Swivel: to swing or turn on a circular path.

Chair: a piece of furniture extant in many versions created to offer seating to a person; normally consisting of a frame, a seating surface and a backrest.

The great Charles Darwin (1809-1882) is generally regarded as the pioneer of the swivel chair as we know it today: he attached four wheels to his laboratory chair in order to be able to get faster across the room to his samples. Today, these so-called Castor wheels fulfil this service. We know them from shopping carts, and their advantage is that they will automatically align themselves to the current direction of movement.

Most swivel chairs possess a gas pressure spring which uses a gas – normally nitrogen – in order to provide the pressure for suspension. This allows the seat to be effortlessly moved up or down. The same principle is employed in the boot lids or engine compartment lids of cars. If freedom of movement is an issue, flat springs or elastomer springs are the technology of choice: Flat springs – originally used in heavy vehicle suspensions – give more elasticity to backrests thanks to their flat, slightly curved shape. Elastomer springs made of rubberized material were formerly used in the suspension of the Mini Cooper, today they allow flexible angle adjustments of seat surfaces in all directions.

Looking at the interplay of seat and backrest, there’s the difference between synchronous and asynchronous mechanisms. With a synchronous mechanism, the angle of the backrest is coupled to the angle of the seat. When the user leans backward, the seat follows. This avoids the so-called “shirt take-off effect”, all clothes stay in place. In contrast, the asynchronous mechanism allows an independent adjustment of the angles of backrest and seat, thus allowing individually desired postures between “upright” and “reclined”, depending on the respective activity.

By the way: the next German championship in office chair racing will take place in the summer of 2011 in the southern Hessian town of Bad König-Zell. The acting German champion is called Jan Paul and lives in Baden-Württemberg.