Abstract: An improved retainer mechanism for retaining a gate relative to a frame has two spring bars and a pin. The spring bars may be attached to the frame. The pin may be attached to the gate. The spring bars are made of resilient material and each is shaped and mounted to the frame such that the free ends of the bars form a constriction between them. The width of the pin is greater than the width of the constriction. The space between the bars widens on either side of the constriction. The relative position of the gate, the pin and the bars is such that when the gate is closed, the flared free ends of the bars distally of the constriction between the bars constrains (excludes) the pin, retaining the gate in a closed position. The pin must move through the point of constriction, deflecting the bars apart, when the gate is moved towards an open position. In one embodiment, the invention is suited for use on the discharge chute gates of railway hopper cars.