SINGLE SHAFT SHIFTING MECHANISM
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to single shaft shifting mechanisms for
change-gear transmissions or transmission sections of the type wherein a
selected one of three or more selectable gear ratios are engaged and/or
disengaged by the axial movement of gears or gear-engaging jaw clutch
members. In particular, the present invention relates to single shaft shifting
mechanisms of the type described wherein radially extending pins are utilized
to provide at least one of the shifting or interlocking functions.
Description of the Prior Art
Single shaft shifting mechanisms for selecting and engaging or
disengaging the selectable ratios of a multiple-speed vehicular mechanical
transmission are known in the prior art, as may be seen by reference to U.S.
Pats. No. 4,621,537; 4,920,815; 5,285,694 and 5,297,453, the disclosures
of which are incorporated herein by reference. Such mechanisms, in certain
situations, are improvements relative to the multiple parallel shift rail-type
devices as disclosed in U.S. Pats. No. 4,445,393; 4,275,612; 4,584,895
and 4,722,237, the disclosures of which are incorporated herein by
reference, as they require fewer parts, utilize a single moving shaft, making
use of the improved bearings and finishes more economically feasible,
require less space, allow easier control of an auxiliary transmission and/or
allow easier, more economical sensing of transmission neutral and
transmission in-gear conditions.
While the prior art single shaft shifting mechanisms, especially the
type illustrated in aforementioned U.S. Pat. No. 4,920,815, are
improvements over the prior art and commercially successful, they are not
totally satisfactory, as the shifting and interlocking functions require the use
of a shift key and an interlock key, each key received in a separate axially
extending groove or keyway in the surface of the shift shaft. The use of
such keys and keyways resulted in an elevation of the complication and
expense of the shifting mechanism. The keyways or grooves run the length
of the shaft, which is a long machining operation; the keyways and the
depth thereof often resulted in distortion of the shaft after heat treatment,
requiring additional processing and/or stress cracks in the corners of the
keyways. The keys tended to be difficult and/or costly to produce and often
required additional processing after heat treatment. To avoid requiring a
squared-off shift pattern, the corners of the shift key radial extensions might
require rounding off of the corners thereof.
SUMMARY OF THE INVENTION
In accordance with the present invention, the drawbacks of the prior
art are minimized or overcome by the provision of a single shaft shifting
mechanism which is easier and less expensive to produce. The foregoing is
accomplished by utilizing radially extending pins, preferably generally annular
pins to minimize the requirement for a squared-off shift pattern, received in
radially extending bores in the shaft, shift yoke hubs and/or housing to
replace one or both of the shift key and keyway or interlock key and
keyway.
Accordingly, it is an object of the present invention to provide an
improved single shaft shifting mechanism.
This and other objects and advantages of the present invention will
become apparent from a reading of the following description of the preferred
embodiment taken in connection with the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic illustration of a compound transmission having
a range-type auxiliary section and utilizing the single shaft shifting
mechanism of the present invention.
Fig. 1A is schematic illustration of the shifting mechanism of the
transmission of Fig. 1.
Fig. 1B is a schematic illustration of the shift pattern of the
transmission of Fig. 1.
Fig. 2 is a schematic illustration of a compound transmission of the
automatic range-shift type utilizing the shifting mechanism of the present
invention.
Fig. 2A is a schematic illustration of the shift pattern and typical ratio
steps for the transmission of Fig. 2.
Fig. 3 is a top view of the prior art single shift shaft and shift yoke
assembly.
Figs. 3A and 3B are top views of the shift key and interlock key,
respectively, used in the prior art assembly of Fig. 3.
Fig. 3C is a front view of a shift yoke hub portion utilized in the prior
art assembly of Fig. 3.
Figs. 4 is a matrix showing the positions of the shaft and keys of the
prior art assembly of Fig. 3 for each selection position thereof.
Fig. 5 is a top view of a preferred embodiment of the single shift shaft
shifting mechanism of the present invention.
Fig. 5A is a side view of the shifting mechanism of Fig. 5.
Fig. 5B is a top view of the shaft assembly of the mechanism of
Fig. 5.
Fig. 5C is a top view of a shift pin used in the assembly of Fig. 5.
Fig. 6 is a matrix, similar to Fig. 4. showing the assembly of Fig. 5 in
each selection position thereof.
Fig. 7 is a top view of an alternate embodiment of the present
invention.
Fig. 7A is a top view of the shift pin used in the assembly of Fig. 7.
Fig. 8 is a top view of another alternate embodiment of the present
invention.
Fig. 8A is a top view of the shift pin used in the assembly of Fig. 8.
Figs. 9A and 9B are illustrations of alternate hub constructions for the
preferred embodiment of Figs. 5 through 8.
Fig. 10 illustrates an alternate embodiment of the present invention in
which pins are utilized to replace the interlock key and the shift key.
Fig. 11 is a matrix, similar to Fig. 6, of the position of the shaft, shift
pins and interlock key of the embodiment of Fig. 10 for each selection
position.
Fig. 12 is a matrix, similar to Fig. 11, for the embodiment of Fig. 10
as utilized with the automatic range-shift transmission of Figs. 2 and 2A.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Certain terminology will be used in the following description for
convenience in reference only and will not be limiting. The words
"upwardly," "downwardly," "rightwardly" and "leftwardly" will designate
directions in the drawings to which reference is made. The words "forward"
and "rearward" will refer to the front and rear ends, respectively, of the
transmission as conventionally mounted in a vehicle, being respectively from
the left and right sides of the transmission as illustrated in Fig. 1. The words
"inwardly" and "outwardly" will refer to directions toward and away from,
respectively, the geometric center of the device and designated parts
thereof. Said terminology will include the words above specifically
mentioned, derivatives thereof and words of similar import.
The term "compound transmission" is used to designate a change-
speed or change-gear transmission having a multiple-forward-speed main
transmission section and a multiple-speed auxiliary transmission section
connected in series whereby the selected gear reduction in the main
transmission section may be compounded by further selected gear reduction
in the auxiliary transmission section. "Synchronized clutch assembly" and
words of similar import shall designate a clutch assembly utilized to non-
rotatably couple a selected gear to a shaft by means of a positive clutch in
which attempted engagement of said clutch is prevented until the members
of the clutch are at substantially synchronous rotation in a relatively large-
capacity friction means are utilized with the clutch members and are
sufficient, upon initiation of a clutch engagement, to cause the clutch
members and all members rotating therewith to rotate at substantially
synchronous speed.
The term transmission as used herein shall refer to either a simple
transmission or to the main transmission section of a compound
transmission.
Referring to Figs. 1, 1A and 1B, a prior art range-type compound
transmission 10 with which the shifting mechanism of the present invention
is advantageously utilized, is illustrated. Compound transmission 10
comprises a multiple-speed main transmission section 12 connected in series
with a range-type auxiliary section 14. Transmission 10 is housed within a
housing H and includes an input shaft 16 driven by a prime mover, such as
diesel engine E, through a selectively disengaged, normally engaged friction
master clutch C having an input or driving portion 18 drivingly connected to
the engine crankshaft 20 and a driven portion 22 rotatably fixed to the
transmission input shaft 16.
In main transmission section 12, the input shaft 16 carries an input
gear 24 for simultaneously driving a plurality of substantially identical
countershaft assemblies 26 and 26A at substantially identical rotational
speeds. The two substantially identical countershaft assemblies are
provided on diametrically opposite sides of mainshaft 28, which is generally
coaxially aligned with the input shaft 16. Each of the countershaft
assemblies comprises a countershaft 3C supported by bearings 32 and 34
in housing H, only a portion of which is schematically illustrated. Each of
the countershafts is provided with an identical grouping of countershaft
gears 38, 40, 42, 44, 46 and 48, fixed for rotation therewith. A plurality of
mainshaft gears 50, 52, 54, 56 and 58 surround the mainshaft 28 and are
selectively clutchable, one at a time, to the mainshaft 28 for rotation
therewith by sliding clutch collars 60, 62 and 64, as is well known in the
prior art. Clutch collar 60 may also be utilized to clutch input gear 24 to
mainshaft 28 to provide a direct drive relationship between input shaft 16
and mainshaft 28.
Typically, clutch collars 60, 62 and 64 are axially positioned by means
of shift forks (also called shift yokes! 60A, 62A and 64A, respectively,
associated with the shift housing assembly 70, as well known in the prior
art. Clutch collars 60, 62 and 64 may be of the well known acting
synchronized or non-synchronized double acting jaw clutch type.
Mainshaft gear 58 is the reverse gear and is in continuous meshing
engagement with countershaft gears 48 by means of conventional
intermediate idler gears (not shown). It should also be noted that while main
transmission section 12 does provide five selectable forward speed ratios,
the lowest forward speed ratio, namely that provided by drivingly connecting
mainshaft drive gear 56 to mainshaft 28, is often of such a high gear
reduction it has to be considered a low or "creeper" gear which is utilized
only for starting of a vehicle under severe conditions and, is not usually
utilized in the high transmission range. Accordingly, while main transmission
section 12 does provide five forward speeds, it is usually referred to as a
"four plus one" main section as only four of the forward speeds are
compounded by the auxiliary range transmission section 14 utilized
therewith.
Jaw clutches 60, 62, and 64 are three-position clutches in that they
may be positioned in the centered, non-engaged position as illustrated, or in
a fully rightwardly engaged or fully leftwardly engaged position by means of
a shift lever 72. As is well known, only one of the clutches 60, 62 and 64
is engageable at a given time and main section interlock means are provided
to lock the other clutches in the neutral condition.
Auxiliary transmission range section 14 includes two substantially
identical auxiliary countershaft assemblies 74 and 74A, each comprising an
auxiliary countershaft 76 supported by bearings 78 and 80 in housing H and
carrying two auxiliary section countershaft gears 82 and 84 for rotation
therewith. Auxiliary countershaft gears 82 are constantly meshed with and
support range/output gear 86 while auxiliary section countershaft gears 84
are constantly meshed with output gear 88 which is fixed to transmission
output shaft 90.
A two-position synchronized jaw clutch assembly 92, which is axially
positioned by means of shift fork 94 and the range section shifting actuator
assembly 96, is provided for clutching either gear 86 to mainshaft 28 for low
range operation or gear 88 to mainshaft 28 for direct or high range operation
of the compound transmission 10. The shift pattern for compound range
type transmission 10 is schematically illustrated in Fig. 1B. Selection of low
or high range operation of the transmission 10 is by means of an operator
actuated switch or button 98 which is usually located at the shift lever 72.
Alternatively a "double-H" type shifting device may be utilized.
Although the range type auxiliary section 14 is illustrated as a
two-speed section utilizing spur or helical type gearing, it is understood that
the present invention is also applicable to range type transmissions utilizing
combined splitter/range type auxiliary sections, having three or more
selectable range ratios and/or utilizing planetary type gearing. Also, as
indicated above, any one or more of clutches 60, 62 or 64 may be of the
synchronized jaw clutch type and transmission sections 12 and/or 14 may
be of the single countershaft type.
Transmissions of this general type are well known in the prior art and
may be appreciated in greater detail by reference to U.S. Pats.
No. 4,754,665; 5,193,410 and 5,390,561, the disclosures of which are
incorporated herein by reference.
Figs. 2 and 2A illustrate a "(2+1) x (2) x (2)" 10-speed
transmission 110 of the automatic range shift type, which also may
advantageously utilize the shifting mechanism of the present invention.
Transmissions of this general type are well known in the prior art, sold under
the trademark "Super 10" by the assignee of this invention, Eaton
Corporation, and illustrated in greater detail in U.S. Pat. No. 5,000,060, the
disclosure of which is incorporated herein by reference.
Transmission 110 includes a rnainsection 112 and an auxiliary
section 114, both contained within housing 116. Housing 116 includes a
forward end wall 116A and a rearward end wall 116B, but not an
intermediate wall.
Input shaft 118 carries input gear 1 20 fixed for rotation therewith and
defines a rearwardly opening pocket 118A wherein a reduced diameter
extension 158A of output shaft 158 is piloted. A non-friction bushing 118B
or the like may be provided in pocket or blind bore 118A. The forward end
of input shaft 118 is supported by bearing 118C in front end wall 116A
while the rearward end 158C of output shaft 158 is supported by bearing
assembly 158D in rear and wall 116B. Bearing assembly 158D may be a
pair of opposed taper bearings or a single roller or ball bearing as is
illustrated in Fig. 3.
The mainshaft 146, which carries mainshaft clutches 148 and 150,
and the mainshaft splitter clutch 180 is in the form of a generally tubular
body 146A having an externally splined outer surface 146B and an axially
extending through bore 146C for passage of output shaft 158. Shift
forks 152 and 154 are provided for shifting clutches 148 and 150,
respectively. Mainshaft 146 is independently rotatable relative to input
shaft 118 and output shaft 158 and preferably is free for limited radial
movements relative thereto.
The mainsection 112 includes two substantially identical mainsection
countershaft assemblies 122, each comprising a mainsection counter-
shaft 124 carrying countershaft gears 130, 132, 134, 136 and 138 fixed
thereto. Gear pairs 130, 134, 136 and 138 are constantly meshed with
input gear 118, mainshaft gears 140 and 142 and idler 157, which is
meshed with reverse mainshaft gear 144.
Mainsection countershaft 124 extends rearwardly into the auxiliary
section where its rearward end 124A is supported directly or indirectly in
rear housing end wall 116B.
The auxiliary section 114 includes two substantially identical auxiliary
countershaft assemblies 160 each including an auxiliary countershaft 162
carrying auxiliary countershaft gears 168, 170 and 172 for rotation
therewith. Auxiliary countershaft gear pairs 168, 170 and 172 are
constantly meshed with splitter gear 174, splitter/range gear 176 and range
gear 178, respectively. Splitter clutch 180 is fixed to mainshaft 146 for
selectively clutching either gear 174 or 176 thereto while synchronized
range clutch 182 is fixed to output shaft 158 for selectively clutching either
gear 176 or gear 178 thereto.
Auxiliary countershafts 162 are generally tubular in shape defining a
through bore 162A for receipt of the rearward extensions of the mainsection
countershafts 124. Bearings or bushings 162B and 162C are provided to
rotatably support auxiliary countershaft 162 on mainsection counter-
shaft 124. Bearing 162D directly or indirectly supports the rear ends of
countershafts 124 and 162 in the rear and wall 116B.
As may be seen by reference to Figs. 2 and 2A, by selectively axially
positioning both the splitter clutch 180 and the range clutch 182 in the
forward and rearward axial positions thereof, four distinct ratios of mainshaft
rotation to output shaft rotation may be provided. Accordingly, auxiliary
transmission section 114 is a 3-layer auxiliary section of the combined range
and splitter type providing four selectable speeds or drive ratios between the
input (mainshaft 146) and output (output shaft 158) thereof. The
mainsection 112 provides a reverse and three potentially selectable forward
speeds. However, one of the selectable mainsection forward gear ratios, the
low speed gear ratio associated with mainshaft gear 142, is not utilized in
the high range. Thus, transmission 110 is properly designated as a
"(2 + 1) x(2x2)" type transmission providing nine or ten selectable forward
speeds, depending upon the desirability and practicality of splitting the low
gear ratio.
The shift pattern for shifting transmission 110 is schematically
illustrated in Fig. 2B. Divisions in the vertical direction at each gear lever
position signify splitter shifts, while movement in the horizontal direction
from the 3/4 and 5/6 leg of the H pattern to the 7/8 and 9/10 leg of the H
pattern signifies a shift from the low range to the high range of the
transmission. As discussed above, splitter shifting is accomplished in the
usual manner by means of a vehicle operator-actuated splitter button or the
like, usually a button located at the shift lever knob, while operation of the
range clutch shifting assembly is an automatic response to movement of the
gear shift lever between the central and rightwardmost legs of the shift
pattern, as illustrated in Fig. 2 and which will be described in greater detail
below. Range shift devices of this general type are known in the prior art
and may be seen by reference to U.S. Pats. No. 3,429,202; 4,455,883;
4,561,325 and 4,663,725, the disclosures of which are incorporated herein
by reference.
As will be discussed in greater detail below, due to the automatic
range-type shift pattern for transmission 110, two independent positions,
one in low range (3/4 and 5/6) and one in high range (7/8 and 9/10), must
be provided for selecting and engaging and disengaging the ratios associated
with clutch 148.
Figs. 3, 3A and 3B illustrate a prior art single shift shaft and hub
assembly 200. Assembly 200 includes a shift shaft 202 axially slidable and
rotatable in housing H, hubs 60B, 62B and 64B of shift yokes 60A, 62A and
64A, respectively, a shift block member 204, a shift or selector key 206,
and an interlock key 208. The shift block 204 is fixed for axial and
rotational movement with shaft 202 as by a set screw 205 and defines a
socket 210 for receiving a shift actuator, such as a shift lever (see Fig. 4),
and a spring-biased detent subassembly 212 for interacting with detent
notches 214 provided on the interlock key 208.
Each of the hubs is provided with a through bore 60C, 62C and 64C,
respectively, of a diameter 216 slightly greater than the outer diameter 218
of shaft 202. The shift key 206 is carried in a keyway 220 in shaft 202 for
axial movement with the shaft 202. The shift key is axially and rotatably
movable with shaft 202 relative to housing H and defines a plurality of
radially outwardly extending shift or selector teeth 222, 224, 226, 228 and
230. The interlock key 208 is received in an axially extending keyway 232
in shaft 202 for rotational movement with and axial movement relative to
shaft 202. The ends of interlock key 208 axially abut portions of housing H
whereby the interlock key is axially fixed in housing H. Interlock key 208
defines a plurality of radially outwardly extending interlock teeth 234, 236,
238, 240 and 242, similar to the shift teeth defined by shift key 208.
The structure and operation of single shaft shift assembly 200 may
be appreciated in greater detail by reference to aforementioned U.S. Pat.
No. 4,920,815. With the transmission in neutral, each of the hubs is
located between a set of shift key teeth and a set of interlock key teeth.
Each of the hub portions 60B, 62B and 64B of the shift forks 60A, 62A, and
64A, respectively, is provided with a plurality of grooves extending radially
outwardly from the inner diameter bore surfaces thereof and extending
axially through the entire axial extent of each of the hub portions. Each of
the grooves is of a dimension such that, when circumferentially aligned with
one of the shifting or interlock keys, the aligned key may be received within
the groove, allowing relative axial movement between the hub and the
aligned tooth.
As may be seen by Fig. 3C and Fig. 4, hub portion 60B of shift
fork 60A is provided with a groove 60D and a double-width groove 60E/F.
Hub portion 62B of shift fork 62A is provided with grooves 62D, 62E and
62F. Hub portion 64B of shift fork 64A is provided with groove 64D and a
double-width groove 64E/F.
Axial displacement and rotation of shaft 106 relative to housing H are
controlled by a remote or direct sniffing actuator acting on the socket
connector of block member 204, which is axially and rotationally fixed to the
shaft 202.
The grooves in the various nub portions of the various shift fork
members are arranged such that, for each of the three selection positions of
the shifting mechanism, the grooves of all the hub portions (except that hub
portion to be axially moved) are in circumferential misalignment with the
interlock teeth, while one of the grooves in the hub portion of the shift fork
to be axially moved is aligned with the interlock teeth, allowing that shift
fork to be axially moved relative to the housing. Further, at least one groove
in the hub portions of all the shift forks (except that shift fork to be axially
moved) is aligned with the shifting teeth, allowing the shaft 202 to be axially
moved relative to those shift forks, while none of the grooves on the hub
portion of the shift fork to be axially moved is aligned with the shifting teeth,
whereby that shift fork will be axially engaged by the shift teeth on both
axial sides thereof for axial movement with the shift shaft 106.
The interaction of the various teeth and grooves may be seen by
reference to Fig. 4. Fig. 4 defines a 3x3 matrix showing the relative
positions of the interlock teeth, shifting teeth and grooves of the hub portion
for various operating conditions of the shifting mechanism. The right column
illustrates hub portion 64B for various rotational positions of shift shaft. The
middle column illustrates hub portion 62B for various rotational positions of
shift shaft, and the left column illustrates hub portion 60B for the various
rotational positions of shift shaft. The top row illustrates the position of the
shift shaft in the selection position for engaging and disengaging either the
reverse or low speed gear ratios. The middle row illustrates the position of
shift shaft for engaging or disengaging either the first or second speed gear
ratios. The bottom row illustrates the position of shift shaft relative to the
various hub portions of the shift shaft in the shift shaft position for engaging
or disengaging either third or fourth speed gear ratios. The various views
shown in Fig. 4 (and in Figs. 6, 11 and 12) are sectional views taken from
the rear of the transmission or shifting mechanism.
By way of example, assuming the operator has rotationally positioned
shaft 202 for selection of engagement or disengagement of either first or
second speed gear ratios, the shaft 202 will be rotationally positioned as
illustrated in the second column. In this position, the interlock teeth 240 and
242 will not be in alignment with groove 64D of the hub portion 64B and,
thus, the shift fork 64A will be axially locked relative to the housing H.
Similarly, interlock teeth 234 and 236 will not be in alignment with
groove 60D, and the shift fork 60A will be axially locked relative to
housing H. Interlock teeth 238 and 240 will be axially aligned with
groove 62D of hub portion 60B of shift fork 62A, allowing shift fork 62A
and the clutch member 62 to be axially moved relative to the housing H for
engagement or disengagement of either gear 52 or 54 to main shaft 28.
Shifting teeth 228 will align with groove 64E/F in hub portion 64B and
shifting teeth 222 and 224 will align with groove 60E/F in hub portion 60B,
allowing the shaft 202 to be axially moved relative to the shift forks 60A
and 64A which are now held axially fixed relative to the housing by action
of the interlock teeth. Shifting teeth 224 and 226 will not align with either
groove 62E or 62F in hub portion 62B of shift fork 62A, thereby fixing the
shift fork 62A for axial movement with the shaft 106.
While the single shaft shifting mechanism of the prior art is illustrated
in connection with a five-forward-speed, one-reverse-speed main
transmission section 12, such mechanisms, and the single shaft shifting
mechanism of the present invention, also could be utilized with
transmissions having a greater number of selectable ratios by the provision
of additional shift fork and hub assemblies and proper positioning of the
groove in each of the hub assemblies. As will be described in greater detail
below, such mechanisms also may be utilized with transmissions, such as
transmission 110, having an automatic range shifting feature.
A preferred embodiment of the single shift shaft and shift yoke hub
assembly 300 of the present invention, functionally substantially identical to
the assembly 200 illustrated in Fig. 3, may be seen by reference to Figs. 5,
5A, 5B, 5C, 6 and 9A.
The shift shaft and yoke assembly 300 includes a shift shaft
assembly 301 and three shift yoke hubs 302, 304 and 306 corresponding
to the shift yoke hubs 60B, 62B and 64B, respectively, for controlling the
axial positioning of clutches 60, 62 and 64, respectively.
The shift shaft assembly 302 has a shaft 308 with a key way 310 for
receiving an interlock key 312 substantially structurally and functionally
identical to the keyway 232 and interlock key 214 described above. A shift
block member 314, substantially structurally and functionally identical to
shift block member 204, is fixed to shaft 308.
Shaft assembly 302 differs from the comparable assembly of
embodiment 200 in that a shift key 206 and a shift key keyway 220 are not
utilized and three shift pins, 316, 313 and 320, fixed to and radially
extending from the shaft 308, provide the shift selection function.
In the embodiment of Figs. 5, 5A and 5B, the shift pins (see Fig. 5C),
which may be "D" or "H" shaped, are pressed into radially extending blind
bores 322, 324 and 326 provided in the surface of the shaft 308.
Referring to Fig. 9A, it may be seen that shift yoke hub 306 differs
from hub 64B in that a transversely extending slot 330 is provided for
receiving shift pin 320, allowing the pin 320 and shaft 308 to rotate relative
to hub 306 and defining opposed strike surfaces 332 and 334 for
engagement by the pin 320 when the; pin is not aligned with an axially
extending groove corresponding to grooves 64E/64F.
Fig. 9B illustrates a modified embodiment 400 of the hub and shaft
assembly of the present invention. In this embodiment, hub 64B may be
utilized without a slot corresponding to slot 330, but a pair of shift pins 402
and 404 extending radially from shaft 406 and axially surrounding the
hub 64B are required in place of a single shift pin. In embodiment 400,
pins 402 and 404 correspond to teeth 228 and 230 of shift key 206.
Fig. 6 is a matrix, similar to Fig. 4, illustrating the relative positions of
the shift pins, interlock key teeth and grooves in hubs 302, 304 and 306 for
each selection position of assembly 300.
Figs. 7 and 7A and Figs. 8 and 8A, similar to Figs. 5B and 5C,
illustrate alternate embodiments 500 and 600, respectively, of the present
invention. The embodiments 500 and 600 differ from embodiment 300 in
that shafts 502 and 602, respectively, utilize radially extending countersunk
through bores 504, 506 and 508 and flared through bores 604, 606 and
608, respectively, to receive corresponding headed pins 510, 512 and 514
and 610, 612 and 614, respectively. In both embodiments, the interlock
key 516 or 616, respectively, engages the heads of the shift pins to retain
the pins in the through bore. The embodiments 500 and 600 are otherwise
substantially structurally and functionally identical to embodiment 300.
Fig. 10 illustrates another alternate embodiment of the present
invention, shift shaft and yoke assembly 700. Assembly 700 differs from
assembly 300 in that the interlock key and associated keyway are eliminated
and replaced by sliding interlock pins slidably received in bores in the yokes
and interacting with notches provided in the shift shaft and housing. Sliding
pin interlocks are known in the prior art, as may be seen by reference to
U.S. Pats. No. 4,676,155; 4,974,474 and 4,944,197, the disclosures of
which are incorporated herein by reference.
The structure and function of embodiment 700 may be seen by
reference to Fig. 10 and Fig. 11, which is a matrix similar to Figs. 4 and 6.
Shift shaft 702 carries the shift yokes 704, 706 and 708 and includes
shift pins 710, 712 and 714, which correspond to shift pins 610, 612 and
614, respectively. The shift yokes 704, 706 and 708, respectively, define
grooves 704E/F, 706E and 706F and 708E/F, which correspond to
grooves 64E/F, 62E and 62F and 60E/F, respectively. The shift pins and
shift grooves of embodiments 300, 400, 500, 600 and 700 are functionally
identical to the function of the shift key teeth and shift grooves of the prior
art embodiment illustrated in Figs. 4.
Each of the yokes 704, 706 and 708 is provided with a generally
radially extending bore 716, 718 and 720, respectively, for sliding receipt
of an interlock pin 722, 724 and 726, respectively. The housing H is
provided with interlock notches or depressions 728, 730 and 732,
respectively, aligned with the bores 716, 718 and 720, respectively. The
shaft 702 is also provided with interlock notches 734, 736 and 738, only
one of which will, for each rotation position of shaft 702, align with one of
the bores 716, 718 and 720, respectively.
The interlock pins 722, 724 and 726 are of an axial length such that,
if not received in one of the notches 734, 736 or 738, respectively, in the
shaft, will be forced by the outer diameter surface 740 of the shaft into
housing interlock notches 728, 730 or 732, respectively, to prevent axial
movement of the associated yoke relative to housing H. By way of example,
referring to Fig. 10A wherein the 3-4 shift yoke 704 is selected, the interlock
pin 722 is received in shaft notch 734, allowing yoke 704 to move relative
to housing H, while pins 724 and 726 are forced by the outer diameter
surface 740 of the shaft 702 into housing interlock notches 730 and 732,
locking the 1-2 shift yoke 706 and the L-R shift yoke 708 to the housing.
A further embodiment of the present invention may be seen in Fig. 12,
which also is a matrix similar to Fig 11. The shift shaft and yoke
assembly 800 of Fig. 12 is similar to the embodiment of 700, except that
the shift grooves and shaft interlock notches are configured to operate with
the "(2 +1) x (2) x (2)" 10-speed automatic range transmission 100 of Figs. 2
and 2A.
The hub 148B of the 3-4/1-2 shift yoke in fork 148A and hub 150B
of the L-R shift yoke 150A are carried by shift shaft 802. The shaft is
provided with two interlock notches 804 and 806, which will align with the
interlock pin 808 carried by hub 148B in two positions, 3-4 selected (top
row) or 1-2 selected (middle row), allowing the shift yoke 148A to move
relative to the housing H in both positions. Additionally, the shift pin 810
associated with hub 148B will misalign with the shift groove 812 and
engage the hub in both the 1-2 and 3-4 selection positions. Otherwise, the
structure and function of embodiment 800 is substantially identical to that
of embodiment 700.
Accordingly, by the use of pins received in bores (preferably
substantially annular pins and bores) to replace keys and keyways, a more
economically produced, assembled and/or serviced single shaft shifting
mechanism, having a more user friendly shift pattern, is provided.
Although the present invention has been described with a certain
degree of particularity, it is understood that the description of the preferred
embodiment is by way of example only and that numerous changes to form
and detail are possible without departing from the spirit and scope of the
invention as hereinafter claimed.
WE CLAIM:
1. A single shift shaft mechanism for axially positioning a selected
one of two or more selectable engagement members while axially fixing the
non-selected ones of said engagement members to a housing, said
mechanism comprising a single shift shaft having an outer surface axially
and rotationally movable in the housing, shift means axially and rotationally
fixed to and extending radially from said outer surface, and interlock means
having a first portion rotationally fixed to said shaft and a second portion
axially fixed to said housing; said mechanism characterized by:
at least one of said shift means and said interlock means comprising
a plurality of individual pins, at least one pin for each engagement member,
extending radially outwardly from said surface.
2. The mechanism of claim 1 wherein said engagement members
are axially movable jaw clutch members.
3. The mechanism of claim 1 wherein said pins are received and
retained in radially extending bores in said shaft opening to said outer
surface.
4. The mechanism of claim 2 wherein said pins are received and
retained in radially extending bores in said shaft opening to said outer
surface.
5. The mechanism of claim 4 wherein said bores are blind bores
and said pins are press-fit into said bores.
6. The mechanism of claim 4 wherein said bores are countersunk
through bores and said pins are headed pins.
7. The mechanism of claim 4 wherein said shifting means are
defined by said pins and said interlock means are defined by interlock teeth
extending from an interlock key axially slidably retained in an axially
extending keyway provided in said outer surface, said keyway located
circumferentially opposite said openings of said bores.
8. The mechanism of claim 5 wherein said shifting means are
defined by said pins and said interlock means are defined by interlock teeth
extending from an interlock key axially slidably retained in an axially
extending keyway provided in said outer surface, said keyway located
circumferentially opposite said openings of said bores.
9. The mechanism of claim 6 wherein said shifting means are
defined by said pins and said interlock means are defined by interlock teeth
extending from an interlock key axially slidably retained in an axially
extending keyway provided in said outer surface, said keyway located
circumferentially opposite said openings of said bores.
10. The mechanism of claim 7 wherein each clutch member is
associated with a shift yoke having a hub portion with an axially extending
through bore receiving said shaft, each of said hubs having a transverse slot
for receiving one of said pins and for defining opposed strike surfaces for
axial engagement thereby.
11. The mechanism of claim 2 wherein each clutch member is
associated with a shift yoke having a hub portion with an axially extending
through bore receiving said shaft, said interlock means comprising interlock
pins axially slidably received in interlock pin bores provided in said hub
portions.
12. The mechanism of claim 2 wherein said shifting means are
defined by shifting pins received and retained in axially extending bores in
said shaft and each clutch member is associated with a shift yoke having a
hub portion with an axially extending through bore receiving said shaft, said
interlock means comprising interlock pins axially slidably received in interlock
pin bores provided in said hub portions.
13. The mechanism of claim 11 wherein said interlock means first
portion fixed to said shaft comprises a shaft depression for receiving one end
of said interlock pin, and said interlock means second portion fixed to said
housing comprises a housing depression for receiving the other end of said
interlock pin, said interlock pin of an axial length greater than the axial length
of said interlock pin bores.
14. The mechanism of claim 12 wherein said interlock means first
portion fixed to said shaft comprises a shaft depression for receiving one end
of said interlock pin, and said interlock means second portion fixed to said
housing comprises a housing depression for receiving the other end of said
interlock pin, said interlock pin of an axial length greater than the axial length
of said interlock pin bores.
15. The mechanism of claim 3 wherein said pins and bores are
substantially annular.
16. The mechanism of claim 4 wherein said pins and bores are
substantially annular.
17. The mechanism of claim 11 wherein said pins and bores are
substantially annular.
18. The mechanism of claim 12 wherein said pins and bores are
substantially annular.
19. A single shaft shifting mechanism for selection and engagement
of selectable gear ratios in a change speed transmission including a housing,
said mechanism comprising a shift shaft mounted for relative axial and
rotational movement in said housing and defining an outer surface, a shift
block member axially and rotationally connected to said shaft, a plurality of
shift forks including sleevelike hub portions having an axially extending
through bore and a pair of opposed strike surfaces extending generally
perpendicular to the axis of said shaft, a set of shift members projecting
radially outwardly from said shaft in an axially-spaced relationship such that
each of said hub portions cooperates with a different one of said shift
members, said shift members being axially and circumferentially fixed
relative to said shaft, a set of interlocking teeth projecting radially from said
shaft in an axially-spaced relationship such that each of said hub portions is
arranged between two adjacent teeth of said set of interlocking teeth, said
set of interlocking teeth being axially movable but circumferentially fixed
relative to said shaft and axially fixed relative to said housing, each of said
hub portions having at least one pair of axially extending grooves being
formed to receive a corresponding one of said shift members and interlocking
teeth, said grooves being arranged in predetermined positions along the
through bores of said hubs such that when one of said grooves of one of
said hubs is aligned with a corresponding one of said interlocking set of
teeth, none of the grooves in said hub is aligned with one of said shifting
members and one of said grooves of each hub portion other than said one
hub portion is aligned with a corresponding one of said shifting members and
none of the grooves of each of said hub portions other than said one hub
portion is aligned with one of said set of interlocking teeth, said shifting
mechanism characterized by:
said shift members comprise generally annular shift pins, at least one
for each hub portion, extending radially from said shaft and said interlock
teeth are defined by a single interlock key slidably received in an axially
extending interlock keyway provided in said shaft.
20. The mechanism of claim 19 wherein said shift pins are received
and retained in radially extending bores in said shaft opening to said outer
surface.
21. The mechanism of claim 20 wherein said bores are blind bores
and said shift pins are press-fit into said bores.
22. The mechanism of claim 20 wherein said bores are countersunk
through bores and said shift pins are headed pins.
23. The mechanism of claim 19 wherein each clutch member is
associated with a shift yoke having a hub portion with an axially extending
through bore receiving said shaft, each of said hubs having a transverse slot
for receiving one of said shift pins and for defining opposed strike surfaces
for axial engagement thereby.

An improved single shift shaft shifting mechanism (300) for shifting
a mechanical change-gear transmission (10/110) is provided. The shifting
mechanism includes a shift shaft (302) which is mounted for axial and
rotational movement in a housing (H) for selectively axially moving and/or
locking selected or non-selected, respectively, shift forks (302, 304, 306)
relative to the housing. To provide an easily shifted, reliable and economical
assembly, the shifting projections are defined by a plurality of generally
annular shift pins (316, 318, 320) extending radially from bores (322, 324,
326) provided in the shift shaft (308).