Abstract: A wiping device for windows of power vehicles comprises a wiper arm, and a unit for changing an abutment force of the wiper arm. The unit includes a wiper shaft, one part of the wiper arm being mounted in the wiper shaft while another part of the wiper arm being hingedly connected with the one part of the wiper arm, a wiping element arranged on a free end of the other part of the wiper arm, a pulling spring loading the wiper element toward a window of a power vehicle. A unit is provided for changing a pretensioning of the pulling spring and includes two hinge rods hingedly connected in their coupling point on an axle, while another end of a first one of the hinge rods is turnable about a fixed axle and another end of a second one of the hinge rods is displaceable by a force in direction to the fixed axle of the first hinge rod. The pulling spring has an end which is spaced from the wiping element and suspended on the axis of the coupling point.