If you remove the lever from the polarity switch you can insert an axle through the switch which will cycle the switch continuously between fwd/off/rev/off. Since most of the tension in the switch is actually provided by the lever slot, this axle (...) (25 years ago, 23-Jan-00, to lugnet.robotics)
(...) <snipped description of polarity/rotation sensor> Ben, I think that the polarity switch is one of the most underused Technic/Train elements. The fact that it switches polarity as well as providing an off period is probably due to a (...) (25 years ago, 23-Jan-00, to lugnet.robotics)