Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~L~3~1~33
This invention relates to ratio shiftin~
transmlssions and in particular to such transmissions
adapted for power shiftin~ and for use in land vehicles.
This is a dlvision oE copendin~ Canadian Pa-tent
~pplication 322,737, iled r1arch 5, 1979.
It is known in the transmission art to first
synchronize and clutch an intermediate shaft or ratio
gear with the transmission output and to then clutch the
intermediate shaft or ratio ~e~r to the trans~ission input.
; 10 Such synchronizin~, which ~ay be referre~ to as output
synchronizin~, is also known in prior art transmissic)ns
havin~ plural countershafts. Many prior art transmissions,
which employ plural countershafts and output s~nchronizing,
power shiEt from one countershaft to another to upshiEt
or downshift the transmission and synchronize a non-driving
countershaft ~ith the transmission output in preparation
for the next shift.
When the above prior art trans~issions are used
in combination with a tor~ue converter, the sole source
of power input to the transmission is throu~h the tor~ue
converter ~Jhich is rather ineficient and not needed in
the hi~her speed ratios of the transmission. To ne~ate
this inefficiency, tor~ue converter bypass or lock out
clutches have been used. Such clutches have the disadvanta~e
in that they and their needed control systems may increase
the cost and complexity of the trans~issions.
An object of the invention is to provide a trans-
mission which is low in initial cost and economical in use.
mb/ ~C
~:~3~33
Another object of the invention is to provide a
transmission which is readily shifted without a break in power
between the transmission input and output.
The present inven-tion resides in a power shift
transmission of the type including an input shaft adapted to
be continuously driven by an engine, an output shaft adapted
to be continuousl~ connected to a load, an intermediate shaft
and means mounting the shafts for rotation independently of
each other. In the present invention means is operative to
synchronize the intermediate shaft means with the continuously
driven input shaft while the intermediate shaft means is
drivingly disconnected from the output shaft. Means is operative
after the synchroni~ing to positively clutch the intermediate
shaEt means with the input shaft while the intermediate shaft
means remains drivingly disconnected from the output shaft.
Friction clutch means is drivingly interposed between the
intermediate shaft means and the output shaft and is operative
after the positive clutclling to power clutch the intermediate
shaft means with the output shaft.
In the specific embodiment of the invention the
in-termediate shaft means includes the countershaft and there
is pxovided an input gear nonrotatably fixed -to the input shaft,
an output gear nonrotatably fixed to the output shaft, a driven
gear rotatably supported by the countershaft and in mesh with
the input gear, and a drive gear rotatably supported by the
countershaft and in mesh with the output gear, the friction clutch
means being interposed between the countershaft and the drive gear.
In one form of the invention the intermediate shaft
means includes first and second countershafts with input
' ~ pc/~
1~3~
gear means nonrotatably Eixed to the input shaft, ou-tput
gear means nonrotatably fixed to the output shaft, a
driven gear rotatably supported by each countershaft and in
mesh with the inpu-t gear means, and a drive gear rotatably
supported by each countershaftc~nd in mesh with the output gear
means, the riction clutch means being interposed between each
countersha.ft and each drive gear.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiment of the invention is shown
in the accompanying drawings in which:
FIGIJRE ]. is a schematic view of the transmission
looking in the direction of arrows 1-1 of FIGURE 2;
FIGURE 2 is a schematic view of the transmission,
looking in the direction oE arrows 2-2 of FIGURE 1;
FIGURE 3 is a detailed view of the transmission
of FIGURE 1, looking in the direction of arrows 1-1 of
FIGURE 2;
FIGURE 4 i5 a detailed view of a portion of the
-transmission, looking in the direction of arrows 3-3 of
FIGURE 2; and
t~./ -. -3-
~:L3~3;3
FIGURE 5 is a schematic view of a portion
of a countershaft assembly of FIGURES 1 and 3~
Certain terminology referring to direction and
motion will be used in the following descrip-ti~n. The
terminology is for convenience in describing the pre-
ferred embodiment and should not be considered limiting
unless explicitly used in the claims.
DE'TAILED DESCRIPTION OF TH~ PREFERRED EMBODIMENT
Looking first at FIGURF 1~ therein is schemat-
ically illustrated a power shift transmission assembly 10adapted for use in an unshown land vehic:le, but not: limited
to such use. Transmission 10 is preferably automatically
shifted by an unshown control system, which control system
f~rms no part of the instant invention. rrransmission 10
includes an input shaft 12 which may be direc-tly driven
by an unshown internal combustion engine, a housiny
assembly 14, a -torque converter assembly 16, a ratio change
gear assembly lS which is driven by input shaft 12 through
torque converter assembly 16 in first, second, and reverse
ratios and is driven directly by a bypass input shaft 13
in third and fourth ratios, and an output shaft 20 axially
aligned with input shafts 12 and 13.
The torque converter assembly 16 is conventional
in that it includes a fluid coupling of the torque con-
verter type having an impeller 22a driven by input shaft 12through a shroud 24, a turbine 22b hydraulically driven by
the impeller and in turn driving a sleeve shaft 26 which
extends into gear assembly 18, and a runner or stator 28
which becomes grounded to housing 14 via a one-way xol~er
clutch 30 carried by a sleeve shaft 32 fixed to housing
assembly 14. Shroud 24 also drives a pump 34 for pressur-
izing the torque converter, for lubricating the transmission,
and for selec-tively pressurizing friction clutches in
gear assembly 18.
..
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Sleeve 26 provides a fluid power or tor~ue .
converter driven shaft for first, second, and reverse
ratio gears in gear assemhly 18. Bypass shaft 13 is in
continuous direct drive with inpu-t shaft 12 and provides
a torque converter bypass for drivin~ third and fourth
ratio gears; this arxangement of the bypass shaEt negates
the need of a separate torque converter bypass clutch.
Looking now at FIGURES 1 and 2, the schematically
illustrated ratio change gear assembly includes two
countershaft assemblies 36 and 38, which are disposed
about axes which are parallel to and radially outward o
an axis defined by shafts 12, 13, and 20. Assembly 36
includes a shaft 40 rotatably supported at its elids 40a
and 40b by housing assembly 14, a double acting sync:hron-
izer clutch 42, first and third speed ratio gears 44 and~6 rotatable relative to`and supported b~ shaft ~Q, and
a hydraulically actuated friction clutch 48. ~irst speed
ratio gear 44 is driven by and in continuous mesh with
an input drive gear 50 which is non-rotatably secured to
: 20 bypass shaft 13. Synchronizer clutch 42 may be a conven- .
tionaI double ac-ting synchronizer having a clutch member
54 at one end which is non-rotatably secured to gear 44,
a clutch member 5~ at the other end which is non-rotatably
: secured to gear ~6, and a center clutch member 58 at the
center which is non-rotatably secured to shaft 40. Center
clutch member 58 may be slidably shifted ieftwardly or
rightwardly in a conventional manner to, respectively,
couple gear 44 or 46 to shaft 40.. Such slidable shifting
of the center clutch member first frictionally couples
countershaft 40 with one of the ratio gears and after
synchronism is reached, then positively clutches the
shaft with the gear via a iaw clutch shown in ~IGURE 3.
Center clutch member S8 includes a radially extending
flange portion 60a which Inay be gripped by an unshown shift
fork to effect the leftwdrd and rightward shifting in a
aonventional mdnner. Fric~ion clutch 48 includes a housiny
.l~.a~
~6--
member 62 non-rotatably secured to sha:Et 40, two sets of
interdigitated disks 64 and 65, and a sleeve shaft 66
rotatably supported by shaft 40. Disks 6~ ar~ non-.rotat-
ably secured to sleeve shaft 66 and disks 65 are non- i
S rotatably secured to housinc3 member 62. Both disk sets
are axially moveable in housincJ 62 and are Erictionally
intereonnected in response to hydraulic pressure beincJ
seleetively applied to an unsho~7n pi.ston in -the housing
member 62. Sleeve shaft 66 is non-rotatably secured to a
drive gear 68 whieh is rotatably supported by shaft ~0.
Drive gear 68 is in continuous mesh with an output gear
70 which is non-rotatabl~ secured to output sha-t 20.
Countershaft assembl~ 38 di.f~ers from assembly
36 mainly in that it also includes a :reverse ratio ~ear.
~ssembly 38 ineludes a shaft 72 rotatably supp~rted at its
ends 72a and 72b by housinc3 assembly 14, a douhle actinq
s~nchronizer eluteh 74 r second, fourth and reverse speed
xatio c~ears 76, 78, 80 whieh are xotatable relative to and
supported by shaft 72, a hydraulically aetuated friction
elutch 82, and a positive type jaw eluteh assembly 84.
Clutch 84 may be a synchroniæea eluteh similar to clutches
42 and 7~. Second speed ratio gear 76 is driven b~ and
in continuous mesh with an input drive gear 86 which is
non-rotatably seeured to torque converter driven shaft 26.
Fourth speed xatio gear 78 is driven by and in continuous
mesh with input drive gear 52 which is non-rotatably
seeured to bypass shaft 13. Synchronizer elutch 74 is a
double acting elutch and may be identical -to synchronizer
42. Synchronizer clutch 7~ includes a elutch member 90
at one end whi.ch is non-ro-tatably seeurea to ~ear 76,
a elu-tch member 92 at the okher end which is non-rota-tably
secured to gear 78, and a center clutch ~nember 9~ at the
center which is non-rotatably secured to shaft 72. Center
elutch member ~ includes a radially extendirlg flange
portion 96a which may be ~ripped by an unshown shift
fork to effect leEt-~7ard and ric~htward shif-ts in the same
~:~3~3;~
manner as described for synchronizer 42. Friction clutch
82 may be identical to fri.ction clutch 48~ Friction
clutch 82 includes a housing member 98 which is non-
rotatably secured to shaft 72, two setc; oE disks 100 and
101, and a sleeve shaft 102 rotatably supported by shaft
72. Disks 100 are non-rotatably secured to sleeve shaft
102 and disks 101 are non-rotatably secured to housing
member 98. Both disk sets are axially moveable in
housing 98 and are-frictionally interconnected in
response to hydraulic pressure being selectively applied
to an unshown piston in housing member 98. Sleeve
shaft 102 i5 non-rotatably secured to a drive gear 104
which is rotatabl~ supported by shaft 72. Drive gea.r
104 is in continuous mesh with an output gear lQ6 which
is non~rotatably secured to output shaft 20.
Reverse.gear 80 is rotatab:Ly supported by
shaft 72 and is driven by an idler gear assembly 108,
seen onl~ in FI~URES 2 and ~. Idler gear assembly 108
includes a shaft 110 which is non-rotatabl~ supported
by housing assel~bly 14, a gear 112 which is rotatably
supported on shaft llC and in continuous mesh wi-th input
drive gear S0 which is driven by torque converter driven . `
shaft 26, and a gear 114 which is rotatably supported on
shaft 110 and non-rotatably secured to geax 112. Gear
114 is in continuous mesh with reverse gear 80. ~aw
clutch assemb~y 84 includes jaw clutch teeth 116 which
are non-rotatably secured to gear 80 and a jaw clutch
member 118 mounted for sliding movement relative to shaft
72 and secured against rotation relative to shaft 72.
Member 118 includes jaw clu-tch tee-th 118a which engage
with teeth 116 and an annular groove 118b wh.ich receives
a shift fork 152 engaging the clutch in a conventional
manner. ShiEt ~ork 152 is shown in FIGURE 3.
By way of example, the ratios of ratio change gear
assembly 18 are: first gear - ~.05, second gear - 2.22,
third gear - 1.42, fourth gear - 1.0~, and reverse gear - ~.76.
113~133
-8-
As may be seen, bypass shaft 13 and output 20 rotate
at the same speeds when drive is through fourth year.
Gear assembly 18 may also be provided with
a direct drive clutch 120 at the confronting ends 13a
and 20a and the bypass of output shaEts 13 and 20 for
bypassing fourth speed ratio drive through countershaft
38. Such a clutch may be a non-synchronized positive
type jaw clutch as illustrated herein, since herein
shafts 13 and 20 rotate at the same speeds in the fourth
speed drive ratio. Further, the direct drive of clutch
120 could be used to provide a fifth speed ratio by
decxeasing the ratio spacing of first, second, third,
and fourth ratio geaxs so that output shaft 20 would
rotate slower than bypass shaft 13 when drivin~ in
fourth speed. When using clutch 120 to provide a
fifth speed ratio, the clutch is preferabl~ a fluid
! actuated friction clutch or a synchronized iaw clutch,
both of which may be o a conventional type.
Looking now at F~GURES 3 and 4, therein the
;20 transmission of FIGU~FS 1 and 2 is disclosed in greater
detail to show additional features not readily shown in
a schematic. The transmission of FIGURES 3 and 4 does
not include the direct drive clutch 120 but is otherwise
the same as that previously described. Thus, in FIGVRES
3 and 4 the numerals corresponding to those of ~IGURES 1
and 2 will refer to parts already ~escribed.
In ~IGURE 3, housing assembly 14 includes a
front housing member 14a havin~ a bell housing portion
14b formed integral therewith, a rear housing member 14c,
and an intermediate plate member l~d. Members 14a, l~c,
; and 14d are secured together via plurality of b~lts 121,
one of which is shown. A flan~e portion 14e of the bell
housing pro~ides means for securing the transmission to
the rear of an engine housing. ~ntermediate plate l~d
includes through bores lgf and l~c3 ~or the passage of
shafts 40 and 72, a bore 14h having a bearinc3 122 disposed
:
113gl33
therein for rotatably supporting end 13a of shaft 13.
End 20a of shaft 20 extends into a blind bore 13b in
shaft 13 and is supported therein by a roller bearing
124. Intermediate plate 14d also includes several
unshown oil passages for directing lubrica-ting oil to
various portions o~ the transmission and for directing
oil to actuate clutches 48 and 82.
Shroud 24 of torque converter-assembly 16
includes a front portion 24a and a rear portion 24b
which are non-rotatably secured together at 126. Front
portion 24a is integrall~ formed with a cup shaped portion
defining shaEt 12 and having in~ernal splines 12a which
receive splines 13c for driving shaft 13. Front
portion 24a also includes a plurality o~ studs 12~3 for
securing the transmission input to an unshown crankshaEt
or output shaft o~ an engine or mo-tor. '~he rear portion
24b is fixed to impeller 22a at 130 and is welded to a
! sleeve 132. Sleeve 132 rotatably supports the rear
portion 24a via a bearing 134 and drives pump 34.
Pump 34 may be a well known crescent gear p~p. Bearing
~ 134 is supported by pump housing 34a which is bolted to
; housing portion 14a via a plurality of bolts 136.
Shafts 13 and 26 are rotatabl~ supported relative to
each other and housîng assembly 14 via roller bearings
138, 139, 140, 141, and, as previously mentioned, by
bearing 122. Shafts 13 and 26 are axially retained
relative to housing assembly 14 and each other by a ball
bearing 122 and roller bearings 142 and 144.
Looking now at cross-sectioned countershaft 38,
ends 72a and 72b o:E shaft 72 are supported by ball bearings
1~6 and 1~8 which also axially retain the shaft. Reverse
gear 80 is rotatably supported on shaft 72 by a roller
bearing 150 and includes an axially extending portion 80a
having e~ternal splines defining jaw clutch teeth 116
of the jaw clutch assembly ~4. Clutch assembly 84
fur-ther includes a ring memher l51 splined on its I D to
.
--10--
shaft 72 and splined on its O.D. to jaw clutch teeth 118a
of member 118. Annular groove 118b in member 118
receives a shift fo.rk 15~ which is slidably connected
to a shift rod 154 of an actuator 156. Actuator 156
includes a pist.on portion 15*a ~ormed on or fixed to
rod 15~ and disposed in a cylinder 14i cast.into
intermediate plate 14d, and an end plate 158 for closing-
the cylinder. A spring 15~ disposed between a snap
ring assem~ly 160 and shift fork 152 resiliently urges
clutch teeth ~8a .into engagement with clutch teeth
116 in response to leftward movement of rocl 154 and
piston 154a. A snap ring 162 contacts the shift fork
for disengaging the jaw clutch in response to r.i~htward
movement of the rod and pi.ston. C~linder 14i is
prov.ided with oil on hoth sides of piston 154a by
unshown passages in intermed.iate plate 14d. H~draulic
sealing of the piston and cylinder is provided by
O-ring seals in a conventional manner. ~Iydraulic
actuators for shifting synchronizers 42 and 74 are
~0 provi.ded in a similar manner.
. Gear 76 includes an axially extending sleeve
portion 76a having external jaw clutch splines 76b
which xeceive internal splines of clutch member ~0.
Gear 76 and sleeve portion 76a are rotatably supported
on shaft 72 by a pair of roller bearings 164~ In a
like mannex, gear 44 of countershaft assembly 36 includes
an axially extending portion 44a, but of longer length,
splined to clutch membex 54 and unshown roller bearings
for rotatably supporting the gear and sleeve portion
on shaft 40. In a similar manner, gear 78 is rotatably
supported on shcaft 72 by a roller bearing 166 and includes
an axially extending portion having external jaw clutch .
splines 78a which xeceive internal splines of clutch
member 92. Gear ~6 is rotatably mounted on shaft 40
and c~nnected to clutch member 56 in the same manner.
.~
~^~L3~
Double acting synchronizer 74, of which members
90 and 92 are part, is well known in the prior art. The
synchronizer and in particular center clutch 94 includes
a sleeve 167 splined on its I.D. to shaft 72 and on its
S O.D. to internal jaw clutch splines 96b of a slidable
positive type jaw clutch member 96 integrally formed
with flange portion 96a, a pair of friction rone rin~s
168 and 170 rigidly secured together b~ three circumfer-
entiall~ positioned pins 172, and a pair of internal
friction conc surfaces 90a and 92a which are engageable
with external cone surfaces defined by rings 16~ and 170.
Pins 172, which extend through three chamfered openings
96c circumferentially positioned in flange '~6a, have
at their centers (the position of the flan~e in its
neutral position) an annular groove 172a having chamfered
ends. The I.D. o~ each chamfered opening 96c is slightly
greater than the major O.D. of each pin 172. ~nnular
t grooves 172a are slightl~ wider than the flange. Center
clutch member 94 further includes three axiall~ split
~0 pins 174 extending through three chamfered openings ~6d
which are alternately spaced between openings 96c. Pins
174 each consist of a pair of semicylindrical haLves
which are biased apart by a leaf spring 176. Each pair
of semicylindrical halves define an annular groove 17~a
having chamEered ends. Annular groove 174a is formed
by a semiannular groove defined by each pin half.
Spring 176 biases the semiannular grooves outward i~to
engagement with openings 96d. The I.D~ of openings 96d
is slightly greater than the major O.D~ of pins 174.
Annular grooves 174a closely fit the width of flange 96a.
The center clutch member 94 is shown in the
neutral position, therefor both gears 76 and 88 are
disenga~ed, the friction cone surfaces are slightly
spaced apart, pins 17~ and 174 and their respective
grooves are concentric with openings 96c and 96d, and
the semiannular grooves defining grooves 174a are biased
.. .. . . . . . . ...
113~133
-12-
into engagement with holes 96d. When i~ is desired to
couple gear 76 to shaft 72, flange portion 96a is moved
axially to the left by an appropriate shift mechanism.
Such movement, which is transmitted through split pins
174, shifts the cone surface of cone ring 168 into
contact with cone surface 90a. This contact (provided
gear 76 and flange 96a are no-t synchronous with each
other) causes pins 172 to move out of concentric
alignment with openings 96c, whereby the chamfers of
the openings 96c and the chamfers of the grooves 172a
engage and prevent further axial movement of the flange
due to torque at the interface of the chamfers. ~s
synchxonous speeds are reached, the tor~ue at the
interface of the chamfers diminishes and the axial force
on flange 96a moves pins 172 back into a concentric
relationship with openings 96c, thereb~ allow.ing flange
1 96a and jaw member ~6 to move axially to the l.eft for
; engaging jaw clutch splines 96b with jaw clutch splines
76b. Gear 78 is coupled to shaft 72 in the same manner
by moving the flange rightward.
The transmission gears are preferably helical
years and as such they are axiall~ loaded with s~stantial
forces when they are transmitting torque. Further, since
the gears are in continuous mesh, the~ rotate at diff~
erent speeds. Hence, it is preferred that the gears
be axially isolated from each other to prevent the
transmittal of the axial forces across surfaces rotating
at different speeds to reduce wear and energ~ losses.
Isolation and axial retention of gears 80, 76~ and 78 is
as follows:
Gear 80 is retained against axial movemen-t
relative to shaft 72 in the leftward direction by a
thrust plate 178 and in the rightward direction through
ring member 151 by a shoul~er 72c defined by a step
in shaft 72. Shoulder 72c prevents axial loading being
imposed on gear 76 when gear 80 is engaged Gear 76
~, .
.
~:~L3~3 L3~ ~
-13-
is retained against axîal movement relative to shaf-t 72
in the leftward direction through ring member 151 b~
a snap ring 180 and in the rightward direction through
ring member 167 which abuts a shoulder 72d de~ined by
a step in shaft 72~ Gear 78 is retained against axial
movement relative to shaft 72 in the leftward direction
through ring member 167 by a snap ring 182 and in the
rightward direction by a thrush plate 184. f
~riction clutch 82, which is structurall~
and functionally conventional and identical to clutch a8,
includes the housing member 98 splined to sha~t 72 at
98a, the set o~ disks 101 which are slidably splined to
internal splines 98b defined by the housing member, the
set of disks 100 which are slidably splined to external
splines 102a defined by an extension of sleeve 102,
a reaction member 186 which i9 non-rotatabl~ secured
! to housing member 98 hy splines 98b, a piston 18~ for
s~ueezing the disks together in response to pressurized
fluid being introduced into a chamber 190 defined by
housing member 98 and piston 188, and a return spring
192 for retracting the piston. Eousing member 98 is
axially retained by a .shoulder 72e defined by a step
in shaft 72 and a snap ring 194. Sleeve 102 and gear
104 are rotatably supported on shaft 72 by a pair of
roller bearings 196 and are axially retained by snap
rings 194 and 204 through thrust bearings 198 and 200.
The gear 68 and clutch 48 o~ countershaft
assembly 36 are rotatably and axially retainea on shaft
40 in a similar manner.
Out:put sha~t 20 is rotatably supported by
the roller bearing 124 and a ball bearing 206. The
outer race 206a of bearing 206 is supported by housing
portion 14c and is axially retained thereto by a
shoulder 14k and a snap ring 208 Axial retention
of sha~t 20 is provided by the inner race 206b o~
beariny 206 which is sandwiched between a shoulder 20b
~3~3
-14-
defined by shaft 20 and a spacer sleeve 210. Sleeve
210 is held in place by an output yoke 212 which is
splined to shaft 20 and axially retained by a bolt 21
Output gears 70 and 106 are splined to shaft 20 and
are xetained in the leftward direction by a flan~e portion
20c defined by shaft 20 and in the rightward direction
by the inner race 206b.
OPERATION
In reviewing the operation, it will be assumed
that the transmission 10 is installed in a land vehicle
- having an internal combustion en~ine, that the engine
crankshaft is connected to torque converter shroud,2
by studs 1~8, that the crankshaft rotates the .shroud
clockwise when view.ing the shroud from the front, and
that a shift contxol system will automatically eEfect
shiFting to the desired'speed ratios in the proper
! sequence. Such control systems are well known and ,
are oten made responsive to parameters such as engine
load and vehicle speed. It will also be assumed that the
control system includes a shift control lever which is
selectively placed in neutral to disengage the transmission,
or in drive to effect forward movement of the vehicle,
or in reverse to effect reverse movement of the vehicle.
The shift control system xeferred to herein is b~ way
of example only and does not form part of the invention
herein or any preferred ~orm of a control system.
With the shit control lever in neutral and
the engine running, bypass shaft 13 and torque converter
driven shaft 26 rotate clockwise and rotate input drive
gears 50, B6, and 52 clock~ise, whereby driven gears
44, 46, 76, 78 rotate counterclockwise and c3ear 80
rotates clockwise since it is driven through idler gear
assembly 108~ Further, countershafts 40 and 72 are
completely disconnected from the transmission input and
output since synchronizers ~2 and 74 and fluid actua-ted
...
~:~3~3~9
clu-tches ~8 and ~ are disengacJed while the shift control
lever is in neutral.
Assuming now that a vehicle opera-tor places the
shift control lever in drive and wishes to accelera-te the
vehicle in a forward direction to a speed which will cause
the control s,ystem to sequentially upshift through each of
the four forward ratio gears. When the shift lever is placed
in drive, the control system connects the tor~ue converter
driven shaft to the output shaft through the first speed
ratio gear in the followiny secluence: l) Synchronîzer flange -
60a is moved slightly to the left by an appropriate actuator
(not shown) to effec-t a frictional connec-tion of the Eixs-t
gear 4~ to shaft ~0, whereby shaft 40, which is disconnectecl
from the OlltpUt shaft, is pulled up toward synchronous speed
with gear 4~ thereby rotating countershat 40 relatlve to
' , gear '68'said gear 68 is unclutched a-t this time; 2) Flange
60a will then move further to the lefk and clu-tch ~ear ~4 to
shaft 40 by the jaw clutch in the synchronizer when the
synchronous speed is reached; and 3) Clu-tch 48 is then
actuated by pressurized fluid. First gear is now fully engaged.
When engine load decreases and vehicle speed
increases to predetermined amounts, the torque converter '
driven shaf-t is connected to the output through the second
speed ratio gear in the following sequence: l) Synchronizer
f:lange 96a is moved sli~htly to -the left by an unshown
actuator to effect a frictional connection of the second gear
76 to sha-ft 72, whereby shaEt 72, which is disconnec-ted from
the outpu-t shaf-t, is pulled up -toward synchronous speed with
gear 76; 2) Flange 96a will then move further to the left and
,
cbr/~5 -15-
clutch ~ear 76 to shaft 72 by the ]aw clutch in the
synchronizer when the synchronous speed is reache~; 3)
Clutches ~8 and ~2 are then deactua-ted and actua-ted,
respectively, to drivin~ly disconnec-t shaft 40 and drivin~ly
connect shaft 72; and 4) Flan~e 60a is then
.
.. :
-15a-
cbr/~`S
33
-16-
moved back to its neutral position to clisengage the
synchronizer. Second gear is now full~ engaged and
first ~ear is disengayed. In the forectoing secluence '~
in upshifting to second ~ear, it shoulcl be noted that
shaft 72 is synchronized with gear 76 through a drive
connection wi.th the transmission input and while drive
is through the first gear and shaft 40. Such synchronizing
may be characterized as input synchronizing. The other
ratio gears and the associated countershafts are
synchronized in a like manner.
When engine load decreases and vehicle speed
increases to a predeter~ined amount., bypass shaft 13
is then connected to the output shaft through third
speed ratio ~ear 46 in a four step sequence simila.r to
the above sequence for second gear: 1) Flange 60a is
moved slightly to the right to frictionally connect
gear 46 to shaft 40, 2) When synchronous speed is
reached, flange 60a moves further to the right to engage
the synchronizer jaw clutch; 3~ Clutches 82 and 48 are
~0 deactuated and actuated, respectively; and 4) Flange 96a
is moved back to neu-tralO Third gear is now fully
engaged and the torque converter is automatically
b~passed.
The sequence for upshifting to four-th gear
should be obvious from the foregoing and it should
suffice to say that synchronizer 74 is actuated to the
right, clutches 48 and 82 are deactuated and actuated,
respectively, and synchronizer ~2 is disengaged.
Downshifting from fourth gear is merely the
reverse of the upshift sequence in that the ne~t lower
ratio gear is first synchronized with its respective
shaft while drive continues in the hicJher ratio, the
drive is then switched from one countershaft assembly
to the other by deactuating and actuating the ~luid
actuated clutches ~8 and 82.
33
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Assuming now that the vehicle operator wishes
to move the vehicle in the reverse di.rection, the shift
control lever is placed in the reverse position,
whereby the control system will connect the torque
converter driven shaft to the outpu-t shaft through
reverse gear 80 and idler assembly 108. The sequence
of events to effect drive in reverse may var~; one
sequence which may be automa-tically effected by the
control system is as follows: 1) Tor~ue converter
driven shaft 26 is pulled d~7n to a low speed by
momentarily effecting a driving connection to the output
shaft through countershaft assembly 36; this is done
by connecting irst gear ~ to shaft 40 and momentar:ily
actuating clutch 48 in the manner descri~ed for fort~7ard
lS drive in first gear; and 2) Clutch member 118, of the
clutch assembl~ 8~, is then resil.iently moved le~tward
by actuator 156 to effect interengag~ment O:e ~aw clutch
teeth 118a and 116.
The position of first gear 44 on countershaft
40 and reverse gear 80 on countershaft 7~ allows the
vehicle operator to power shift between irst and
reverse. Such power shifting is accomplished by moving
the shift control lever between drive and re~erse and
by programming the control system to momentarily delay
or leave reverse clutch 84 engaged and then actuating
and deactuating clutches 48 and 82 in accordance with
the position of the shift control lever. This facilitates
~uick reverse to forward power s~lifting which ~reatl~
enhances the operator's abilit~ to rock the vehicle as is
often necessary in sn~7 and mud conditions.
Looking n~7 at a feature provided b~ the
arrangement of the helical teeth of the gears in the
transmission, it .is w211 known in force analysis of
gears having meshed helical teeth that forces acting
on the contacting teeth of each gear ma~ be resolved
i~ltO tangential, radial, and axial components. The
:~13~133
-18~
tangential force component is useful si.nce it serves
to rotate the driven gear~ The radial and axial force
components on the other hand are not normally useful;
they merely add to bearing loads and te.nd to bend
the shaft that the gear is mounted on.
Looking now at the schematic illustration of
FXGURE 5, therein is shown gears 44, 46, and 68 which
are mounted on countershaft 40. These gears are
provided with helical teeth which are arrayed with a
helical hand such that the ~endin~ moments imposed
on shaft 40 by axial force components acting on gears
44, 46, and 68 will subtract from bending moments .
imposed on the shaft by radial orce components, thercb~
reducing the net bending forc~s on shaft 40 to a level
less than would be caused if the gears had the opposite
hana. More specificall~, gears M , 46, and 68 rotate .
counterclockwise when viewed fxom the left encl oE
shaft 40. Gears 44 and 46 are driven gears and gear 68
is a drive gear. The radial forces Erl, fr2, and fr3,
acting on these gears all act in the indicated directions
and tend to bend or bow the simply mounted shaf-t 40
upward. To counter the bending forces of frl, fr2, and
fr3, gears 44, 46, and 6~ each have left hand helical
teeth. Since gears 44 and 46 are driven gears, the
25 j axial forces fa~ and ~a2 on the helical contact teeth
of each will act to the left, thereby imposing a cloc~-
wise bending moment on their respective gears which
tends to ~end or bow shaft 40 downward. Since gear 68
is a drive gear, the axial force fa3 will act to the
right, thereb~ imposing a counterclockwise bending
moment on gear 68 which tends to bend or bow shaft 40
downward. Hence, it may be seen that the axial forces
subtract fxom the radial forces to decrease the net
bending forces acting on shaft 40. It s~ould be kept
in mind tha-t at any given t~ne, only one of gears 44
and 46 are engaged. The magnitude of the axial :Eorces
33
~19-
acting on each of the years 44, 46, and 68 may of couxse
be varied by var~in~ the degree of the helical angle
on each gear to balance the forces.
Gears 80, 76, 78, and 104 of countersha~t
assembly 3~ have helical teeth inclined in the sa~e
direction as the gear teeth of countersha-Et assembl~
36 and ~or the s~me reasons given for sha:Et 40 oE
countershaft assembly 36.
The preferred embodimen-ts of the invention
have been disclosed for illustrative purposes. Man~ ¦
variations and modifications of the preferred embodiment
are balieved to ba within the spi.rit o~ the invention.
The following claims are intended to cover the inventive
portions o~ the preferred embodiment and the vari.ati.on
and modification within the spirit o~ the invention~
.
