It took me a while work out what this series of Dad's old snaps were (from negatives), seemingly all taken on the same day, suggesting it was something all a bit new and fascinating. I could be wrong, but it looks like charcoal-making.
At a time when petrol came only in 4 gallon drums on the train from Pt Lincoln, and supply was expensive and uncertain, many resorted to fitting their cars, but especially the trucks, with "gas producers", those big drum things that hung on the side and turned charcoal into a gas that was combustible enough to power those old low-compression engines.