Complex sentence: Production of SAT grew heavily in 1950s and 1960s; the volumes quadrupled to 800 vehicles per year durng 1950s and in addition to lorries and bus chassises the company also produced trams and rail vehicles to the Finnish State Railways.
Split into simpler sentences: Production of SAT grew strongly in 1950s and 1960s; the volumes quadrupled to 800 vehicles per year during 1950s. In addition to producing lorries and bus chassis, the company provided trams and rail vehicles to the Finnish State Railways.