A lawn mower comprising a mobility assembly including a first set of wheels and a second set of wheels, the second set of wheels being selectively operably coupled to an engine of the lawn mower to provide mobility of the lawn mower responsive to at least in part to operation of the engine; and a rocking transmission operably coupled to the second set of wheels to provide drive power to the second set of wheels via a drive system responsive to engagement of the rocking transmission, wherein the drive system comprises: a drive belt; a drive pulley disposed at the rocking transmission to transfer drive belt motion to power the second set of wheels of the lawn mower via the rocking transmission when the rocking transmission is in an engaged position; a drive shaft pulley operably coupled to a drive shaft of the lawn mower to rotate responsive to rotation of the drive shaft, the drive shaft pulley engaging the drive belt responsive to the rocking transmission being in the engaged position; characterized by an idler pulley disposed substantially between the drive pulley and the drive shaft pulley and configured to engage the drive belt when the rocking transmission is in the engaged position to result in a belt wrap around the drive shaft pulley that is greater than about 200 degrees and result in a belt wrap around the drive pulley that is greater than about 190 degrees, wherein the rocking transmission is configured to rotate relative to an axle corresponding to the second set of wheels between the engaged position and a disengaged position, wherein rotation of the rocking transmission to the engaged position causes tension to be applied to the drive belt and rotation of the rocking transmission to the disengaged position releases the tension on the drive belt, wherein the idler pulley is disposed to push a first belt run of the drive belt extending between the drive pulley and the drive shaft pulley toward a second belt run of the drive belt extending between the drive shaft pulley and the drive pulley to form a gap between the first and second belt runs, wherein the gap is formed proximate to a belt keeper disposed to extend substantially parallel to the second belt run, wherein rotation of the rocking transmission to disengage the rocking transmission pushes the drive belt toward the drive shaft pulley, and wherein the belt keeper and the idler pulley combine to cause the drive belt to expand in belt wrap diameter at a location of the drive belt proximate to the drive shaft pulley and thereby disengage the drive shaft pulley from the drive belt. a drive belt; a drive pulley disposed at the rocking transmission to transfer drive belt motion to power the second set of wheels of the lawn mower via the rocking transmission when the rocking transmission is in an engaged position; a drive shaft pulley operably coupled to a drive shaft of the lawn mower to rotate responsive to rotation of the drive shaft, the drive shaft pulley engaging the drive belt responsive to the rocking transmission being in the engaged position; characterized by an idler pulley disposed substantially between the drive pulley and the drive shaft pulley and configured to engage the drive belt when the rocking transmission is in the engaged position to result in a belt wrap around the drive shaft pulley that is greater than about 200 degrees and result in a belt wrap around the drive pulley that is greater than about 190 degrees, wherein the rocking transmission is configured to rotate relative to an axle corresponding to the second set of wheels between the engaged position and a disengaged position, wherein rotation of the rocking transmission to the engaged position causes tension to be applied to the drive belt and rotation of the rocking transmission to the disengaged position releases the tension on the drive belt, wherein the idler pulley is disposed to push a first belt run of the drive belt extending between the drive pulley and the drive shaft pulley toward a second belt run of the drive belt extending between the drive shaft pulley and the drive pulley to form a gap between the first and second belt runs, wherein the gap is formed proximate to a belt keeper disposed to extend substantially parallel to the second belt run, wherein rotation of the rocking transmission to disengage the rocking transmission pushes the drive belt toward the drive shaft pulley, and wherein the belt keeper and the idler pulley combine to cause the drive belt to expand in belt wrap diameter at a location of the drive belt proximate to the drive shaft pulley and thereby disengage the drive shaft pulley from the drive belt.