Abstract: A mobile base for moving on a surface is provided having a driving and steering unit and a plurality of wheel assemblies. The driving and steering unit provides a drive force and a steering force. Each wheel assembly has a wheel assembly axis, and also has a steering column, concentric drive shafts, and two wheels. The concentric drive shafts respond to the drive shaft force, and provide a concentric drive shaft force. The steering column responds to the steering force, and provides a steering column force. The two wheels respond to the steering column force and rotate in the same direction for pivoting the steering column means about the wheel assembly axis. The two wheels respond to the concentric drive shaft force and rotate in the opposite directions to move the mobile base forwards or backwards along the surface.

Abstract: A lifting device incorporating first and second arm assemblies with associated rotatable shafts and a platform rotationally connected to the second arm assembly so as to maintain a fixed relationship to a reference surface as the first and second arm assemblies are angularly moved from one position to another. The shaft associated with the first arm assembly is rotated about its axis as the first arm assembly is angularly moved so as to impart similar angular movement to the platform through a rotatable shaft of the second arm assembly; thereby maintaining the platform's fixed relationship to a reference surface. A second embodiment of the lifting device provides an additional device to adjust the angular orientation of the platform with respect to the reference surface, which allows the platform to be maintained in a level orientation when traversing an inclined reference surface.