Lawn care vehicle with front drive caster wheels

1 . A riding lawn care vehicle comprising:

a frame to which at least a first drive wheel and a second drive wheel of the riding lawn care vehicle are attachable;

a steering assembly configured to facilitate turning of the riding lawn care vehicle based on drive speed control of the first and second drive wheels;

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 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 that contacts the caster wheels in the engaged state and does not contact the caster wheels in the disengaged state,

wherein in the engaged state, the friction drive assembly contacts the caster wheels at respective contact points disposed forward of the wheel axis and at an opposite side of the wheel axis from the first and second drive wheels, and

wherein the drive assembly inhibits rotation about the wheel axis and spindle axis so the wheel axis is substantially perpendicular to the longitudinal centerline of the riding lawn care vehicle in response to the friction drive assembly not being powered in the engaged state.

2 . The riding lawn care vehicle of claim 1 , further comprising an actuator configured to shift the drive assembly between the engaged state and the disengaged state, and

wherein the actuator comprises a foot-operated pedal.

3 . The riding lawn care vehicle of claim 1 , wherein the friction drive assembly is 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.

4 . The riding lawn care vehicle of claim 3 , wherein the friction drive assembly comprises an axle and friction wheels provided at opposing ends of the axle, and

wherein the friction wheels inhibit rotation of the caster wheels about the spindle axis in the engaged state.

5 . The riding lawn care vehicle of claim 4 , wherein the friction drive assembly comprises a motor having an output shaft 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.

6 . The riding lawn care vehicle of claim 5 , wherein the motor is an electric motor or a hydraulic motor.

7 . The riding lawn care vehicle of claim 5 , wherein the motor is supported on a carrier plate, the carrier plate being configured to pivot between the engaged state and the disengaged state.

8 . The riding lawn care vehicle of claim 7 , wherein the carrier plate comprises a support tube inside which the axle is rotatably mounted, and

wherein one or more carrier assist springs is provided to extend between the frame and the support tube to facilitate lifting the carrier plate to the disengaged state.

9 . The riding lawn care vehicle claim 1 , wherein the riding lawn care vehicle is a zero turn mower.

10 . The riding lawn care vehicle of claim 4 , wherein the caster wheels comprise a first caster wheel and a second caster wheel, the first and second caster wheels being disposed at a front portion of the riding lawn care vehicle, and

wherein the friction wheels simultaneously engage the first caster wheel and the second caster wheel when the friction drive assembly is in the engaged position.

11 . A riding lawn care vehicle comprising:

a frame to which at least a first drive wheel and a second drive wheel of the riding lawn care vehicle are attachable;

a steering assembly configured to facilitate turning of the riding lawn care vehicle based on drive speed control of the first and second drive wheels;

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 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 that contacts the caster wheels in the engaged state and does not contact the caster wheels in the disengaged state,

wherein in the engaged state, the friction drive assembly contacts the caster wheels at respective contact points disposed forward of the wheel axis and at an opposite side of the wheel axis from the first and second drive wheels,

wherein the friction drive assembly comprises a motor having an output shaft 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,

wherein the friction drive assembly comprises an axle and friction wheels provided at opposing ends of the axle,

wherein the friction wheels inhibit rotation of the caster wheels about the spindle axis in the engaged state

wherein the friction drive assembly is 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,

wherein the output shaft comprises a drive wheel and the axle comprises a power wheel, and

wherein sizes of the drive wheel and the power wheel are selected to enable the motor to drive the axle proportional to the speed over ground provided by the first and second drive wheels.

12 . A drive assembly of a riding lawn care vehicle including caster wheels, wherein the riding lawn care vehicle comprises first and second drive wheels operably coupled to a frame, wherein the riding lawn care vehicle further comprises a steering assembly configured to facilitate turning of the riding lawn care vehicle based on drive speed control of the first and second drive wheels, and wherein 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 comprising:

a friction 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 friction drive assembly contacts the caster wheels in the engaged state and does not contact the caster wheels in the disengaged state,

wherein in the engaged state, the friction drive assembly contacts the caster wheels at respective contact points disposed forward of the wheel axis and at an opposite side of the wheel axis from the first and second drive wheels, and

wherein the friction drive assembly inhibits rotation about the wheel axis and spindle axis so the wheel axis is substantially perpendicular to the longitudinal centerline of the riding lawn care vehicle in response to the friction drive assembly not being powered in the engaged state.

13 . The drive assembly of claim 12 , wherein the friction drive assembly is 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.

14 . The drive assembly of claim 13 , wherein the friction drive assembly comprises an axle and friction wheels provided at opposing ends of the axle, and

wherein the friction wheels inhibit rotation of the caster wheels about the spindle axis in the engaged state.

15 . The drive assembly of claim 14 , wherein the friction drive assembly comprises a motor having an output shaft 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.

16 . The drive assembly of claim 15 , wherein the motor is an electric motor or a hydraulic motor,

wherein the motor is supported on a carrier plate, the carrier plate being configured to pivot between the engaged state and the disengaged state,

wherein the carrier plate comprises a support tube inside which the axle is rotatably mounted, and

wherein one or more carrier assist springs is provided to extend between the frame and the support tube to facilitate lifting the carrier plate to the disengaged state.

17 . The drive assembly of claim 15 , wherein the output shaft comprises a drive wheel and the axle comprises a power wheel, and

wherein sizes of the drive wheel and the power wheel are selected to enable the motor to drive the axle proportional to the speed over ground provided by the first and second drive wheels,

wherein the caster wheels comprise a first caster wheel and a second caster wheel, the first and second caster wheels being disposed at a front portion of the riding lawn care vehicle, and

wherein the friction wheels simultaneously engage the first caster wheel and the second caster wheel when the friction drive assembly is in the engaged position.