Free pendulum clock maintained by rolling balls

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Free pendulum clock maintained by rolling balls
Manufacturer	Captain E.E. Craig
Production years	(unknown)
Production location	(unknown)

In this clock, invented and made by Captain E.E. Craig, the pendulum receives its impulses from a pair of light steel balls which roll down two short ramps attached to the pendulum by horizontal arms. It is termed a ‘free pendulum clock’ because the pendulum has no ‘unlocking’ duty to perform, and swings freely except while it is actually receiving its impulse, and for the small fraction of a second during which the ball rests against the edge of the ramp before rolling down it.

[edit] How it works

The cycle of operations during a complete double swing of the pendulum is as follows: after the right-hand ball has imparted its impulse to the pendulum, it rolls away towards the back of the clock movement and operates a trigger which allows the right-hand mercury switch to tilt over and close its circuit. The right-hand electro-magnet operates, and the resulting movement throws the right-hand ball upwards to its highest position, and at the same time releases the small catch holding the left-hand ball. This ball then rolls a small fraction of an inch until it rests against the edge of the left-hand pendulum ramp, which is then on its downward travel. As the ramp descends, the ball is able to roll down it, impart its impulse, and then roll away towards the back of the clock movement. The second half of the cycle is similar, but with ‘right’ and ‘left’ reversed. The rocking movement of the lever driven by the two electro-magnets is converted to a rotary movement which drives the hands of the clock.

[edit] Memories

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[edit] In the Science Museum's Records

Inv. No: 1946-193