Patent Description:
Lawn care tasks are commonly performed using various tools and/or machines that are configured for the performance of corresponding specific tasks. Certain tasks, like grass cutting, are typically performed by lawn mowers. Lawn mowers themselves may have many different configurations to support the needs and budgets of consumers. Walk-behind lawn mowers are typically compact, have comparatively small engines, and are relatively inexpensive. Meanwhile, at the other end of the spectrum, riding lawn mowers, such as lawn tractors, can be quite large. Riding lawn mowers can sometimes also be configured with various functional accessories (e.g., trailers, tillers, and/or the like) in addition to grass cutting components. Riding lawn mowers provide the convenience of a riding vehicle as well as a typically larger cutting deck as compared to a walk-behind model.

Some riding lawn mowers have been provided with very short (e.g., near zero) turning radiuses. Such mowers have employed separate steering levers that each allow individual control of a corresponding drive wheel on the same side of the mower. The drive wheels are generally rear wheels, and wheels at the front of the mower tend to be caster wheels that can freely rotate about an axis perpendicular to the ground in order to support movement in any direction, and the tight turning radiuses that can be achieved with such mowers.

This operational paradigm (i.e., having powered rear wheels and unpowered front caster wheels) generally performs quite well in most situations. However, there are a few situations where the unpowered front caster wheels do not contribute positively to the operation of the mower. For example, the front caster wheels themselves may not be stable on hills. In this regard, such instability may be experienced when mowing perpendicular to the slope of a steep hill, or when going straight up or down steep hills. When attempting to back up a steep hill, weight may transfer to the front wheels (i.e., the caster wheels), and the unit may lose traction. When descending steep hills, the user may need to pull the steering levers rearward (thereby applying drive power in the rearward direction) in order to slow the decent of the mower down the hill. In these cases, the rearward drive power acts as a brake during the descent and the front caster wheels do not contribute positively to the control of the mower. Thus, it may be desirable to provide a capability for improved contribution to the stability of the front caster wheels (and perhaps also the mower in general) such as by lessening or even stopping rotation of the front caster wheels.

<CIT> discloses a riding lawn care vehicle with a frame to which drive wheels are attached, a steering assembly, caster wheels to support unpowered rotation about a wheel axis and rotation about a spindle axis.

The subject matter according to the invention is defined in claim <NUM>.

Some example embodiments of the present invention provide the ability to engage a drive assembly to the front caster wheels. This arrangement, as will be discussed in greater detail below, tends to provide a more stability when mowing perpendicular to a slope or when transiting up or down a steep slope and may result in improved operator experience during employment of the riding lawn care vehicle.

According to the invention, a riding lawn care vehicle is provided. The riding lawn care vehicle includes a frame, a steering assembly, caster wheels and a drive assembly. At least a first drive wheel and a second drive wheel of the riding lawn care vehicle are attachable to the frame. The steering assembly is configured to facilitate turning of the riding lawn care vehicle based on drive speed control of the first and second drive wheels. The caster wheels are configured to support unpowered rotation about a wheel axis that extends substantially parallel to the ground and rotation about a spindle axis that is substantially perpendicular to the ground. The drive assembly is configured to be selectively placed in a disengaged state in which rotation about the spindle axis and the wheel axis is uninhibited, and an engaged state in which the caster wheels are at least partially inhibited with respect to rotation about both the wheel axis and the spindle axis.

The drive assembly includes a friction drive assembly. The friction drive assembly may be configured to be selectively placed in a disengaged state in which rotation about the spindle axis and the wheel axis is uninhibited, and an engaged state in which the caster wheels are at least partially inhibited with respect to rotation about both the wheel axis and the spindle axis.

Some example embodiments may improve an operator's ability to control or operate a lawn care vehicle for operations on hills. The user experience associated with operating the riding lawn care vehicle may therefore be improved.

Having thus described some embodiments of the present invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:.

Some example embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all example embodiments are shown. Indeed, the examples described and pictured herein should not be construed as being limiting as to the scope, applicability, or configuration of the present disclosure. Rather, these example embodiments are provided so that this disclosure will satisfy applicable legal requirements. Furthermore, as used herein, the term "or" is to be interpreted as a logical operator that results in true whenever one or more of its operands are true. As used herein, the phrase "operable coupling" and variants thereof should be understood to relate to direct or indirect connection that, in either case, enables functional interconnection of components that are operably coupled to each other.

Some example embodiments may improve the ability of an operator to control operation of riding lawn care vehicles on hills. However, the concepts described herein for improving control of the riding lawn care vehicle may also have benefits in other situations as well. In an example embodiment, a caster wheel drive assembly (or simply a drive assembly) may be selectably either engaged or disengaged to provide positive engagement with the caster wheels when engaged and remove such engagement when disengaged. The caster wheel drive assembly may include or be embodied as a friction drive assembly that can be rotated into or out of contact with the caster wheels. When engaged (or in an engaged state), the caster wheel drive assembly may be configured to rotate the caster wheels at a speed that matches the speed over ground being applied by the drive wheels (e.g., the rear wheels). This also means that the caster wheel drive assembly, when engaged while no power is applied, actually provide a braking function to enhance braking capabilities for the vehicle. The engaged state also holds the caster wheels in a generally fixed (e.g., fixed but with the potential for some amount of play to be designed in) orientation directed forward. Meanwhile, when disengaged, the caster wheels are free to operate normally in the way they typically operate in the absence of the caster wheel drive assembly of an example embodiment.

<FIG>, which includes <FIG> and <FIG>, illustrates a riding lawn care vehicle <NUM> according to an example embodiment. <FIG> illustrates a perspective view of the riding lawn care vehicle <NUM>, and <FIG> illustrates a top view of the riding lawn care vehicle <NUM> according to an example embodiment. In some embodiments, the riding lawn care vehicle <NUM> may include a seat <NUM> that may be disposed at a center, rear, or front portion of the riding lawn care vehicle <NUM>. The riding lawn care vehicle <NUM> may also include a steering assembly <NUM> (e.g., a set of steering levers or the like) functionally connected to wheels <NUM> and/or <NUM> of the riding lawn care vehicle <NUM> to allow the operator to steer the riding lawn care vehicle <NUM>.

<FIG> illustrates a perspective view of a steering assembly with steering levers positioned to be pulled back for rearward propulsion of the riding lawn care vehicle <NUM> of <FIG>. Referring to <FIG> and <FIG>, the operator may sit on the seat <NUM>, which may be disposed to the rear of the steering assembly <NUM> to provide input for steering of the riding lawn care vehicle <NUM> via the steering assembly <NUM>. However, some models may be stand-up models that eliminate the seat <NUM>. If the seat <NUM> is eliminated, the operator may stand at an operator station proximate to the steering assembly <NUM>. In an example embodiment, the steering assembly <NUM> may include separately operable steering levers <NUM> shown specifically in <FIG> and <FIG>.

The riding lawn care vehicle <NUM> may also include a cutting deck <NUM> having at least one cutting blade (e.g., three cutting blades) mounted therein. The cutting deck <NUM> may be positioned substantially rearward of a pair of front wheels <NUM> and substantially forward of a pair of rear wheels <NUM> in a position to enable the operator to cut grass using the cutting blade(s) when the cutting blade(s) are rotated below the cutting deck <NUM> when the cutting deck <NUM> is in a cutting position. However, in some alternative examples, the cutting deck <NUM> may be positioned in front of the front wheels <NUM>. Each of the front wheels <NUM> may be a caster wheel that has two separate axes (e.g., each of which may be referred to as a wheel axis) about which rotation is possible. In this regard, each of the caster wheels has a wheel axle that extends parallel to the ground and about which the wheel rotates during rolling motion over the ground. The wheel axle may define the wheel axis. Each of the caster wheels also has a spindle <NUM> that extends substantially perpendicular to the ground. Rotation around the spindle <NUM> enables the caster wheels to rotate to support movement in any direction (i.e., over the <NUM> turn radius of the riding lawn care vehicle <NUM>). The spindle <NUM> may therefore define a spindle axis.

In some embodiments, a footrest <NUM> may also be positioned above the cutting deck <NUM> forward of the seat <NUM> to enable the operator to rest his or her feet thereon while seated in the seat <NUM>. In embodiments that do not include the seat <NUM>, the footrest <NUM> may form the operator station from which a standing operator controls the riding lawn care vehicle <NUM>. When operating to cut grass, the grass clippings may be captured by a collection system, mulched, or expelled from the cutting deck <NUM> via either a side discharge or a rear discharge.

In the pictured example embodiment, an engine <NUM> of the riding lawn care vehicle <NUM> is disposed to the rear of a seated operator. However, in other example embodiments, the engine <NUM> could be in different positions such as in front of or below the operator. As shown in <FIG>, the engine <NUM> may be operably coupled to one or more of the wheels <NUM> and/or <NUM> to provide drive power for the riding lawn care vehicle <NUM>. The engine <NUM>, the steering assembly <NUM>, the cutting deck <NUM>, the seat <NUM>, and other components of the riding lawn care vehicle <NUM> may be operably connected (directly or indirectly) to a frame <NUM> of the riding lawn care vehicle <NUM>. The frame <NUM> may be a rigid structure configured to provide support, connectivity, and/or interoperability functions for various ones of the components of the riding lawn care vehicle <NUM>.

In some example embodiments, the steering assembly <NUM> may be embodied as an assembly of metallic and/or other rigid components that may be welded, bolted, and/or otherwise attached to each other and operably coupled to the wheels of the riding lawn care vehicle <NUM> to which steering inputs are provided (e.g., rear wheels <NUM>). For example, the steering assembly <NUM> may include or otherwise be coupled with hydraulic motors that independently power one or more drive wheels (e.g., rear wheels <NUM>) on each respective side of the riding lawn care vehicle <NUM>. The steering levers <NUM> may be operable to move forward (i.e., in a direction opposite arrow <NUM> in <FIG>) and rearward (i.e., in the direction shown by arrow <NUM> in <FIG>) while in the inboard position (shown in both <FIG> and <FIG>).

When a steering lever <NUM> is pushed forward (e.g., away from the operator an opposite the direction of arrow <NUM>), the corresponding hydraulic motor may drive the corresponding wheel forward. When a steering lever <NUM> is pulled rearward (e.g., toward the operator as shown by the direction of arrows <NUM> in <FIG>), the corresponding hydraulic motor may drive the corresponding wheel backward. Thus, when both steering levers <NUM> are pushed forward the same amount, the riding lawn care vehicle <NUM> travels forward in substantially a straight line because approximately the same amount of forward drive input is provided to each drive wheel. When both steering levers <NUM> are pulled back the same amount, the riding lawn care vehicle <NUM> travels backward (e.g., rearward) in substantially a straight line because approximately the same amount of rearward drive input is provided to each drive wheel. When one steering lever <NUM> is pushed forward and the other steering lever <NUM> is pulled back, the riding lawn care vehicle <NUM> begins to turn in a circle and/or spin. Steering right and left may be accomplished by providing uneven amounts of input to the steering levers <NUM>. Other steering control systems may be employed in some alternative embodiments.

Although the steering levers <NUM> are generally moved forward (i.e., opposite the direction of the arrows <NUM> shown in <FIG>) or backward (i.e., in the direction of the arrows <NUM> shown in <FIG>) in any desirable combination while they are in the operating positions shown in <FIG> and <FIG>, it should be appreciated that the steering levers <NUM> may also be moved to an outboard position (e.g., in a non-operational state) by moving the steering levers <NUM> outwardly in the direction shown by arrows <NUM> in <FIG>. In this regard, although the steering levers <NUM> are shown in the inboard (or operational) position in <FIG> and <FIG>, the steering levers <NUM> may be moved in the direction of arrows <NUM> (i.e., outboard) relative to their inboard position and into a non-operational position. In some cases, each of the steering levers <NUM> may be operably coupled to respective lever mounts <NUM> that may pivot to enable the steering levers <NUM> to move outwardly (e.g., to the outboard position) or inwardly (e.g., to an inboard and/or operating position). In some embodiments, when at least one (and sometimes both) of the steering levers <NUM> is pivoted outwardly, brakes may be applied and the operator may easily mount or dismount the riding lawn care vehicle <NUM> and sit in or leave the seat <NUM>.

<FIG> illustrates a block diagram of some components that can be added to the riding lawn care vehicle <NUM> of <FIG> and <FIG> to provide front drive capability in accordance with an example embodiment. The components added may be operably coupled to the frame <NUM> (proximate to the front of the footrest <NUM>) to interface with the front wheels <NUM>. As shown in <FIG>, a drive assembly <NUM> according to an example embodiment may be added to the riding lawn care vehicle <NUM>. The drive assembly <NUM> may be referred to as a "front drive assembly" in this case, since the front wheels <NUM> are the caster wheels, or as a "caster wheel drive assembly. " However, it is also possible that the caster wheels could be located elsewhere (e.g., at the rear or on sides of a mower) in which case the drive would not be properly characterized as a "front drive assembly. " Thus, the more generic term of "drive assembly" will be used hereinafter.

As shown in <FIG>, the drive assembly <NUM> includes a friction drive assembly <NUM> which is movable into and out of contact with each of the front wheels <NUM> responsive to operation of a positioning assembly <NUM>. The position assembly <NUM> may be operable responsive to positioning of an actuator <NUM> based on a user input <NUM>. In an example embodiment, the friction drive assembly <NUM> may be considered to be engaged or in an engaged state, when the friction drive assembly <NUM> is moved into contact with the front wheels <NUM>. In an example embodiment, the friction drive assembly <NUM> may simultaneously contact both of the front wheels <NUM> in the engaged state. Meanwhile, when the friction drive assembly <NUM> is moved such that there is no contact with the front wheels <NUM> (i.e., moved to be spaced apart from the front wheels <NUM>), then the friction drive assembly <NUM> may be considered to be disengaged or in the disengaged state.

The positioning assembly <NUM> may, in some cases, be defined by a pivot structure that is configured to rotate about an axis (responsive to operation of the actuator <NUM>) in order to move between the engaged and disengaged states. In some cases, the disengaged state may be reached by lifting the friction drive assembly <NUM> away from the front wheels <NUM>. This arrangement enables gravity to assist with maintaining friction and engagement between the friction drive assembly <NUM> and the front wheels <NUM> in the engaged state. Thus, the weight of the friction drive assembly <NUM> (and perhaps also some or all of the weight of the positioning assembly <NUM>) will bias the friction drive assembly <NUM> toward contact and engagement with the front wheels <NUM> to improve the amount of friction between the friction drive assembly <NUM> and the front wheels <NUM> to enhance responsiveness and general operational effectiveness of the friction drive assembly <NUM>.

It should be appreciated that although the pivot structure described above may be employed, other operable coupling strategies for the friction drive assembly <NUM> and the front wheels <NUM> could also be utilized in alternative embodiments. For example, a linear (horizontal or partially vertical) movement of the friction drive assembly <NUM> could also be provided for engagement with the front wheels <NUM> in some cases. The use of springs or other biasing members may be used more prominently in such designs to the extent the designs do not rely on the assistance of gravity. It should also be appreciated that, in some cases, some play between the friction drive assembly <NUM> and the front wheels <NUM> in the engaged state may be desirable. Thus, for example, the positioning assembly <NUM> may make strategic use of springs or other such components that can hold the friction drive assembly <NUM> in contact with the front wheels <NUM>, but provide some amount of play or movement of the positioning assembly <NUM> (and therefore also the friction drive assembly <NUM>) in the engaged state to accommodate some amount of movement of the friction drive assembly <NUM> relative to one or both of the front wheels <NUM> at any given time.

The actuator <NUM> of some embodiment may be a foot operated pedal or lever. However, in other cases, the actuator could be embodied as a hand operated lever, or other mechanical actuation device. In still other examples, the actuator <NUM> may be an electrically operated device or may be electromechanical. Thus, for example, the actuator may be embodied as a button or switch in some cases.

In an example embodiment, the friction drive assembly <NUM> may be operated by a speed controller <NUM> that is in turn powered by a power source <NUM>. In some cases, the speed controller <NUM> may be embodied as an electric motor with a corresponding motor controller for determining speed of the turning of the friction drive assembly <NUM>. In other examples, the speed controller <NUM> may be a hydraulic motor or may otherwise be powered via hydraulic fluid or hydrostatics. In such an example, the power source <NUM> may be a hydrostatic pump. Other power source and speed control strategies may also be employed in alternative embodiments.

In an example embodiment, the speed controller <NUM> may be configured to receive an input indicative of (or proportional to) the ground speed of the riding lawn care vehicle <NUM>. This input, which may be referred to as a ground speed input <NUM>, may be used to determine (or otherwise dictate) the speed at which the front wheels <NUM> are driven. For example, the friction drive assembly <NUM> may be powered by the speed controller <NUM> to turn the front wheels <NUM> at a rate that matches the speed over ground that is being supplied by the power provided to the rear wheels <NUM>. In some cases, the speed controller <NUM> may only operate (i.e., only drive the friction drive assembly <NUM>) when the positioning assembly <NUM> has been actuated to place the friction drive assembly <NUM> in the engaged state. However, in other cases, the speed controller <NUM> may turn the friction drive assembly <NUM> at a speed that matches the speed over ground achieved by powering of the rear wheels <NUM> in both the engaged and disengaged states. In such an example, the friction drive assembly <NUM> could essentially be driven (proportional to speed of the riding lawn care vehicle <NUM>) without a load when disengaged.

As can be appreciated from the description above, the drive assembly <NUM> can be physically instantiated in a number of different ways. <FIG> illustrate one example physical structure via which the drive assembly <NUM> can be instantiated. In this regard, <FIG> is defined by <FIG>, <FIG> is defined by <FIG>, and <FIG> is defined by <FIG>. With respect to <FIG>, it should be further noted that <FIG>, <FIG> and <FIG> each show the drive assembly <NUM> in the disengaged state, and <FIG>, <FIG> and <FIG> each show the drive assembly <NUM> in the engaged state.

Referring now to <FIG>, the actuator <NUM> of <FIG> may be embodied as a pedal <NUM>. The pedal <NUM> may be operably coupled to a pedal mount <NUM>. The pedal mount <NUM> of this example comprises to parallel plates that face each other and have slots <NUM> formed in a top surface thereof. The slots <NUM> are provided in pairs and each respective pair of slots <NUM> is configured to receive and retain the pedal <NUM> in a respective one of an engaged position (which corresponds to the forward most pair of slots <NUM> in this example) and a disengaged position (which corresponds to the rearward most pair of slots <NUM> in this example. The operator can push the pedal <NUM> with his/her foot (in this case the left foot, but alternatively the right if the pedal <NUM> is moved to the opposite side) to change between the engaged position and the disengaged position. When the pedal <NUM> has repositioned to alignment with the other pair of slots <NUM>, the pedal <NUM> may be released by the operator and may settle into and be retained at the corresponding pair of slots <NUM> by the pedal mount <NUM>.

The pedal <NUM> may also be operably coupled to a pedal arm <NUM>. The pedal arm <NUM> may be operably coupled to the pedal <NUM> at a proximal end thereof (relative to the operator). The pedal arm <NUM> may be operably coupled to the positioning assembly <NUM> at the distal end of the pedal arm <NUM>. In an example embodiment, the pedal arm <NUM> may be an elongate metallic member that extends between the parallel plates of the pedal mount <NUM>, and the pedal arm <NUM> may be pivotally coupled to each of the pedal <NUM> and the positioning assembly <NUM>.

In some cases, the pedal arm <NUM> may further include or be operably coupled to one or more cam surfaces or other L-shaped pivot arms that may be configured to allow rotation of the positioning assembly <NUM> through a pivoting or hinged range of motion when changing states of the friction drive assembly <NUM>. As best seen in <FIG>, a projection <NUM> (e.g., a catch or detent) may be provided at the end of an L-shaped pivot assembly <NUM> at a proximal end of the pedal arm <NUM> (relative to the pedal <NUM>). Meanwhile, another L-shaped bracket <NUM> may be provided at the distal end of the pedal arm <NUM> to facilitate movement of the positioning assembly <NUM>.

The positioning assembly <NUM> may include a hinge assembly <NUM> and a carrier plate <NUM>. The hinge assembly <NUM> may include one or more butterfly hinges, butt hinges, piano hinges or other pivotal couplers that operably couple a portion of the frame <NUM> that is forward of the footrest <NUM> to the carrier plate <NUM>. The hinge assembly <NUM> may define a hinge axis that extends substantially parallel to the ground and substantially perpendicular to a longitudinal centerline of the riding lawn care vehicle <NUM>. The carrier plate <NUM> may therefore be operably coupled to the frame <NUM> at a rear portion thereof (or proximal end thereof), and the distal end of the carrier plate <NUM> may rise away from the ground (and away from the front wheels <NUM>) when the carrier plate <NUM> pivots upward and lower toward the ground (and toward the front wheels <NUM>) when the carrier plate <NUM> pivots downward.

The carrier plate <NUM> may be a metallic, plastic or other rigid structure either having a plate-like surface (e.g., being formed substantially of one sheet metal structure with structural supports potentially being provided around edges thereof, or at middle portions thereof. However, the carrier plate <NUM> need not necessarily have a plate-like surface and may instead be a collection of frame members that are arranged to form a pivotable support structure for supporting the friction drive assembly <NUM>. Regardless of the specific structure used to embody the positioning assembly <NUM>, the positioning assembly <NUM> (and in this case the carrier plate <NUM>) may support the friction drive assembly <NUM>, and sometimes also the speed controller <NUM>, in the engaged state (e.g., when the pedal <NUM> is in the engaged (forward) position) and in the disengaged state (e.g., when pedal is in the disengaged (rearward) position). In an example embodiment, the carrier plate <NUM> may support or include a support tube <NUM> at a distal end thereof. The support tube <NUM> may extend parallel to the hinge axis of the hinge assembly <NUM>.

The friction drive assembly <NUM> may include an axle <NUM> with friction wheels <NUM> disposed at opposing ends thereof. The friction wheels <NUM> may be knurled metallic, plastic or other rigid members that are configured to frictionally engage with the front wheels <NUM> when the friction drive assembly <NUM> is in the engaged state. The friction wheels <NUM> may be operably coupled to and turn with the axle <NUM>. In some cases, the axle <NUM> may be supported within the support tube <NUM> such that the axle <NUM> can turn within the support tube <NUM> with relatively little friction. As such, a bearing assembly may be provided within the support tube <NUM> to enable relatively free rotation of the axle <NUM> within the support tube <NUM> when the speed controller <NUM> turns the axle <NUM>.

In this regard, the speed controller <NUM> of this example is embodied as an electric motor <NUM>. The electric motor <NUM> is supported on the carrier plate <NUM> and operably coupled to the axle <NUM> via a belt <NUM> (or a chain or other flexible drive member). The belt <NUM> may extend from a drive wheel attached to an output shaft of the electric motor <NUM> to a power wheel <NUM> mounted directly on the axle <NUM> to turn the axle <NUM> responsive to turning of the output shaft of the electric motor <NUM>. In some cases, the drive wheel on the output shaft of the electric motor <NUM> may have a smaller diameter than the power wheel <NUM> to increase the speed of the axle <NUM> relative to the speed of the output shaft. The sizes of these wheels in relation to the sizes of the front wheels <NUM> may be selected to enable the ground speed of the rear wheels <NUM> to be matched relatively accurately when the friction drive assembly <NUM> is in the engaged state.

The electric motor <NUM> may therefore determine the speed (e.g., in revolutions per minute (RPM)) of the output shaft of the electric motor <NUM> based on the speed over ground being provided by the powering of the rear wheels <NUM>. The electric motor <NUM> may therefore be understood to have the potential for variable speed control based on and matching the speed of the riding lawn care vehicle <NUM>. As noted above, in some cases, the electric motor <NUM> could be replaced with a hydraulic motor, and hydraulic lines (e.g., instead of electrical wiring) may be used to operably couple the hydraulic motor to the power source <NUM> (which would then be hydraulic instead of electrical).

When the pedal <NUM> is moved to the disengaged position (shown in <FIG>, <FIG> and <FIG>), the pedal <NUM> may be drawn in the direction of arrow <NUM>, and the pedal arm <NUM> may lift carrier plate <NUM> upward as shown by arrow <NUM>. The pedal <NUM> may be received in the slots <NUM> (i.e., the rearward-most slots) that correspond to the disengaged position on the pedal mount <NUM>. In some cases, a set of carrier assist springs <NUM> may be positioned between the frame <NUM> and the support tube <NUM> (or a portion of the carrier plate <NUM>) to assist in lifting the carrier plate <NUM> against the force of gravity. As such, lifting the carrier plate <NUM> unloads the carrier assist springs <NUM>, whereas lowering the carrier plate <NUM> loads the carrier assist springs <NUM>.

The pedal <NUM> and/or the pedal arm <NUM> may also include one or more assisting springs <NUM> that may be positioned to bias the pedal <NUM> toward the disengaged position. In this regard, for example, as shown in <FIG>, the assist spring <NUM> may extend between a distal end of the pedal arm <NUM> and a proximal end (or top) portion of the carrier plate <NUM>. The lifting of the carrier plate <NUM> loads the assist spring <NUM>, and the lower of the carrier plate <NUM> unloads the assist spring <NUM>. The lifting of the carrier plate <NUM> also lifts the support tube <NUM>, the axle <NUM> and the friction wheels <NUM> so that the friction wheels <NUM> are no longer in contact with the front wheels <NUM> and the friction drive assembly <NUM> is in the disengaged state. When the friction drive assembly <NUM> is in the disengaged state, the front wheels <NUM> are free to rotate unpowered about the wheel axis, and also free to rotate about the spindle axis.

When the pedal <NUM> is moved to the engaged position (shown in <FIG>, <FIG> and <FIG>), the pedal <NUM> may be pushed in the direction of arrow <NUM>, and the pedal arm <NUM> may push the carrier plate <NUM> (against the biasing of the carrier assist springs <NUM>) downward as shown by arrow <NUM>. The pedal <NUM> may be received in the slots <NUM> (i.e., the forward-most slots) that correspond to the engaged position on the pedal mount <NUM>. The pushing of the carrier plate <NUM> lowers (assisted by gravity) the support tube <NUM>, the axle <NUM> and the friction wheels <NUM> downward so that the friction wheels <NUM> are forced into contact with the front wheels <NUM> and the friction drive assembly <NUM> is in the engaged state.

When the friction drive assembly <NUM> is in the engaged state, there are two distinct impacts on the front wheels <NUM>. First, the front wheels <NUM> are no longer free to rotate unpowered about the wheel axis. Instead, the front wheels <NUM> are held (through friction with the friction wheels <NUM>) to tend to move at the speed dictated by the movement of the friction wheels <NUM>. Thus, if the friction wheels <NUM> are being driven (by the electric motor <NUM>) to achieve the same speed over ground that is being provided at the rear wheels <NUM>, then the front wheels <NUM> will also be driven at the same speed. Conversely, if the friction wheels <NUM> are not powered, then the friction wheels <NUM> will not only be inclined not to move, but the friction wheels <NUM> will effectively act as a brake on the front wheels <NUM> by applying friction that resists rotation of the front wheels <NUM> about the wheel axis.

Second, the front wheels <NUM> are also no longer free to rotate about the spindle axis. Instead, when the friction wheels <NUM> engage the front wheels <NUM>, the front wheels <NUM> will generally be aligned straight ahead (e.g., so the wheel axis is substantially perpendicular to the longitudinal centerline of the riding lawn care vehicle <NUM>). This generally prevents the front wheels <NUM> from becoming unstable on slopes or when going up or down hills and keeps the front wheels <NUM> pointing relatively straight and in alignment with the rear wheels <NUM>. Of note, the existence of the carrier assist springs <NUM> and the assisting springs <NUM> may provide for some amount of play in the carrier plate <NUM> (or more generally in the positioning assembly <NUM>). This play may allow the front wheels <NUM> to rotate slightly about the spindle axis (e.g., up to ten degrees in either direction). Of note, in some cases, edges of the carrier plate <NUM> or the support tube <NUM> may be extended outwardly toward the front wheels <NUM> to further limit rotation thereof about the spindle axis. In particular, a gap between either the carrier plate <NUM> or the support tube <NUM> may help to define the maximum amount of play or rotation of the front wheels <NUM> that is allowed in the engaged state.

Accordingly, some example embodiments may provide a riding lawn care vehicle. The riding lawn care vehicle may include a frame, a steering assembly, caster wheels and a drive assembly. At least a first drive wheel and a second drive wheel of the riding lawn care vehicle are attachable to the frame. The steering assembly is configured to facilitate turning of the riding lawn care vehicle based on drive speed control of the first and second drive wheels. The caster wheels are configured to support unpowered rotation about a wheel axis that extends substantially parallel to the ground and rotation about a spindle axis that is substantially perpendicular to the ground. The drive assembly is configured to be selectively placed in a disengaged state in which rotation about the spindle axis and the wheel axis is uninhibited, and an engaged state in which the caster wheels are at least partially inhibited with respect to rotation about both the wheel axis and the spindle axis.

The riding lawn care vehicle (or the drive assembly) of some embodiments may include additional, optional features, and/or the features described above may be modified or augmented. Some examples of modifications, optional features and augmentations are described below. It should be appreciated that the modifications, optional features and augmentations listed below may each be added alone, or they may be added cumulatively in any desirable combination. For example, in some embodiments, the drive assembly may include a friction drive assembly that contacts the caster wheels in the engaged state and does not contact the caster wheels in the disengaged state. In an example embodiment, the friction drive assembly may be configured to enable a power source to provide power to the caster wheels via frictional engagement between the caster wheels and the friction drive assembly in the engaged state. In some cases, the friction drive assembly may include an axle and friction wheels provided at opposing ends of the axle, and the friction wheels may inhibit rotation of the caster wheels about the spindle axis in the engaged state. In an example embodiment, the friction drive assembly may include a motor having an output shaft that may be operably coupled to the axle to turn the axle at a speed proportional to speed over ground provided by the first and second drive wheels. In some cases, the motor may be an electric motor or a hydraulic motor. In an example embodiment, the motor may be supported on a carrier plate that may be configured to pivot between the engaged state and the disengaged state. In some cases, the carrier plate may include a support tube inside which the axle is rotatably mounted, and one or more carrier assist springs may be provided to extend between the frame and the support tube to facilitate lifting the carrier plate to the disengaged state. In an example embodiment, the output shaft may include a drive wheel and the axle comprises a power wheel, and sizes of the drive wheel and the power wheel may be selected to enable the motor to drive the axle proportional to the speed over ground provided by the first and second drive wheels. In some cases, the caster wheels may include a first caster wheel and a second caster wheel, and the first and second caster wheels may be disposed at a front portion of the riding lawn care vehicle. The friction wheels may simultaneously engage the first caster wheel and the second caster wheel when the friction drive assembly is in the engaged position. In an example embodiment, the riding lawn care vehicle may further include an actuator configured to shift the drive assembly between the engaged state and the disengaged state. In some cases, the actuator may include a foot-operated pedal. In an example embodiment, the riding lawn care vehicle may be a zero turn mower.

Claim 1:
A riding lawn care vehicle (<NUM>), in particular a zero turn mower, comprising:
a frame (<NUM>) to which at least a first drive wheel (<NUM>, <NUM>) and a second drive wheel (<NUM>, <NUM>) of the riding lawn care vehicle (<NUM>) are attachable;
a steering assembly (<NUM>) configured to facilitate turning of the riding lawn care vehicle (<NUM>) based on drive speed control of the first and second drive wheels (<NUM>, <NUM>);
caster wheels configured to support unpowered rotation about a wheel axis that extends substantially parallel to the ground and rotation about a spindle axis that is substantially perpendicular to the ground; and
a drive assembly configured to be selectively placed in a disengaged state in which rotation about the spindle axis and the wheel axis is uninhibited, and
an engaged state in which the caster wheels are at least partially inhibited with respect to rotation about both the wheel axis and the spindle axis,
wherein the drive assembly comprises a friction drive assembly (<NUM>) that contacts the caster wheels in the engaged state and does not contact the caster wheels in the disengaged state.