a centrifugal force and are brought into frictional contact with the inner peripheral surface of the cup 33 to apply the braking action in this case normally this braking force brakes the pivotable movement of the seat 2 but since the seat is being forcibly moved pivotably an overload is applied to the worm shaft 31 at this time the ratchet 34a rotating in a clockwise direction in fig8 is flexed so that the engagement between its engaging teeth 34b and the recesses 34c of the friction receiving member 34d is released so as to avoid the above overload one of the seat 2 and the lid 3 may be connected to either of the first and second input shafts 8 and 9 while the other is connected to the remaining input shaft however considering the transmitting force of the clutches it is preferred that the pivotable member of a greater mass i e the seat 2 in the illustrated embodiment be connected to the outer shaft of the double shaft construction i e the second input shaft 9 another example of the one way transmission clutch now will be described with reference to fig3 and 37 first and second input.