{Composite and multiple pendulums; Synchronisation of mechanical pendulums, e.g. electrical synchronisation [CPC: G04C3/025]; pendulum systems [CPC: G04C13/028]}
{Composite and multiple pendulums; Synchronisation of mechanical pendulums, e.g. electrical synchronisation [CPC: G04C3/025]; pendulum systems [CPC: G04C13/028]}