Tipping disc, to provide moving seat surface for stool ; has upholstered plate with ball section having channel, which fits on hemisphere on base plate on stool, to guide ball section

摘要

The disc may or may not have an upholstered seat surface (4). A ball section (2) is fixed to a plate (3), and has a channel (7), which serves as a guide to enable free movement in all directions. A base plate (5) has a hemisphere (6), which guides the ball section.