Abstract: A device for responding to rotational acceleration of the type having a looped conduit and in which a fluid filled housing has first and second expansible chambers each having a movable wall, with the movable walls being mounted for generally coaxial movement upon expansion of the volume of one of the chambers and simultaneous contraction of the volume of the other. Fluid pressure at one distal side of the loop is transmitted to fluid filling one of the chambers and fluid pressure at the other distal side of the loop is transmitted to the other chamber. Upon movement of the movable walls, a control device such as a wheel brake control is actuated. Preferably the sensor device is a two part device with one part mounted on a wheel hub and the other mounted on a wheel, with the wheel parts being identical so that any wheel so equipped may properly cooperate with any hub so equipped irrespective of the normal direction of rotation of a wheel so mounted.