Wheeled vehicle adapted to turn on the spot

A vehicle comprising:

• a load-carrying body;
• a base provided with at least three swivelable support wheels angularly spaced about a vertical axis, said body having a shaft in line with said axis journaled in said base;
• a central guide wheel mounted on the lower end of said shaft for rotation in a vertical plane having an invariable orientation with reference to said body;
• steering means for rotating said body relatively to said base about said axis;
• drive means coupled with said drive wheel for propelling said base over said surface in a direction determined by the orientation of said guide wheel;
• cushioning means in said base supporting said body while letting said guide wheel come to rest on said surface with sufficient force to exert traction at least under load;
• and
• a linkage positively interconnecting all said wheels for swiveling parallel to one another.

A vehicle comprising:

• a load-carrying body;
• a base provided with at least three swivelable support wheels angularly spaced about a vertical axis, said body having a shaft in line with said axis journaled in said base;
• a central guide wheel mounted on the lower end of said shaft for rotation in a vertical plane having an invariable orientation with reference to said body;
• steering means for rotating said body relatively to said base about said axis;
• drive means coupled with said guide wheel for propelling said base over said surface in a direction determined by the orientation of said guide wheel;
• a coil spring on said base surrounding said shaft and supporting said body while letting said guide wheel come to rest on said surface with sufficient force to exert traction at least under load;
• and
• adjusting means for varying the upward force exerted by said coil spring upon said body, said adjusting means including a threaded bushing screwed into said base and traversed by said shaft, said spring bearing upon said bushing.