“Reflex” Pendulum Control

"Reflex" Pendulum Control

Synchronise pendulum network from a single master clock impulse

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With the Patent "Reflex Control," the clock mechanism of such Recorders remains intact, the controlling device operating on the pendulum.

For Workmen's Recorders or any type of Clock with Pendulum.

N.B.-We do not make Workmen's Time Recorders, but can fit "REFLEX" Control to those you now have and use.

The introduction of the “Pul-Syn-Etic” Electric Impulse Clock for industrial purposes has resulted in universal and accurate time being available throughout the factory, works, etc., where installed. The bringing in line of Workmen’s Time Recorders with such a system was originally accomplished by fitting an impulse driven escapement to the time gear in lieu of the spring driven escapement.

With the Patent “Reflex Control,” the clock mechanism of such Recorders remains intact, the controlling device operating on the pendulum.

As will be seen from the illustration, the “Reflex Control” consists of a small attachment secured to the existing pendulum which is engaged by a rack attached to an electro-magnet energised by the half-minute impulse of the system.

The “Reflex Control” can be fitted to existing or new Recorders of any modern make using a pendulum.

You con fit the “Reflex.”

PRICE

£4· 10·0 Codeword:ziybd (E)

If Recorder or Clock is sent to these Works for fitting £5-12-6 Code word: zoejl

FIG. CI04. REFLEX CONTROL FITMENT.

Credited to the publication: ELECTRIC CLOCKS by S.J. Wise (Fellow, British Horological Institute)

Assuming an impulse master clock has already been installed for general timekeeping purposes then the difficulty mentioned above can quite easily be overcome by a device called the “Reflex” pendulum control. This is an extremely useful invention, by means of which the pendulums of any number of clocks may be synchronized with that of the master clock impulses, enabling the timekeeping of all clocks included in the installation to have the same “rate” as that of the master; at the same time, the .means of bringing this about does not demand either electrical or mechanical connexion with the gearing of the clock it is desired to synchronize.

The actual synchronizing of the pendulum is brought about by the normal half-minute impulses which are transmitted through a circuit by a master clock which automatically adjusts the tension of a spring, or other suitable device, thus influencing the rate of the pendulum so that its vibrations are synchronized with the periodicity of the circuit impulses. Another unique feature confined to this system of synchronization is that no major changes have to be made in the mechanism of the recorder clock, the only additional items required being a light spring which is attached to the pendulum rod, and a controlling electro-magnet which is rigidly fixed to the recorder case, the latter item of which is connected in series with the “time circuit” of the master clock.

Each recorder to be controlled has a separate life of its own, i.e. each being wound in the usual manner, the pendulum synchronization merely enables the pendulum to faithfully keep in step (or multiple thereof) with that of the master clock thereby enabling all the clocks to indicate the same time.

Operation of the System

To describe the action of this system, the drawing, Fig. 12, should be examined, from which it will be seen that the apparatus consists of two main parts:

(i) The “vibrator” which is readily clamped to the pendulum rod, without drilling or defacing the rod in any way.

(ii) The controller (or “stator”) which is screwed to the recorder case.

The spring “vibrator” consists of a light spring pivoted at its upper end to a bracket which is clamped to the pendulum rod, approximately two-thirds up its length. A suitable stop anchored to the bracket is arranged to prevent the spring being deflected during that half vibration when the pendulum is being synchronized, i.e. when the impulse is transmitted in the master clock circuit.

The controller or “stator” consists of an electro-magnet connected in series with the time circuit and is so constructed that whenever an impulse is • transmitted from the master clock a specially shaped armature is actuated. This armature is pivoted at its centre, thus leaving an extension on either side of its fulcrum. The upper surface of the left-hand extension is acted upon by the electro-magnet referred to above, while the extension nearest the pendulum is provided with a number of ratchet teeth. An adjustable screw attached to the base forms a “stop” for the armature, and is so adjusted that under normal conditions the toothed end of the armature can clear the free end of the spring “vibrator” during the oscillation of the pendulum from right to left.

At each half minute when an impulse is transmitted in the time circuit, the following sequence occurs:

(i) The electro-magnet of the “stator” becomes energized and the armature is attracted thus elevating the toothed extension sufficiently far to be in the “track” of the vibration spring.

(ii) During the travel of the pendulum from “right” to “left” the extreme end of the spring “vibrator” engages one tooth of the “ratchet” thus deflecting it, and therefore tending to arrest slightly the progress of the pendulum.

(iii) The duration of the impulse then ceases, and the armature returns to its normal position, thus allowing the spring “vibrator” to swing clear of the ratchet teeth until the sequence is repeated.

It will be understood from the foregoing description that whenever the spring vibrator is arrested by the “ratchet” it will have a tendency to terminate the vibrations of the pendulum sooner, but during the next half vibration (or return swing), the straightening out of the spring will assist the acceleration of the pendulum, thus enabling it to arrive at the end of its arc a little sooner.

Installing the Device

It is necessary when installing this synchronizing device to adjust the clock for a slightly losing rate (approximately two minutes a day), which can be accomplished as follows:

(i) Turn the key of the “stator” to its “off” position and regulate the clock to approximately the above rate.

(ii) Turn the key of the “stator” to the “on” position and the pendulum will vibrate in unison with all other clocks con- nected in the circuit.

So effective is this control system that a pendulum giving eighty- eight vibrations per minute (as is standard in most recorders), can be synchronized to give “master clock” time, although it normally had a losing rate of as much as ten minutes a day. Another example worth mentioning is that irrespective of the number of clocks (in which this device is fitted) all their pendulums will indefinitely swing in synchronism.

The makers of this device, called the “Reflex control”, are Messrs. T. Gent & Co. Ltd., of Leicester, who also make a larger type suitable for turret clock application.