handle storage case 42 is fixed to the rear end of a cylindrical portion 44 a an inward projection 44 c is provided at the front end of the cylindrical portion 44 a in a handle 44 the inward projection 44 c is used as an operating portion 44 d the front end of the cylindrical portion 44 a faces an opening 41 the rear end portion 44 b can be slightly tilted from a rest position where it contacts the rear wall of the handle storage case 42 in the middle of the rear surface of the rear end portion 44 b one end of a wire 46 is mounted through an opening 45 in the middle of the handle storage case 42 the other end of the wire 46 is coupled to the middle of a turning latch 47 the latch 47 is able to turn between a rest position in fig1 and a working position in fig1 and is urged toward the rest position by urging means not shown in the embodiment the wire 46 connects the handle 44 to the latch 47 when the handle 44 is tilted in any direction from the rest position the wire 46 is pulled to.