A transmission speed control system for a walk-behind lawn mower includes a transmission, a transmission positioning assembly, and an electronic control unit. The transmission is tiltable about and operably engaged with a drive axle shaft. The transmission positioning assembly tilts the transmission between first and second angular positions. A belt tension between a drive belt and a transmission pulley of the transmission continuously increases from a minimum belt tension when the transmission is in the first angular position to a maximum belt tension when the transmission is in the second angular position. The rotational drive force exerted on the drive axle shaft by the transmission and a resulting driving speed of the lawn mower vary proportionally with the belt tension. The electronic control unit controls the transmission positioning assembly to tilt the transmission based on target and detected driving speeds.

A transmission speed control system for a walk-behind lawn mower includes a transmission, a transmission positioning assembly, and an electronic control unit. The transmission is tiltable about and operably engaged with a drive axle shaft. The transmission positioning assembly tilts the transmission between first and second angular positions. A belt tension between a drive belt and a transmission pulley of the transmission continuously increases from a minimum belt tension when the transmission is in the first angular position to a maximum belt tension when the transmission is in the second angular position. The rotational drive force exerted on the drive axle shaft by the transmission and a resulting driving speed of the lawn mower vary proportionally with the belt tension. The electronic control unit controls the transmission positioning assembly to tilt the transmission based on target and detected driving speeds.

A first gear pair includes a first pinion on an input shaft and a first ring gear on an intermediate shaft. A second gear pair includes a second pinion on the intermediate shaft and a second ring gear on an output shaft. A first case that stores the first gear pair is coupled to a base member in a rotatable manner around an input shaft rotational axis. A second case is coupled to the first case in a rotatable manner around an intermediate shaft rotational axis.

A first gear pair includes a first pinion on an input shaft and a first ring gear on an intermediate shaft. A second gear pair includes a second pinion on the intermediate shaft and a second ring gear on an output shaft. A first case that stores the first gear pair is coupled to a base member in a rotatable manner around an input shaft rotational axis. A second case is coupled to the first case in a rotatable manner around an intermediate shaft rotational axis.

The speed reducer includes: a gear housing to enclose a worm wheel and a worm shaft and including one of a first magnetic member and a second magnetic member, which generate attractive force or repulsive force therebetween as current is applied to a position facing the worm shaft in an axial direction; a first bearing coupled to an end of the worm shaft at an opposite side to a motor shaft-coupling portion; and a moving member coupled, at one side thereof, to an outer race of the first bearing and including, at a remaining side thereof, a remaining one of the first and second magnetic members, so that the moving member is axially moved according to the attractive force or the repulsive force.

The speed reducer includes: a gear housing to enclose a worm wheel and a worm shaft and including one of a first magnetic member and a second magnetic member, which generate attractive force or repulsive force therebetween as current is applied to a position facing the worm shaft in an axial direction; a first bearing coupled to an end of the worm shaft at an opposite side to a motor shaft-coupling portion; and a moving member coupled, at one side thereof, to an outer race of the first bearing and including, at a remaining side thereof, a remaining one of the first and second magnetic members, so that the moving member is axially moved according to the attractive force or the repulsive force.

A ring gear arrangement, including: a ring gear mount including: a ring gear having at least one internal gear for interaction with one or more gear wheels; a ring gear stator; and, a plurality of couplings which locate the ring gear within the gear stator, each coupling having a drive arm connected to the ring gear and a resiliently deformable connection, wherein the drive arm is movable between a first position in which the ring gear is in a rest position and a second position in which the ring gear has undergone some radial or rotational movement relative to the ring gear stator, wherein movement of the drive arm from a the first position to the second position loads the resiliently deformable connection against the ring gear, wherein the resiliently deformable connection biases the drive arm to return to the first position when in the second position.

A ring gear arrangement, including: a ring gear mount including: a ring gear having at least one internal gear for interaction with one or more gear wheels; a ring gear stator; and, a plurality of couplings which locate the ring gear within the gear stator, each coupling having a drive arm connected to the ring gear and a resiliently deformable connection, wherein the drive arm is movable between a first position in which the ring gear is in a rest position and a second position in which the ring gear has undergone some radial or rotational movement relative to the ring gear stator, wherein movement of the drive arm from a the first position to the second position loads the resiliently deformable connection against the ring gear, wherein the resiliently deformable connection biases the drive arm to return to the first position when in the second position.

A supporting device includes first and second supporting flanges coupled with first and second transmissions, respectively, and a support via which a supporting force is transmittable from the first supporting flange to the second supporting flange. The support includes a lever element which is coupled in an articulated manner with an attachment element on the first supporting flange and thus articulated with the first supporting flange, and a supporting element which is coupled in an articulated manner with the lever element and connected to the second supporting flange and which includes two spaced-apart supporting parts. The lever element is arranged partly between two spaced-apart attachment parts of the attachment element and partly between the supporting parts of the supporting element and is coupled in an articulated manner with the attachment element via the attachment parts and in an articulated manner with the supporting element via the supporting parts.

A supporting device includes first and second supporting flanges coupled with first and second transmissions, respectively, and a support via which a supporting force is transmittable from the first supporting flange to the second supporting flange. The support includes a lever element which is coupled in an articulated manner with an attachment element on the first supporting flange and thus articulated with the first supporting flange, and a supporting element which is coupled in an articulated manner with the lever element and connected to the second supporting flange and which includes two spaced-apart supporting parts. The lever element is arranged partly between two spaced-apart attachment parts of the attachment element and partly between the supporting parts of the supporting element and is coupled in an articulated manner with the attachment element via the attachment parts and in an articulated manner with the supporting element via the supporting parts.