Abstract:
A lawnmower including a frame, an engine having an electrical system and attached to the frame, the engine being started by a starter mechanism. A mower deck assembly having a rotating blade is connected to the frame with the blade being selectively engaged with the engine. A reversible transmission is driven by the engine and includes a shift mechanism having a forward, a neutral, and a reverse position, and at least one sensor for sensing the position of the shift mechanism. The sensor is capable of at least one of directing a signal to the mower deck assembly for operation and non-operation of the mower deck assembly and directing a signal to the starter circuit for prevention of start-up when the shift mechanism is not in the neutral position.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 60/402,806, filed Aug. 12, 2002. The entire disclosure of U.S. Provisional Application No. 60/402,806, filed Aug. 12, 2002 is hereby expressly incorporated by reference herein. 
     
    
     
       BACKGROUND  
         [0002]    The present invention relates to transmissions intended primarily for use in the lawn and garden industry on working vehicles such as tractors, riding lawnmowers, lawn and garden implements and the like.  
           [0003]    It is useful to provide a “neutral switch” for use with a working vehicle so that an operator is prevented from starting or activating the vehicle when the vehicle&#39;s transmission is engaged. Such a neutral switch advantageously prevents the vehicle from lurching in a forward or reverse direction on start up.  
           [0004]    Working vehicles include potentially dangerous working devices. For example, riding mowers, including most lawn tractors and garden tractors, include potentially dangerous rotating blades which comprise part of the mower deck and may cause injury to the operator or a bystander. It is desirable to disable the rotating blades of a riding mower when the mower is moving in a reverse direction to prevent possible injury to the operator, a bystander, or nearby property.  
         SUMMARY OF THE INVENTION  
         [0005]    The invention, in one form thereof, comprises an axial piston hydrostatic transmission including a variable displacement axial piston pump, an input shaft rotatably connected to the pump, whereby rotation of the input shaft causes rotation of the pump, an axial piston motor hydraulically connected to the pump, an output shaft rotatably connected to the motor, whereby rotation of the motor causes rotation of the output shaft, a pivotable swash plate associated with the pump, whereby movement of the swash plate controls the speed and direction of the hydrostatic transmission, the swash plate movable between a forward position, a neutral position, and a reverse position, a center adjacent the swash plate, the center operable to sense the position of the swash plate, and a switch connected to the sensor, the switch movable between a closed position and an open position in response to the sensor. In one form of the present invention, the swash plate includes an exterior surface, with the center abutting the exterior surface to, advantageously, directly sense whether the transmission is in forward, neutral, or reverse.  
           [0006]    When referring to swash plate position, a forward position of the swash plate indicates a position of the swash plate in which the vehicle driven by the hydrostatic transmission is being moved forward by the hydrostatic transmission. Similarly, a neutral position of the swash plate corresponds to a neutral condition of the vehicle driven by the hydrostatic transmission, that is, the transmission is not moving the vehicle. Finally, a reverse position of the swash plate indicates a position of the swash plate in which the vehicle driven by the hydrostatic transmission is being moved in a reverse direction by the hydrostatic transmission.  
           [0007]    The invention, in another form thereof, comprises a gear transmission including a plurality of mechanically selectable forward gears, and mechanically selectable reverse gear, a neutral spacer, a shift key for selectively one of the plurality of forward gears on the reverse gear, a shift fork connected to the shift key, whereby movement of the shift fork causes movement of the shift key to control the speed and direction of the transmission, the shift fork movable between a forward position, a neutral position, and a reverse position, a center adjacent said shift fork, the center operable to sense the position of the shift fork, and a switch connected to the sensor, the switch movable between a closed position and an open position in response to the sensor. In one form of the present invention, the sensor abuts an exterior surface of the shift fork to, advantageously, directly sense whether the transmission is in a forward, neutral, or reverse condition.  
           [0008]    With reference to shift fork position, a forward position of the shift fork indicates a position of the shift fork in which the vehicle driven by the transmission is being moved forward by the transmission. Similarly, a neutral position of the shift fork corresponds to a neutral condition of the vehicle driven by the transmission, that is, the transmission is not moving the vehicle. Finally, a reverse position of the shift fork indicates a position of the shift fork in which the vehicle driven by the transmission is being moved in a reverse direction by the transmission.  
           [0009]    The aforementioned hydrostatic and gear transmissions are, in one form of the present invention, utilized in a lawnmower having a mower deck with a rotatable blade connected thereto.  
           [0010]    The invention, in yet another form thereof, comprises a sensing and disabling system for a lawnmower to prevent operation of a mower deck assembly while in reverse and to prevent startup of the mower if not in neutral, including an engine, a transmission having a selectively entered reverse condition, a selectively entered forward condition, and a selectively entered neutral position, the transmission being selectively driven by the engine, a mower deck assembly selectively driven by said engine, a first sensor in communication with said transmission and the mower deck assembly, the first sensor preventing operation of the mower deck assembly when the first sensor senses the transmission is in the reverse condition, and a second sensor in communication with the transmission and the engine, the second sensor preventing start-up of the engine when the second sensor senses the transmission is in either the forward or the reverse position. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The above-mentioned and other features and objects of this invention will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:  
         [0012]    [0012]FIG. 1 is a perspective view of a riding lawnmower having the inventive electrical means for sensing reverse and/or neutral feature incorporated therein;  
         [0013]    [0013]FIG. 2 is a rear view of a manual shift transaxle including the electrical means for sensing reverse and/or neutral;  
         [0014]    [0014]FIG. 3A is a sectional view of the transaxle of FIG. 2 along line  3 A- 3 A thereof;  
         [0015]    [0015]FIG. 3B is a sectional view of the transaxle of FIG. 3A along line  3 B- 3 B thereof;  
         [0016]    [0016]FIG. 4A is an enlarged view of the shift fork of the transaxle of FIG. 3A;  
         [0017]    [0017]FIG. 4B is an enlarged end view of the shift fork of FIG. 3A;  
         [0018]    [0018]FIG. 5A is a top schematic view of a transaxle having a means for sensing reverse and a means for sensing neutral in accordance with the present invention;  
         [0019]    [0019]FIG. 5B is a side schematic view of a portion of a shift fork and the two means of FIG. 5A;  
         [0020]    [0020]FIG. 5C is a side schematic view of an alternative arrangement of the shift fork and two means for sensing;  
         [0021]    [0021]FIG. 6A is an exploded view of a hydrostatic transmission including the electrical means for sensing reverse and/or neutral incorporated therein;  
         [0022]    [0022]FIG. 6B is a sectional view of a hydrostatic transaxle including the hydrostatic transmission module of FIG. 6A;  
         [0023]    [0023]FIG. 7 is a rear cross-sectional view of the assembled hydrostatic transmission of FIG. 6A taken along line  7 - 7  of FIG. 6A including the electrical means for sensing reverse and neutral;  
         [0024]    [0024]FIG. 8 is a partial fragmentary view of the hydrostatic transmission of FIG. 6 showing the swash plate and switch associated with the electrical means for sensing, as viewed from the bottom of the upper casing half;  
         [0025]    [0025]FIG. 9A is a top perspective view of a swash plate used with the hydrostatic transmission of FIG. 6 in which the swash plate is structured for reverse sensing only;  
         [0026]    [0026]FIG. 9B is a top view of the swash plate of FIG. 9A;  
         [0027]    [0027]FIG. 9C is a side, partial cutaway view of the swash plate of FIG. 9A;  
         [0028]    [0028]FIG. 10 is a perspective view of a swash plate used in accordance with the electrical means for sensing neutral;  
         [0029]    [0029]FIG. 11A is a perspective view of a swash plate used in accordance with the electrical means for sensing reverse and neutral;  
         [0030]    [0030]FIG. 11B is a top view of the swash plate of FIG. 11A;  
         [0031]    [0031]FIG. 11C is a perspective view of the swash plate of FIG. 11A with two switches and two sensors in accordance with the present invention;  
         [0032]    [0032]FIG. 12 is a bottom view of the swash plate of FIG. 9A with the sensor and switch for sensing reverse, the swash plate being positioned such that the transaxle is in the reverse position;  
         [0033]    [0033]FIG. 13 is a bottom view of the swash plate and the switch of FIG. 12 with the swash plate being positioned in the neutral position;  
         [0034]    [0034]FIG. 14 is a bottom view of the swash plate of FIG. 12 with the swash plate being positioned in the forward position;  
         [0035]    [0035]FIG. 15 is an electrical schematic diagram showing the connection of the electrical means for sensing reverse and the electromagnetic clutch associated with the mower deck assembly;  
         [0036]    [0036]FIG. 16 is an electrical schematic diagram showing two electrical means for sensing, one for reverse sensing and one for neutral sensing, being connected to the electromagnetic clutch of the mower deck assembly and the starter mechanism of the mower, respectively; and  
         [0037]    [0037]FIG. 17 is a flow chart showing the operation of a reverse sensing switch. 
     
    
       [0038]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0039]    For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.  
         [0040]    Referring first to FIG. 1, mower  20  has engine  22  mounted to frame  24  and mower deck assembly  26  mounted on the frame&#39;s underside. At the rear of mower  20  is transaxle  28  having axle  30  with ground engaging wheels  32  mounted at the ends thereof. Two ground engaging wheels  32  are also located at the front of mower  20 . An operator can selectively operate transaxle  28  through manual shift lever  33  extending from transaxle  28 .  
         [0041]    As shown in FIG. 3A, transaxle  28  includes a manual shift transmission, such as that disclosed in U.S. Pat. No. 5,287,769, issued Feb. 22, 1994, U.S. Pat. No. 4,966,574, issued Oct. 30, 1990, and U.S. Pat. No. 4,791,825, issued Dec. 20, 1998, all of which are assigned to the assignee of the present invention, the complete disclosures of which are expressly incorporated herein by reference.  
         [0042]    Referring now to FIG. 2, a rear exterior view of transaxle  28  is shown, with transaxle  28  having two casing halves, upper casing half  34  and lower casing half  36 , which abut at horizontal interface  38 . Upper casing half  34  and lower casing half  36  are joined together by bolts  40  inserted through apertures in bosses  42  on upper casing half  34 , and threaded into threaded apertures of bosses  44  on lower casing half  36 . As can be seen, a portion of axle  30 , which is supported by the transaxle casing, extends from either end of transaxle  28  to be attached to a ground engaging wheel  32 .  
         [0043]    Transaxle  28  is shown in FIG. 3A, and further includes conventional differential mechanism  46  through which the two respective portions of axle  30  are coupled to the gear train. Ring gear  48  of differential  46  intermeshes with gear  50  mounted on shaft  52  to transfer motion from the rest of the gear train to differential  46 . Within transaxle  28 , output gear set  54  is rotatably disposed on shaft  56  and intermeshes with input gear set  58 , comprising gears which are individually rotatably fixed onto shaft  60  via splines. Gear sets  54  and  58  each include a plurality of gears of varying diameters. One forward gear of output gear set  54  is selected through the key shift mechanism to obtain one of a plurality of forward speeds when operating mower  20 . Also rotatably mounted on shaft  56  are reverse gear  62  and neutral spacer  64 . Mounted on shaft  52  is gear  66  intermeshing with small gear  68  mounted on shaft  56 .  
         [0044]    Surrounding shaft  56  and extendable through the forward gears of gear set  54 , gear  62  and spacer  64 , is sleeve  70  having key  72  disposed thereon and in communication with shift collar  74 . Key  72  moves to engage the gear or spacer selected by the operator using manual shift mechanism  33  (FIG. 1) to select one of the reverse, neutral or forward speeds. As can be seen, each gear of gear set  54 , gear  62  and spacer  64  is provided a recess  76  in which the tines of key  72  are received to select that particular gear or spacer. Engaged with shift collar  74  is shift fork  78  (FIG. 3B), which is rotatably fixed to shaft  80  (FIGS. 4A and 4B).  
         [0045]    Referring now to FIGS. 3B, 4A, and  4 B, it can be seen that shift fork  78  and plate  82  share shaft  80 . Both shift fork  78  and plate  82  are attached via a known attachment method, such as, for example, brazing or use of a key and keyway, to shaft  80  such that as shaft  80  is rotated both shift fork  78  and plate  82  are rotated as well. Shift fork  78  further includes pins  88  therein for engagement with shift collar  74 , such that as shaft  80  and shift fork  78  are rotated, pins  88  which engage shift collar  74  move the tines of key  72  to the selected forward gear of gear set  54 , reverse gear  62 , or neutral spacer  64 .  
         [0046]    As illustrated in FIGS. 3B and 4A, shift fork  78  includes oblong hole  89  in portion  79  of shift fork  78  surrounding shaft  80 . As illustrated in FIG. 3B, switch  84  is mounted proximate shaft  80  in transaxle  28  and includes ball sensor  86  which abuts shift fork  78  such that as shift fork  78  is rotated, ball sensor  86  rides over portion  79  until reaching hole  89 . Oblong hole  89  is positioned such that ball sensor  86  will be seated within hole  89  when the operator has selected reverse, or shift fork  78  is moved into a position whereby key  72  will select gear  62 . Thus, when the transmission has been shifted into reverse, an electronic signal is not directed by the switch to the electromagnetic clutch associated with mower deck assembly  26 , and the mower blades are not operational. At all other times, i.e., when a forward gear of gear set  54  or neutral spacer  64  has been selected, ball sensor  86  is riding on and pressed against the surface of portion  79 , and a signal is directed by the switch to the electromagnetic clutch, and mower deck assembly  26  may be operated. When the transmission has been shifted into neutral or forward, switch  84  is closed, thereby causing an electronic circuit between switch  84  and clutch  134  (FIG. 15) to be complete. When transaxle  28  is shifted into reverse and gear  62  is selected, switch  84  is opened, and the circuit is interrupted and mower deck assembly  26  becomes nonoperational. Oblong hole  89  may be replaced with a depression formed in shift fork  79  for the purposes of this document, “depression” is inclusive of a hole  
         [0047]    Alternatively, the inventive means may instead comprise a switch which may be in an open position when its sensor is riding on the surface of portion  79 , so that a circuit between the switch, and clutch  134  is interrupted and allows operation of mower deck assembly  26 . The circuit is complete, or closed, when switch  84  is closed, or the sensor  86  is extending into oblong hole  89 .  
         [0048]    It is to be noted that although sensor  86  is shown as extending into oblong hole  89  when transmission  28  is shifted into reverse, by adjusting the width of hole  89 , sensor  86  may extend into hole  89  when transmission  28  is moved to a forward or neutral position. Again, a circuit between switch  84 , sensor  86 , and electromagnetic clutch  134  is either completed, or interrupted, dependent upon the position of sensor  86  and whether the circuit is to be used to prevent operation of mower deck assembly  26  or used to allow operation of mower deck assembly  26 .  
         [0049]    Although transmission  28  is shown has having five forward gears, transmission  28  may alternatively include additional forward gears to provide further options to the operator of mower  20 . If a different transmission  28  is utilized, the structure of shift fork  78 , plate  82 , and shaft  80  may require modifications to accommodate the changes to transmission  28 .  
         [0050]    A portion of transmission  28 , specifically within upper casing half  34 , is schematically illustrated in FIGS. 5A and 5B as including two sensors  86 , designated as  86 A and  86 B, in association with two switches  84 , designated as  84 A and  84 B. Wires  85  extend from switches  84 A and  84 B for electrical connection to, e.g., an electrical power supply (not shown), such as a battery (not shown) or the magneto (not shown) of engine  22 . Included in shift fork portion  79  are two holes  89 A and  89 B, one for each sensor  86 . Through arrangement of holes  89 A and  89 B, as shown in FIG. 5B, sensor  86 A will be seated within hole  89 A when shift fork  78  is moved into a reverse position while sensor  86 B will be seated in hole  89 B when shift fork  78  is moved into the neutral position, thereby providing sensing for both the reverse and neutral positions. One wire  85  of each pair is electrically connected to either electromagnetic clutch  134  or starter mechanism  136  (see FIG. 16), with the other wire of the pair connected to power source  22 . With reference to FIG. 5C, an alternative structure of sensors  86 A and  86 B and switches  84 A and  84 B is shown in which switches  84 A and  84 B are arranged in a horizontal side-by-side relationship and a single, larger hole  89  is used in place of holes  89 A and  89 B for receipt of sensors  86 A and  86 B.  
         [0051]    Referring now to FIGS. 6A and 6B, transmission  90  is a hydrostatic transmission such as that disclosed in U.S. Pat. No. 6,422,109, issued Jul. 23, 2002, and assigned to the assignee of the present invention, the complete disclosure of which is expressly incorporated herein by reference. Transmission  90  includes pump  92  and motor  94  mounted on center section  96 , all of which are contained within casing  98 . Casing  98  includes upper half  100  and lower casing half  102  secured together by bolts  104  extending through apertures in bosses  106  on lower casing half  102  and threaded into threaded apertures in bosses  108  on upper casing half  100 .  
         [0052]    Transmission  90 , specifically variable displacement pump  92 , is controlled by control rod  110  in communication with swash plate  114  of swash plate assembly  112 . As control rod  110  is rotated, swash plate  114  is pivoted to vary the displacement of fluid pump  92  and control the speed and direction of transmission  90 . Transmission  90  is connected to axle assembly  31  (FIG. 6B) to create a transaxle structure for mower  20 . Within axle assembly  31 , ring gear  48 ′ of differential  46 ′ intermeshes with gear  50 ′ mounted on shaft  52 ′ to transfer motion to differential  46 ′ and subsequently to axles  30 ′. Gear  66 ′ is mounted on shaft  52 ′ and intermeshes with small gear  68 ′ on shaft  56 ′, which may be piloted to motor output shaft  95  as illustrated. When shafts  95  and  56 ′ are joined by the collar of disconnect mechanism  91 , rotary motion is transferred from transmission  90  to axles  30 ′ through gears  66 ′,  68 ′, and  50 ′ and differential  46 ′. The axle assembly, differential, reduction gearing, and mechanical disconnect mechanism are described in further detail in U.S. Pat. No. 6,422,109, incorporated above.  
         [0053]    Referring to FIG. 7, in a manner similar to transaxle  28 , transmission  90  includes switch  84 ′ and sensor  86 ′ mounted on casing  98  and extending into transmission  90 . However, where sensor  86  rode along the surface of shift fork  78  of transaxle  28 , sensor  86 ′ instead rides along side  123  of swash plate  114  (FIG. 8) located opposite side  121  which is in contact with control rod  110 .  
         [0054]    Control rod  110  includes arm  116  and connector  118  for connection to swash plate  114 , with the rotation of control arm  110  causing arm  116  and connector  118  to rotate, thereby causing swash plate  114  to pivot and create fluid displacement within pump  92 . With reference to FIG. 8 showing the upper half of transmission  90  from the bottom and bottom  119  of swash plate  114 , it can be more easily seen that control rod  110 , arm  116  and connector  118  would be connected to swash plate  114  on side  121  of swash plate  114  while sensor  86 ′ would be in abutting engagement with swash plate  114  on opposite side  123  of swash plate  114 . The operation of transmission  90  and the movement of swash plate  114  is described in further detail in U.S. Pat. No. 6,422,109, incorporated above.  
         [0055]    [0055]FIGS. 9A, 9B,  9 C,  10 ,  11 A, and  11 B depict different structures of swash plate  114  with those of FIGS. 9A, 9B, and  9 C being for reverse sensing only, the structure of FIG. 10 for neutral sensing only, and the structures in FIGS. 11A and 11B being for a combination of reverse and neutral sensing; all three structures would be operated in the manner as described above.  
         [0056]    On one side of swash plate  114   a , shown in FIGS. 9A, 9B, and  9 C, are two extending portions  120  which will receive connector  118  therebetween for control of movement of swash plate  114   a ; such extending portions  120  are common to all three swash plate structures. On opposite side  123  of swash plate  114   a  is a single raised area  122   a  which depresses sensor  86 ′ when swash plate  114   a  is rotated into either a neutral or a forward position. The portion of swash plate  114   a  not having raised area  122   a  is the portion of the swash plate along which ball sensor  86 ′ would ride when swash plate  114   a  is rotated into the reverse position. In this position, sensor  86 ′ would not be depressed inwardly.  
         [0057]    Referring now to FIG. 10, swash plate  114   b  has been modified from swash plate  114   a  and is disclosed in further detail in U.S. Pat. No. 6,378,300, issued Apr. 30, 2002, and assigned to the assignee of the present invention, the complete disclosure of which is expressly incorporated herein by reference. Swash plate  114   b  includes extending portions  120 , as with swash plate  114   a , but instead of a single raised area has two raised areas, raised area  122   b  and secondary raised area  124 . Raised area  122   b  covers that portion of swash plate  114   b  which would be in an abutting relationship with ball sensor  86 ′ when in the forward position only. Raised area  124  represents the area of swash plate  114   b  that would be in an abutting relationship with ball sensor  86 ′ when rotated to the reverse position. It is to be noted that both raised areas  122   b  and  124  have the same lateral level, whereas area  130  located on side  123  between raised areas  122   b  and  124  has a reduced lateral level to form a recess in the form of a groove in side  123 . Thus, swash plate  114   b  of FIG. 10 is used for neutral sensing only, since that portion of the swash plate not having either raised area  122   b  or  124  represents the zero displacement of swash plate  114   b , or when transmission  90  has been shifted into the neutral position.  
         [0058]    [0058]FIGS. 11A and 11B show third embodiment swash plate  114   c  that is used for both neutral sensing and reverse sensing. Swash plate  114   c  has several raised portions, including raised area  122   c  similar to raised area  122   b  (FIG. 10) and which represents that area of swash plate  114   c  that would be in abutting engagement with ball sensor  86 ′ when in the forward position. Unlike swash plates  114   a  and  114   b , swash plate  114   c  further includes laterally raised areas  126  and  128  and two slightly depressed areas  130  and  132 . Laterally raised area  126  extends from raised area  122   c  and is positioned on swash plate  114   c  in a portion of the area which represents the neutral area of swash plate  114   c , or the non-raised area of swash plate  114   b  if compared thereto. Laterally raised area  128  is positioned in a portion of the area of swash plate  114   c  which would abut sensor  86 ′ if a single sensor  86 ′ were used for reverse sensing only, or the non-raised area of comparable swash plate  114   a . In other words, swash plates  114   a  and  114   b  have been combined to a certain extent to create swash plate  114   c  which interacts with two sensors  86 ′, designated as  86 A′ and  86 B′ for sensing of neutral and reverse (FIG. 11C). As stated, two sensors  86 A′ and  86 B′, and thereby two switches  84 A′ and  84 B′, would be used in conjunction with swash plate  114   c  with sensor  86 A′ mounted such that it senses the reverse position of the swash plate, or sensor  86 A′ would follow arc  138  as swash plate  114   c  is rotated, while sensor  86 B′ senses the neutral position, or sensor  86 B′ would follow arc  139 . Ball sensor  86 A′ would be sensing for whether it is abutting laterally raised areas  122  or  126  or extending to touch area  132 , while second sensor  86 B′ would be sensing for laterally raised areas  122  or  128  or extending to area  130 .  
         [0059]    Referring to FIGS. 12, 13,  14 , and  17 , the operation of the ball sensor  86 ′ with switch  84 ′ will be described with reference to a reverse sensing mechanism only. As shown in FIGS. 12 and 17, swash plate  114   a  has been rotated into the position desired by the operator at the time, (block  140 ), in this case the reverse position. Ball sensor  86 ′ is not pressed inwardly by any raised portions on swash plate  114   a  but rather extends outwardly, thus allowing ball sensor  86  to detect the reverse position (blocks  142  and  144 ). Since ball sensor  86 ′ is not pushed inwardly, the electrical connection is not complete and no electronic signal is sent from switch  84 ′ (block  146 ), thereby preventing electromagnetic clutch  134 , which controls the mower deck assembly  26 , from being operational.  
         [0060]    As shown in FIGS.  13 , ball sensor  86 ′ is pressed inwardly as it reaches the edge of raised area  122   a ,when transmission  90  is shifted into the desired neutral position (block  140 ). Since the ball sensor  86 ′ is pushed inwardly and a neutral position is sensed (blocks  142  and  144 ), the electrical circuit is closed, and thus an electronic signal is sent as directed by switch  84 ′ (block  148 ) allowing operation of mower deck assembly  26 . Since mower deck assembly  26  is operational, the user may continue operation of the deck and mower (block  150 ). Lastly, with reference to FIG. 14, swash plate  114   a  has been rotated to a forward position (block  140 ) and ball sensor  86 ′ is pushed inwardly by raised area  122   a  to detect a forward position (blocks  142  and  144 ) resulting in the electric circuit being closed with a signal being sent, again as directed by switch  84 ′ (block  148 ), thereby allowing full and continued operation of mower deck assembly  26  (block  150 ).  
         [0061]    Although the operation of switch  84 ′ and sensor  86 ′ has been described with respect to reverse sensing only, in those situations where switch  84 ′ and ball sensor  86 ′ would be sensing for neutral only, the general operation would be similar in terms of a signal being sent when ball sensor  86 ′ is pushed inwardly, or when swash plate  114   b  has been rotated into a forward or a reverse position. Likewise, in those situations where two such switches  84 ′ are used, or both reverse and neutral are being sensed, the general operation would be similar in that a signal is sent from switches  84 ′ when a respective sensor  86 ′ is pushed inwardly. In operation, the reverse sensing and neutral sensing structure would be a combination of both systems described above. The sensor  86 ′ being used to sense reverse would be pushed inwardly in both the forward and neutral positions as described with reference to FIGS. 12 through 14. The ball sensor  86 ′ being used to sense neutral would be pushed inwardly in the forward and reverse positions with the appropriate signals being sent by the corresponding switches  84 ′.  
         [0062]    As described with reference to manual shift transmission  28 , alternative structures of the reverse sensing may be utilized. For example, rather than having the forward and neutral positions in raised area  122   a ,the reverse position may be raised. Likewise, similar alternatives, that is the raised areas being flattened and the currently flattened areas raised, may be constructed for the neutral sensing only and the reverse and neutral sensing swash plates, or swash plates  114   b  and  114   c.    
         [0063]    Also, in a manner similar to that described relative to manual shift transmission  28 , switch  84 ′ may be structured to be open when forward and neutral are sensed, and closed when reverse is sensed, thus causing the signal to be sent to prevent operation of mower deck assembly  26 . The circuits associated with the neutral sensing only and the reverse and neutral sensing systems may likewise be structured to send signals to prevent operation rather than sending signals to allow operation.  
         [0064]    Referring to FIG. 15, a schematic circuit diagram is shown with electromagnetic clutch  134  being in electrical communication with switch  84 ,  84 ′ and ball sensor  86 ,  86 ′. As can be seen, ball sensor  86 ,  86 ′ may be in communication with either transaxle  28  or transmission  90  such that when the reverse position is sensed, ball sensor  86 ,  86 ′ moves outwardly, thereby breaking the circuit between switch  84 ,  84 ′ and clutch  134  and interrupting any electronic signal that could be sent to electromagnetic clutch  134  by switch  84 ,  84 ′. Referring to FIG. 16, two such sensors  86 A and  86 B and  86 A′ and  86 B′, and switches  84 A and  84 B and  84 A′ and  84 B′ are shown. Sensors  86 A and  86 A′ are electronically connected to electromagnetic clutch  134  and are used to sense the reverse position of transmission  90 , while sensors  86 A and  86 B′ are used to sense the neutral position and are connected to starter mechanism  136  of mower  20 . Thus, if reverse is sensed by reverse sensing ball sensor  86 A,  86 A′ then that circuit with electromagnetic clutch  134  is broken, whereas if neutral is sensed by the neutral sensing ball sensor  86 B,  86 B′, then the circuit with starter mechanism  136  is broken and no signals are sent to the respective units.  
         [0065]    By using electronic sensors  86 ,  86 ′ for determination of the position of the transmission  28 ,  90 , continuous sensing may occur. Thus, when the operator returns the transmission to a neutral or forward position from a reverse position, such movement may be sensed and the mower deck assembly allowed to operate again without a need to shut down and restart the mower or other complicated procedures. Furthermore, only minor modifications to the shift fork  78 ,  78 ′, swash plates  114 , and the respective transmission casings are required for implementation of the sensing systems. Thus, the sensing systems may be incorporated into existing transmission designs without extensive retooling and redesign by the manufacturers. Additionally, since all sensing is done as the operator operates the mower, the operator does not need to perform contorted maneuvers to safely operate the mower and to disengage the mower blades when the transmission is shifted into reverse.  
         [0066]    While this invention has been described as having exemplary structures, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.