A carriage drive system includes a timing belt pivotally anchored to a carriage. A drive motor rotates the timing belt, moving the carriage along a carriage path. The drive belt moves along a pair of pulleys. A first pulley is coupled to the motor's drive shaft. A second pulley is coupled to an idler spring. The idler spring determines the belt tension when the belt is stationary. Acceleration of the carriage alters the belt tension. A pivot connection occurs between the drive belt and the carriage. During acceleration, the pivotal connection rotates shortening the effective length of the belt, which in turn stretches the idler spring, and increases belt tension. While the carriage is at rest or moving at constant velocity, the pivot connection serves to reduce side load impact on the drive motor's shaft and windings. The pivot connection also isolates the carriage from high frequency vibrations.