a tilt sensing mechanism the pendulum tilt mechanism 210 includes a hanger bracket 212 that supports a metal plumb bob 214 via a hook 216 the plumb bob includes a shaft 218 extending from its lower end the shaft 218 extends through a hole 220 formed in a lower contact bracket 222 the hook 216 is coupled to one polarity of the power source while the contact bracket is coupled to the other polarity of the power source when the atm is tilted the shaft 218 will contact an edge of circle 220 of the contact bracket 222 to complete the electrical circuit and provide the necessary signal additionally a gravity ball tilt mechanism 230 as shown in fig1 may be utilized to produce the actuation signal for the actuator such a gravity ball tilt mechanism is disclosed in u s pat no 4 799 505 which is incorporated herein by reference however a short description of the main components and method of operation are as follows the gravity ball tilt mechanism 230 includes a housing 232 that has a concave bottom portion 234 threadedly received in the center of the concave bottom 234 is a threaded screw 236 the threaded screw 236 includes a concave upper end designed to hold a steel ball 238 a spring loaded.