Abstract: The present invention realizes a digital switching equipment provided with an extra PCM highway without an unnecessary increase in the capacity of the time division switch. A time division switch is provided with first PCM highways connected to all card slots and a second highway connected to a predetermined card slots. Each of all the card slots have a function of outputting first address setting signal signifying an initial time slot position of the card slots capable of using the first PCM highways. Each of the predetermined card slots, to which the second PCM highway is connected, has a function of outputting a second address setting signal signifying an initial time slot position of the card slots capable of the second PCM highway can use.

Abstract: A maintenance cart in a maintenance system is substituted for a material handling cart in a continuous train of material handling carts circulating on a closed track. The maintenance cart includes both inspection and cleaning functions which may be divided among separate maintenance carts, as desired. Inspection includes location sensing (preferably with a bar-code reader), inspection with one or more television-like cameras and clearance measurements. Cleaning functions include removal of dust and debris from a channel-like track by a vacuum arrangement. The maintenance cart or carts may be continuously left in place or substitute as needed in the train and provide continuous cleaning service and system diagnostics for scheduling repairs prior to failure while in use. The system is particularly advantageous for application to mail sorting systems which are largely unaccessible and which permit only brief time windows during which maintenance, repair and inspection can otherwise be carried out.