Puffing Billy incorporated a number of novel features, patented by Hedley, which were to prove important to the development of locomotives.
It had two vertical cylinders on either side of the boiler, and partly enclosed by it, and drove a single crankshaft beneath the frames, from which gears drove and also coupled the wheels allowing better traction.

The engine had a number of serious technical limitations.
Running on cast-iron wagonway plates, its eight-ton weight was too heavy and broke them, encouraging opponents of locomotive traction to criticise the innovation.
This problem was alleviated by redesigning the engine with four axles so that the weight was spread more evenly.
The engine was eventually rebuilt as a four-wheeler when improved edge rails track was introduced around 1830.
It was not particularly fast, being capable of no more than 5 mph (8 km/h).
Puffing Billy incorporated a number of novel features, patented by Hedley, which were to prove important to the development of locomotives. It had two vertical cylinders on either side of the boiler, and partly enclosed by it, and drove a single crankshaft beneath the frames, from which gears drove and also coupled the wheels allowing better traction.
The engine had a number of serious technical limitations. Running on cast-iron wagonway plates, its eight-ton weight was too heavy and broke them, encouraging opponents of locomotive traction to criticise the innovation. This problem was alleviated by redesigning the engine with four axles so that the weight was spread more evenly. The engine was eventually rebuilt as a four-wheeler when improved edge rails track was introduced around 1830. It was not particularly fast, being capable of no more than 5 mph (8 km/h).
Puffing Billy (locomotive)