US Patent 9991143 Carrier transport system and transport method

Carriers to be temporarily stored are increased in number, without providing a local vehicle with a lateral transfer mechanism. Carriers are transported between load ports of equipment by overhead travelling vehicles and local vehicles, both provided with a hoist, and the overhead travelling vehicles are provided with a lateral transfer mechanism for laterally moving the hoist. A travelling rail for the overhead travelling vehicles is provided so as to pass over a load port, and a travelling rail for the local vehicle is provided below the travelling rail for the overhead travelling vehicles and over the load port. Slidable buffers are provided and configured to slide between forward positions under the travelling rail for the local vehicle and rearward positions laterally separated from the positions under the travelling rail for the local vehicle. A space over the slidable buffers at the rearward position is open for the transfer of carriers.