Gents' WT 'open' motionwork.

I have been kindly sent some excellent images of various Gents' WT motionworks. These would have been connected to the lead-off rods from a WT movement. Motionwork is a simple four gearwheel train [in two pairs] to reduce the 1rpr  [1 revolution per hour] lead-off [minute shaft] speed [from the WT] by 12:1. The simple gear arrangement drives the hour hands on a public clock dial once in 12 hours from the minute hand drive input.

The first image shows an (almost hidden) WT driving the large, bare hands of a [missing] dial which might easily be 6' [2m] in diameter. A second WT movement is situated on the wall in the background. The active WT being seen end-on, in lighter grey paint, almost hidden behind the clock hands. Part of the bottom half of a controlling, electric master clock is seen on the extreme right.

Motionwork has another important task in supporting the large and [often heavy] clock hands without adding too much friction. The inner shaft carries the minute hand concentric within the outer hour pipe which carries the hour hand. Arrangements are usually made to secure the hands against rotation under their own weight or when covered in ice. Or even when supporting a perching flock of birds. The security of the hands in all weathers is obviously a very high priority to avoid injury to life or property below the raised clock dial. A hand falling from a great height would cause very serious harm!

Note how the thin metal hands are typically ribbed along their length for stiffness without added weight. The counterweights for the hands are often hidden behind the short extension beyond the hub. As can be seen from the rivets in this case. Alternatively the counterbalances can be fixed direct to the minute shaft and hour pipe within the safer environment of the clock room. This arrangement saves adding overhanging weight to the very exposed clock hands. Counterbalances for the clock hands are quite normal practice for the hands of even quite small public clock dials. When the hands are not counterbalanced they have to be lifted uphill for one half of their rotation. They will then try to "run away downhill" on the second half. This would not help accurate timekeeping with most turret clocks. Which are usually weight driven and "friction governed" by their gear trains and escapements.

Motionwork can be "open" [as seen here] or housed within a protective case. Dust and dirt being common factors in clocks rooms and bell towers. The following images show open motionwork with exposed gears seen from many different angles for greater clarity.

The usual arrangement is two pairs of gears giving speed reductions of 3:1 and a 4:1 ratio in series. Being in series the two ratios can be simply multiplied by each other to give the final drive ratio. [12:1]

The substantial pairs of brass [or bronze] gears are well seen in these images. Avoiding lubrication to the gear teeth will prevent dust adhering to them which would cause accelerated wear. It is normal practice not to oil or grease most clock gears. Falling dust can then drop through or off the gear teeth without adhering. Gears are known as wheels [large] and pinions[small] in horological circles.

The projecting, silver coloured, double forked device is a universal joint [or expansion coupling] to the leading off work's shafts, pipes or rods. These joints allow for the movement of the building under settlement, in changing weather and temperature without the lead off work binding. This is important because most lead off work is situated in exposed and draughty conditions in towers and roofs. Often attached to ancient timber constructions. The temperature can plummet in winter and soar in high summer. The sheer length of many lead off systems allows considerable changes in the active length of the metal shafts and pipes. This is due to the linear coefficient of expansion [and contraction.]

Clock dials fixed on both gable ends of a large building are quite typical. These would use huge lengths of lead off work to reach both dials from the clock movement. Which may not necessarily be situated in the center of the building. The lead-off shafts [or pipes] would pass through simple, plain bearings to ensure they rotated in a reasonable straight line. These bearing brackets would be fixed to available timbers and walls to keep costs and complexity to a minimum. Though wooden troughs are sometimes constructed to house the lead-off work. Particularly where the space might also be used for storage.

Note the sturdy construction of all the support brackets and gears. Reliability over decades without maintenance is a vital feature of most public clock installations. Access to the lead-off work is often difficult to impossible with modern safety demands. Rotational "play" or backlash must be avoided between the clock movement and and the dial[s]. Multiple dials would run fast or slow of each other if their was any slack in their respective drives. Such "competition" between various clock dials was a cause for worker irritation when very few of the working classes owned watches. It must be remembered that for several centuries timekeeping was usually provided by public clocks and bells.

The cast brackets of the motionwork are designed to allow dismantling of one set of gears without touching the other pair. This is an important factor where access is often difficult and the security of the heavy, attached clock hands is absolutely vital.

The deep blue-green paint is familiar to Gents' WT made sometime around WW2.

Here the arrangement of all four gears is nicely seen. Only the pair on the right are connected together [as one unit] on their short, offset shaft. The larger of this right hand pair is driven by the input [minute hand] pinion. This is the steel gear just behind the universal/expansion coupling. While the smaller gear of the second pair drives the larger gear fixed to the hour pipe. This motionwork arrangement is common to almost every clock and watch, fitted with two hands, regardless of size.

Usually only 'early' or village church clocks continued with one [hour] hand. At one time it was normal for rural clock owners to have their long case [grandfather] clocks made to order with only one hand. So used were they to reading their one-handed, village, church clock. City dwellers, with their far greater collective wealth, would have enjoyed two handed turret clocks. They would order clocks with two hands despite its greater expense.

The difficulty with one handed clocks was that the hour hand is driven directly. It is very difficult [to impossible] to add a special motionwork to increase the speed to drive a [new] minute hand at 12 times the speed. Not without having serious 'slop' in the movement of the minute hand.

Many early and rural-made, 30 hour grandfather clocks have been converted to have a minute hand to match demand and modern tastes. Often these clock's dials have no minute markers. Usually the dials have only 1/4 hour markings in a ring further towards the dial center. Many antique dealers have profited from having a minute hand fitted. Because they could fool the gullible buyer into believing they were actually buying a much more expensive [and therefore far more desirable] 8-day clock. A glance at the engravings on a brass dial clock will soon show that it was originally fitted with only one [hour] hand and NO motionwork!

WARNING: Those finding themselves with a public clock installation in obvious need of repair should be very aware of the great importance of safety. Particularly where motionwork and the clock hands are concerned. Attempting to dismantle the motionwork [inside the building] could easily release the heavy clock hands. Even if they did not actually fall from the clock tower they might turn suddenly around their axes. The hands will always seek to balance themselves on their shafts and pipes. They may even have built-up torque in the lead-off work which caused the original stoppage.

It is not impossible for rivets to rust away allowing the hand's external counterweights to fall away unnoticed. The clock hands, hidden outside, on the other side of the obscuring dial plate, would then be non-counterbalanced!

If serious rust has set into the minute shaft or hour pipe [through poor material choice or great age] then a dangerous situation could easily arise. Easy access to the outside of the dial and the hands is not normal turret clock practice. Steeple jacks may well be needed to examine the dial, hands and counterweights! Or to bring them down for safety and subsequent repair. Preferably in the workshop of a skilled, experienced [and qualified] turret clock repairer. Mechanics and DIY enthusiasts are likely to make poor and dangerously ignorant clock repairers.

While clock botchers can [and will] ruin any clock they can lay their hands on, public safety is rarely an issue. Public clocks tend to use very large and very heavy components by their very nature. These same components are often raised high above the ground in very public spaces. The results of even a simple mistake could easily be fatal! How could the untrained amateur have any concept [at all] of the very real risks involved?

Just because a WT is a compact movement does not make it any less dangerous in its other parts. The hands on the WT's exposed dials used much the same techniques as all other turret/tower clocks. The hands and dials may even be considerably larger than normal weight driven clocks thanks to the enormous torque generated by the WT movement!

In many cases, though, the WT would be installed in place of an existing, possibly obsolete or badly worn out, weight driven clock. Being so compact and lacking any need for weight shafts, cables and weights made the WT an extremely flexible timekeeping option. It could be and was installed in many inaccessible places like war memorials and chimneys. Where regular maintenance was often all but impossible without the aid of a steeplejack.

Click on any image for an enlargement.

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