Patent Publication Number: US-10306831-B2

Title: Walk power mower having forward and reverse traction drive

Description:
TECHNICAL FIELD 
     This invention relates to a walk power mower for cutting grass and, more particularly, to a traction drive system for self-propelling the mower. 
     BACKGROUND OF THE INVENTION 
     Self-propelled walk power mowers are well known for cutting grass. For example, such mowers are commonly used by property owners, such as homeowners, to cut their lawns. Such mowers have a cutting deck that houses a rotary grass cutting blade. The deck is supported by a plurality of wheels for rolling over the ground. A handle extends upwardly and rearwardly from the deck. A user who walks on the ground behind the deck grips a handle grip of the handle to manipulate and guide the mower during a grass mowing operation. 
     It can be difficult or is undesirable for some users to manually push a walk power mower over the ground in order to cut one&#39;s lawn. It is tiring to do so, particularly when the area being mowed is either large, hilly, or both. Thus, many mowers have traction drive systems that utilize part of the power generated by the prime mover carried on the mower to drive at least one pair of the mower&#39;s wheels, either the front wheels or the rear wheels, in a forward direction. Such a self-propelled mower relieves the user of the necessity of having to bodily push the mower over the ground. This greatly eases the physical effort required from the user in mowing one&#39;s lawn. The user now primarily guides or steers the mower during the powered forward motion provided by the traction drive system and the prime mover. 
     There are times when mowing one&#39;s lawn when the user needs to pull the mower in reverse at least over short distances. For example, when a user cuts grass under the branches of a bush, the user will ordinarily drive the mower forwardly so that the cutting blade reaches under the branches sufficiently to cut whatever patch of grass lies beneath the branches. However, once this patch of grass is cut, the user must pull back on the handle to pull the mower out from under the branches of the bush. While the traction drive system is designed with a one way clutch to allow the drive wheels to free-wheel during reverse motion so that the user is not pulling back against the resistance provided by the gearing in the traction drive system, the drive wheels of the mower are typically unpowered during this reverse motion. 
     As a result, many users end up having to manhandle or wrestle the mower back in this reverse motion scenario. This requires the user to expend physical energy and for some users accomplishing manual reverse motion of the mower may be difficult or impossible in some situations. This difficulty is exacerbated for those users in which trimming operations requiring reverse motions of the mower are numerous or are required on difficult terrain. For example, in trimming beneath a bush, pulling back on the mower is even more difficult if the user has to pull the mower back up a slope to get it out from under the branches of the bush. Accordingly, it would be an advance in the art to provide a reliable, durable, and cost effective traction drive system that provides powered motion of a walk power mower in both forward and reverse directions. 
     SUMMARY OF THE INVENTION 
     One aspect of this invention relates to a walk power mower which comprises a deck supported by a pair of front wheels and a pair of rear wheels. The deck has at least one grass cutting blade that rotates in a substantially horizontal plane about a substantially vertical axis to cut grass. The deck also has an upwardly and rearwardly extending handle that is gripped by a user who walks on the ground behind the deck to guide and manipulate the deck during motion of the deck over the ground. A prime mover is carried by the deck, the prime mover being operably coupled to the blade for effecting powered rotation of the blade. A variable speed traction drive system is carried on the deck, the prime mover being operably coupled to the traction drive system for effecting powered rotation of the front wheels and the rear wheels. The traction drive system comprises a rear transmission having a rear axle that is operatively connected to the rear wheels for powering the rear wheels to provide self-propelled motion of the deck in a first direction of motion over the ground, a front transmission having a front axle that is operatively connected to the front wheels for powering the front wheels to provide self-propelled motion of the deck in a second direction of motion over the ground that is opposite to the first direction of motion, and a control system carried on the handle that is selectively operable by a user for placing only one transmission at a time into operation so that the rear transmission is active to propel the deck in the first direction while the front transmission is inactive or the front transmission is active to propel the deck in the second direction while the rear transmission is inactive. 
     Another aspect of this invention relates to a walk power mower which comprises a traction drive system on a grass cutting deck having a pair of front wheels and a pair of rear wheels. A pair of transmissions power at least one pair of wheels on the deck. A first one of the transmissions provides forward motion of the mower when it is active and a second one of the transmissions provides rearward motion of the mower when it is active. A slidable handle grip is provided on a handle extending upwardly and rearwardly from the cutting deck. The handle grip has a cross bar long enough to be gripped by both hands of the user. The handle grip activates the first one of the transmissions when it is slid downwardly on a handle out of a neutral position thereof as a user walks forwardly holding the cross bar of the handle grip. The handle grip activates the second one of the transmissions when it is slid upwardly on the handle out of the neutral position as a user walks rearwardly holding the cross bar of the handle grip. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This invention will be described more fully in the following Detailed Description, when taken in conjunction with the following drawings, in which like reference numerals refer to like elements throughout. 
         FIG. 1  is a perspective view of one embodiment of a walk power mower according to this invention; 
         FIG. 2  is an enlarged perspective view of a portion of the handle of the mower of  FIG. 1 , particularly illustrating the return to neutral system that causes the slidable handle grip of the handle to return to a neutral position in which the traction drive system is disengaged once the user releases the handle grip; 
         FIG. 3  is a perspective view of the underside of the cutting deck of the mower of  FIG. 1 , particularly illustrating the dual transmission traction drive system; 
         FIG. 4  is a perspective view of a portion of a second embodiment of a walk power mower according to this invention; 
         FIG. 5  is an enlarged perspective view of a portion of the handle of the mower of  FIG. 4 , particularly illustrating a second embodiment of the return to neutral system that causes the slidable handle grip of the handle to return to a neutral position in which the traction drive system is disengaged once the user releases the handle grip. 
     
    
    
     DETAILED DESCRIPTION 
     One embodiment of a walk power mower  2  according to this invention is illustrated in  FIG. 1 . Mower  2  comprises a cutting deck  4  that is formed with a generally toroidal cutting chamber  6  that faces downwardly and is open at its bottom. Deck  4  is supported for rolling over the ground by a pair of front wheels  8  and a pair of rear wheels  10 . A prime mover  12 , such as an internal combustion engine, is carried on top of deck  4 . Referring now to  FIG. 3 , the drive shaft  14  of the prime mover extends vertically downwardly with its lower end extending into cutting chamber  6 . A horizontal cutting blade  16  is positioned within cutting chamber  6  and is removably secured to the lower end of drive shaft  14  to rotate in a generally horizontal cutting plane to cut grass. 
     Referring again to  FIG. 1 , mower  2  is a three-in-one mower having side discharge, rear bagging and mulching modes of operation. In the side discharge mode, a side discharge chute  18  can be mated with a side discharge opening to discharge grass clippings to the side of mower  2  when a side discharge door  20  is opened. In the rear bagging mode, a grass clipping collection bag  22  is mated with a rear discharge opening to collect grass clippings being discharged to the rear of mower  2  when a rear discharge door  24  is opened. While  FIG. 1  illustrates deck  4  as being both in the side discharge mode and the rear bagging mode, this is only for the purpose of illustration as these two modes would not be used simultaneously. When side discharge chute  18  is removed and side discharge door  20  is closed and when bag  22  is removed and rear discharge door  24  is closed, mower  2  is placed into its mulching mode in which grass clippings are driven downwardly out of cutting chamber  6  to discharge the clippings beneath mower  2 . However, mower  2  need not have multiple modes of operation, but could be built as a single purpose side discharge, rear bagger, or mulching mower. 
     An upwardly and rearwardly extending handle  26  comprising a pair of laterally spaced handle tubes  28  joined by a top cross member  30 . The lower ends of handle tubes  28  are attached to the rear of deck  4 . Handle  26  includes a U-shaped handle grip  32  that has a pair of laterally spaced legs  34  connected together by an upper cross bar  36 . Legs  34  of handle grip  32  are telescopically received on handle tubes  28  of handle  26  for sliding movement relative thereto. Thus, handle grip  32  is able to slide downwardly on handle tubes  28  as a user walks forwardly while gripping cross bar  36  of handle grip  32  with both of the user&#39;s hands. 
     Handle grip  32  slides downwardly by an amount that depends upon how fast the user walks forwardly. As will be described in more detail hereafter, the extent or amount of downward travel of handle grip  32  controls a traction drive system  38  of mower  2  to vary the forward ground speed of mower  2  to correspond to the user&#39;s walking pace. This type of speed controlling, slidable handle grip is used on the Personal Pace® line of walk power mowers manufactured and sold by The Toro Company, the assignee of this invention. In addition, this type of slidable handle grip is disclosed more fully in U.S. Pat. 6,082,083 to Stalpes, which patent is hereby incorporated by reference and shall be referred to as “Stalpes” hereafter. 
     In Stalpes, handle grip  32  is in a neutral, i.e., a drive disengaged position, when handle grip  32  is at the top of handle  26  with handle grip  32  located adjacent to cross member  30  that joins handle tubes  28  together. The only control motion of handle grip  32  in Stalpes is the downward sliding motion that engages the traction drive system of Stalpes in forward and that varies the forward ground speed in concert with the user&#39;s forward walking pace. When the user lets go of handle grip  32  in Stalpes, handle grip  32  is spring biased to slide back up handle  26  to return to the top thereof at which point the traction drive system becomes disengaged once again. 
     In mower  2  of this invention, the Stalpes handle grip  32  has been modified so that the neutral position of handle grip  32  is no longer at the top of the range of motion of handle grip  32 . Now, the neutral position of handle grip  32  is displaced somewhat downwardly from cross member  30  of handle  26 . A return to neutral system  40  maintains handle grip  32  in its now lower neutral position relative to cross member  30  of handle  26 . 
     Handle grip  32  functions as it did in Stalpes when the user grips cross bar  36  of handle grip  32  and walks forwardly, i.e., handle grip  32  slides downwardly in the direction of the arrow A in  FIG. 1  to activate traction drive system  38  in forward and to vary the forward ground speed in concert with the user&#39;s forward walking pace. Now, however, if the user grips cross bar  36  of handle grip  32  and walks rearwardly, as when pulling mower  2  back, handle grip  32  is now also able to slide upwardly out of neutral rather than being held in neutral as in Stalpes. This upward sliding motion of handle grip  32  is shown by the arrow B in  FIG. 1 . This activates traction drive system  38  in reverse and varies the reverse ground speed of mower  2  in concert with the user&#39;s rearward walking pace. In either forward or reverse powered motion of mower  2 , when the user lets go of handle grip  32 , return to neutral system  40  causes handle grip  32  to slide back to its centered neutral position between the lower and upper limits of the range of motion of handle grip  32  to disengage traction drive system  38 . 
     Referring now to  FIG. 2 , return to neutral system  40  comprises a rod  42  having an upper end fixed by a bracket  44  to a laterally extending cross member  46  that is also part of handle grip  32 . Rod  42  has spaced upper and lower push nuts  48   u  and  48   l  fixed thereto to move with rod  42 . Push nuts  48  bear respectively against one end of cylindrical, upper and lower, push tubes  50   u  and  50   l  which are spaced along the length of rod  42  and through which rod  42  slides. Each push tube  50  has an annular thrust surface  52  that is formed as an integral part thereof. Push tubes  50  are assembled in an inverted relationship relative to each other along the length of rod  42  such that thrust surface  52  of upper push tube  50   u  is at the lowermost end of upper push tube  50   u  while thrust surface  52  of lower push tube  50   l  is at the uppermost end of lower push tube  50   l . 
     Return to neutral system  40  further includes a U-shaped clevis  54  fixed to handle  26  with the spaced, parallel side walls  56  of clevis  54  forming an upper wall  56   u  and a lower wall  56   1 . Upper and lower push tubes  50   u  and  50   l  when assembled on rod  42  are arranged to pass through bores in upper and lower walls  56   u  and  56   l  of clevis  54  with thrust surfaces  52  on upper and lower push tubes  50   u  and  50   l  being inside clevis  54  immediately adjacent to upper and lower walls  56   u  and  56   l  of clevis  54 . A compression spring  58  is arranged inside clevis  54  with the ends of spring  58  bearing against thrust surfaces  52  of upper and lower push tubes  50   u  and  50   l . When return to neutral system  40  is properly adjusted and traction drive system  38  is in neutral, spring  58  will force upper and lower push tubes apart  50   u  and  50   l  until thrust surfaces  52  thereon abut against the upper and lower walls  56   u  and  56   l  of clevis  54  and the opposite ends of upper and lower push tubes  50   u  and  50   l  are immediately adjacent to upper and lower push nuts  48   u  and  48   l . 
     When the user pushes down on handle grip  32  to initiate powered forward motion of mower  2 , upper push nut  48   u  on rod  42  presses down on the upper end of upper push tube  50   u  to slide upper push tube  50   u  downwardly relative to clevis  54 . Note that lower push tube  50   l  remains stationary with rod  42  simply sliding through lower push tube  50   l  since the lower push nut  48   l  moves away from the lowermost end of lower push tube  50   l  and lower push tube  50   l  remains within clevis  54  since thrust surface  52  on lower push tube  50   l  is held in place by its engagement with lower wall  56   l  of clevis  54 . The downward motion of upper push tube  50   u  compresses spring  58  downwardly. Thus, when the user eventually releases handle grip  32 , the compressed spring  58  pushes back upwardly on upper push tube  50   u  to cause the uppermost end of upper push tube  50   u  to push the upper push nut  48   u  back upwardly, thereby returning handle grip  32  to its centered neutral position. 
     Return to neutral system  40  works the same way but in an opposite fashion when handle grip  32  is pulled upwardly in the direction of the arrow B to initiate reverse powered motion of mower  2 . This time it is lower push tube  50   l  that is pushed upwardly by lower push nut  48   l  with upper push tube  50   u  remaining stationary. Thus, spring  58  is compressed upwardly. When handle grip  32  is eventually released, the lowermost end of lower push tube  50   l  pushes downwardly on lower push nut  48   l  as the upward compression of spring  58  is released to slide handle grip  32  back downwardly to return handle grip  32  to its centered neutral position. 
     Referring now to  FIG. 3 , traction drive system  38  comprises a first rear transmission  60   r  which powers rear wheels  10  of mower  2  and a second front transmission  60   f  which powers front wheels  8  of mower  2 . Transmissions  60  preferably comprise, but are not limited to, mechanical gear drive transmissions that use various speed reduction stages to reduce the relatively high rotational speed of drive shaft  14  of prime mover  12  to a lower speed suitable for self-propelling mower  2  at ground speeds that match the walking pace of the user. Some of these speed reduction stages are built into the gearing inside the housings of transmissions  60 . However, the final speed reduction stage is formed by a small diameter drive gear  62  on each end of an axle  64  of each transmission  60  that drives a larger diameter driven gear  66  fixedly attached to one of wheels  8 ,  10 . 
     Drive gears  62  on the opposite ends of axle  64  of rear transmission  60   r  engage the backsides of driven gears  66  of rear wheels  10 . The reverse is true for drive gears  62  for front transmission  60   f  which engage the front sides of driven gears  66  of front wheels  8 . Thus, when axles  64  of transmissions  60  are rotated in opposite directions by the operation of prime mover  12 , front and rear drive wheels  8  and  10  will be rotated in opposite directions relative to each other. For example, if rear drive wheels  10  are rotated in a forward direction to propel mower  2  forwardly, front drive wheels  8  will be rotated in a rearward direction to propel mower  2  in reverse. As a consequence, it should be apparent that only one transmission  60  is active at any given time while the other transmission  60  remains inactive. Either transmission  60  can be selected to be the one that provides forward motion while the remaining transmission  60  will then be the one that provides reverse motion. 
     Rear transmission  60  preferably has a split axle  64  and provides a differential action to permit rear wheels  10  to be driven at different speeds during a turn, such as when the user swings mower  2  around 180° at the end of a pass when mowing his or her lawn, to avoid tearing or scuffing the grass. Rear wheels  10  may rotate at different speeds during turns using either an unpowered or powered differential. For example, in an unpowered differential which is preferred due to somewhat lower cost, the portion of split axle  64  powering whichever rear wheel  10  is on the outside of the turn simply overruns the rotational speed of the portion of split axle  64  powering the rear wheel  10  on the inside of the turn to create the difference in wheel speed. Since front wheels  8  of mower  2  are typically lifted up off the ground during such a turnaround of mower  2 , front transmission  60  preferably has a solid axle and lacks any differential action, thereby reducing overall cost of mower  2 . 
     Each transmission  60  is provided with a one-way clutch that permits the wheels driven by that transmission  60  to free wheel when mower  2  is being propelled in a direction opposite to the direction transmission  60  is designed to operate. In the example where one transmission is active and is driving mower  2  forwardly while the other reverse drive transmission is inactive and is not in operation, the one way clutch in the inactive reverse drive transmission permits the drive wheels coupled to that transmission to rotate freely with respect to the internal gearing of the reverse drive transmission to avoid the drag or resistance such internal gearing would otherwise provide when mower  2  moves forwardly. 
     Each front and rear transmission  60   f  and  60   r  is separately driven by its own independent belt drive  68   f  and  68   r  from drive shaft  14  of prime mover  12 . Each transmission  60  is a rocking transmission of the type disclosed in Stalpes. When handle grip  32  is in neutral and both transmissions  60  are inactive, belts  70  in belt drives  68  are sufficiently slack so that the input pulleys on transmissions  60  are stationary even though drive shaft  14  of prime mover  12  is rotating. Effectively, mower  2  is at rest even with the engine running when handle grip  32  is not being pushed or pulled by the user. 
     However, as the user slides handle grip  32  up or down on handle  26  in either the downward direction A or the upward direction B, this motion rocks one transmission  60  in a direction (rearwardly about its axle  64  for rear transmission  60   r  and forwardly about its axle  64  for front transmission  60   f ) to tighten drive belt  70  to the rocking transmission while leaving drive belt  70  to other transmission slack. As drive belt  70  to the rocking transmission becomes taut, the transmission becomes active to begin rotating the pair of wheels powered by the rocking transmission. The speed of rotation of axle  64  of the rocking transmission, and thus the ground speed of mower  2 , progressively increases as handle grip  32  is moved ever further in the selected direction and the tautness of belt  70  progressively increases. Thus, the ground speed of mower  2  progressively increases from zero to a maximum speed as handle grip  32  travels out of neutral to the end of its range of motion in the selected direction A or B. This enables the ground speed of mower  2  to be matched to the walking pace of the user whether mower  2  is being propelled in forward or reverse. 
     First and second Bowden cables (not shown) having inner wires carried within outer conduits operably couple handle grip  32  to transmissions  60 . The first Bowden cable has a “live cable” setup in which a rear end of the outer conduit is fixed or clamped to handle  26  and the front end of the outer conduit is fixed or clamped to a lower end of one handle tube  28  or to a rear end of deck  4 . The rear end of the inner wire of the first Bowden cable is secured to an opening  72  in a pivotal tab  74  (see  FIG. 2 ) that is rotated rearwardly when handle grip  32  is moved downwardly in the direction of arrow A. The front end of the inner wire of the first Bowden cable is then attached to rear transmission  60   r  to rock rear transmission  60   r  rearwardly during downward motion of handle grip  32  in the direction of arrow A. In this “live cable” setup of the first Bowden cable, the downward motion of handle grip  32  causes the “live” inner wire of the first Bowden cable to slide rearwardly within the outer conduit in order to rock rear transmission  60   r  rearwardly while the outer conduit remains fixed in place. The “live cable” setup of the first Bowden cable and its interaction with pivotal tab  74  is shown and described in more detail in the Stalpes patent which has previously been incorporated by reference herein. 
     The second Bowden cable has a “live conduit” setup in which the front end of the inner wire is fixed or clamped in place to deck  4  and the rear end of the inner wire is fixed or clamped in place to handle grip  32 . The rear end of the conduit in the second Bowden cable is fixed or clamped in place to an upper portion of one handle tube  28  adjacent the place where the rear end of the inner wire of the second Bowden cable attaches to handle grip  32 . The front end of the conduit in the second Bowden cable is clamped or fixed to front transmission  60  to rock front transmission  60  forwardly during upward motion of handle grip  32  in the direction of arrow B. In this “live conduit” setup, the upward motion of handle grip  32  in the direction of arrow B deforms the shape of the clamped inner wire of the second Bowden cable. This deformation in the shape of the inner wire causes the “live” conduit of the second Bowden cable to slide forwardly over the inner wire to push against front transmission  60   f  to rock front transmission  60   f  forwardly. Only one Bowden cable applies force to only one transmission at any given time with the other Bowden cable not applying force to the other transmission so that only one transmission at a time is activated. 
     Mower  2  equipped with traction drive system  38  of this invention has powered operation of rear transmission  60  to propel mower  2  forwardly in a variable speed manner as handle grip  32  is gripped by the user and the user walks forwardly, thereby sliding handle grip  32  downwardly on handle  26  in an amount proportional to the walking pace of the user. However, when trying to pull mower  2  back during a trimming operation or when trying to mow a small patch of grass in reverse, the user no longer has to use manual force to manhandle mower  2  in the reverse direction. Instead, the user merely maintains his or her grip on cross bar  36  of handle grip  32  and walks rearwardly at any desired pace. This will slide handle grip  32  upwardly on handle  26  to initiate powered operation of front transmission  60  to propel mower  2  rearwardly at a variable ground speed commensurate to the walking pace of the user. Thus, the task of operating mower  2  is greatly eased since mower  2  is self-propelled both in forward and reverse while maintaining the functionality of the Personal Pace® control system of The Toro Company that had previously been used only on mowers that were self-propelled in forward only. 
     The advantages of a mower that is self-propelled in both forward and reverse is achieved in a cost-effective manner by using mechanical, gear drive transmissions that are both durable and inexpensive in comparison to using hydraulic motor/pump combinations or electric motor/drive combinations. Moreover, since transmissions  60  used to drive front and rear wheels  8 ,  10  are different from one another and are mounted on separate front and rear axles, this allows rear transmission  60  to have a split axle/differential action configuration while front transmission  60  has a solid axle/non-differential action configuration. The manner of driving front and rear wheels  8 ,  10  using the same size drive gears  62  on the ends of the axles of the front and rear transmissions and the same size driven gears  66  on the wheels, but simply reversing which sides of driven gears  66  are engaged by drive gears  62 , leads to increased part commonality and thus reduced cost. This allows a powered, reversible mower to be manufactured and sold at a reasonable cost. 
     Referring now to  FIGS. 4 and 5 , a second embodiment of a mower according to this invention is illustrated generally as  2 ′. The same reference numerals used in  FIGS. 1-3  to refer to components will be used in  FIGS. 4 and 5  to refer to the same or corresponding components with a prime designation being used to refer to those components in the second embodiment, e.g. mower  2 ′ in  FIGS. 4 and 5  as opposed to mower  2  in  FIGS. 1-3 . 
     Referring now to  FIG. 4 , in mower  2 ′ front transmission  60   f ′ and its axle  64  have been relocated from the front to the back of mower  2 ′ so that only rear wheels  10 ′ are reversibly driven by the dual transmissions  60   f ′ and  60   r ′ with such transmissions and their axles being disposed on opposite sides of the axis of rotation of rear wheels  10 ′. In this embodiment, front wheels  8 ′ are present but unpowered with only rear wheels  10 ′ serving to self-propel mower  2 ′. As in the first embodiment concerning mower  2 , only one transmission  60 ′ is active at any given time while the other transmission  60 ′ remains inactive. Propelling rear wheels  10 ′ in opposite directions may yield better traction than using front wheels  8 ′ to drive mower  2 ′ in the direction that is opposite to the direction that rear wheels  10 ′ drive mower  2 ′. This is due to the fact that more of the weight of a mower like mower  2 ,  2 ′ is over rear wheels  10 ′ as compared to front wheels  8 ′. In addition, the filling of a grass clipping collection bag at the rear of mower  2 ′ with grass clippings during a mowing operation only accentuates this rearward weight distribution. 
     In mower  2 ′ as shown in  FIG. 4 , whichever transmission  60 ′ is used to produce forward motion of mower  2 ′ is preferably one having a split axle/differential feature as described earlier with respect to rear transmission  60   r  in mower  2 . The other transmission  60 ′ that is used to produce reverse motion of mower  2 ′ could also be one having a split axle/differential feature since both transmissions are now being used to power rear wheels  10 ′. However, since the times at which reverse motion is needed and the distances over which mower  2 ′ would travel in reverse are much more limited than what is required for forward motion, whichever transmission  60 ′ propels the mower in reverse could remain a transmission having a solid axle without any differential ability. 
     In addition to the use of both transmissions  60 ′ to drive rear wheels  10 ′, a simplified Bowden cable coupling setup is used in mower  2 ′ as shown in  FIG. 5 . In mower  2 ′, pivotal tab  74 ′ now has a second opening  76  that is disposed on an opposite side of a horizontal axis of rotation, illustrated as x in  FIG. 5 , of a pivot rod  78  compared to the location of first opening  72 ′ in tab  74 ′. As taught in more detail in Stalpes, tab  74 ′ is rigidly attached to rod  78  to pivot by virtue of the pivoting motion of rod  78  caused by journaling the ends of rod  78  in the mower handle tubes  28 ′ while a middle U-shaped portion  79  of rod  78  is captured within a channel  80  in cross member  46 ′ of slidable handle grip  32 ′. Again, rod  78  and its interaction with cross member  46 ′ are detailed more fully in the Stalpes patent which has been incorporated by reference herein. 
     When the user slides handle grip  32 ′ downwardly on handle tubes  28 ′, the portion of tab  74 ′ having opening  72 ′ is pivoted rearwardly as described in connection with the operation of mower  2 . This pulls rearwardly on the “live cable” setup of the first Bowden cable that is connected to whichever transmission  60 ′ is arranged to drive mower  2 ′ forwardly to actuate the forward drive transmission  60 ′. Whichever transmission  60 ′ is arranged to drive mower  2 ′ in reverse is now connected by a “live cable” setup of the second Bowden cable to the newly added second opening  76  in tab  74 ′. Thus, when the user pulls handle grip  32 ′ upwardly on handle tubes  28 ′ as he or she walks in reverse, the portion of tab  74 ′ having opening  76  is now pivoted rearwardly to actuate the reverse drive transmission  60 ′. Since both transmissions  60 ′ are now at the rear of mower  2 ′, the length of the second Bowden cable run is shortened compared to the length required in mower  2 , and a “live cable” rather than a “live conduit” setup of the Bowden cable is used. This simplifies the routing and arrangement of the Bowden cables. However, the operation of mower  2 ′is the same as mower  2 , namely pushing handle grip  32 ′ downwardly as the user walks forwardly powers mower  2 ′ in a forward direction at a speed commensurate to the user&#39;s walking pace while pulling handle grip  32 ′ upwardly as the user walks rearwardly powers mower  2 ′ in a rearward direction at a speed commensurate to the user&#39;s walking pace. 
     Referring still further to  FIG. 5 , the use of the double headed tab  74 ′ as described above to activate both transmission  60   f ′ and  60   r ′ in mower  2 ′ permits a simplified return to natural system  40 ′. All that is required now is the use of one or more torsion springs  82 , preferably two such springs  82 , surrounding the ends of rod  78  that lie along and define the rotational axis x of rod  78  with such springs being anchored at one end on rod  78  and at the other end on a portion of the adjacent handle tube  28 ′. When handle grip  32 ′ is located in its centered, neutral, drive disengaging position, torsion springs  82  are in their unstressed state such that handle grip  32 ′ is retained in neutral. As rod  78  is rotated about axis x in either one direction or the other due to motion of handle grip  32 ′ relative to handle tubes  28 ′, torsion springs  82  get coiled up or twisted in one direction or the other to resist the motion of handle grip  32 ′ out of neutral. When the user subsequently releases handle grip  32 ′, the biasing force built up in the coiled torsion springs  82  is now free to act on handle grip  32 ′ to move it back to neutral. 
     The return to neutral system  40 ′ as shown in  FIG. 5  is simpler and thus less costly than system  40  shown in  FIGS. 1-3  and takes up less space on mower  2 ′. Thus, the cable coupling setup and return to neutral system  40 ′ shown in  FIG. 5  could be used with mower  2  shown in  FIGS. 1-3  if so desired. 
     Various modifications of this invention will be apparent to those skilled in the art. Thus, the scope of this invention is not to be limited to the details of the various embodiments described herein, but shall be limited only by the appended claims.