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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