Drive assembly with dynamic tensioning device

A cable drive assembly for a closed loop system in which a cable drives a moveable structure back and forth and in which the cable is wrapped around a drive pulley and an idler pulley that is spaced from the drive pulley, the cable drive system comprising:

• the drive pulley being rotatable about a pulley axis,
• a motor unit having an output shaft rotatable about a drive axis for rotating the drive pulley about the pulley axis, and
• a tensioning mechanism for adjusting the position of the pulley axis of the drive pulley with respect to the drive axis of the output shaft of the motor unit,
• the tensioning mechanism including a first gear driven by the motor unit about the drive axis, and a second gear meshing with the first gear and driven about the pulley axis of the drive pulley by the first gear.

A drive assembly for a closed loop cable system in which a cable is wrapped around and driven by a drive pulley, the drive assembly comprising:

• the drive pulley,
• a motor unit having a motor shaft that rotates about a drive axis for rotating the drive pulley about a drive pulley axis, and
• a tensioning mechanism for adjusting the position of the drive pulley axis with respect to the drive axis responsive to tension in the cable,
• the tensioning mechanism including a first gear driven by the motor about the drive axis, and a second gear meshing with the first gear and driven about the drive pulley axis of the drive pulley.