Abstract:
A lawn mower including a frame, an engine having an electrical system and attached to the frame, a mower deck assembly connected to the frame and having a rotating blade selectively engaged with the engine, a reversible transmission driven by the engine and having a shift mechanism having forward and reverse positions, a switch in electrical communication with the electrical system and mower deck assembly, and a solenoid attached to the transmission, in electrical communication with the switch, and having a plunger. The plunger has an extended position when the switch is in its first position and the blade engages the engine, wherein the plunger blocks movement of the shift mechanism into its reverse position, and a retracted position when the switch is in its second position and the blade disengages the engine, wherein the plunger does not block movement of the shift mechanism into its reverse position.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to garden tractors, riding lawnmowers, and the like, specifically to means for preventing a mower from being shifted into reverse when the mower deck is operating, in conformance with certain proposed industry standards. 
     Riding mowers, including most lawn tractors and garden tractors, include potentially dangerous rotating blades which comprise part of the mower deck and which may cause injury to the operator or another person. New industry standards are being considered which are aimed toward the prevention of such injuries, and safety devices are now being, or will likely be, included on riding mowers in support of these goals. Various types of these devices prevent operation of the mower deck while the mower is being reversed, or prevent the mower from being reversed while the mower deck is in operation. 
     Some of these previous devices will automatically shut off the engine if the mower is reversed while the mower deck is engaged. Such action is inconvenient since the operator would then need to restart the mower. Often, an operator will unintentionally put the mower in reverse with the mower deck engaged, such as when the operator realizes that he just passed an area to be mowed and, without thinking, shifts the mower into reverse to mow that area, consequently killing the engine. 
     Other previous safety devices include an engine kill relay with an override switch which allow the operator to reverse the mower with the mower deck operating only when the override switch is engaged simultaneously with the reverse gear being selected (U.S. Pat. No. 6,109,010). However, if the override switch is not engaged, shifting into reverse causes the engine to be shut off through the kill relay. In operation, the current path between a kill relay and a ground terminal is terminated if a reverse switch is opened and the PTO switch is turned on, thereby terminating engine operation. However, if the override switch is actuated, then as long as the PTO switch is turned on, current will be maintained between the relay and ground. Thus, the override switch eliminates the capability of breaking the current path and terminating engine operation if the mower is shifted into reverse with the mower deck operating, thereby allowing for potential unsafe operation of the mower. Further, such systems require operator manipulation of multiple controls in order to actuate the override switch before shifting into reverse. 
     Other safety devices require the operator to depress and hold down a button, or pull out a device, while shifting the mower into reverse, thereby requiring simultaneous manipulation of multiple controls by the operator to both deactivate the safety device and shift the mower into reverse. These devices are thus inconvenient and may allow potentially unsafe operation of the mower. 
     While these previous devices eliminate the possibility of an operator unintentionally shifting the mower into reverse since the operator would need to manipulate several controls to do so, these devices are rather inconvenient to operate and not intuitively operable by an operator unfamiliar with such controls. Further, potentially unsafe mower operation may be accommodated through such override devices. 
     Other attempts to address the issue of preventing the mower from being reversed with the mower deck operating include the use of mechanical safety interlocks which rotate an arm into a blocking position in the shifting rod slot when the mower deck is engaged (U.S. Pat. No. 3,984,967), and thereby preventing the operator from shifting the mower into reverse. Such devices are cumbersome and expensive. 
     Still other attempts to address this issue include an electrical interlock system in which an electric circuit and switch are opened to de-energize an electromagnetic clutch to automatically disconnect the mower drive when the mower is shifted into reverse (U.S. Pat. Nos. 3,999,643 and 6,026,634). Automatically disconnecting power to the mower deck also inconveniences the operator, who would need to reconnect power to the mower deck. Additionally, such systems are applicable only to mowers having electromagnetic blade engagement clutches, not mechanical clutches such as, for example, a belt tensioner. Thus, such systems may not be used on mowers in which the mower deck is engaged through a non-electrical clutch. 
     It is desirable to provide a device by which the mower is prevented from being reversed while the mower deck is operating without shutting off the engine, and to provide such a device which may be incorporated into all riding mowers, not just those in which the mower deck is electrically engaged. 
     SUMMARY OF THE INVENTION 
     The present invention provides a lawn mower including a frame, an engine having an electrical system and attached to the frame, a mower deck assembly having a rotating blade and connected to the frame, the blade selectively engaged with the engine, a reversible transmission driven by the engine and having a shift mechanism having a forward and a reverse position, a switch in electrical communication with the electrical system and mower deck assembly, and a solenoid attached to the transmission and in electrical communication with the switch and having a plunger. The switch is in a first position when the blade is in engagement with the engine and in a second position when the blade is out of engagement with the engine. The plunger is in an extended position when the switch is in its first position wherein movement of the shift mechanism into its reverse position is blocked by the plunger, and is in a retracted position when the switch is in its second position wherein movement of the shift mechanism into its reverse position is not blocked by the plunger. 
     The present invention further provides a reversible transmission for a lawn mower including a housing, an input shaft and an output shaft rotatably supported in the housing, an operator controlled shift mechanism having a forward position and a reverse position, and a solenoid connected to the housing and having a plunger. The plunger has an extended position wherein movement of the shift mechanism into its reverse position is blocked by the plunger, and a retracted position wherein movement of the shift mechanism into its reverse position is not blocked by the plunger. 
     The present invention also provides a reverse shift lockout system for a lawn mower including an engine, a transmission having a selectively entered reverse condition and a selectively entered forward condition and driven by the engine, an electrical source, a mower deck assembly selectively engaged with the engine, a switch in electrical communication with the electrical source and the mower deck assembly and being in a first position when the mower deck assembly is engaged and in a second position when the mower deck assembly is not engaged, and means in communication with the switch for preventing the transmission from entering its reverse condition when the switch is in its first position and permitting the transmission to enter its reverse condition when the switch is in its second position. 
     The present invention also provides a method of preventing an operator from placing a mower in reverse when its mower deck is operating, including extending the solenoid plunger in response to the mower deck being engaged, blocking movement of a transmission shift mechanism into reverse with the extended solenoid plunger, whereby the mower cannot be placed in reverse with the mower deck being engaged, and retracting the solenoid plunger in response to the mower deck being disengaged, whereby the mower may be placed in reverse. 
     The present invention also provides a lawn mower including a frame, an engine having an electrical system and attached to the frame, a mower deck assembly connected to the frame and having a rotating blade being selectively engaged with the engine, a reversible transmission driven by the engine and having a shift mechanism having a forward position and a reverse position, and means for preventing the shift mechanism from being shifted into its reverse position when the blade is in engagement with the engine. 
     The present invention also provides a reversible transmission for a lawn mower having a selectively engaged mower deck including a housing, an input shaft and an output shaft rotatably supported in the housing, an operator controlled shift mechanism having a forward position and a reverse position, and means for preventing the transmission from being shifted into reverse in response to the mower deck being engaged. 
     The present invention is advantageous in that the need to kill the engine upon placing the mower in reverse while the mower deck is operating has been eliminated since the operator is physically unable to shift the mower into reverse when the mower deck is operating. With this elimination, the operator avoids possibility of the engine dying and the inconvenient task of restarting the engine. In addition, the present invention prevents an operator from unintentionally placing the mower in reverse with the mower deck operating since it is physically impossible to do so. The present invention also enjoys wide applicability to various mower designs because it may be used with various electrical or mechanical means for engaging the mower deck to the engine. Furthermore, the present invention substantially operates at all times and has no override mechanism. Therefore, the potential for unsafe mower operation is mitigated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     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: 
     FIG. 1 is a perspective view of a riding lawnmower having the inventive reverse lockout feature incorporated therein; 
     FIG. 2 is a rear view of a manual shift transaxle including the solenoid of the inventive reverse lockout feature; 
     FIG. 3 is a top sectional view of the transaxle of FIG. 2; 
     FIG. 4 is an enlarged fragmentary view of the shift fork and plate arrangement of the manual shift transmission of FIG. 3 showing the common connection to the rotatable shaft; and 
     FIG. 5 is a sectional view along line  5 — 5  of FIG. 4, showing the shift fork keyed to the shaft. 
     FIG. 6 is an enlarged fragmentary view of the transaxle of FIG. 3, the solenoid plunger shown in its extended position in which the shift mechanism is prevented from entering its reverse position; 
     FIG. 7 is an enlarged fragmentary view of the transaxle of FIG. 3, the solenoid plunger shown in its retracted position in which movement of the shift mechanism into its reverse position is permitted; 
     FIG. 8 is an oblique view of a hydrostatic transaxle including the inventive lockout feature, the solenoid plunger shown in its extended position in which the shift mechanism is prevented from entering its reverse position; 
     FIG. 9 is an oblique view of the hydrostatic transaxle of FIG. 8, the solenoid plunger shown in its retracted position in which movement of the shift mechanism into its reverse position is permitted; and 
     FIG. 10 is a schematic wiring diagram for the inventive lockout feature. 
    
    
     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 
     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. 
     Referring first to FIG. 1, mower  20  has engine  22  mounted to frame  23  and mower deck assembly  28  mounted on the frame&#39;s underside. In the rear of mower  20  is transaxle  24  having axle  34 , at the ends of which are mounted ground engaging wheels  26 . Two ground engaging wheels  26  are also located at the front of mower  20 . Attached to transaxle  24  is solenoid  32  having plunger  74  (FIG. 3) which interacts with a shifting mechanism within the transaxle housing as described hereinbelow. An operator conventionally operates transaxle  24  through manual shift lever  30  which extends from transaxle  24 . 
     As shown in FIGS. 1,  2 , and  3 , transaxle  24  is 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, 1988, all of which are assigned to the assignee of the present invention, the complete disclosures of which are expressly incorporated herein by reference. 
     Referring now to FIG. 2, a rear exterior view of transaxle  24  is shown, with transaxle  24  having two casing halves, upper casing half  38  and lower casing half  40 , which abut at horizontal interface  42 . Upper casing half  38  and lower casing half  40  are joined together through the use of bolts  44  inserted through bosses  46  on the upper casing half  38 , and threaded into bosses  47  on the lower casing half  40 . As can be seen, a portion of axle  34 , which is supported by the transaxle casing, extends from either end of transaxle  24  to be attached to a ground engaging wheel  26 . Solenoid  32  is threaded into an aperture in upper casing half  38 , and secured by lock nut  36 . 
     Transaxle  24  is shown in a sectional top view in FIG. 3, and further includes conventional, known differential mechanism  48  through which the two respective portions of axle  34  are coupled to the geartrain. Ring gear  49  of differential  48 , intermeshes with gear  51  mounted on shaft  62  to transfer motion from the rest of the geartrain to differential  48 . Within transaxle  24 , input gearset  58  is fixedly mounted on shaft  60  and intermeshes with output gearset  50 , comprising gears which are individually rotatably mounted on shaft  56 . Gearsets  50  and  58  each include a plurality of gears of varying diameters. One forward gear of output gearset  50  is selected to obtain one of a plurality of forward speeds when operating mower  20 . Also rotatably mounted on shaft  56  are reverse gear  52  and neutral spacer  54 . Mounted on shaft  62  is gear  64  intermeshing with small gear  67  mounted on shaft  56 . 
     Surrounding shaft  56  and extending through the forward gears of gearset  50 , gear  52 , and spacer  54 , is sleeve  66  having key  70  disposed therein and in communication with shift collar  68 . Key  70  moves to engage the gear or spacer selected by the operator, by using manual shift mechanism  30  (FIG. 1) to select reverse, neutral or one of the forward speeds. As can be seen, each gear  50 ,  52 , or spacer  54  is provided with recesses  55  in which the tines of key  70  are received to select that particular gear or spacer. 
     Engaged with shift collar  68  is shift fork  72 , which is rotatably fixed to shaft  82  (FIGS.  4  and  5 ). Plunger  74  of solenoid  32  extends into the casing of transaxle  24  near the shift mechanism. When shift fork  72  moves, plate  76  fixed thereto rotates in unison therewith as the different gears are selected. Plate  76  of the shift mechanism is limited in its range of rotation when plunger  74  is in its extended position. In that plunger position, plate  76  abuts plunger  74  as the shift mechanism is moved toward its reverse position and is thus prevented from moving into a position wherein the tines of key  70  engage recesses  55  of reverse gears  52 . FIG. 6 shows the abutment of shift mechanism plate  76  with the solenoid plunger. 
     With reference to FIGS. 4 and 5, an enlarged fragmentary view of shift fork  72  and plate  76  is shown. As seen in FIG. 4, plate  76  and shift fork  72  share common keyway  130  in shaft  82 . This sharing of common keyway  130  allows for plate  76  and shift fork  72  to move in unison as the operator rotates shaft  82  in selecting the drive gear. Key  132  is shown in FIG. 5 as connecting shift fork  72  to shaft  82  and keyway  130 . Through the common movement of plate  76  and shift fork  72 , when plate  76  abuts extended plunger  74 , shift fork  72  is also prevented from moving any further toward the reverse position. Thus, shift fork  72  cannot move shift collar  68  into the reverse position and therefore, key  70  cannot engage reverse gear  52 . However, when plunger  74  has been retracted, plate  76  is allowed to move beyond plunger  74 , and shift fork  72  is able to move shift collar  68  such that the tines of key  70  may engage recesses  55  of reverse gear  52 . 
     Referring again to FIG. 6, shift fork  72  engages shift collar  68  by means of opposed pins  78  being received in groove  80  of shift collar  68 . Both plate  76  and shift fork  72  are keyed to shaft  82 , as shown in FIGS. 4 and 5, shaft  82  further having square end  84  and threaded recess  86  therein, to which shift lever  30  is mounted. Referring to FIG. 7, plunger  74  has been moved to its retracted position by solenoid  32 , thereby allowing plate  76 , shift fork  72  and shift collar  68  of the shift mechanism to move into the reverse position wherein the tines of key  70  may then engage recesses  55  of selected reverse gear  52 , and mower  20  is thus able to be reversed. 
     Although transaxle  24  has been described as a manual shift transmission, mower  20  may instead include a hydrostatic transmission of a general type disclosed in U.S. Pat. No. 4,979,583, issued Dec. 25, 1990; U.S. Pat. No. 5,078,659, issued Jan. 7, 1992; or U.S. Pat. No. 5,177,967, issued Jan. 12, 1993, all of which are assigned to the assignee of the present invention, the complete disclosures of which are expressly incorporated herein by reference. Alternatively, transaxle  24  may be a variator style of transmission, such as that disclosed in U.S. Pat. No. 4,768,997, issued Sep. 6, 1988, and assigned to the assignee of the present invention, the complete disclosure of which is expressly incorporated herein by reference. 
     FIGS. 8 and 9 show hydrostatic transmission  88  having a shift mechanism in which shift lever  90  moves a swash plate (not shown) or a track ring (not shown) to vary the hydrostatic pump displacement and the direction of fluid flow between the pump and the motor of the transmission. Shift lever  90  is integrally formed with flat metal piece or portion  92  which abuts plunger  74 ′ of solenoid  32 ′ when plunger  74 ′ is in its extended position and the shift mechanism is moved toward its reverse position. The abutment of portion  92  with extended plunger  74 ′ prevents hydrostatic transmission  88  from being shifted from neutral into reverse. In FIG. 9, plunger  74 ′ of solenoid  32 ′ is in its retracted position and portion  92  is able to move past retracted plunger  74 ′ and into any one of its variable reverse positions. 
     FIG. 10 shows the schematic wiring diagram for activating solenoid  32 ,  32 ′. As shown, the electrical system of mower  20  includes ground  94 , battery  96 , starter  98 , ignition switch  100 , ignition unit  108 , alternator  126 , headlights  128 , and fuse  110 . The electrical system also includes solenoid  104 , which may be used for other operations associated with mower  20 , clutch/brake switch  102 , and seat switch  106 . Clutch/brake switch  102  is shown in the position which represents the pedal being up, and seat switch  106  is shown in the position representing that the seat not being occupied by the operator of mower  20 . Switch  112  is connected to clutch/brake switch  102  by terminals  114 ,  122 , and  120 . Switch  112  is connected to ignition switch  100  at terminal  118  and is connected to the seat switch  106  at terminal  120 . Terminal  116  is connected to solenoid  104  and terminal  124  is connected to solenoid  32 ,  32 ′ for actuation of plunger  74 ,  74 ′; each of the solenoids  104  and  32 ,  32 ′ is further connected to ground  94 . 
     As shown in FIG. 10, the switch portions between terminals  118  and  120  and between terminals  122  and  124  are open when the clutch pedal is up, as indicated by the position of clutch/brake switch  102 , thereby breaking any electrical connection, while the switch portion between terminals  114  and  116  is closed, again when the clutch pedal is up, to provide electrical connection between clutch/brake switch  102  and solenoid  104 . 
     In operation, when the operator starts mower deck  28  after engine ignition, the reverse switch  112  is closed between terminals  122  and  124  since clutch pedal is depressed to engage mower deck  28 , such that current is applied to solenoid  32  and its windings are energized. Plunger  74  is biased into its retracted position, and through energizing the windings of solenoid  32 , plunger  74  is extended, thereby preventing the operator from moving mower  20  into reverse. When mower deck  28  is not operating, or when the clutch pedal is up, the connection between terminals  122  and  124  is opened, and thus no current is applied to solenoid  32 , the windings of the solenoid  32  are not energized, and plunger  74  is not extended. Unless the clutch pedal is depressed, or the mower deck is engaged, plunger  74  assumes its retracted position and mower  20  may be shifted into reverse by the operator. 
     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.