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How clocks work

Mike Szadaj

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My car came with a Tic-Toc-Tach from the factory. The clock didn't work. I know most people don't notice or care if the clock in a car works or not, but I wanted mine to. I Heard about the quartz movement replacements, and figured that was the way to go. When doing the job, the entire original clock movement is replaced. After doing the swap, and putting power to the clock and seeing it work, I figured I would nose around the original. I had always assumed a car clock was like plug in the wall clock - that it used an electric motor. That was a stupid assumption because how is the motor in the clock going to run at a steady rate when the voltage supply is constantly fluctuating? The way the engineers solved that problem was to use an everyday run of the mill spring powered movement, only with a unique (at least in my mind) winder. In the first pic you can see the spring, (it is longitudinal - not circular) and in the foreground the winder. In the second photo I have marked the point attached to the winder "A", the point attached to the kicker "B", and the solenoid as "C". As the spring unwinds, point A moves toward point B. when they touch, (pic 3), they complete an electrical circuit that energizes the solenoid. When that happens the arm with point B is quickly jerked to the left, and that action kicks the winder to the left (pic 4), which puts tension on the spring again. Eventually, just like the points in a distributor, the points wear out. That is when these clocks stop running.
Some of you are aware that these clocks had a way to slow them down or speed them up. If you manually turn the clock ahead, that would speed the clock up a little, and vice-versa for adjusting the hands backwards. In the next 2 pics, you can see the speed adjuster moved from fastest to slowest. The gear on the right turns with the manual adjusting knob. Depending on which way you turn the knob, the gear moves that little "dogbone" which then moves the circular speed adjuster. There is slip between the gear and the dogbone so that each movement of the gear only moves the dogbone a tiny bit.
Cool stuff, if you ask me.
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Fine machinery is interesting. I saw a pocket watch that had a chain drive so small it looked more like a wire until seen with a jeweler's loop. How do people build that small?

Those points can be replaced... but it is spendy. I had a 56 Merc clock fixed for $150. yeouch
 
I’ve had a few of these clocks apart and what usually happens is the solenoid windings get toasted.

When the vehicle battery gets run down (say from leaving the dome light on,) the battery doesn’t supply enough power to wind the clock. The points then stay closed and even though the current is reduced, it’s enough to toast the solenoid windings.
 
I always find myself in awe of the minds that design this stuff. Similar to the passages in a valve body!
Mike
 
This one came out of a dash that looked like it was out of a convertible. It was frozen up. I took it apart, oiled it up, got the gears moving, applied power, and it start running!

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The 66-67 Charger clock has a similar clock movement and works much the same way. Bought a non working " for parts" 67 Charger console clock on E bay many years ago. I had to clean up the "points" that were badly pitted and stuck together. Luckily the coil was not toasted. Points can be carefully cleaned up with ignition file/fine emery cloth. Also good idea to lube all moving shafts at the bearings. I used tiny amounts of WD-40 in a syringe. Clock has been running perfectly for 5 years now and is quite accurate. As protection, i installed an line fuse with the 12 V to the clock so if points would stick together, the solenoid coil would be protected from overheating. If I remember correctly, it was something like a slo-blow 1.5 or 2 amp fuse I used. I would think that most clocks from this era can be revived as long as that coil is not toasted..
 
I took two clock restoration classes at the local community college. The issue with accuracy in the mechanical clocks is the pinion. The pinion wears into an odd shape and the gears bind somewhat. As the gears bind they wear.
Proper repair is drill out the pinion and replace with a bushing.
My instructor soaked clocks in Murphy's oil soap and then slick 50 the movement.
I'd really like to repair clocks someday, but just don'thave the time.
 
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