against which the wire 6 can bear an arcurate slot 33 is formed in the member 32 and receives a bolt 34 which is fixed to the bracket 30 the member 32 is adjusted by pivoting about pin 31 to take up the slack in wire 6 and properly tension it and then is fixed in this adjusted position by tightening the bolt 34 in accordance with the invention an auxiliary mechanism integrated with the wire driving mechanism 12 assists in raising the window 11 and resists its lowering as embodied herein the auxiliary mechanism includes a torsion spring 29 having an inner end 29a inserted in a slot 22b formed in the end of shaft 22 and an outer end 29b which engages a flange 18a formed on case 18 the spring 29 is wound in a direction so that when the handle 15 and pulley 16 are turned in a clockwise direction as seen in fig1 to lower the window 11 the spring 29 is wound to a tightened or compressed condition the spring 29 therefore serves as a resistance to the dead weight of the window 11 and to rotation of the pulley 16 and prevents the window 11 from sudden lowering when.