No American built tanks ever saw service in the Great War, but big efforts were made in the USA to develop these new types of vehicles - quite apart from the British and French designs the Americans themselves were using on the Western Front. The first tank built in the USA was the so called Holt Gas-Electric, an effort by the Holt Tractor Co. of Peoria, Illinois.
Like the French St Chamond, it had a combined petrol-electric propulsion. Hence the name: gas (i.e. petrol) electric. A Holt 90 h.p. 4-cylinder motor produced power for a G.E.C. generator, which in its turn provided current to drive two electric motors, one motor for each track. (The electrical units were built and supplied by the General Electric Co.) Special attention was paid to ventilation and engine cooling, using a forced water cooling system with a radiator placed immediately above the generator. Air was drawn in through a louvre above the engine and foul air was emitted through big louvres in the left hull rear.
The rear drive sprockets were driven from these electric motors by a worm gear to a roller pinion which meshed with the sprocket. Steering was achieved mainly by varying the current to the respective electric motors. When sharp turns were needed this could be effected by braking the drive shaft on the side of the turn. Track and suspension was of the standard Holt type with two sprung bogies, each with six rollers, on each side, covered with light steel plates.
The engine, generator, and drive units were all at the rear of the vehicle leaving the roomy box-like fighting compartment free for the armament. (The exit and entry door was also placed at the rear.) The main armament was a 75mm Vickers mountain howitzer, which was placed low down in the V-shaped nose. The secondary armament consisted of two Browning 0.30in machine guns in sponsons on each side. The tank was to be serviced by a crew of six men.
Only one prototype was built of the Holt Gas-Electric Tank, and work on the vehicle was abandoned after tests. One of the problems with the tank was its weight: because of the rather complex propulsion and transmission systems this had been pushed up to some 25 tons, which in its turn lowered the speed to some 9 km/h. The use of unaltered Holt suspension probably limited the trench crossing ability compared to rhomboid style tracks.
| Motor | Holt 90 hp (67.1 kW) petrol engine |
| Maximum speed | 9.6 kph |
| Weight | 25,402 kg |
| Dimensions | 5.03m L x 2.37m H x 2.76m W |
| Main Armament | 1 x 75mm Vickers Mountain Gun |
| Secondary Armament | 2 x 0.30in MGs |
| Max. Armour | 15mm |
| Min. Armour | 6mm |
To tell you the truth: you can’t. Not if by modelling you mean buying a kit in plastic or resin or white metal and putting it together. Because there exists no kits of this AFV. You will have to scratchbuild it yourself.