Abstract:
The parking brakes at the drive wheels of a zero turning radius mower are automatically set when a pair of drive levers used for determining speed, steering and forward or reverse travel are placed in their neutral positions and swung outwardly to widespread, operator dismount positions. When the drive levers are widespread, switches associated with a control circuit are opened, allowing air cylinders to immediately exhaust pressurized air so that tension springs may actuate the brake assemblies to set the brakes. When the drive levers are returned to their operating modes and the ignition is turned on, the control switches are closed, energizing the control circuit to pressurize the air cylinders and release the brakes against the bias of the tension springs.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to zero turning radius riding mowers of the type in which the seated driver controls speed, turning and forward/reverse travel by appropriately manipulating a pair of drive levers adjacent the seat. More particularly, it relates to a way of automatically applying parking brakes or other wheel retaining mechanism when the ignition is turned off or the drive levers are swung outwardly to their widespread positions for operator dismount. 
       BACKGROUND AND SUMMARY OF THE INVENTION 
       [0002]    Zero turning radius mowers are typically provided with twin drive levers that are manipulated by the seated operator to regulate the speed, turning, and forward or reverse operations of the mower. In a typical such mower, the ground-engaging drive wheels utilize reversible hydraulic motors that are supplied with hydraulic fluid in variable amounts by pumps linked to the drive levers. Steering of the machine is accomplished by speeding up or slowing down one of the hydraulic motors relative to the other through the appropriate manipulation of the drive levers. In some instances, one of the motors may be reversed relative to the other to turn the machine about a zero turning radius. Mechanical drive mechanisms have also been utilized in lieu of the hydraulic pumps and motors. 
         [0003]    The drive levers are moveable independently of one another along fore-and-aft paths of travel to control the pumps and hydraulic motors. However, when the levers are aligned with one another in side-by-side relationship in neutral, they can be swung outwardly to widespread positions to make it more convenient for the operator to dismount the mower. In the present invention, through use of an electrical control circuit, swinging of the drive levers to their widespread positions causes the parking brakes or other wheel retaining mechanisms to be automatically applied, holding the mower against further movement. The electrical control circuit is also such that when the ignition is turned off for any reason, even if the drive levers are not in their widespread positions, the parking brake or retaining mechanism will be automatically applied as a safety means. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a left, front isometric view of a zero turning radius mower incorporating the principles of the present invention; 
           [0005]      FIG. 2  is a right, rear isometric view of the mower; 
           [0006]      FIG. 3  is a left, front isometric view of the mower as in  FIG. 1  but showing the drive levers swung out to their widespread positions for dismounting; 
           [0007]      FIG. 4  is a right, rear isometric view of the mower with wheels and other exterior structure removed to reveal internal details of construction; 
           [0008]      FIG. 5  is an enlarged, fragmentary, left front isometric view of the left drive lever illustrating its relationship with the T-shaped guide slot in the floor panel of the mower; 
           [0009]      FIG. 6  is an enlarged, fragmentary, left front isometric view of the right drive lever and its electrical brake switch for releasing or setting the right wheel brake; 
           [0010]      FIG. 7  is a vertical, transverse cross-sectional view through the mower chassis looking forwardly from a point just rearward of the drive levers; 
           [0011]      FIG. 8  is a fragmentary, vertical, transverse cross-sectional view through the mower chassis similar to  FIG. 7  but showing the left drive lever swung out to its widespread position; 
           [0012]      FIG. 9  is a fragmentary, front isometric view of the left wheel support tower and brake assembly; 
           [0013]      FIG. 10  is a fragmentary, rear isometric view of the left wheel support tower and brake assembly; 
           [0014]      FIG. 11  is a vertical cross-sectional view of the left wheel support tower and brake assembly with the brake assembly in an applied or set condition; 
           [0015]      FIG. 12  is a vertical cross-sectional view of the left wheel support tower and brake assembly similar to  FIG. 11  but with the brake assembly released; 
           [0016]      FIG. 13  is a schematic illustration of the electrical control circuit for the brakes of the mower showing the brakes in an applied or set condition; and 
           [0017]      FIG. 14  is a schematic illustration of the electrical control circuit for the brakes of the mower showing the brakes released. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The present invention is susceptible of embodiment in many different forms. While the drawings illustrate and the specification describes certain preferred embodiments of the invention, it is to be understood that such disclosure is by way of example only. There is no intent to limit the principles of the present invention to the particular disclosed embodiments. 
         [0019]    Referring initially to  FIGS. 1 and 2 , a mower incorporating the principles of the present invention is depicted therein and indicated by the numeral  10 . Mower  10  includes a mobile chassis  12  supported by a pair of ground-engaging drive wheels  14 ,  16  at the rear of the mower and a pair castor wheels  18 ,  20  at the front of the machine. A mower deck  22  is suspended under the belly of the machine. A gasoline engine  24  or other type of prime mover is supported on chassis  12  at the rear of the machine for supplying driving power to drive wheels  14 ,  16  and the cutter blade or blades (not shown) associated with mower deck  22 . 
         [0020]    An operator&#39;s seat  26  is supported on chassis  12  in front of engine  24  in such a position that an operator sitting on seat  26  can readily grasp a pair of drive levers  28  and  30  for controlling speed, turning, and forward or reverse travel of the mower. Levers  28  and  30  are moveable independently of one another along fore-and-aft paths of travel within respective T-shaped slots  32  and  34  in chassis  12  for accomplishing such control in a well-known manner. Fore-and-aft or longitudinal legs  36  ( FIG. 5 ) of T-slots  32 ,  34  limit levers  28 , 30  to fore-and-aft movement through forward, neutral and reverse modes, but transverse legs  38  at the mid-point of the fore-and-aft legs  36  (corresponding to the neutral position of levers  28 ,  30 ) permit the levers to be swung out to their widespread positions as illustrated in  FIG. 3  to facilitate mounting and dismounting by the operator. 
         [0021]    Mower  10  may be provided with mechanical drive mechanism operably interconnecting the output shaft (not shown) of engine  24  with drive wheels  14 ,  16 . However, in a preferred embodiment the engine output shaft is connected with a pair of hydraulic pumps  40  and  42  ( FIG. 4 ) that supply hydraulic fluid to a pair of reversible hydraulic motors  44  and  46  operably connected with respective ones of the drive wheels  14 ,  16 . The volume and direction of hydraulic flow from the pumps  40 ,  42  is regulated by an internal swash plate (not shown) in each pump whose position is controlled by a lever  50 . Levers  50  are operated by a pair of fore-and-aft extending control links  56  that are operably connected at their front ends to a pair of inverted, box-like brackets  58  that support the drive levers  28 ,  30 . Brackets  58  are independently mounted on a stationary cross shaft  60  for rotational movement relative to the shaft  60  about the longitudinal axis thereof. Thus, as levers  28 ,  30  are moved by the operator in fore-and-aft paths of travel, they swing or pivot brackets  58  about shaft  60  to operate pumps  40 ,  42 . A pair of dampeners  61  are connected between chassis  12  and the operating levers  50  of pumps  40 ,  42  to provide a measure of resistance to movement of levers  50 . 
         [0022]    Each of the drive levers  28 ,  30  is pivotally attached to its corresponding support bracket  58  by a fore-and-aft pivot  68  ( FIGS. 6 ,  7 , and  8 ). The pivots  68  thus permit levers  28 ,  30  to swing laterally in and out when levers  28 ,  30  are in the neutral position of  FIG. 1  in which they are aligned with transverse legs  38  of T-slots  32 ,  34 . 
         [0023]    At least one of the drive wheels  14 ,  16 , and preferably both, is provided with retaining mechanism broadly identified by the numeral  70  (detailed in  FIGS. 6 ,  7  and  8 ) for selectively, releasably holding the drive wheel against rotation. Each retaining mechanism  70  may take a variety of different forms including, for example, a lockable park mechanism including interengageable mechanical locking components, or a parking brake. In the illustrated and preferred embodiment, each retaining mechanism  70  takes the form of a parking brake  72 , which is preferably a friction brake. An actuator lever or member  74  projects through an upright slot  76  in a stationary rear wall  78  of brake  72  and is moveable up and down between an upper, actuated position in which a braking force is applied to hold the drive wheel against rotation, and a lower released position in which the braking force is released from the wheel to permit it to rotate. In one preferred form of the invention each brake, hydraulic motor, and drive wheel hub may comprise an integrated unit such as that available from White Hydraulics, Inc. of Hopkinsville, Ky. as a Model CE motor/brake. 
         [0024]    Retaining mechanism  70  further includes a tension spring  80  operably coupled with brake member  74  in a manner to yieldably bias member  74  toward its raised actuated position, thus applying the brake. Tension spring  80  is connected at its upper end to an adjustable eye-bolt  82  that is secured to a mounting bracket  84  on the outside of an upright, formed metal, generally channel-shaped tower  86  that is secured to and forms a part of chassis  12 . The lower end of tension spring  80  is connected to the outer end of a generally horizontally extending lever  88  that is pivotally mounted to tower  86  by a transverse pivot  90 . Spring  80  thus yieldably biases the outer end of lever  88  upwardly. Also coupled with the outer end of lever  88  is an adjustable, upright turnbuckle  92  that is connected at its lower end with an inverted, generally L-shaped bracket  94  fixed to brake member  74 . Lever  88 , link  92  and bracket  94  thus transmit the biasing force of spring  80  to the member  74  to apply a braking force to the drum of brake  72 . 
         [0025]    An electric control circuit  96 , shown schematically in  FIGS. 13 and 14 , is provided for electrically releasing and applying the parking brake  72 . As noted above, it is within the scope of the present invention to provide only one of the drive wheels  14 ,  16  with a retaining mechanism  70 , in which case control circuit  96  would be operative to control only the one mechanism. However, in a preferred embodiment, both of the drive wheels  14 ,  16  are provided with retaining mechanisms, preferably in the form of parking brakes  72  as illustrated in the drawings, and control circuit  96  is operable to control both parking brakes  72 . 
         [0026]    One primary component of control circuit  96  is an electrically powered control device  98  for each wheel  14 ,  16 , such device  98  being mounted on and supported by the support tower  86  associated with that wheel. Each control device  98  includes, in one preferred form, a single-acting air cylinder  100  powered by a pump  102 . In a preferred form, the air cylinder  100  and pump  102  are integrated into a single unit such as that available from North American Clutch Corporation of Milwaukee, Wis. as NORAM brand part number 700A020. 
         [0027]    Each air cylinder  100  includes a ram or piston  103  ( FIGS. 13 and 14 ) that has a rod  104  projecting downwardly from the cylindrical housing  106  of the cylinder. At its lower end, rod  104  is provided with a clevis  108  that connects to the inboard end of lever  88  via a pivot  110 . Thus, when pressurized air is introduced into the rod end of housing  106  from pump  102 , rod  104  is retracted, causing lever  88  to be lifted, which forces the outer end of lever  88  downwardly against the resistance of brake spring  80 . This motion thus pushes brake lever member  74  downwardly within slot  76  via turnbuckle  92  and releases the brake  72  ( FIG. 12 ). On the other hand, when pressurized air within housing  106  is exhausted via an electrically valved exhaust port  112  associated with pump  102 , such release of air pressure allows spring  80  to pull upwardly against the outer end of lever  88 , applying the brake  72  and lowering the inner end of lever  88  as it causes rod  104  to extend ( FIG. 11 ). 
         [0028]    When air cylinder  100  is electrically energized, it retracts piston rod  104  and releases the brake  72 . An electrically controlled valve (not shown) associated with exhaust port  112  helps hold sufficient air pressure within housing  106  as to maintain rod  104  retracted such that the motor of pump  102  need not be constantly running during the time that pressurized air maintains piston rod  104  retracted. When air cylinder  100  is de-energized, the valve of exhaust port  112  opens to set the brake. 
         [0029]    Provision is made to manually release the brake  72  and releasably maintain it in a released condition in the event that control device  98  is disabled or it is simply desired to maintain the brake released for any other reason, such as while the mower is being serviced. To this end, lever  88  is provided with a manual retaining rod  114  connected to the inner end of lever  88  via a generally upright slot  116  in lever  88 . At its upper end, retaining rod  114  is joggled outwardly and passes through the proximal side wall of tower  86  to terminate in a finger loop  118 . The upper end of retaining rod  114  is received within a vertical slot  120  in the proximal side wall of tower  86  so that link  114  may be manually grasped and pulled upwardly to the upper limit of slot  120 . In such position, the rod  114  may be pushed to one side in a transverse leg  122  of slot  120  so as to releasably hold rod  114  in its upwardly raised position. Thus, by pulling upwardly on retaining rod  114  when the brake is in an applied condition, the brake  72  will become released as the inner end of lever  88  is swung upwardly by rod  114 . By then temporarily pushing rod  114  into transverse leg  122 , rod  114  will remain fully raised with the brake released and piston rod  104  retracted into housing  106 . 
         [0030]    Normally, retaining rod  114  is out of the transverse leg  122  of slot  120  and is resting on the bottom of slot  120 . Under such conditions, the vertical slot  116  in lever  88  serves as a lost motion connection with rod  114  and permits piston rod  104  to retract and extend without causing manipulation of retaining rod  114 . Of course, retaining rod  114  may also be pulled upwardly and hooked over the edge of transverse leg  122  when the brake is already in a released condition with piston rod  104  retracted into cylinder  100 , thereby avoiding the need to manually overpower the spring  80 . 
         [0031]    Control circuit  96  further includes a pair of normally closed switches  124  that are mounted on the brackets  58  associated with drive levers  28 ,  30  and are electrically connected with the air pumps  102  associated with air cylinders  100 . Each of the switches  124  has an actuating button  126  positioned within the path of travel of the lower end of the corresponding drive lever  28  or  30  so as to be depressed and thus open the circuit when levers  28 ,  30  are in their widespread position as illustrated in  FIG. 8 . When drive levers  28 ,  30  are in neutral or other positions within the longitudinal legs  36  of the T-slots  32 ,  34 , the lower ends of drive levers  28 ,  30  are out of engagement with buttons  126 , thereby allowing switches  124  to return to their normal closed conditions as illustrated in  FIGS. 6 and 7 . 
         [0032]    Control circuit  96  also includes a storage battery  128  electrically connected with the pumps  102  and switches  124 , and an ignition switch  130  that is positioned for access by the operator when seated on the mower. Ignition switch  130  must be closed in order to energize pumps  102 . Because switches  124  are connected in parallel, at least one of them must also be closed to complete the circuit and energize pumps  102 . Switches  124  could be connected in series relationship with one another, in which case both of them would need to be closed, along with ignition switch  130 , before pumps  102  would be energized. 
       Operation 
       [0033]    During mowing operations, drive levers  28 ,  30  are disposed within the longitudinal fore-and-aft legs  36  of T-slots  32 ,  34 . This enables drive levers  28 ,  30  to be shifted independently of one another in appropriate fore-and-aft movements to control steering, speed and forward or reverse travel. Movement of levers  28 ,  30  forwardly from the neutral position illustrated in  FIG. 1  causes the mower to move forwardly, while moving them rearwardly from the neutral position causes the mower to move rearwardly. Steering of the mower is accomplished by moving one of the levers  28 ,  30  more forwardly or reversely relative to the other lever. 
         [0034]    During mowing operations, because ignition switch  130  is closed and drive levers  28 ,  30  are spaced away from actuating buttons  126  of switches  124 , control circuit  96  is energized to keep brakes  72  released. This condition is illustrated in  FIG. 14  wherein piston rods  104  are retracted within housings  106 , overcoming the bias of tension springs  80  and releasing brakes  72 . In reaching this condition, pumps  102  will have been energized to force air into housings  106  below pistons  103 , causing them to rise in housings  106  until such time as a limit switch (not shown) is engaged and operated, which shuts off pumps  102  and closes a valve associated with exhaust port  112 . This allows cylinders  100  to remain pressurized during mowing operations without requiring continuous operation of pumps  102 . 
         [0035]    When the mower is to be parked and dismounted, the operator places drive levers  28 ,  30  in their neutral positions aligned with transverse legs  38  of T-slots  32 ,  34  and then swings the levers out to their widespread positions of  FIGS. 3 and 8 . Such movement causes the lower ends of levers  28 ,  30  to engage and depress buttons  126  of switches  124 , thereby opening the circuit and causing the valve (not shown) that controls exhaust ports  112  to open and quickly exhaust trapped air from the underside of the pistons within cylinders  100 . This allows tension springs  80  to pull the outer ends of levers  88  upwardly, setting parking brakes  72  as illustrated in  FIG. 13 . The operator would then typically turn off the ignition to open switch  130 . 
         [0036]    It will be appreciated that the brakes  72  may also be set by simply turning off the ignition switch  130  (open the circuit) when the machine is running and the drive levers  28 ,  30  are in their operating modes within the longitudinal legs  36  of T-slots  32 ,  34 . Thus, brakes  72  may be set by either placing the drive levers  28 ,  30  in neutral and swinging them out to their widespread positions, or by simply turning off the ignition through switch  130 . Conversely, to release brakes  72 , the ignition must be turned on through switch  130  and at least one of the drive levers  28 ,  30  swung inwardly to the operating mode within the longitudinal leg  36  of the T-slot  32  or  34 . 
         [0037]    The inventor hereby states his intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of his invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.