and formed continously with each other across a ridge a also there is defined a cutout hole 25 extending between the first finger contact face 23 and the second finger contact face 24 the clutch control member 8 is disposed inside this cutout hole 25 in such a manner that the recessed border between the forward control portion 81 and the reverse control portion 82 of the member 8 is located adjacent the ridge a of the bowl shaped cover 22 further at an intermediate position between the control portions 81 and 82 there is inserted a pivot shaft 83 supported adjacent the ridge a for vertically pivotably supporting the clutch control member 8 moreover the clutch control member 8 is pivotably supported to the second side frame 2 so that with depression of either of the control portions 81 and 82 the undepressed control portion 81 or 82 may project further outwardly from the cutout hole 25 through the cover 22 than the depressed control portion 82 or 81 that is to say the clutch control member 8 i e its control portions 81 and 82 pivot like a seesaw relative to the second side frame 2 also when the forward control portion 81 is depressed the reverse control portion 82 becomes substantially level with the.