Forecarriage of a rolling motor vehicle

Method of blocking rolling movements of a rolling motor vehicle with three or four wheels, having:

• a forecarriage frame,
• at least one pair of front wheels kinematically connected one to each other and to the forecarriage frame by means of a kinematic rolling mechanism which enables the front wheels to roll in a synchronous and specular manner, each front wheel being connected to said kinematic rolling mechanism by means of a respective axle journal, said axle journal being mechanically connected to a rotation pin of the front wheel in order to support said rotation pin rotatably around an axis of rotation,
• suspension means which provides each axle journal at least one spring suspension movement with respect to said kinematic rolling mechanism,
• said method comprising the following operating steps:
• a) providing a steering device that kinematically connects the axle journals one to each other in such a way as to command the rotation of the axle journals about respective steering axes of each front wheel, said steering device comprising a horizontal steering bar that directly connects the two axle journals with each other at two ends of said horizontal steering bar by means of hinging means, said horizontal steering bar being in turn hinged to a steering column at an intermediate point between said two ends so as to oscillate with respect to said steering column about a first rotation axis substantially orthogonal to a rolling plane of the two front wheels defined by said kinematic rolling mechanism,
• b) providing releasable means to reversibly block a lying position of said steering bar with respect to a vertical projection plane, which is transverse to a centreline plane of the motor vehicle,
• c) activating said releasable means in such a way that said steering bar is prevented from changing its lying position with respect to said vertical projection plane so as to constrain the relative position between the two axle journals, and thus block the rolling movements of the two front wheels;
• and
• d) deactivating said releasable means in such a way that said steering bar is free to change its lying position with respect to said vertical projection plane so as to passively follow the movements of said two front wheels with respect to each other and to the frame without interfering with said two front wheels except to control the steering and thus free the rolling movements of the two front wheels.