Westclox kept changing their winding ratchet mechanism. The first four types listed here engage with projections pressed out of the body of the mainwheel.
Time Click 1: Spring click riveted outside BP:
Spring click riveted to the top of the back plate. Approximately 1 3/8 inches long. Used on very early four inch movements through ca. 1895.
Time Click 2: Spring click Integral to BP:
Spring clicks integral to the back plate. They are made in the plate stamping process by removing material, then bending the end down so it engages with the projections on the mainspring barrel. Used until around 1899 on the four inch movement, but the FW used it for the time barrel until 1904.
Time Click 3: Traditional click & spring inside BP:
Traditionally shaped click riveted inside the back plate, pressed toward the projections on the barrel by a flat steel clickspring. Commonly seen on clocks with the circular form of the 1885 patent.
Time Click 4a: Single-end flat spring click inside BP:
Flat brass spring click whose acting end engages with the projections on the barrel. A rectangular hole in the back plate limits the motion of the acting end. These are commonly found broken. Big Ben had these for the time barrel until near the end of 1912.
Time Click 4b: Double-end flat spring click inside BP:
Flat brass, double-end spring click whose acting ends engage with the projections on the barrels. The spring click is attached to the back plate at its center. One end is the click for the time barrel, and the other end is the click for the alarm barrel. Two rectangular holes in the back plate limit the motion of the acting ends.
Time Click 5: Traditional click & spring on plate or bridge:
Traditional brass click and clickspring mounted to the plate or bridge, engaging with a traditional brass ratchet gear. Big Ben had this for the time barrel starting near the end of 1912.
