The Bonnor–Swaminarayan solutions are boost-rotation symmetric space-times which describe
the motion of pairs of accelerating particles which are possibly connected to strings
(struts). In an explicit and unified form we present a generalised class of such solutions with
a few new observations. We then investigate the possible limits in which the accelerations
become unbounded. The resulting space-times represent spherical impulsive gravitational
waves with snapping or expanding cosmic strings. We also obtain an exact solution for a
snapping string of finite length.