Clutch helps keep century-old clock ticking

April 5, 2012
Tower clocks throughout the U.S. have been retrofit by the Balzer Family Clock Works with electric motors that rewind or reset the 55-lb weights

Ogura Industrial Clutch
To see more of the Balzer Family Clock Works projects and designs,

Tower clocks throughout the U.S. have been retrofit by the Balzer Family Clock Works with electric motors that rewind or reset the 55-lb weights that power the clock hands and mechanisms that toll the bells. In one typical project, Balzer refurbished the clockworks in the 1841 First Congregational Church, Rowley, Mass.

As in many such projects, the church wanted the actual clockworks brought down from the tower so they could be used to demonstrate physics, mechanics, and mathematics to local students. They also serve as functional artwork. This required adding a shaft to transfer mechanical motion to the back of the clockface atop the tower and another one to control the tolling of the bells. The Balzers also upgraded the mechanism used to set the clocks, converting it from muscle to electric power.

Originally, a church worker had to climb up into the tower and turn a crank, which raised the weights some 40 ft, enough to power the clock for at least a week. With the works on the first floor, this was no longer possible. Instead, a pair of 8-ft steel tracks, sized to fit in the available space, were made to hold the two weights. Each has a limit switch about a foot from the bottom and two at the top.

When the weight controlling the clock, for example, travels down and activates the lower switch, it signals an Ogura CT 20 electric clutch to engage and a 0.33-hp motor to spin and lift the weight. The firm chose the Ogura clutch based on its compact size, corrosion resistance, high torque, and simple installation. “It also cost about half as much as the ones from our original supplier,” says Linda Balzer, president of the Maine-based company. “And the second firm we used for clutches could never deliver on time. Ogura has been great with deliveries and performance.”

If there’s a power outage or electrical problem, the weight can continue to fall and power the clock for about a day as it uses up that final foot or so, says Balzer. When the weight hits the top limit switch, the motor switches off and the clutch disengages. The second limit switch at the top is a backup. And while the weight is being raised, it no longer powers the clock. Instead, the clock gets power from a heavy-duty “maintaining-power” spring, which periodically gets rewound.

“The technology might be hundreds of years old, but it is still quite accurate and reliable, and the best timekeeping mechanisms for tower clocks,” says Balzer. “In fact, electrical replacements that have been tried tend to break down after 10 to 15 years, and in some areas, especially up here in New England, quartz circuits do not work in our cold winter weather. These, on the other hand, have been used for 600 years and can always be restored.”

Balzer’s automatic-winding systems also do not damage or change the original clock movements or components, preserving the historical and horologic value of the timepiece.

© 2012 Penton Media, Inc.

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