Gents Pulsynetic Bell Striker C54 description of actions.

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Click on any image for an enlargement.

Having studied the illustrations kindly provided by Anthony Roberts I have reduced the details to the  following: (A fully illustrated, rewrite of my original post will also follow. The original post was far too wordy and unhelpful for those simply seeking advice on returning a Gents C54 Pulsynetic Bell Striker to working order)

It is possible that somebody has arrived here having discovered a similar mechanism in a dark roof space or disused building. You may have found a label and then searched for the very strange name "Pulsynetic" online. Do not scrap the device without seeking further help or advice. If it really cannot be retained in its original installation then sell it on eBay. Where its value to the world will be maximised. A local mixed auction is very unlikely to raise much interest through complete ignorance of the unusual subject matter. While eBay is monitored by the world's active collectors of electrical horological items.

Thirty years ago very few clock collectors who had any interest in electrical-industrial horology. There are now (probably) several thousand enthusiasts around the globe willing to compete for ownership of items from the heyday of master clocks and impulse systems. Some collectors like to discuss their new find or acquisition in online forums with other enthusiasts. Selling on eBay will not unduly increase the price of such artefacts as is sometimes thought. The advice given is just an attempt to keep the devices in this world. Rather than ending up on the world's scrap heaps. As has happened to so much of our industrial, engineering and technical heritage.



A skilled collector will probably restore an item to its (original) former glory and maintain it for future generations to examine and enjoy. They may even study the object carefully and then publish a useful description which is freely available online. Hopefully giving enough advice to keep other bell strikers working in their original situation.   

Note: A bell striker needs a master clock and an hourly impulse timer to work as intended. 
Oh, and a bell, a gong or tubular bell to strike on, for the hours to be heard!

Please refer to the labelled image above to help in recognition of the various components mentioned in the following:

Gents C54 Pulsynetic (early model) Bell Striker sequence of actions:

At rest:

The bell striker mechanism sits motionless with the motor shaft brake applied by its coil spring.

The see-saw control arm is raised by its counterweight and unlatched.

The strike locking detent sits deep in a notch on the count wheel rim.

Since the control arm is raised the microswitch contacts remain open.
No power is flowing in any component.

Hourly Impulse and strike release:

On the hour, a low voltage impulse arrives from the impulse timer. (Gents Contact Timer or Bell Ringer)

The twin electromagnets pull down the control arm against its opposing counterweight.

The control arm drops, at its far end, closing the microswitch contacts.
The relay, in its separate box, is activated and closes its switching contacts.
The arm becomes temporarily latched in the down position. 

Current flows, the motor starts and the brake solenoid is activated, instantly releasing the brake.

Striking:

The bell striking system runs under the power of the electric motor.

The cam rotates every 3 seconds to strike the bell via the long black lever, pull wire and hammer.

The long finger on the camshaft  repeatedly releases the control arm latch via the rearward extension.

Counting:

The count wheel/plate slowly rotates but the intervening 'land' won't allow the locking detent to rise.

The locking detent gently rubs along the rim of the count wheel as it turns.
The length of the 'land' on the slowly rotating circumference of the count wheel dictates how many blows are struck. 

Striking continues until the locking detent is finally allowed to rise with the arrival of the next notch on the count wheel rim.

Release:

The locking detent rises into the notch as the control/switching arm is raised by its counterweight.

The microswitch contacts open and the mains power is switched off by the relay contacts opening.

The motor tries to run on due to rotational momentum.

But, without power, the brake solenoid also switches off.

Its spring instantly reapplies the brake to quickly stop the motor shaft from turning.

At rest again:

The system sits and waits for the next hourly impulse from the remote impulse timer.

Note: The mechanism can only strike the hours in numerical sequence.
The remote contact device supplies only one low voltage DC impulse on the hour to initiate striking.
The bell striker itself counts how many hours to strike using its rotating count wheel/plate.
If there were no notches in the rim of the count wheel the striking would continue, without pause, forever.

Note:

Later examples of Gents C54 Bell Striker use heavy motor switching contacts rather than a microswitch. This is to avoid switching contact burning from the high current demands and even possible arcing from the motor starting and stopping. The microswitch on the example shown here uses a relay to carry out the actual motor and brake switching.

Night/Weekend silencing:

By delaying the hourly impulse from the bell ringer/contact maker for exactly 13 hours the count wheel strike will restart the striking correctly next morning. For example: Allow 8pm to strike in the evening. The next possible correct strike next morning will be at at 9 o'clock.

Of course, any other hours (separated by 13 hours) may be selected. Though these may not be quite so socially acceptable or even useful. For bell striking silencing to take place the contact maker/bell ringer must be stopped from sending its normal hourly impulses. This may easily be arranged by removing contact pins or using a contact masking cam on the 24 hour contact maker (or Gents programmable bell ringer) wheel when strike silencing is desired.

The problem with count wheel/plate striking is that it cannot recover lost hours. If silenced by an absence of starting impulse it can only strike the next hour from the last which it struck. 1,2,3,4,5,6 etc. If you want to change the strike to an earlier hour then you must let it strike "right around the clock" until it gets there. This can take some considerable time! The consequent racket may also confuse or irritate the neighbours! Though you can always silence the bell by temporarily disconnecting the hammer pull wire during Daylight Saving Time adjustments. 

Mechanical clocks moved on from the earlier count plate/count wheel to the rack and snail strike system. This had the advantage that the strike count is controlled by a stepped, snail cam. Which is constantly driven on the hour hand pipe of the clock mechanism. Thus the striking cannot get out of synchronisation with the timekeeping shown on the clock dial.

Conversely, the count wheel strike is controlled by the rotation of its own striking train without any reference to the actual timekeeping being shown on the clock dial. The Gents C54 bell striker had no local timekeeping train available to monitor the time, via a constantly rotating snail. So had to rely on the earlier count wheel (or count plate) strike counting system. Though later, a rather complex device was designed by Gents. Which used two independent, Gents clock slaves to maintain synchronisation between the number of hours being struck and the time shown on the dial. The bell striker was then reduced to a simple electric motor, a speed reduction gearbox and a bell hammer lifting cam.  

WARNING!

Pulsynetic Bell Strikers may have live mains electricity on exposed components! 

TREAT WITH EXTREME CAUTION AND AVOID ALL PHYSICAL CONTACT UNLESS THE MAINS POWER IS SAFELY ISOLATED! 

Count plate and count wheel are interchangeable terms for exactly the same thing. Count plate striking has been in use for well over 500 years in turret clocks. 

My thanks go again to Anthony and Donald for pointing out the correct sequence of operations and for supplying additional information. See the next piece for a lengthy, illustrated description of the Gents C54 Pulsynetic Bell Striker:

Click on any image for an enlargement.

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