caption: The image shows a black and white photo of a machine with gears, which appears to be a synchronous converter. The machine is composed of several metal components, including a gear wheel, a shaft, and several gears, all connected together to form a complex system. The gears are arranged in a circular pattern, with the shaft at the top and the gears at the bottom. The shaft is connected to the machine by a series of wires and cables, and the machine is surrounded by a metal frame.