Back Up Next

Maker, Warren Telechron, Inc., Ashland, Massachusetts, USA. Model Type E, c. early 1930's, serial no. 17.

Telechron E (49).jpg (117488 bytes)

The genius of Henry Warren's design was his automatic frequency control mechanism. A full explanation is featured in his patent    #1906439. This covers an earlier design but it is similar. Described briefly: A cam rotates once per period of the pendulum. This cam lifts and lets drop a very small lever that imparts an impulse to the pendulum. If the cam, which is driven from the frequency of the electrical line, is in full agreement with the pendulum, which is assumed to be set correctly to a 1 second beat, the lever will contact the pendulum at or very near the center of its swing which at that point imparts the minimum of disturbance to its rate of oscillation. Through a complex system of levers the movement can sense when and by how much the lever is out of phase with the pendulum. This reading is then translated to a moving pointer that engages a set of curved contacts (see diagram above). Depending upon where on the curve the pointer lands on either contact it energizes a bi-directional motor to turn in either direction for an amount of time depending on where the pointer touches the contact. The further toward the outside of each curve, the longer the motor is energized which, through a planetary gear system will advance or retard the cam to bring it into phase with the pendulum. If the cam, and therefore the frequency of the line are in agreement with the pendulum, then the pointer will be positioned between the two contact curves resulting in no electrical current to the motor and no change in the output. This same motor is connected to the commutator that translates these adjustments into electrical signals that can be reproduced by Mr. Warren's patented motion reproducing motors. These motors control the actuators that, in turn, control the mechanisms that mediate the rate at which the generators in a power station will turn. This could be, for example, a sluice gate in a hydraulic setting such as dam in the TVA (Tennessee Valley Authority) as was probably the case where this clock came from, or to control a valve for the intake of steam in a conventional coal or gas fired plant.

Photo from NAWCC Bulletin August 1991.

Back Up Next