[Abs-Zero]

 

Current Project - 1947 Vauxhall 10

Dashboard clock repair

Not much to repair really, but I did learn how it worked and quickly diagnosed the fault. 

The clock is driven by a combination of an electromagnet, a switch and the 6V supply from the car battery.  The electromagnet is energised while the switch is closed, then a piece of steel attached to the escapement wheel is drawn round, rotating the escapement wheel against its spring.  As the wheel rotates, the switch opens and the field collapses, allowing the wheel to rotate back under the force from the spring.  The switch closes again and the process repeats itself, all the while outputting slow rotation via what looks like a simple part of a worm gear into the dividing gearbox of the clock.

To say it's simple is an understatement and I imagine the clock consumes very little electrical power, but I guess we'll find that out once it's reinstalled.

In the case of my clock, all that had happened was that the switch had gummed up, meaning that when exercised manually, it did operate briefly but emitted small sparks before stopping.  All I had to do was to clean the contacts with a clean screwdriver (repeatedly) until it became able to operate unaided.

While it was apart, I took the opportunity to clean the bezel, glass and face, which (uncharacteristically of the rest of the chrome on the car) cleaned up perfectly.

A few photos below, although my little Fuji camera is somewhat challenged in terms of capturing the detail.

 

Clock... done.

 

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And the [ science] bit...

Last review was Friday, 31 October 2008