Flat-track unit for motor vehicle test beds

A flat-track unit for motor vehicle test beds, comprising:

• a roadway-simulating belt which is guided over two rollers for accommodating a vehicle wheel on a top on its upper side;
• the top of the upper side of the belt is orientated roughly horizontally at ground level and is supported in a sliding or rolling manner at a wheel contact region by a supporting shoe;
• the two rollers are mounted in a frame which is supported in a vertically floating manner and is mechanically guided in the vertical direction;
• excitement means are provided to develop vertical oscillations in the frame;
• the excitement means including a vertically orientated hydraulic cylinder and a cylinder housing locating roughly in line with wheel contact region;
• one of the two rollers is connected via a universal-joint shaft to a drive and braking unit which is arranged to be vertically immovable and is spaced at a distance from the frame;
• the drive and breaking unit is provided with an output shaft which is aligned with a roller axis of the one roller;
• wherein the hydraulic cylinder of the excitement means is firmly secured on a foundation to resist tilting and rotation and has a piston and piston rod rigidly connected to the frame in terms of rotation and tilting to act as a mechanical vertical guide for the frame;
• said piston being rotatable together with the cylinder housing forming a pivot bearing for pivoting the frame about a vertical axis;
• a pivot drive means for pivoting the piston rod and its rigidly connected frame about the vertical axis;
• wherein said universal-joint shaft between the one roller and the drive and braking unit is provided with length-compensation means having a diameter corresponding to a multiple of the diameter of corresponding to a multiple of the diameter of the universal-joint shaft;
• wherein the drive and braking unit is attached to a drivable slide which is displaceable along a circular arc-shaped horizontal guide running concentrically to the vertical axis;
• and wherein there is
• a drivable slide means for displacing the drivable slide as a function of a deflection angle of the universal-joint shaft to position the universal-joint shaft into a straightened position between the drivable slide an the one roller.