WT Bevel Wheels

It has come to my notice that a number of C40A WT's lack one or more bevel wheels. Some lack a crownwheel too. It should be noted that not all WTs will have driven four dials originally. Though owners of WTs might well wish otherwise. If only for appearance sake. Even if they do not plan to build themselves a four dial, clock tower on their house or outbuilding.

Four dials may need bevel wheels, leading-off rods and motion work for each dial unless the WT is raised up to dial level. Which might be a shame, if not easily accessible. Because one cannot enjoy watching the WT clock movement in action. An alternative is a single vertical lead-off rod and a raised, crownwheel gear cluster at dial level. Though you may not want your WT in the middle of the room. If placed against a wall a further two pair of bevel wheels will drive the raised cluster via further leading-off rods.


I have contacted four potential UK sources of bevel wheels (March 2011) but none has responded as yet. (I will, of course,  update if this should change)

Note that all images can be enlarged by clicking on them. Those on a slow connection might want to avoid doing this. So I have sized these "thumbnail" images appropriately. Making them all even larger would mean quite a long download time for some visitors.

As a service to those lacking bevel wheels I have carefully measured my own with a vernier calliper. Then appended the dimensions to some images which I have taken specially for the purpose: First a couple of older images:

The crownwheel bevel cluster in place on the back of the WT movement.

A close-up of the four bevel wheels meshing with the larger crownwheel on top. The crownwheel has to be larger than the lower bevel wheels or the cluster would be completely locked by opposing teeth all meshing simultaneously.

Strictly speaking these are mitre bevel wheels since they meet at 90 degrees. (wheel is the normal horological term for a gear wheel to differentiate them from cruder engineering gears) The bevel wheel on the right in this picture is the first wheel and drives the crownwheel. The crownwheel then drives the three remaining bevel wheels. A coupling on the far end of the rod driving the first wheel provides drive to the fourth dial.

 The crownwheel cluster seen through an aperture in the WT main casting. The two large bolt heads, below the hand setting dial, hold a supporting casting for the gear cluster. This is an early shot taken soon after obtaining my WT. When some missing parts had yet to be fabricated. The dial pointer and Hipp toggle damper are both missing here. These would be held by screws in the open, threaded holes near the bolt heads.

The gear cluster from the front with the forward facing wheel carrying the hand setting dial. Ignore the rather crude (temporary) dial pointer.  It is a great shame when the gear cluster is missing from a WT if the hand setting dial is also lost. A dial engraver should make a good job of a replica if bevel wheels can be obtained. Some clever computerised engraving or milling machines could also reproduce such a dial. 

The bevel wheel support bracket removed from the movement. Provided the top support block fits in place on the movement the black painted casting is not strictly necessary in this fancy form. Meaning that a simpler block could replace the casting. One could saw out something from a solid block to provide clearance. This would achieve the necessary offset and supply a stable platform for the bright metal, stub axle block.

The gear cluster and casting from below. The forked objects at the bottom and left of the image are couplings or universal joint for leading off work. A T-shaped crossbar fits in the slots and drives a rod or tube leading off towards the dial work. The long slot allows for length variations due to thermal expansion of the leading-off rods.

Note the clearance between the bevel wheels provided by the larger crown wheel. The teeth at the meeting edges of the bevel wheels are travelling in opposite directions. So would lock up if they actually touched.

Dimensioned bevel wheel.

Dimensioned bevel wheel 2. 

Dimensioned bevel wheel 3.

Bevel or crownwheel wheel cluster seen from the bracket face which mates behind the WT main movement casting. The two diagonal holes are for locating or steady pins. I have removed the original, forked, universal joint from the face of the dial since I need no leading off work in this direction. 

Dimensioned crownwheel bevel gear. The rod shown is simply to support the wheel on its edge for taking the photograph.

Dimensioned crownwheel 2.

Dimensioned crownwheel 3.

The support block for the bevel wheels.

Bevel wheel block inverted. This component looks to be hard chrome plated.

The complete bevel cluster component

 WT Hand setting dial. It should ideally be re-silvered and clear lacquered to ensure maximum clarity in poor light. I have run out of old-style silvering salts. Which produce a much whiter and clearer silver than the more modern "burnished stainless steel" look of today's, cheaper, silvering salts. 

Here's the hand setting dial after re-silvering. A bit bright for my taste. An effect which is reinforced by the 500 wet-and-dry spun graining. Still excellent legibility with good whiteness.


An old, brass-dial clock with a modern silvered dial (or chapter ring) looks completely wrong. It ought to have been re-silvered with the whiter and more expensive 18th century salts. Producing a very high contrast, matt, silver-white against the very black, wax-filled numerals.

This finish, along with the dark, blued-steel hands was developed specifically for very poor, indoor lighting conditions. Typical of most houses of past centuries when window glass was hand made and very expensive. Only candles and oil lamps were available to check the time at night. Which is why loud striking was so important to a household. Bedroom clocks were strictly for the rich.  

A modern, shiny silver finish reflects the contents of the room regardless of viewing angle. Greatly reducing contrast and legibility of time reading dramatically. The worst silvering powder produces a finish which is actually bluish as well as too shiny. The hands often seem to disappear against such a shiny dial. At its worst a modern silvered brass dial can even look like polished and printed aluminium.

On a safety note: Do not warm an old brass dial without it having had a bath in clock cleaning solution. The effects are extremely toxic if you apply heat to an old and dirty brass dial!

The irony is that it is not strictly the "done thing" to clean the back of an old dial. Something to do with proof of originality, I would imagine. Given the large numbers of dial and movement "marriages" in the antique clock trade it may be simple paranoia. A dirty dial plate can hide old, patched pillar holes.

I have been caught out a couple of times while warming an old brass dial plate or chapter ring for re-waxing the numerals. The effect feels exactly like having one's lungs collapse suddenly and catastrophically! I have twice had to take to my bed to recover! Avoid at all costs! Rinsing has no effect on an old dial! It must be cleaned properly to avoid toxic fumes. You might try working outside. Or with forced air extraction. Still risky!

Click on any image for an enlargement. Back click to return to the text.

No comments: