Antique and Vintage Mechanical Clocks

Recently, I was working on an interesting early American banjo clock made by John Sawin*, dating to approximately 1825. Sawin was an apprentice under one of the Willard brothers, and the influence of the Willard clockmaking tradition is evident in this particular example.

The movement in this weight-driven banjo clock is remarkably similar in size and design to the movements found in early Willard banjo clocks. This is hardly surprising. While Simon Willard patented his original banjo clock design he did not protect the patent, and consequently, the design was copied extensively by other clockmakers. John Sawin was among those who produced clocks based on this distinctive and successful design.

Although the movement is relatively straightforward in appearance, a problem with the motion works presented an interesting troubleshooting challenge.

The Problem: Hands Stalling at the Half-Hour

After assembling the clock and attaching the minute and hour hands, I noticed that the hands would advance normally for a period of time but eventually lose resistance at approximately the half-hour position.

For example, with the hands set at 2 o’clock, the minute hand would begin advancing and the hour hand would follow as expected. However, as the minute hand approached the 30-minute position, the movement appeared unable to advance the hands any further.

This suggested that there was insufficient tension or friction within the motion works to maintain the proper relationship between the minute and hour wheels.

On the central arbor is a small, bowed piece of steel that functions as a tension washer or friction spring. It presses against the back of the minute wheel and provides the friction necessary for the motion works to operate correctly.

I suspected that this component might be responsible for the problem, but before making any adjustments, I wanted to isolate the source of the resistance.

Troubleshooting the Motion Works

Rather than immediately altering the tension washer, I proceeded through a series of tests to determine where the problem originated.

1. Testing with the minute hand only

I first removed both hands and reinstalled only the minute hand.

With the minute hand attached, the clock advanced smoothly through an entire hour without hesitation. This was an important observation because it suggested that the basic movement and minute-wheel assembly were functioning properly.

2. Testing with the hour hand only

Next, I removed the minute hand and attached the hour hand to the hour wheel.

The result was quite different. The hour hand remained stationary and did not advance with the movement. I confirmed that the hand was secure on its mounting, which suggested that the problem was not simply a loose hand.

Further observation indicated that the hour wheel itself was not turning.

3. Examining the hour wheel and minute wheel

I then removed the hour wheel from the movement while leaving the minute wheel installed.

With the hour wheel removed, the minute hand once again advanced normally. I could also observe the pinion responsible for driving the hour wheel rotating correctly.

This indicated that the minute-wheel drive was functioning, but something was preventing the assembled motion works from transmitting that movement to the hour wheel.

4. Testing without the tension washer

I next reinstalled the hour wheel and minute wheel but left the tension washer off.

This test revealed another important characteristic of the assembly. Without the tension washer, the motion works became loose and floppy. The minute wheel no longer maintained its proper position, and the assembly would not function correctly.

It became apparent that the tension washer was doing more than simply providing friction. It also played an important role in maintaining the correct positioning and relationship between the motion-work components.

Adjusting the Tension Washer

Having established the importance of the tension washer, I examined it more closely.

The washer was bowed, but its curvature was not uniform. One side was more curved than the other, suggesting that it was not applying even pressure against the back of the minute wheel.

I made a small adjustment, bending the less-curved side slightly to bring the two sides into a more uniform position. I then reassembled the motion works, reinstalled the hour and minute hands, and set the clock to approximately 1:40.

I allowed the clock to run while observing the movement of both hands, paying particular attention to whether the minute hand would advance beyond the half-hour position and whether the hour hand would follow as intended.

The Final Adjustment

The troubleshooting process ultimately revealed that the original tension washer was not providing sufficient tension to operate the motion works reliably.

The tension washer required a slight bend on one side to increase its pressure against the minute wheel. This additional tension provided the necessary friction for the hour and minute wheels to function together properly. It worked the first time and I suppose I got lucky.

This was a relatively small adjustment, but it made the difference between a clock whose hands would stall at the half-hour and one whose motion works operated as intended.

It is a good reminder when working on early American clock movements that seemingly insignificant components can have a substantial effect on the operation of the clock. Before replacing parts or making major adjustments, it is often worthwhile to understand the function of each component and methodically isolate the source of the problem.

*While several design features such as painted iron Roman numeral dial, push door catches, wooden dial bezel, turned wooden top finial, cut steel hands, mahogany venered panels, and brass weight driven movement with “mounting ears”, point to John Sawin as the likely maker, the attribution remains one of high probability rather than certainty. At this stage, I believe John Sawin is the most plausible maker, but I cannot definitively attribute this unmarked clock to him.

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