<p>The device (1) has a frame comprising a telescopic bar (3) whose free ends (4) is provided with a blocking unit (5) for blocking the device by pressing against vertical uprights of splay. The blocking unit has a front stop (6) and a rear stop (7) separated from each other to support on both sides of the upright and to ensure blocking of the device under the effect of its weight across the center of gravity of-centered from a side of one of the stops. Adjustment unit adjusts spacing between the stops. Gripping units i.e. handles (9), are connected to the bar and/or the blocking unit.</p>
