US Patent 7584682 Adjustment device with a dual-guiding structure

An adjustment device with a dual-guiding structure has two worm wheels respectively meshed with two coaxial worm gears. The two worm gears are pivotally and longitudinally fixed by a driving shaft in line. An adjacent end of each worm gear has a locking recess to receive a locking head mounted on the driving shaft. Thereby, the locking head is selectively engaged with the locking recess of one of the worm gears to drive the corresponding worm gear when the locking head on the driving shaft is reciprocated. Then, one worm wheel engaged with the corresponding worm gear is rotated to rewind or release the wires on the work wheel.