Abstract: A sheet transport system (20) comprising at least one sheet transporter (30,36) that receives and hands off a sheet being transported by the system so as to transport the sheet from a first position to a second position, wherein the at least one transporter (30,36) comprises at least one orifice (44) through which air is aspirated to create a vacuum that grips a sheet when it is received by the transporter (30,36); a vacuum system coupled to the at least one orifice (44) controllable to aspirate air through the at least one orifice (44) to grip the sheet; at least one vacuum sensor (60) that generates signals responsive to magnitude of vacuum of the at least one orifice (44); and a controller (49) that receives the signals generated by the at least one vacuum sensor (60) and provides a signal indicative of a location of the sheet in the transport system (20) from the signals.