mode of operation may correspond to when the locomotive engine is shutdown and another source of power is used such as shore power as described above referring now to fig2 a a flowchart of one embodiment of the present invention is depicted when the diesel engine of the locomotive is running as at 210 the following logic would be used to govern the operation of the multiple air compressor system 100 at 220 based upon a time interval one compressor would be favored for operation over the other if air pressure remains above a predetermined amount at 230 one air compressor will continue to be used to satisfy the air demand if the system air pressure falls below the predetermined amount at 230 the control system 104 will energize both air compressors 102 to satisfy the air demand as at 240 once an air compressor 102 is energized it will be run until the temperature of air compressors oil 124 is at a predetermined level if the current locomotive air demand is satisfied the air compressor 102 will be run unloaded until the oil 124 reaches the predetermined temperature once the locomotive air demand is satisfied the energized air compressor s 102 will be unloaded for a predetermined time period during this predetermined time period air pressure throughout the system may be monitored by the control system 104 to determine if it is falling at a rate which would require an air compressor 102 to be reenergized within a determined interval of shutdown if this condition is met the energized air compressor s 102 will continue to operate in an unloaded state until the locomotive air demand necessitates further air pressure for.