apparatus and methods for locking a discharge chute of a mixing vehicle are disclosed . the locking apparatus can be mounted to existing discharge chutes and frame arrangements and may utilize existing pneumatic systems of the mixing vehicle . the locking apparatus generally include a base having a first arm and a second arm pivotally secured to the base . an airbag may be positioned between the first arm and the second arm to bias a clamping region of the locking apparatus in a locked or a released state depending on the configuration of the locking apparatus .