For physical protection of the machine and to make a player legitimately earn a free game, all pinball machines have several tilt mechanisms inside. There are three different types, the rolling ball switch, the pendulum switch and the slam switch. Just inside the front door and to the left there is a panel that contains one of each type of tilt switch. A picture of this panel is shown and at the top is the rolling ball switch. In the lower left is the pendulum switch and just to the right of it is the slam switch.

The physics:

The rolling ball switch prevents a player from lifting the playfield, possibly to prevent a ball from draining. This would be the only time this tilt switch could possibly be activated. The ball you see sits in a metal track that slopes slightly toward the coin door of the machine. When lifted, the track will tilt the other way and the ball rolls to the right where it eventually makes contact with a switch blade, completing the circuit to the tilt relay. Notice one wire connects to the metal track on the left and the other connects to the leaf swich blade on the right.

The slam switch is activated only if the player decides to get violent with the machine. The slam switch is normally open and one leaf of the switch has a mass attached to its end. If the machine is shook suddenly and forcefully in any of the three dimensions, the inertia of the mass allows that switch leaf to remain while the other moves with the machine. Of course the metal leaf holding the mass is bent a little and some elastic potential energy is established. As a result the mass will oscillate back and forth, making contact with the other part of the switch. The switch you see in the picture will be activated if the player decided to lift and drop the machine. There's another on the coin door that works when the door is smacked with force. There are many of these swiches scattered all over the game, including the backbox.

The pendulum switch is the one that the player must contend with during game play. The gentle nudging back and forth or side to side will cause the pendulum to begin to swing. The sensitivity of this switch is adjustable by setting the bob higher or lower on the hanging rod. Notice one wire connects to the hanging pendulum and the other attaches to the ring surrounding the bob. When the bob makes contact with the ring, the circuit to the tilt relay is completed.