BMW's 'Active Seat' is designed to reduce driver muscle stiffness during
long drives, It does this by employing fluid cushions under the seat that
gently massage the driver's legs. An ASF Thomas rotary pump, which
alternately fills and drains the cushions to provide this massaging
action, was based on a modified air/gas pump. All of its functional parts
had to be re-designed and additional new parts included to suit the
automotive application, and everything from the motor winding to the
electrical interconnections also had to be changed. ASF Thomas supplies a
complete system to BMW, including pump, motor, control unit, pressure
switches, tubing and the cushions themselves.