Antique Pendulum Suspension Spring
Most used on early antique clock movements. These clocks were popular prior to 1950 and goes way back from there. It is called a suspension because it suspends the pendulum in the air. It is called a spring because it flexes back and forth. If a spare spring is ordered it would be a good idea. One can be put on the bottom of the weight section of the clock for next time. That way the search to find the next one will be saved.
Does not have to be exact
Suspensions do not have to be exact in length. If the clock runs slow simply raise the pendulum bob with the screw at the bottom. If the clock is running fast then turn the nut as too lower the pendulum bob.
Most common springs
The suspension spring A is by far the most common style suspension spring. It is most likely the one needed by default. If the old suspension spring looks similar to this one it will be the right one. Small mantle clocks take suspension A1, wall clocks and small grandmother units will take A2. The A3 size is for grand father clock sized units with a larger bob diameter. It also can be used on a grandmother sized clock with a larger bob diameter. The larger A3 is used with large bob diameters so the bob will not wobble front to back. If using a pendulum with a bob of 8 1/2 inch diameter or larger please order suspension A3 for this reason.
Not as common
Urgos uses the single hook style as seen in the picture suspension B. However they also used suspension A style and this is much more common. Suspension C and D are used mainly on very old antique round movements. These are mainly French clocks and US made units made prior to 1945.
Suspension spring installation
The two styles of holding the suspension into the suspension post. One way is a thumb screw that just gets removed and the suspension falls out of its slot. The other way uses a tapered pin, this is a pin that is skinny on one side and wide on the other. The skinny side is pushed through the hole in the suspension post. It travels through the hole in the suspension spring and to the other side of the post. To remove is to use needle nose pliers to twist and yank it out from the wide side. Please note, some set screws may or may not be too wide for the suspension top hole. In this situation it would be required to use a taper pin to secure the suspension instead.
Connecting the leader
The leader hooks onto the suspension spring prior to installing. The intent is to have the suspension hooked, the leader engaged with the crutch. At this point the suspension can be lifted into position and set screw inserted. The suspension is lifted with the leader hanging on it, and that leader is engaged with the crutch.
What is next
Hang the pendulum onto the newly installed leader. Just hook it right on and give the pendulum a good swing. The swing should be an over swing to set the beat of the clock. No mechanical clock that has a pendulum will run if not put into beat. If this term is unfamiliar please see instructions on how to put my clock in beat.