Gents long shaft, heavy duty, turret slave on eBay

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Another turret slave for sale on eBay(UK) with a longer 12" 30cm shaft. (Mounting plate to tip)


HEAVY DUTY ELECTRIC TURRET CLOCK SLAVE UNIT | eBay

Double locking is present. As is usual in these larger slave movements.  This ensures the longer and heavier hands do not move of their own accord between impulses. This plated, slave movement looks later than the last one on eBay.                                                                      

This slave movement will expect a short electrical impulse every half minute to step the time forwards.  The seller claims that it will need 24V. Though the resistance of the coil is not mentioned. It is usual to take the total clock system series resistance and multiply by 0.22 to obtain the nominal voltage in the case of Gents' Pulsynetic components.               

I have done my best with the original auction images: Rotate, re-size larger, sharpen, gamma and contrast adjustment. The very light background has completely confused the camera as usual. Fawn packaging cardboard makes a far better photographic background.

None of the auction images was correctly orientated for normal slave function. So I have deliberately rotated the images to show how the slave would be used purely for educational purposes. The coil usually lies along the bottom of the slave movement. This is because some slave components rely on gravity for simplicity and reliability.






I suppose we should be grateful that any images are available at all. The eBay trend seems to be towards zoom-able pictures which can neither be saved nor shared. Which is fine if the seller doesn't want any further publicity for his item. Otherwise the seller is playing Russian roulette with those who might just happen to discover his auction by sheer chance. Though the majority of keen collectors will probably have eBay saved searches for items that may potentially interest them. Saving auction images for further or later study must surely be the norm with many collectors by now. If only for direct comparison with items already in their collection. 

Click on any image for an enlargement.

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Superb new Gents 'Waiting Train' videos on YouTube:

General view. This C40A is probably from the 1940s. Showing  a mixture of later and earlier details. The cast, contact assembly steady bars and softly curved mainframe are early features. The taped drive electromagnets are later.  I haven't seen the outboard, lead-off rod support on any other WTs so far.



Waiting train action. The L-shaped lifting arm or masking pawl is set slightly too high here. The gathering pawl can be seen hopping up over the masking pawl front edge which will cause local wear. There is an eccentrically bored adjustment roller stop. (not seen in this view) This can be rotated to raise and lower the arm in its (normal) rest or lowered position. But this will not affect the height of the arm in the temporary (waiting) locked position. Only bending the vertical brass arm or filing away the small step at the very bottom of the brass limb will lower the masking pawl. Careful examination of the general view (above) shows the brass locking arm is quite hooked at the tip. Straightening the tip (very carefully) may lower the masking pawl enough to provide a smooth ramp when in the locked position. The masking pawl is a later design with a deeper section and heavily curved on the underside where the D-shaped pin lifts it.



The Hipp toggle and drive electromagnets. An interesting mix of period details here:  A later, plated rocking armature and bandaged coils but many earlier, lacquered brass components throughout. The contact steady bars are earlier cast and lacquered brass. Later steady bars were pressed steel with soft curves instead of sharply angular steps.

No doubt Gents would use a mix of components as design improvements steadily evolved with experience in active use. I believe the matt silver finish on the gathering wheel and other parts is hard chrome plating. This is not only resistant to corrosion but wear resistant and attractive in the longer term. No doubt lacquered brass was seen as a rather dated feature to some eyes. Later WTs did away with the lacquered brass entirely and used only plated components. The later cast mainframe also took on a straight sloping section above the drive electromagnets. The paint colour looks darker than usual for an early mainframe. The earliest C40A frames were painted flat black.


 Posted by "The Clockworks" on YouTube. Full screen viewing is well worthwhile.

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Gents turret slave

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Here is a late model turret slave on eBay(UK)

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=271364739829&ssPageName=ADME:B:SS:GB:3160


I have done my best with the images having enlarged, sharpened and increased both gamma and contrast. The original images were undersized and probably taken with flash.

A soft wash of daylight (overcast or not direct sunshine) against a plain (uncluttered) neutral density background is far better for technical images.

Packaging cardboard makes an excellent background since it is neutral in density and colour and reflective without gloss. It is also readily available in all sizes. Often completely free of charge at supermarkets and shops.

Larger images are far easier to examine for fine detail and capable of much greater enlargement.

This slave is unusual for having only 60 teeth on the impulse wheel. This would need a short, low voltage, drive impulse at only one minute intervals. An unusual requirement where most master clocks impulse at 30 second intervals. NEVER MAINS ELECTRICITY! The unit looks to be in excellent condition with only minor corrosion on the hour sleeve.

Later master clocks offered impulses at 1 minute intervals. An irony considering that 1/2 minute impulse dials are showing the correct time, more accurately for most of the time. (The hands move very briefly and then remain still until the next short impulse arrives)  It follows that a 1-minute activated dial is only showing the correct time for 1 second in 60.


The hour pipe sleeve will just reach through a single skin brick wall. Though the dial itself would probably need to be thin and flat to allow the hands to turn freely.

Turret slave dials can be very reliable when the hands are not too large and reasonably sheltered. Problems arose when they were asked to drive the hands of a large, very exposed dial to save money.

Unfortunately placing the dial and hands behind glass makes reading the time very difficult indeed when the glass is reflecting the open sky.

These later Gents slave units were made with conservation of materials in mind.

Brackets would be bent as tabs from the solid sheet rather than adding a bolt on component.

The double-locking mechanism holds the hands quite still against external forces until the impulse frees the action and moves the hands on.

The hands would still need to be light and balanced to avoid the slave having to work beyond its physical limitations.

The actual drive to the hands is by means of a spring. The spring is drawn back by the electromagnet(s) armature. Then the impulse wheel is driven by a pawl pushing a tooth forwards on the rim as the spring gives up its applied tension.

Since the electromagnet only receives a very short impulse and has limited drawing power this, in turn, handicaps the maximum potential strength of the drive spring. Larger slaves used twin electromagnets to obtain more power.
They could then use stronger drive springs to push against larger impulse wheels for more leverage and hand control.

Should the clock hands be subject to icing, perching birds or strong winds the slave's drive mechanism might stall temporarily. Many turret slave clocks were placed behind glass to avoid such problems. Or used under cover such as in train and bus stations, large factory buildings, etc.

Where larger, exposed dials were required the Waiting Train mechanism was an incredibly powerful but far more expensive option. For modest dial sizes the turret slave was a relatively inexpensive option. After all, the smaller, office-sized, slave dials were made in their millions with excellent reliability.

This interesting item sold for £83.57 after 16 bids.

Click on any image for an enlargement.

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