Abstract: A trigger mechanism for a dust filter pulse cleaning system includes a trigger frame, a trigger valve assembly including a reciprocating valve member having a valve head resiliently urged toward a valve seat and a striker head at an opposite end, a trigger arm pivotally connected to the trigger frame and including a cam follower, a twin lobed trigger cam journaled on the trigger frame and engaging the cam follower, and a pinion gear joined to the trigger cam and adapted for engagement with a fixed spur gear mounted coaxially with a rotary pulse cleaning air distribution arm extending from a rotary air tank. The trigger mechanism is mounted on the air tank and rotates therewith. An air release conduit is connected to the trigger valve and causes the opening of a main diaphragm valve to release air pulses from the air tank when pressure is released from the release line. Compressed air within the release line also acts to urge the valve head against the valve seat.