The Gear Trains

THE relative POSITIONS, rotational rates, and tooth counts of the shafts and gears are given in the text that follows. Tooth counts on the movement have been obtained and verified by physical counts. Italicized items and tooth counts were calculated by the author, and though they are representative of the actual dial gearing, they have not been verified by physical counts. Rotational rates of dial indications are likewise based on the calculated counts, and aldiough I believe them to be correct, they may not be in complete conformance with those of the clock. A photo of the gearing located between the plates, as well as a line drawing of the gearing is illustrated in Figure 15. The line drawing illustrates the designations and locations of each gear listed in Tables 1 through 4. Table 1 describes the time train gearing located along the central portion of the movement, whereas Table 2 describes the music train gearing located along die right-hand portion of the movement. Table 3 describes the strike train gearing located along the movement's left portion. An analysis oi the number of hammer strikes required for the strike settings, Hourly and Quarterly, appear in Table 4. The analysis is performed twice. Once if the clock is assembled to strike the quarters as 0, 1, 2, 3 and as it strikes quarters today 1, 2, 3, 4. Because of modifications made over the years it is difficult to determine what the original intended sequence was. However, if the strike quarters are struck as 0, 1, 2, 3, the winding of both the strike and time trains can be performed together every 32 days. This fact is a strong indication that the clock originally did not strike four quarters after the hour strikes were completed. GEARING ON THE FRONT PLATE Figure 16 is a photograph of the gearing on the front plate of the movement. Figure 17 is a line drawing of the same gearing, which also shows the flow of power transmission among the gear trains. Motive power is supplied to die gearing on the front plate by die T2 shaft of the movement, which extends through the plate. The T2 shaft is shown as a solid dot in Figure 17. The connecting lines indicate the transmission of motive power along the gear trains. The diagram is repeated in Figure 18 without the labels, enabling it to be presented in a larger format. Figure 18 also identifies the location and position of each gear shown in Table 5. Gear Al on the T2 shaft drives A2, which in turn drives A3. The minute, hour, and calendar elements are separate coaxial mounted wheels. The shaded circle on the center shaft, A3, is the minute wheel and quarter-hour snail. A3 drives D2, which drives D3. The crosshatched portion of D3 is the hour wheel and hour snail. Teeth on the back of D3 drive A4. The clear outer portion is the calendar wheel, L4, driven by L3. The L3 gear consists of two gears, one slightly smaller in diameter than the other. The power transmission path is A4, A3, A6, L2, L3, L4. THE DIAL GEAR TRAINS Figure 19 is a photograph of the gearing on the rear of the clock dial. All dial indications are driven by the time train of the clock movement. Although the dial has many gears and appears to be rather complex, it is no more complicated than many clock movements. …