US Patent 7258138 Methods and apparatus for an on-off controller

Methods and apparatus according to various aspects of the present invention comprise an on-off controller configured to control the flow of pressurized pneumatic fluid. In one embodiment, the on-off controller comprises a body having an inlet, at least one outlet, a vent, a vent passage, a rod positioned axially in the body, a position mechanism configured to move the rod axially in the body, a seal configured to sealably contact the rod and seal the vent passage, wherein the position of the rod may define operating states comprising: an on-state, an off-state, and a vent-state.