of lever 12 has a bent shape and carries an acrylic cone 61 free end 13 of lever 12 may also be rectilinear lever 12 is in operative connection with a swiveling eccentric member 15 which is driven by a swiveling motor 14 the outer edge of eccentric member 15 may have a circumferentially extending groove in which the free end 13 of lever 12 may be guided if this free end has a round cross section current is supplied to swiveling motor 15 through a hanging line 22 hanging line 22 is fastened by means of a line fastening member 26 to plate 16 as fig2 further shows line 22 is tensioned by means of a roller 24 and a weight 25 line 22 is connected by means of a line fastening member 26 from which a supply cable 60 extends to the electrical control in the base upper cover plate 49 is attached to the upper end 34 of support rod 33 support member 31 for the lifting motor 29 is also attached to support rod 33 support rod 33 is connected to the output shaft 36 of a gear motor 35 which in turn is mounted on a stand 37 within base 43 stand 37 is mounted on a base plate 42 gear motor 35 includes a swivel limit switch 38 which can be switched from an actuating member 40 which is mounted on support rod 33 as a result the support rod 33 may be rotatable only about a certain angle for example an angle of 360 u00b0 support rod 33 extends through an opening 46 in cover 44 of base 43 opening 46 is arranged eccentrically relative to the base a wall 47 of.