A zero turning radius mower park brake system includes an over-center pivot member that pivots to a park brake engaged position in response to moving a control arm fully outward, and to a park brake disengaged position in response to moving the control arm fully inward. The control arm is disconnected from the over-center pivot member in the park brake engaged and disengaged positions. An actuator on a lower end of the control arm may contact the over-center pivot member between the park brake engaged and disengaged positions. A biasing spring urges the over-center pivot member to the park brake engaged position and park brake disengaged position.