Re: clock rebuild

Posted by HH56 On 2017/12/18 10:28:14

I believe the two biggest problems with car clocks are dirt and oxidized or burned contacts. The clocks are nothing more than a wind up clock and the old lube dries or gets sticky stopping the action.

There are spray solvents which will clean the mechanism but if you use them be sure not to flood the clock so the stuff runs all over and gets on the painted face or under pressure damages the hairspring on the balance wheel. After cleaning use a tiny amount of clock oil applied with a fine pointed applicator such as a toothpick just on the pivot points for the gear shafts. There are some who have been successful short term with WD40 but that is not a good long term solution because it sprays over everything and as it ages it gets sticky again and collects dust. There are some sprays used for cleaning electrical mechanisms that contain lubricants but I don't know if they are suitable for this use. Clock oil is the standard. It is a thin almost water like fluid which doesn't get sticky and retains lube properties for a lengthy period.

The winding mechanism is an electromagnet which attracts a spring loaded moving arm. The arm rotates several degrees tightening the spring which then pulls the arm back to power the clock. Near the end of the unwind travel there is a set of contacts that close to supply power to the electromagnet to pull the arm back and start the cycle over. This happens every few seconds but the length between the cycles varies between clocks. The usual issue is the contacts need to snap open to break the connection to minimize arcing but as the lube starts making things sticky the action slows down and may not have enough inertia to snap the contacts open so they stay closed longer and can burn. A weak battery also can't pull the movable arm fast enough so the same result. Time can also take a toll with oxidation on the contacts so not enough power to the electromagnet for a proper winding. Use a point file or contact burnisher to clean the contacts.