Posted 4 years ago
rlwindle
(151 items)
The Poole gravity electric clock originated in Westport, Connecticut, about 1923. In a shop located over a grocery store on Main
Street, Arthur F. Poole, with two employees, made battery-operated clocks for the Westport public schools. Based on this experience
and his electrical engineering training, Poole filed a patent for an "Electric Clock" on January 10, 1924, which was granted April 29,
1930. At the time of filing, Poole lived in Pelham Manor, New York,and assigned his patent to Poole Manufacturing Co., Inc. of Westport, Connecticut, a corporation of New York.
The force of gravity that keeps this clock running is accomplished by a drop arm (weight) to restore the swing of a pendulum basically the drop arm pushes the pendulum when it tries to stop). The French "Remontoire" principle, Whereby the arm impulses the pendulum that in turn drives the time-keeping wheel train reverses that normally used in clocks where the wheel train drives the pendulum. The gravity arm is raised to its poised position by an electromagnet energized by three dry-cell batteries (see compartment in the second picture.. The 4,5-volt assembly powers the clock for about one year. The batteries are needed only for very short intervals after about 16 to 22 swings of the pendulum. The gravity arm is raised to a latched position, and when unlatched carries a small roller that falls on a pin on the pendulum crutch that impulses the pendulum to increase the oscillation for its maximum swing. As the gravity arm falls, electric wiping contacts close the circuit from the batteries to the electromagnets that rotate an armature that restores the gravity arm to its latched-poised position.
These clocks must be level to operate thus the inclusion of the level bubble on the base of the clock. see picture 3.
