About The Tank
This is a model of the Mark IV Tank as used by the British Army during the latter stages of the First World War. The model is built to approximately 1/16th scale, as dictated by the Meccano plastic tracks. The Haynes Manual 'Great War Tank' (ISBN-978-0-85733-242-4) was also used as an excellent reference, as it includes many photographs and copies of original drawings.
The drive set-up is similar to the real tank, with a short chain drive from the rear track drive sprockets to twin 2 speed gearboxes (one for each track). Restricted space means the 2:1 ratio is hidden underneath each track, the 3:1 ratio is inside the main frame. The 2 speeds (and neutral) are selected via a small lever at the back of each sponson. The individual track drives are then joined via a spur differential, which is connected to a 125rpm geared motor via a 2.5:1 Helical Gear pair. The motor is powered by a stack of 4 AA cells giving 6 volts.
The tank moves quite slowly, as it weighs just over 3kg, and is rather hampered by a lack of grip on the plastic tracks!
Picture below is of the rear part of the tank, with the covers removed, looking down.