Abstract: An apparatus for supplying tactile signals to the user of a vehicle or other machine to indicate the operational status or condition of the vehicle or machine, or a functional part thereof. A cam undergoes rotary movement within a flexible cylindrical wall having a corrugated inner surface, as with ridges of the like. The distal end of the cam contacts the inner surface as the cam rotates. The rotary motion of the cams modulated and regulated in response to output signals associated with operating conditions, for example, fluid pressure, engine speed, oil temperature, transmitted from corresponding sending units. The rotation of the cam causes periodic flexure of displacement of the wall which is palpable to the user. In one embodiment, the rotating cam causes one or more movable plungers to move to-and from in and out of the wall, also resulting in a tactile signal to the user. The cam may be driven by an electric motor which is responsive to the input signals.