Abstract: Tripping of the poles of a multi-pole breaker requires less force from current sensing actuators, through use of a lost motion linkage including a trip link which unlatches the linkage holding one pole contact set closed before operating the inter-pole tripping elements. Preferably the breaker has a fast forcing arrangement for forcing a movable contact open under short-circuit conditions, faster than the normal contact opening spring can respond. The lost motion linkage is provided by a trip link which first releases a secondary latch to permit contact opening at normal speed, and then operates an inter-pole tripping element. Under short-circuit conditions the trip link engages the movable contact to force it open, between unlatching and engagement of the inter-pole tripping element.

Abstract: A concrete slab structure for supporting railway track is itself resiliently supported on a base structure by a spring system comprising tubes secured against longitudinal movement in holes extending through the slab from its top surface to its bottom surface, springs each arranged in a respective one of the tubes and an adjustable spring abutment at the upper end of each of the tubes for pre-loading the springs against the base structure.