Complex sentence: In the 19th century, as well as ironforging, the business produced axles for horse-drawn vehicles; as motor vehicles became more common, in the early 20th century, the forge had departments specialising in motor vehicle axles and in steel bar.
Split into simpler sentences: In the 19th century, as well as ironforging, the business produced axles for horse-drawn vehicles. As motor vehicles became more common, in the early 20th century, the forge specialised in motor vehicle axles and in steel bar.