It is driven via a four-bar linkage: blue lever, pink conrod and grey crank. Way to overcome dead point at start: turn the right rear wheel.
Violet steering wheel controls front wheel via spatial four-bar linkages. Orange conrods have spherical joints at their ends. Centers of lower joints must be laid on axis of the revolution joint between the blue lever and the frame to eliminate angular oscillation of the green fork.
In fact one conrod is needed only. Two conrods help reducing their longitudinal compression but cause over constraint that is eliminated thanks to gaps in the joints and flexible deformations of the conrods.
Advantage: Propelling and turning the tricycle just by moving the violet wheel.
Disadvantage: there is small angular oscillation of the green fork when the tricycle is turning.
The tricycle goes straight on if the front wheel is kept straight. So the driver has to bear some torque from the front wheel.
This type of tricycles is used popularly in Vietnam for invalids. See:
Link for downloading STEP files of this video:
Inventor files:
