The Bolton Mill Engine is a horizontal single cylinder slide valve unit. Crankshaft, eccentric and big end bearings are of sealed ball type, concealed to look like plain bearings, but giving long life and zero maintenance. A boiler feed pump and steam lubricator are fitted, together with belt driven dynamo with voltage regulator and lamp standard. Other features are a dummy, but fully operational, ball governor and adjustable load damper, together with cylinder and steam chest drain, valves and sump.