Antique Clocks/Gilbert clock mechanism
Tom Williams wrote at 2012-11-27 13:04:53
Your clock appears to be a little newer than what I had expected. Thus, it probably had a rack and snail movement. Rack and snail has the advantage of automatically synchronizing the chime after the clock has been set to the correct time.
Your clock has only two winding arbors, hence it was time and strike only. It has a small hole at the top right under the #12 for adjusting the pendulum sweep rate. One of the difficult things in replacing movements is to get these holes to line up with the arbors. Most movements have the beat rate set with a gnurled nut on the bottom of the pendulum so the small hole at the top is probably not going to matter. However, the winding arbors are quite critical.
when installing a new movement it may be necessary to replace the dial. If you install a westminster movement you would have to drill an additional hole to wind the time function of the clock. Drilling in these thin dials can be tricky and is best done with a wood bit if it is brass. Steel dials require the dial be clamped between two pieces of wood to prevent tearing as the drill bit cuts through. Merritts offers brass grommets on page 58 of their catalog.
I assume your clock has two chime bars. Sometimes one hammer would hit and then the other. This is called a bim bam clock. Other clocks drop both hammers at the same time creating a rather pleasant musical note. I would thumb through the Merritts catalog and also Timesavers (timesavers.com) catalog to see if there is anything that will fit your case. In most cases the dimensions given for movement winding arbors is in mm.
A very easy installation can be made with battery powered quartz movements. These have no winding arbors to worry about and are extremely accurate. They are available with Westminster, Whittington and St. Michael chime as well as strike. They use a loud speaker to produce the sound. If the speaker is kept in the case they it is preferable to have a hole in the bottom or to leave the door slightly open to let the sound out. Some people simply put the speaker behind the clock for maximum sound output.
I hope this info is helpful to you. I do not have any financial interest in either Merrits or Timesavers but have found their clock supply prices to be fairly reasonable and their inventory adequate.