For example, an elastic hose element (half-tore) pumped up with technological compressed air or an elastic tore located in a cylinder can play a role of a piston (like in a traditional piston machine) but, while moving within a cylinder and performing certain function, the hose-piston or tore-piston turn inside out and roll instead of sliding along the cylinder surface. In this case there is no sliding friction, which eliminates any lubrication. Besides, due to elasticity, the walls of the hose or tore, being pressed from inside with compressed air or liquid, adjoin tightly to the walls of the cylinder and copy its internal surface. Hence, there is no necessity in producing a regular geometrical shape and mechanical treatment (boring, grinding and polishing) of the internal surface of the cylinder, which decreases significantly cost of manufacturing and increases the range of piston machines both in diameter of the cylinder and in length of piston stroke.
Besides, in case of using an elastic tore as a piston moving a plunger rod, there is a possibility of two-fold decrease of the length of a cylinder relative to rod stroke (due to features of the tore).
Design of the torus with the central body ensures the movement of the central body at a double velocity compared to that of the tore relative to the bearing surface. It occurs due to the addition of two relative movements: that of the tore relative to the bearing surface and the simultaneous movement of the central body relative to the tore. Equal velocities of both movements result from the movement of the tore over the surfaces of the two bodies - the bearing surface (extermal tore surface) and the surface of the central body (internal tore surface). This feature can be used, for example, in designing speed multipliers.
As the mass (weight) of elastic hose-piston/ elastic tore-piston is less than that of conventional (metal) pistons, the inertial loads during reciprocaal motion of a piston are negligible as compared to traditional piston machines, which enables significant increase in the number of strokes per time unit, even at greater diameters and velocities of motion.A propulsor of a transport vehicle, made on the base of ELASTIC ENGENERING, will have the following features as compared to analogs (wheel, caterpillar):