sentences:  The stall doors are designed to give way in case a horse prematurely attempts to bolt through the front or back, in order to reduce or prevent injury to horse or rider.When the starter is satisfied that all horses are in place and ready to start the race, he presses a button, cutting the electric current, simultaneously opening the front stall doors, ringing a loud bell, and sending a signal to the totalizator system that the race is begun and no more bets should be accepted.Puett's gate was first used at Exhibition Park in Vancouver, British Columbia in 1939, though the management of Bay Meadows Racetrack in San Mateo, California claims that their track was the first to use Puett's gate.