Complex sentence: By the 1960's they were making Diesel electric cranes for British Railways and hydraulic cranes for the Admiralty, and for use on oil tankers, and dockside cranes for the Thames Conservancy.
Split into simpler sentences: By the 1960s they were making diesel-electric cranes for British Railways and hydraulic cranes for the Admiralty. Their cranes were used on oil tankers, and they sold dockside cranes for the Thames Conservancy.