(DE4119722-A)      Composting bed unit has a first transverse bridge equipped with devices for spreading material in a first heap layer, a second transverse bridge which can travel along the length of the bed and which is equipped with displaceable devices for turning the material over to form progressively further heap layers, and a device for collecting and conveying material from the last heap layer.    (i) the first bridge can travel above or below the second bridge along the length of the bed and its devices are loaded from a conveyor running along the bed; (ii) the second bridge devices discharge material, via a second conveyor running along the second bridge onto the first conveyor; (iii) the first bridge devices are also used to spread the further heap layers in the travel direction of the first conveyor behind the second bridge devices; and (iv) the first conveyor also acts as the device for collecting and conveying material from the last heap layer.    ADVANTAGE -   The first layer spreading device of both units (A,B) can also be used for turning over the material so that variable turn-over times can be used for the layers, e.g. the first layer may be left for 2 weeks and then turned over each week.    (EP518135-A3)      Bed limit has a first transverse bridge equipped with devices for spreading material in a first heap layer, a second transverse bridge which can travel along the length of the bed and which is equipped with displaceable devices for turning the material over to form progressively further heap layers and a device for collecting and conveying material from the last heap layer.    The novelty is that (i) the first bridge can travel above or below the second bridge along the length of the bed and its devices are loaded from a conveyor running along the bed; (ii) the second bridge devices discharge material, via a second conveyor running along the second bridge onto the first conveyor; (iii) the first bridge devices are also used to spread the further heap layers in the travel direction of the first conveyor behind the second bridge devices; and (iv) the first conveyor also acts as the device for collecting and conveying material from the last heap layer.    ADVANTAGE -   The first layer spreading device of both units can also be used for turning over the material so that variable turn-over times can be used for the layers, e.g. the first layer may be left for three weeks and then turned over each week    (EP518135-B1)      A rectangular installation (1,2) for composting waste material laid out therein in transversely extending piles, having a device (11-13) for laying the material out in a first pile and in continuous additional piles, said device being arranged on a bridge (10) spanning the composting bed (2) and travelling longitudinally of the composting bed (2); a device (20,21) for taking up the material to transfer the same to the continuous additional piles and for taking up the material from its final pile for removal purposes, said device being arranged on a second bridge (19) spanning the composting bed (2) and travelling longitudinally of the composting bed (2), and said device (20,21) further being displaceable along the second bridge (19); with the first-given device (11-13) being loaded by a conveying means (4,7) running along the composting bed (2); and with the device (20,21) for taking up the material discharging the same onto the first-given conveying means (4) via a conveying means (20) running along said second bridge (19); characterised in that the first-given bridge (10) can be moved over or under the second bridge (19).