Pendulum motor for turret clock, 1936

In depth

This is the C40A ‘Waiting Train’ movement produced by electric clock manufacturers Gent of Leicester from c.1908. During this period, Gent successfully made and installed what they termed ‘mammoth clocks of British Empire’: electrically controlled dials in factories, railway stations and post offices, including the Singer Factory, Clydebank, Terry’s Chocolate Works in York, and, most famously, behind the four dials of the clock in the Royal Liver Building, Liverpool, installed in 1911. The ‘Waiting Train’ allowed these dials to expand significantly in size while still remaining electrically actuated, thus obviating the need for large weights and weekly winding.

Also referred to as a pendulum motor, the movement sits at the interface between the external dial and a controlling clock transmitting the time. It incorporates a Hipp Toggle (named for its nineteenth-century inventor, Matthaus Hipp – see TCW 1035) to impulse the pendulum whenever its arc decays, and thus ensure the hands on the external dial receive as much power as is required. In inclement weather conditions, for example, this requirement will increase, and the pendulum will be impulsed more frequently, with the driving force transmitted to the dial via a worm and wheel arrangement at the back of the clock.

Meanwhile, the eponymous ‘waiting train’ sits at the top left of the movement: a pin on a countwheel will automatically put the clock into ‘waiting mode’ at the end of each minute, until it receives the time impulse from the controlling clock. Since the Waiting Train itself is set to run slightly fast, this ensures consistent timekeeping.