3D model of a compound reduction gearbox with a locking mechanism and variable-speed drive, primarily used for mechanical transmission education and engineering demonstrations. The left-hand horizontal shaft serves as the input shaft, and the first-stage high reduction is achieved through worm–worm gear meshing, while simultaneously changing the direction of power transmission (horizontal to vertical).

• Features: large reduction ratio, smooth operation, and strong self-locking capability (which prevents load reversal).

• Can be used to illustrate key engineering concepts such as reduction ratio calculation (total reduction ratio of a multi-stage transmission = product of individual stage reduction ratios), material selection, lubrication and sealing, and tolerance fit.

• The transparent housing allows students to observe details such as meshing clearances and installation alignment.