Patent Document

[0001]    This application claims priority to and the benefit of U.S. Provisional Application Nos. 61/446,157 and 61/446,173, filed Feb. 24, 2011, the full disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to an automatic transmission for a motor vehicle that includes planetary gearsets and clutches and brakes whose state of engagement and disengagement determines speed ratios produced by the transmission. 
         [0004]    2. Description of the Prior Art 
         [0005]    In a front wheel drive vehicle, the axial space available for the transmission is limited by the width of the engine compartment and the length of the engine. In addition, the trend to increase the number of ratios available generally increases the number of components required. For these reasons, it is desirable to position components concentrically in order to minimize axial length. The ability to position components concentrically is limited, however, by the need to connect particular components mutually and to the transmission case. 
         [0006]    Furthermore, it is desirable for the output element to be located near the center of the vehicle, which corresponds to the input end of the gear box. An output element located toward the outside of the vehicle may require additional support structure and add length on the transfer axis. With some kinematic arrangements, however, the need to connect certain elements to the transmission case requires that the output element be so located. 
         [0007]    An automatic transmission conventionally includes a manual valve, which is moved by a cable in response to manual movement of the gear selector to the selected range position. Shift-by-wire and range-by-wire selector systems usually have no manual valve, thereby requiring some other means to protect against energizing a solenoid or engaging a gear that is other than the solenoid or gear corresponding to the selected range. 
         [0008]    Generally the lube flow rate is set at a rate required to maximize the service life of the clutches, brakes, gears and bearings due to a maximum torque condition. This flow rate is usually greater than that required for normal driving conditions. 
         [0009]    A need exists for a device that provides both a lube path, in which lubricant flows to cool and lubricate the clutches, brakes, gears and bearings of the transmission and a parallel path to the sump. 
       SUMMARY OF THE INVENTION 
       [0010]    A system for controlling a transmission fluid circuit includes a lube circuit, a source of control pressure, a first valve for engaging and disengaging a control element whose engagement produces desired forward gears, and a control valve, responsive to control pressure, that alternately connects the lube circuit to a sump and disconnects fluid feed to the first valve, and disconnects the lube circuit from the sump and feeds fluid to the first valve. 
         [0011]    The automatic transmission control system includes no manual valve, yet the range-by-wire selector system of the transmission protects against energizing a solenoid or engaging a gear that is other than the solenoid or gear corresponding to the selected range. 
         [0012]    Due to the use of a OWC for first gear, only the ACL needs to be applied to engage first gear, without a manual valve. If this clutch inadvertently applies, first gear will engage, even outside of the driver selection of Drive. In the event of a failure of the ACL, the control valve will go to the OFF condition and the cut-off valve disconnects line pressure from the clutch whose engagement is required. 
         [0013]    The cut-off valve provides both a lube path in which lubricant flows to cool and lubricate the clutches, brakes, gears and bearings and a parallel path to the sump, thereby providing maximum lube flow when a maximum torque condition occurs. 
         [0014]    The scope of applicability of the preferred embodiment will become apparent from the following detailed description, claims and drawings. It should be understood, that the description and specific examples, although indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications to the described embodiments and examples will become apparent to those skilled in the art. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0015]    The invention will be more readily understood by reference to the following description, taken with the accompanying drawings, in which: 
           [0016]      FIG. 1  is a cross sectional side view of a multiple speed automatic transaxle; 
           [0017]      FIG. 2  is cross sectional side view of the transaxle showing the front and middle cylinder assemblies; 
           [0018]      FIG. 3  is a side perspective view showing sleeves that are fitted on the front support and middle cylinder assembly, respectively; 
           [0019]      FIG. 4  is a view cross sectional side view of the transfer gears and shaft near the output of the transaxle of  FIG. 1 ; 
           [0020]      FIG. 5  is a side view showing a motor mounted within valve body and above the elevation of the oil level in the valve body; 
           [0021]      FIG. 6  is a perspective view of the motor secured to a separator plate on the valve body; 
           [0022]      FIG. 7  is a perspective view showing the outer valve body, inner valve body, and the motor mounted on the inner valve body; 
           [0023]      FIG. 8  is a schematic diagram of a hydraulic control circuit for the transmission; and 
           [0024]      FIG. 9  is a table showing the applied and unapplied states of the clutches, brakes of the transmission and the solenoids of the control circuit of  FIG. 8 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0025]    Referring now to the drawings,  FIG. 1  illustrates gearing, clutches, brakes, shafts, fluid passages, and other components of a multiple-speed automatic transaxle arranged substantially concentrically about an axis  11 . 
         [0026]    A torque converter includes an impeller driven by an engine, a turbine hydrokinetically coupled to the impeller, and a stator between the impeller and turbine. A transmission input shaft  20  is secured by a spline connection  21  to the turbine. The stator is secured by a spline connection  22  to a front support  24 , which is secured against rotation to a transmission case  26 . 
         [0027]    A double pinion, speed reduction planetary gearset  28  includes a sun gear  30 , secured by a spline connection  31  to input shaft  20 ; a carrier  32 , secured by a spline connection  33  to the front support  24 ; a ring gear  34 , secured by a spline connection  35  to a front cylinder assembly  36 ; a first set of planet pinions  38  supported on carrier  32  and meshing with sun gear  30 ; and a second set of planet pinions  40 , supported on carrier  32  and meshing with ring gear  34  and the first pinions  38 . Ring gear  34  rotates in the same direction as input shaft  20  but at a reduced speed. 
         [0028]    Rear gearset  46  and middle gearset  48  are simple planetary gearsets. Gearset  46  includes a set of planet pinion  50  supported for rotation on carrier  52  and meshing with both sun gear  54  and ring gear  56 . Gearset  48  includes a set of planet pinions  58  supported for rotation on carrier  60  and meshing with both sun gear  62  and ring gear  64 . Sun gear  54  is splined to a shaft that is splined to a shell  66 , on which shaft sun gear  62  is formed, thereby securing the sun gears  54 ,  62  mutually and to the shell  66 . Carrier  52  is fixed to a shell  68 . Carrier  60  and ring gear  56  are fixed to each other and to output pinion  70  through a shell  72 . Ring gear  64  is fixed to shell  74 . 
         [0029]    Front cylinder assembly  36 , which is fixed to ring gear  34 , actuates clutches  76 ,  80 . Plates for clutch  76  includes plates splined to front cylinder assembly  36  alternating with plates splined to shell  74 . When hydraulic pressure is applied to piston  78 , the plates are forced together and torque is transmitted between ring gears  34  and  64 . When the hydraulic pressure is released, ring gears  34  and  64  may rotate at different speeds with low parasitic drag. Similarly, plates for clutch  80  include plates splined to front cylinder assembly  36  alternating with plates splined to shell  66 . When hydraulic pressure is applied to piston  82 , torque is transmitted between ring gear  34  and sun gears  54 ,  62 . Pressurized fluid is routed from a control body  84 , through front support  24 , into front cylinder assembly  36  between rotating seals. 
         [0030]    Middle cylinder assembly  86 , which includes carrier  32 , actuates brake  88 . Plates for brake  88  include plates splined to carrier  32  alternating with plates splined to shell  66 . When hydraulic pressure is applied to piston  90 , the brake holds sun gears  54 ,  62  against rotation. Pressurized fluid is routed from the control body  84 , through case  26  to front support  24 , between planet pinions  38 ,  40 , into middle cylinder assembly  86 . Due to the location of clutch pack  88 , output element  70  is located in the more favorable position near the front of the gear box. 
         [0031]    Rear cylinder assembly  92  is secured by a spline connection  93  fixed to input shaft  20 . When hydraulic pressure is applied to piston  94 , the plates of clutch  96  transmit torque between input shaft  20  and carrier  52 . Similarly, when hydraulic pressure is applied to piston  98 , the plates of clutch  100  transmit torque between input shaft  20  and sun gears  54 ,  62 . Pressurized fluid is routed from the control body  84 , through case  26  and cover  111  into rear cylinder assembly  92 . 
         [0032]    When hydraulic pressure is applied to piston  102 , brake  104  holds carrier  52  and shell  68  against rotation. A one-way brake  106  passively prevents carrier  52  and shell  68  from rotating in the negative direction, but allows them to rotate in the forward direction. One-way brake  106  may optionally be omitted and its function performed by actively controlling brake  104 . 
         [0033]    The D brake  104  is used only as a latching device not as a dynamic brake. To minimize parasitic viscous drag loss produced in brake  104  it is desired that excess oil not be present in the brake. Therefore, an oil dam formed by an oil seal  103  between the piston  94  of E clutch  96  and the inner race  107  of one-way brake  106  is provided to limit or prevent oil from entering the D brake  104 . The inner radial end of return spring  108  continually contacts the piston  102  that actuates brake  104 . The outer radial end of return spring  108  continually contacts a fixed structure, so that the spring flexes as the piston  102  moves in the cylinder of the D brake  104 . In this way, return spring  108  also participates in the oil dam by limiting or preventing radial flow of oil into the D brake  104  caused by centrifugal force. 
         [0034]    This arrangement permits brake  88  and clutches  76 ,  80  to be mutually concentric, located at an axial plane, and located radially outward from the planetary gearsets  28 ,  46 ,  48  such that they do not add to the axial length of the gearbox. Similarly, clutches  96 ,  100  and brake  104  are mutually concentric and located radially outward from the planetary gearing  28 ,  46 ,  48 . Clutches  76 ,  80 ,  96 ,  100  and brakes  88 ,  104 ,  106  comprise the control elements. 
         [0035]    As  FIGS. 2A ,  2 B illustrate, the front cylinder assembly  36  is supported for rotation on the fixed front support  24  and carrier  34 . The front cylinder assembly  36  is formed with clutch actuation fluid passages, each passage communicating with one of the cylinders  114 ,  116  formed in the front cylinder assembly  36 . Cylinder  114  contains piston  78 ; cylinder  116  contains piston  82 . One of the fluid passages in front cylinder assembly  36  is represented in  FIG. 2  by interconnected passage lengths  109 ,  110 ,  111 ,  112 , through which cylinder  116  communicates with a source of clutch control hydraulic pressure. Another of the fluid passages in front cylinder assembly  36 , which is similar to passage lengths  109 ,  110 ,  111 ,  112  but spaced angularly about axis  11  from passage lengths  109 ,  110 ,  111 ,  112 , communicates a source of clutch control hydraulic pressure to cylinder  114 . Passage lengths  109  are machined in the surface at the inside diameter of the front cylinder assembly  36 . 
         [0036]    The front cylinder assembly  36  is also formed with a balance volume supply passage, similar to, but spaced angularly about axis  11  from passage lengths  109 ,  110 ,  111 ,  112 . The balance volume supply passage communicates with balance volumes  120 ,  122 . As shown in  FIG. 2A , the balance volume supply passage includes an axial passage length  124 , which communicates with a source of balance volume supply fluid and pressure, and a radial passage length  126 , through which fluid flows into the balance volumes  120 ,  122  from passage  124 . Passage  124  may be a single drilled hole extending along a longitudinal axis and located between the two clutch balance areas of the A clutch and B clutch. Passage  124  carries fluid to cross drilled holes  126 , which communicate with the balance volumes  120 ,  122 . 
         [0037]    Coiled compression springs  128 ,  130 , each located in a respective balance dam  120 ,  122 , urge the respective piston  78 ,  82  to the position shown in  FIG. 2 . Ring gear  34  is secured to front cylinder assembly  36  by a spline connection  132 . 
         [0038]    Middle cylinder assembly  86  includes carrier  32 , which is grounded on the front support  24 . Carrier  32  includes first and second plates  134 ,  135  and pinion shafts secured to the plates, one pinion shaft supporting pinions  38 , and the other pinion shaft supporting pinions  40 . Plate  135  is formed with a cylinder  140  containing a brake piston  90 . 
         [0039]    A source of brake actuating hydraulic pressure communicates with cylinder  140  through a series on interconnected passage lengths  142 ,  143  and a horizontal passage length that extends axially from passage  143 , through a web of carrier  32 , between the sets of planet pinions  38 ,  40 , to cylinder  140 . These brake feed passages are formed in carrier  32 . When actuating pressure is applied to cylinder  140 , piston  90  forces the plates of brake  88  into mutual frictional contact, thereby holding sun gears  54 ,  62  and shell  66  against rotation. A Belleville spring  146  returns piston  90  to the position shown in  FIG. 2 , when actuating pressure is vented from cylinder  140 . 
         [0040]    The front support  24  is formed with passages, preferably spaced mutually about axis  11 . These passages in front support  24  are represented in the  FIGS. 1 and 2  by passage lengths  150 ,  151 ,  152 , through which hydraulic fluid is supplied to clutch servo cylinders  114 ,  116 , brake servo cylinder  140 , and balance dams  120 ,  122 . A passage of each of the front support passages communicates hydraulic fluid and pressure to cylinders  114 ,  116  and balance dams  120 ,  122  of the front cylinder assembly  36  through the fluid passages  109 ,  110 ,  111 ,  112 ,  113 ,  124  formed in the front cylinder assembly  36 . Another passage of each of the front support passages communicates hydraulic fluid and pressure to cylinder  140  of the middle cylinder assembly  86  through the fluid passages  142 ,  143  in carrier  32 . 
         [0041]    The front support  24  includes a bearing support shoulder  154 , which extends axially and over an axial extension  156  of the front cylinder assembly  36 . A bushing  158  and bearing  160  provide for rotation of the front cylinder assembly  36  relative to the front support  24 . This arrangement of the front support  24 , its bearing support shoulder  154 , and front cylinder assembly  36 , however, prevents radial access required to machine a passage or passages that would connect first passage  152  in front support  24  to the second passage  109  in the front cylinder assembly  36 . To overcome this problem and provide hydraulic continuity between passage lengths  109 ,  152 , first passage  152  is formed with an opening that extends along a length of first passage  152 , parallel to axis  11 , and through an outer wall of the front support  24 . The opening faces radially outward toward second passage  109 . Similarly, second passage  109  is formed with a second opening that extends along a length of second passage  109 , parallel to axis  11 , and through an inner wall of the front cylinder assembly  36 . The second opening faces radially inward toward first passage  152 . 
         [0042]    A first sleeve  162  is inserted axially with a press fit over a surface at an outer diameter of the front support  24 , thereby covering the opening at the outer surface of passage length  152 . Sleeve  162  is formed with radial passages  164 ,  165 , which extend through the thickness of the sleeve  162 . Seals  176 , located at each side of the passages  164 ,  165  prevent leakage of fluid from the passages. 
         [0043]    A second sleeve  170  is inserted axially with a press fit over the second opening at the inside diameter of the front cylinder assembly  36 , thereby covering and enclosing the length of the second opening in the second passage  109 . Sleeve  170  is formed with radial openings, two of which are represented in  FIG. 2  by openings  172 ,  174 , aligned with the radial passages  164 ,  165  formed in the first sleeve  162 . 
         [0044]    Sleeves  164  and  170  provides hydraulic continuity from the source of fluid pressure carried in the passages of the front support  24  to the balance dams  120 ,  122  and the servo cylinders  114 ,  116 ,  140 , through which clutches  76 ,  80  and brake  88  are actuated. 
         [0045]    Sleeves  162 ,  170  also provide access that enables machining of the first and second passages  152 ,  109  in the surface at the outside diameter of front support  24  and in the surface at the inside diameter of the front cylinder assembly  36 .  FIG. 3  shows sleeves  162 ,  170  and three seals  176 , which are fitted in recesses on sleeve  162  between each of its radial passages  164 ,  165 . 
         [0046]    As  FIG. 4  shows output pinion  70  meshes with a transfer gear  180 , which is formed integrally with transfer pinion  182  on a transfer wheel  184 . A transfer shaft  186 , is secured at one end by a pinned connection  188  to a non-rotating housing component  190 , and at the opposite end is seated in a recess  192  formed in a non-rotating torque converter housing component  194 . Ball bearing  198  supports transfer wheel  184  on the torque converter housing  194 . Housing components  190 ,  194  comprise a reaction component and may be formed integrally or preferably as separate components. 
         [0047]    Ball bearing  198  is supported radially by being seated on a surface  196  of the torque converter housing  194 . A shoulder  199  on torque converter housing  194  contacts the right-hand axial surface of the inner race of bearing  198 , the second surface of bearing  198 . A snap ring  200  contacts the right-hand axial third surface  201  of the outer race of bearing  198 . Shoulder  199  and snap ring  200  limit rightward axial movement of bearing  198 . 
         [0048]    A shoulder  202  formed on gear wheel  184  contacts the left-hand axial first surface of the outer race of bearing  198 . A thrust washer  204  contacts a left-hand axial fourth surface  205  of the inner race of bearing  198 . The thrust washer  204  contacts a shoulder  206  formed on transfer shaft  186 . Shoulders  202  and  206  limit leftward axial movement of bearing  198   
         [0049]    The ring gear  210  of a differential mechanism  212  meshes with transfer pinion  182  and is supported for rotation by bearings  214 ,  216  on housing  190 ,  194 . Rotating power transmitted to output pinion  70  is transmitted through transfer gears  180 ,  182  and ring gear  210  to the input of differential, which drives a set of vehicle wheels aligned with axis  220 . 
         [0050]    A roller bearing  222  supports transfer wheel  184  on transfer shaft  186 . The thickness of a washer  224 , fitted in a recess  226  of housing  190 , is selected to ensure contact between thrust washer  204  and the inner race of bearing  198 . 
         [0051]    The output pinion  70  and transfer gears  180 ,  182  have helical gear teeth, which produce thrust force components in the axial direction parallel to axis  220  and in the radial direction, normal to the plane of  FIG. 4 . A thrust force in the right-hand direction transmitted to the transfer gear wheel  184  is reacted by the torque converter housing  194  due to its contact at shoulder  199  with bearing  198 . A thrust force in the left-hand direction transmitted to the transfer gear wheel  184  is reacted by the housing  190  due to contact between snap ring  200  and bearing  198 , contact between bearing  198  and thrust washer  204 , contact between the thrust washer and transfer shaft  186 , and contact between shaft  186 , washer  224  and housing  190 . 
         [0052]    As shown in  FIG. 1A , the D brake  104  includes a first set of thin discs  230  secured to the outer race  232  of one-way brake  106  by a spline connection, which permits the discs  230  to move axially and prevents them from rotating relative to the race  232 , which is fixed to the transmission case or end cover against rotation. 
         [0053]    Similarly, the D brake  104  includes a second set of thin discs  234  secured to the inner race  107  of one-way brake  106  by a spline connection, which permits the discs  234  to move axially and prevents them from rotating relative to the inner race  107 . Inner race  107  is fixed to the carrier  68  of gearset  46 , such that they rotate together as a unit at the same speed. Preferably the outer and inner races  232 ,  107  of one-way brake  106  are formed of a ferrous alloy of sintered powdered metal, and discs  230 ,  234  are of steel. Preferably the one-way brake  106  is a rocker one-way brake of the type having a pivoting rockers, each rocker retained is a pocket and actuated by centrifugal force and a compression spring, as described in U.S. Pat. Nos. 7,448,481 and 7,451,862. 
         [0054]    The reaction spline for the D clutch  104  is preferably not formed in the aluminum case or end cover because of high local stresses caused by the thin discs  232 ,  234  used to reduce parasitic loss. The D clutch reaction splines are formed as an integral part of the raceways of the one-way brake  106 . The brake  106  is then splined to the transmission case. 
         [0055]      FIG. 5  is a side view showing an electric motor  290 , preferably a brushless motor, mounted within an inner valve body  292  and above the elevation  294  of the oil level in the valve body  292 , such that the motor is not submerged in the oil. The rotor  296  of a hydraulic pump  298  runs against a separator plate  300 . No seal is required between the motor  290  and pump  298 . Due to its elevation the motor  290  is vented to atmosphere, thereby improving the operating efficiency of the electrically driven pump, sometimes called an E -pump. The inlet of pump  298  is connected to a source of filtered automatic transmission fluid (ATF), i.e., oil. 
         [0056]      FIG. 6  is a perspective view of the motor  290  and pump  298  secured through the separator plate  300  to the valve body  292 . 
         [0057]      FIG. 7  is a perspective view showing an outer valve body  302 , which contains solenoids, located adjacent the inner valve body  292 , which contains valves that are actuated by the solenoids to control operation of the transmission. 
         [0058]    Referring now to  FIG. 8 , the hydraulic circuit includes a cut-off lube control valve  310 ; a SS 1  solenoid-operated valve  312 , which responds to solenoid feed pressure in line  313 ; a source cooled clutch feed fluid  314  connected to an oil cooler  316 ; a source of line pressure  317  produced by an engine-driven pump  326 ; an lube line  324  connecting valve  310  to an elevated clutch vent  319  at an oil sump; a line  320  that feeds oil to a clutch, such as A clutch  78 ; and a line  322  carrying pressure from valve  312  to valve  310 . 
         [0059]    Regulated line pressure LP is carried in line  317 . Output from pump  326  is supplied to a main oil pump valve  301 , which regulates line pressure in response to a line pressure control signal LPC carried in line  302  to valve  301  from a solenoid-operated LPC valve  303 . Solenoid pressure SF is carried in line  313  from a source of solenoid pressure, i.e., the output a variable displacement solenoid—actuated valve, to the line pressure control solenoid valve  303  and to SS 1  valve  312 . 
         [0060]    When pressure in line  322  from SS 1  valve  312  is high, the spool of valve  310  moves against the force of its compression spring to the left-hand end of its valve chamber, thereby connecting line  317  from line  320 , which carries pressure to A clutch  78 . Clutch feed pressure is carried in lines  317  to the six control element, i.e., the clutches and brakes from a source of clutch feed pressure. Line  314  carries ATF to the lube circuit  324 , which supplies the balance dams  120 ,  122 , and balance dams in clutches  96  and  100 . 
         [0061]    When pressure in line  322  from valve  312  is low, valve  310  shuttles to the right-hand end of the valve chamber, thereby connecting line  314  and line  318 . An orifice  419  can be used to control the flow rate in line  318  to the sump  331  from valve  310 . 
         [0062]    Generally the lube flow rate is set at a rate required to maximize the service life of the clutches, brakes, gears and bearings due to a maximum torque condition. This flow rate, however, is greater than that required for normal driving conditions. Valve  310  provides both a lube path, in which lubricant can flow to cool and lubricate the clutches, brakes, gears and bearings and a parallel path to the sump  331 . 
         [0063]    The hydraulic circuit supplies filtered ATF drawn from sump  331  to an auxiliary pump  298 , driven by brushless motor  290 . When the vehicle includes an automated start-stop function, which automatically stops the engine at a traffic light or when no torque is demanded and automatically restarts the engine when torque is demanded, the auxiliary pump valve  330  is supplied through pump  298  and line  332  with ATF from sump  331 . 
         [0064]    In operation, when regulated line pressure in line  317  is high, valve  330  shuttles to the left-hand end of its chamber, thereby connecting fluid in line  332  from the E-pump  298  to line  334 , oil cooler  316 , line  314  and lube circuit  324 . 
         [0065]    When line pressure in line  318  is low, the spool of valve  330  moves to the right-hand end of its chamber, thereby disconnecting the outlet of pump  298  from line  334 , cooler  316  and lube circuit  313  and connecting circuit  332  to line pressure circuit  317 . 
         [0066]    In this way, when the engine is running, the engine-driven hydraulic pump  326  is running, and regulated line pressure to be high, AFT from E-pump  298  increases the ATF flow rate to the cooler  316 , thereby helping to reduce the temperature of ATF in the hydraulic circuit, and to lube circuit  324 , thereby increasing the flow of lubricant that lubricates the transmission. This operation of the E-pump  298  and motor  290  can occur, without limitation, when the vehicle is towing a heavy load, or immediately following a high engine torque condition, or whenever ATF temperature is high, and combination of these conditions. 
         [0067]    An automatic transmission conventionally includes a manual valve, which is moved by a cable in response to manual movement of the gear selector to the selected range position. Shift-by-wire and range-by-wire selector systems usually have no manual valve. The range-by-wire system of this transmission therefore requires some means to protect against energizing a solenoid or engaging a gear that is other than the solenoid or gear corresponding to the selected range. 
         [0068]    When the spool of valve  310  moves to the right-hand end of the chamber due to low pressure from SS 1  valve  312  in line  322 , line pressure  317  entering at the inlet port of valve  310  is blocked by valve  310 , thereby preventing line pressure from being feed through PC 1 F line  320  to the A clutch  76 , and directing clutch feed pressure in CF line  314  through the elevated clutch vent  319  to sump  331 . Due to low pressure in line  322 , the A clutch  78  is disengaged because no actuating pressure is feed to clutch  78 . As indicated in the clutch/solenoid application chart of  FIG. 9 , the A clutch  78  must be engaged to produce the first through fifth forward gears. Pressure in line  322  is low when the range-by wire system selects a range other than the gears one through five. 
         [0069]    When valve  310  shuttles to the left-hand end of the chamber due to high pressure from SS 1  valve  312  in line  322 , line pressure in line  317  at the inlet port of valve  310  is connected through valve  310  to PC 1 F line  320 , thereby connecting line pressure to valve  340 , which feeds shift control pressure to the A clutch  78  subject to control of PC 1  solenoid  342 . Also CF line  314  is disconnected from sump  331  through line  318  and vent  319 . This action allows the A clutch  76  to engage, thereby enabling each of the first five lowest forward gears to engage as required and allowing a high rate oil flow to the lube circuit  324 , due to valve  310  disconnecting line  314  from line  318  to sump  331 . Pressure in line  322  is high when the range-by wire system selects the DRIVE range with gears one through five. 
         [0070]    Therefore, even without a manual valve and while pressure in SS 1  line  322  is low, the first through fifth gear cannot be produced, but reverse drive and sixth, seventh and eighth forward gears can be produced, thereby permitting the vehicle to be driven. In the event of a failure of the ACL in the ON condition in conjunction with the OWC, the result would be first gear in Neutral and Park, but the cut-off valve  310  can disconnect line pressure in LP line  317  from PC 1 F line  320  to the A clutch  78  through ACL line  344 , allowing the A clutch to disengage and producing no first gear. 
         [0071]    In accordance with the provisions of the patent statutes, the preferred embodiment has been described. However, it should be noted that the alternate embodiments can be practiced otherwise than as specifically illustrated and described.

Technology Category: 4