The basic constructive element of the elastic machines and mechanisms is a toroidally shaped pressurized elastic shell – collectively called elastic toroids. The simple toroid can be created from a piece of a flexible hose by connecting the ends of the hose inside the hose or by inverting a tore made from a flexible, elastic material (See Picture 1).

Picture 1 Inversion: from torus/tore to toroid
A. Non-elastic torus does not create a toroid. B and C. Inverted elastic torus create toroid.

There are single-component (single-cavity or single-chamber) or multi-component (multi-cavity or multi-chamber) elastic toroids.
The basic attribute of an elastic toroid is its ability to translate forward along the lengthwise direction when specific forces are applied. The working surfaces of the elastic toroid are in a specific way kinematically connected with central bodies and/or external and/or internal peripheral bodies that originate the inversion of the toroidal shell and thus make elastic toroid enveloping the space along its path and move forward (See Picture 2)

Picture 2 Complex Toroidal Device
1 - 3 - Elastic Toroidal Shell with Working/Fluid Medium – Elastic toroid: 1 – Central part (Pinc), 2 - Peripheral part (Brown), 3 – Working medium (Pt).
4 - Internal peripheral body, 5 - External peripheral body, 6 - Central body, 7 – Obstacle, 8 - Curved line (oval) of Elastic Toroid’s Inflection, 9 - Elastic Toroid’s Master End Face with Funnel+-Predictor (P+), 10 - Elastic Toroid’s Driven End Face with Funnel—-Corrector (P-), 11 – Folds, 12 – “Running” Curling, Twisting/Winding, 13 – Cylindrical/Conical “Well”

Toroids have no less than five degrees of freedom. The elastic toroid can provide a vast controlled contact area and small specific pressure over the bearing surface with low pressure of the fluid medium in the shell. The elastic toroid can also move in the crosswise direction simply by rolling. For a toroid to function as intended, the toroid materials must be impermeable, strong and elastic and at the same time thin and lightweight.