Abstract: A drive unit includes an electric motor, a worm shaft coupled to the motor, a worm gear engaging with the worm shaft, and an output shaft connected to the worm gear. The motor has a motor shaft on which the worm shaft is fixed. The worm shaft is made of plastic. The drive unit further includes a metallic sleeve press fitted to the motor shaft. An outer profile of the sleeve is non-circular. A correspondingly shaped receiving hole is formed in the worm shaft to receive the sleeve. The sleeve rotates with the motor shaft and drives the worm shaft.

Abstract: A floor panel may include a bottom layer and an upper layer overlying the bottom layer. The bottom layer may have first and second edges, and the bottom layer may include at least one male protrusion on the first edge, and have at least one female protrusion receptacle on the second edge corresponding to a shape of the at least one male protrusion. The bottom layer may further include at least one male lip on the second edge, and have at least one female lip receptacle on the first edge corresponding to a shape of the at least one male lip. The upper panel may vertically overly the at least one female lip receptacle and the at least one female protrusion receptacle.

Abstract: A new interlocking or interconnection mechanism for securing floor covering panels is invented, whereas the covering panels can be any sizes, shapes, structures, and of any materials. The mechanism is consisted of independent features rendering the vertical and the lateral couplings, where vertical is defined as the direction perpendicular to the surface of the panel that is exposed and lateral is defined as the direction parallel to the exposed surface. The new mechanism provides a gradual progressive tightening effect during the installation process for securing the panels, which is completely different from the outcome by all the existing mechanisms including tongue-and-groove, snap-on, etc.