TABLES FOR СOMPARISON OF SPECIFICATIONS AND PARAMETERS OF TRACKS AND TESH GEARS. COLLATIONS AND CONCLUSIONS The all-terrain vehicles, where well-known tracks are used as support-running elements, which represent a system of wheel supports rotating inside a closed caterpillar tread (where the principle of a moving road is implemented), are most popular. The track vehicles can be maneuvered in two ways: (1) one of the tracks is stopped or slowed down, the other one beginning to rotate or continuing to rotate at a constant speed; (2) one of the tracks is reversed. The friction force, which is proportional to the area of the track contact with the surface and to the vehicle weight, resists rotation of the track. As a result, some energy consumed by the propulsion plant while maneuvering is wasted on destruction of the track, which changes its geometry and stretches. This is why tracks have to be entirely replaced after some time, when the vehicle has run some certain distance. By the way: During the Desert Storm operation in Iraq (1991) the NATO forces had to spend more than 23 million US dollars on replacement of worn-out tracks of combat and transport vehicles As far as a vehicle equipped with two TESH support-running elements is concerned, maneuvering can be done in one of the two ways as well, when either forward or back TESH gear is working in the worm mode, i.e. segments of the helical blade are turned so as to form a continuous helix. In case of a vehicle having two articulated semi-frames (coupled with a hinge) (YASHCHER System), trajectory of motion can change with the help of two hydraulic cylinders located on the sides of the articulating hitch. In case of a failure the articulating hitch is rigidly fixed, and the trajectory is changed with the help of the forward or the back TESH gear working in the worm mode. In this mode the area of contact of TESH segments with the surface, if it is a stable solid pavement, is much smaller than that of the tracks, resulting in lower power inputs required by a TESH vehicle for maneuvering. Only segment damper plates are worn out, but replacing them is not a problem. Since tracks are most often not protected from foreign objects like sand, stones, etc. getting into their working area, where support rollers contact the inner surface of the closed caterpillar tread, their reliability and durability are considerably decreased, while their resistance to rotation is increased, which results in higher fuel consumption. The transformable worm, like its predecessor, represents a barrel, all the mechanisms of which are covered, so that no foreign objects may get inside, and greased, which makes the whole system reliable and durable, and decreases rolling resistance to a comparatively low level. Owing to this a damaged TESH vehicle can be towed, unlike a damaged track vehicle. Changeable parameters of the support-running elements, a comparison of TRACKS and TESH: TRACKS TESH Caterpillar width Rotor width Support roller diametre Quantity of rotors (1, 2) Track spacing Quantity of turns in a helical blade --------------------------- Quantity of segments per 360° turn --------------------------- Monofilar and multifilar helix --------------------------- Segment height --------------------------- Frame type: solid frame or two semi-frames --------------------------- Rotors with mono-directional and opposite-directional helical blades fitted on the same frame --------------------------- Turning or retraction of the helical blade segments As it follows from Table 1, TESH concept has more changeable parameters than tracks have, which makes it more flexible and allows to use it wider than tracks. Comparison of Characteristics of ATV Systems:   TRACKS TESH Degrees of freedom 1 2 Maneuverability lower (it follows from the 1st line) higher Amphibian qualities lower high ("hollow" means "buoyant"!) Sailing qualities low (big draught) high (longitudinal cover plates can be used) Speed on the ground low higher (determined experimentally) Speed on the water 8-10 km/h higher (determined experimentally) Motion surface vulnerability high much lower (especially with retractable segments) Working capacity depends on the integrity of tracks being on the rollers depends on the drive performance only Cost of manufacturemuch lower much lower high (especially with retractable segments) Maintenance difficult (tracks tend to fall off the rollers and wear out) easy To improve amphibian qualities of the tracks they are made as low-pressure tyres, whose elastic light material is rather vulnerable. When they move on a surface with some regular contour, some vertical vibrations (heaving) appear in them, which may result in a turnover. Hence this solution has not been widespread. The cavities free of mechanisms can be filled with gas or a light water-resistant material like foam plastic to provide buoyancy for the transformable worms. As regards TESH with rotary segments, there is a vessel in the core of the barrel, into which compressed air can be supplied to prevent water from getting inside the barrel. There is a special cavity designed for the segment control mechanisms. These features provide proper buoyancy of the equipment without prejudice to its land-going capabilities. TESH does not need additional mechanisms, a screw propeller or a water jet propeller to move on the water and function as a paddle wheel and a water jet. As a result, the vehicle is easier and cheaper in manufacturing and maintenance. Comparing the parameters of tracks and those of TESH presented in Tables 1 and 2, one can see that TESH gear is much more attractive in all respects, except for the cost of its manufacture, which would be compensated quite soon due to its reliability, ruggedness and easy maintenance.