A railway hopper car chute having a discharge opening defined by a sidewall frame with a sliding plate gate operating in the discharge opening. An undercarriage support frame is fixed to the sidewall frame to support the gate for sliding movements relative the opening. A labyrinth seal for preventing the unwanted discharge of granular lading comprising an upwardly directed gate flange is integrally formed on at least part of the periphery of the gate plate. The flange is disposed in the space defined by the outside of the chute frame and the inside of the undercarriage frame. A pair of spaced elongated bars is disposed in the space between the gate flange and the adjacent hopper sidewall frame. These elongated bars together with the flange form a labyrinth seal with one of the bar seal elements being fixed to the gate and the other to the adjacent chute sidewall frame. Both seal elements define a labyrinth gap therebetween which serve as a non-contact seal for any granular lading located within the chute.