General Information on Gents C7 master clocks

These clocks were originally driven by a bank of accumulators. Gents never stress the actual voltage. The clock itself will run on ten volts or less but I have been advised that it's best to run master clocks with or without slaves on 24 volts and I know of at least one company concerned with leasing and servicing Gents who used a 40 volt source. The rheostat is used to set the current to the design value. This is because the system is then much more able to shrug off dirty contacts, and, because the series resistance is high, small changes of resistance in the system have much less effect.

Any additional slave clocks are wired in series with the master clock and so the voltage needed also depended on the length of wiring and the number of slave dials.

Gents state that the current in the circuit should be between 0.17 amp and 0.22 amp. The large variable resistance (rheostat) in the left side of the case is used to set the current while holding the contacts closed (so as to get an accurate figure).

The action of the clock is as follows:

The pendulum carries a pivoted lever mounted below a 15 toothed wheel which it pushes round by means of a pallet or projection on the lever.

The wheel has one space more deeply cut so every 15 pulses the end of the lever rises a bit higher and displaces a latch.

The clock has a lever, called the gravity arm, normally held approximately horizontal by the latch. When unlatched, the gravity arm swings down. A roller is mounted on the gravity arm and this intersects a cam fixed to the pendulum.The roller runs down the cam and in so doing it provides a sufficient impulse to keep the pendulum swinging.

When the gravity arm reaches the bottom of its travel it closes a contact at its left end, energising the magnet and resetting the gravity arm. In throwing up the arm into its locked position the contact is broken. Because any slave dials are in series in the circuit they also receive a pulse of current each time the contacts close.

There is a pull cord which can be used to cause the latch to be released every swing, i.e. at two second intervals, thus adjusting the dials forward quickly.

Serial Numbers and Dates of Gents C7 Clocks

Almost all of the clocks originally had a label glued in the top left corner of the case. This gives the serial number and the date of the clock.

If the label is missing, look for the serial number which is almost always stamped into the wood of the top front member of the case (visible when the door is open). In some cases this number is in very small figures and can be overlooked. The serial is also often given on a card label tacked to the back of the case together with another service number (the latter does not represent a date, nor anything else recognisable).

Once you have a serial number send me an email. I have a graph developed from known serials and dates and in most cases can date a clock to within a year.

If you have both serial and date PLEASE email me so that I can add the information to the graph to help others.