This is a Tasker and Sons B2 'Little Giant' steam road tractor traction engine, on display at Milestones Museum, Basingstoke along with two complete 'Little Giant' tractors. It was built as works number 1643 in 1915 for a customer by the name of House in Gosport, and what you see here are all that remains of this tractor, however does help show how a traction engine works.
Firebox, boiler and smokebox. The firebox, on the lower left, is where coal is put in and lit, the fire heating the water inside the boiler, in the centre. The tubes running through the boiler spread the heat along the entire boiler, the smoke from the firebox and tubes coming out in the smokebox where it escapes up the chimney (at the top right is the chimney base). The smokebox door at the front allows access to clean the smokebox.
Cylinder and motion works - a lever at the driver's position, which would be near the firebox, moves a valve which regulates the amount of steam allowed into the cylinder (on the left) which moves backwards and forwards, producing power via the pistons which moves the engine or rotates the flywheel which would be attached on the right which could power stationary machinery.
Rear axle - the motion work links to the rear axle by gears and levers which moves the rear wheels of the engine, the different gears regulating the speed and direction of the engine.