A large trolley is likely to have had a headboard with the driver's seat on it, as on a lorry but a smaller trolley may have had a box at the front of the deck or the driver seated on a corner of the deck and his feet on a shaft.
They were normally drawn by a single pony or horse but a large trolley would have a pair.
It was primarily an urban vehicle so that, on the paved roads, the small wheels were not a handicap.
The deck was at a good height for taking the bags onto the coalman's back and there was no protruding rear wheel to obstruct his access to them.
Many ended up with rag and bone merchants who were likely to add side and tail boards to keep their purchases aboard.