Device for testing tyres for vehicles

A device for testing vehicle tyres comprising frame means, means supported by said frame means and defining a track, means for driving said track for movement along a given direction relative to said frame means, carriage means supported by said frame means, means slidably interconnecting said carriage means and said frame means for movement of said carriage means along a direction transverse to said given direction and extending towards and away from said track, means for freely rotatably supporting a wheel and tyre combination on said carriage with said tyre in rolling contact with said track, said wheel supporting means including a wheel hub pivotable about two directions extending perpendicular to the axis of symmetry of said hub for orienting the wheel at an angle of lock .alpha. and a camber angle .beta. relative to said track, and means for driving said carriage for sliding movement along said transverse direction towards and away from said track, said carriage driving means comprising connecting rod means connected at one end to the carriage, a load-varying device connected at the other end of said connecting rod means, a mobile platform supporting said load-varying device, rails movably supporting said mobile platform, support frame means carrying said rails, elastic mounting means connecting said rails to said support frame means, control screw transmission means connecting said mobile platform to the support frame means, jack means having a jack piston rod in contact with said mobile platform and a jack cylinder engaging said support frame means, flat slide-bar means formed on said mobile platform and mounted for sliding movement adjacent said support frame means, and immobilising jack means firmly attached to the fixed support frame means and acting in opposition to the elastic mounting means, said immobilising jack means having pistons arranged to move slidably towards and away from said mobile platform.