An automatic locking ball coupler for a power take off includes a ball keeper connected to the power take off and having a longitudinal axis and openings in a cylindrical surface thereof. Locking balls are received in the openings and can move radially with respect to the axis of the cylindrical ball keeper. A ball collar is positioned around the cylindrical ball keeper and has a plurality of internal circumferential rings and recesses between each ring. The ball collar can slide axially with respect to the longitudinal axis of the ball keeper between a coupled position in which the locking balls are on the rings and an uncoupled position in which the locking balls are in the recesses.