Complex sentence: The largest bells weigh several tons such as the Liberty Bell and Big Ben and are meant to be sounded by swinging only the clapper instead of the entire bell as swinging such large bells would cause structural problems for the towers they are housed in.
Split into simpler sentences: The largest bells weigh several tons, such as the Liberty Bell and Big Ben, and are meant to be rung by swinging the clapper instead of the entire bell. Swinging large bells would potentially cause structural problems for the towers they are housed in.