Abstract: A latch mechanism is presented which is useful with a machine which gathers crop material from a windrow and forms it into large round bales. The latching mechanism senses bale density while holding the opposing faces of the tailgate closed during the bale forming operation. Density is sensed by spring mounting the latch slides so that the tailgate comes slightly ajar when pressure in the baling chamber builds up. The amount of separation of the opposing faces of the tailgate is sensed and when it exceeds a specified amount, initiates a bale discharge sequence. The tailgate lifting mechanism is interlocked with the latch release to assure safe operation of the system.