After 1850, an idea of using a water cushion and then air cushion in railway transport came into being. The invention of such an application of a water cushion is attributed to François Louis Girard, a Frenchman who had been educated as a ... plumber! He was the first to consider the use of a water cushion instead of wheels in a vehicle, in 1852. Girard's idea inspired A. Barré, who in 1862 initially used an air cushion, and when the project failed, he switched to a water cushion. He presented a self-designed vehicle on a water cushion in 1869 at an exhibition in Paris. In the early 20th century many engineers revived the idea of using a cushion as a bearing system. One of them was a Frenchman Charles Theryc who used a thin layer of air (so-called film) pumped by a com-pressor in between the vehicle and smooth con-crete surface.
Research into ground effect trains was carried out both in the United States, Japan, United Kingdom and France. Various technologies were applied – starting with a pressurised air cushion, suction air cushion or magnetic cushion. 3 systems of pressurized cushions in use were:
• Laminar film – created by the flow of air under the pressure of 70-300 G/cm2 through a 0.2-1 mm fissure between the rail and the nozzle. It requires a precise nozzle and a smooth rail with minimum tolerance. Such vehicles, called a “Levacar”, developing up to 249 mph (400 km/h) during test rides, were manufactured by Ford.
• Plenum chamber – less efficient but has a simpler design, required a pressure of approx. 40 kG/cm2 and a 10-20 mm fissure. The system was used by the engineer Bertin in aerotrains.
• Annular jet nozzle – requires pressure of 70-140 kG/cm2 and a 10-25 mm fissure. It is more efficient. Used in tracked hovercraft, hovair, and hovertrain.
The apparent benefits offered by the air cushion technology include: lack of rotary motion equipment, transmission gears and bearings, and shock absorption units and spring rigging, combined with the elimination of friction producing motion, as a result of which energy is not lost. Unfortunately, excessive costs of construction imposed a limitation on the performance of such projects.