pin joint hole 74 the hollow tubular member has a splined portion in the interior thereof which engages splined portion 68 of shaft 66 in the embodiment illustrated in fig3 the rotary shaft 66 is locked against longitudinal movement in hollow tubular member 79 by a transversely extending roll pin 73a which is disposed in a transversely extending cavity 73 in member 79 roll pin 73a passes through a complimentary shaped transversely extending cutout portion 67 in rotary shaft 66 which cutout portion 67 is aligned with cavity 73 the second link member 72 comprises a main plate 75 and a rib 76 projecting in a lateral direction the rib 76 has a substantially l shaped form and a substantially l shaped cross section and functions as a reinforcing member the second link member 72 has an end 72a having a clevice like form provided with a pin joint hole 77 by aligning this pin joint hole 77 with the pin joint hole 74 of the first link member 71 and then inserting a pin 78 through the holes 77 and 74 the first link member 71 and the second link member 72 are rotatably joined together the second link member 72 is provided with joint means at the free end thereof for attachment to attaching means 80 fixed to window glass pane 3 the attaching means 80 comprise in the embodiment illustrated a mounting bracket comprised of a bracket arm 83 and bracket plate 82 attached to window glass pane 3 the joint means may as illustrated be ball joint means comprising a ball joint 81 pivotally inserted into a socket of attaching means 80 in operation rotation of rotary shaft 66 in one.