A wheel unit mountable on a ski of a ski-mounted vehicle includes an
actuating plate defining a wheel attachment section and a piston
attachment section The actuating plate is pivotally attached to the ski
intermediate the wheel and piston attachment sections for pivotal
movement about a plate pivotal axis. A wheel attachment assembly is
provided for rotatably attaching the wheel to the wheel attachment
section. An actuator is operatively coupled to the actuating plate for
selectively pivoting the actuating plate about the plate pivotal axis
between a plate deployed configuration and a plate retracted
configuration wherein in the plate deployed configuration the position of
the actuating plate is such that the wheel protrudes at least partially
below the ski gliding surface for engaging the ground surface and in the
plate retracted configuration the position of the actuating plate is such
that the wheel is retracted above the ski gliding surface for preventing
the wheel from engaging the ground surface. A plate transversal moving
assembly is operatively coupled to the actuating plate for selectively
moving the actuating plate substantially transversally relative to the
ski.