and 109 for the stationary switch part 111 of a contactless or proximity switch device 110 the movable switch part 112 of whic is in the form of a metal plate introduced into the free end 104 of each hood 105 and secured there the stationary switch part 111 is secured to one leg of an angle element 113 the other leg of which at right angles to it is secured to a retainer plate 114 in the recess 115 thereof the retainer plate 114 is screwed to the underside of the additional profile element 51 or to its hollow securing profile 91 and to the end of the hollow profile 93 the relative position of the switch parts 111 and 112 for each of the transparent hoods 105 of the protective cover 18 is such that when one of the hooks 105 is opened a switching event is triggered which either shifts the carriage apparatus 24 down to a crawl or stops it completely it will be understood that the length of the switch parts is much less than that of the hoods two light emitting diodes 116 for example are introduced into the wall or screen 101 of the additional profile element 51 such that they are visible from the outside these indicate whether the hood or hoods are open or closed as shown in fig4 the spool table 12 is connected to the angle bars 27 on the ends and possible partly at the middle via the securing profiles 63 81 and 91 with the retainer plate 114 located between them a stationary rail 41 is secured in each of the securing grooves 67 69 of the individual profile elements 46 48 and 50 preferably extending obliquely to them but extending from back.