounting surface 62 for inner race 46. With the gear 6 and the two
rows of rollers 70 in place around the inner race 46, the rib ring
64 is forced over the mounting surface 62 on the inner race 46, and
advanced toward the large ends of the rollers 70 that are at the
mounting surface 62. As the rib ring 64 approaches the large end
faces of the rollers 70, the gear 6 is rotated to insure that the
rollers 70 of the two rows seat against the raceways 24 and 56 and
along the thrust rib 60 and rib ring 64. After the rib ring 64
comes against the large end faces of the rollers 70 in the row that
is along it, the bearing 72 will enter preload. The advance
continues a short distance until the bearing 72 acquires the proper
preload. Then the rib ring 64 is welded to the inner race 46,
producing the weld 66. The gear 6, rollers 70, inner race 46 and
carrier pin 34 34 constitute a subassembly 76, and enough
subassemblies 76 are produced in the foregoing manner to complete
the carrier 8.
[0024] Within each subassembly 76 the tapered surface 38 of the
carrier pin 34 extends beyond the open end of the sleeve 50 for the
inner race 46 and beyond the corresponding end of the planet gear 6
as well. The tapered surface 38 of the carrier pin 34 is inserted
into one of the tapered holes 36 of the carrier flange 30,
whereupon one of the nuts 42 is engaged with the threaded end 40
that projects out of the flange 30. The nut 42 is turned down
firmly against the carrier flange 30 to draw the tapered surface 38
of the carrier pin 34 snugly into the tapered hole 36. This secures
the carrier pin 34 and inner race 46 firmly to the carrier flange
30. The remaining subassemblies 76 are installed on the carrier
flange 30 in a like manner.
[0025] With the carrier 8 so assembled, it is installed over the
sun gear 2 and into the ring gear 4 such that the external teeth 22
on the planet gears 6 engage the external teeth 14 in the sun gear
2 and the internal teeth 18 on the ring gear 4.
[0026] When torque is applied to the shaft 12 to rotate the sun
gear 2, the planet gears 6 revolve and move along the ring gear 4,
thus imparting rotation to the carrier 8 and the shaft 32 extended
from it. The angular velocities of the two shafts 12 and 32 differ
and with that difference a change in the torque ensues. Of course,
the torque may be applied to the shaft 32 and taken from the shaft
12. Actually, any one of the sun gear 2, ring gear 4 and carrier 8
may be held fast and torque delivered to and taken from the
remaining two components.
[0027] In a modified subassembly 78 (FIG. 3) the carrier pin 34 is
formed integral with the inner race 46.
[0028] The cantilever of the carrier pins 34 from the carrier
flange 30 and the cantilever of the inner races 46 from the carrier
pins 34, that is the so-called "double cantilever", insures that
the axes Y of rotation for the ring gears 6 remain parallel to the
center axis X. As a consequence, the ring gears 6 do not require
excessive width to resist skewing. The inner races 46, being
mounted directly on the carrier pins 34, instead of on intervening
components, together with the integration of the outer raceways 24
into the planet gears 6, enables the bearings 72 to be of a
diameter that is smaller than the diameters of bearings in more
conventional epicyclic gear systems. This, in turn, can permit use
of smaller sun and ring gears 2 and 4, and otherwise render the
entire transmission highly compact and light in weight.
[0029] In lieu of a double row tapered roller bearing 70, each
planet gear 6 may be coupled to its carrier pin 34 on the carrier 8
with a double row angular contact ball bearing or even with a
cylindrical or spherical roller bearing. Also, more or less than
four planet gears 6 may be used between the sun gear 2 and ring
gear 4.
1 EPICYCLIC GEAR SYSTEM A transmission X axis Y axes 2 sun gear 4
ring gear 6 planet gears 8 carrier 12 shaft 14 external teeth 18
internal teeth 22 external teeth 24 raceways 26 intervening surface
30 carrier flange 32 shaft 34 carrier pins 36 tapered hole 38
tapered surface 40 threaded ends 42 nut 46 inner race 48 end wall
50 sleeve 52 bore 54 weld 56 tapered raceway 58 separating member
60 thrust rib 62 mounting surface 64 rib ring 66 weld 70 tapered
rollers 72 bearing 76 subassembly 78 subassembly
* * * * *