Abstract: An open top swing assembly uses a unique swing drive mechanism and a control to provide three selective swing height settings. The assembly has a frame which provides an open top structure for ease of access and a trapezoidal shaped front base to provide foot clearance. The swing drive mechanism includes a drive sleeve rotatably mounted to an axle that operatively supports the hanger. A drive flange is mounted on the axle, with a drive flange coupling device positioned between the sleeve and the drive flange to provide a limited lost motion connection. The coupling device includes a hub member coaxially and rotatably mounted on the axle and at least one torsional spring mounted coaxially on the hub member. The hub member includes abutments for engaging with the drive flange, whereby torque applied to the sleeve is transferred to the axle. A crank driven by a motor is linked to the sleeve to oscillate the sleeve. The swing height control device can have a sensor for detecting the swing height or amplitude.