4800/4900/6900 Airline Numbering Circuits 1 to 100 Airline Number System The WST air system assigns separate line numbers for each connection line in the air system design. Most air lines are black but some air lines have been assigned colors and sizes for some common routing and as such the colored air lines will have no number labels. Where a black line is used number labels are used to identify which lines go to different places on the chassis these numbers correspond to the circuit numbers in the schematic drawings.
All black and wire braid lines connecting to the cab will be labeled with a line number on both the cab sides and the chassis line in an area where no paint or over spray will cover them up .
Color designated Lines will not have line numbers see color/size column for more information Airline numbers on black lines Under cab line connections Additional air line ports are provided for easy addition of body builder controls Cab pass through manifold located behind driver side dead pedal Page 1A-20 Rev (2.3) - Feb 2015 Airline Color/Size Airline Number Airline Number Description 1 (BC Air only) - air compressor to wet tank 2 (BC Air only) - wet tank supply to dry tanks 3 Wet tank drain to moisture ejector 4 Governor signal to moisture ejector 5 (BC Air only) - dry tank ‘C’ to governor 6 Dry air supply to relay valve 7 (BC Air only) - cab manifold supply - wet 8 Dry tank supply to emergency tank 9 Transmission supply 10 Emergency tank supply to park valve 11 (BC Air only) - control forward rear axle relay valve 12 (BC Air only) - brake valve supply to front chamber 13 (BC Air only) - front axle quick release valve supply to frame 14 Supply - deep reduction control 15 Trailer service 16 Trailer emergency 17 (BC Air only) - forward rear axle tee supply to service chamber 18 (BC Air only) - relay valve supply to rear axle quick release valve 19 (BC Air only) - rear-rear axle tee supply to service chamber 20 (BC Air only) - cab manifold to control valve - dry 21 (BC Air only) - hand control valve to trailer service 22 (BC Air only) - tractor protection control supply to trailer emergency 23 (BC Air only) - park control supply to frame tee 24 (BC Air only) - quick release valve to park brake chamber 25 Differential lock-out control supply to axle White 25A Differential lock-out control supply to axle Airline Color/Size Airline Number Airline Number Description 51 (BC Air only) - rear brake application gauge supply 52 (BC Air only) - dump valve to low pressure governor 53 (BC Air only) - relay valve to axle tee service brake 54 (BC Air only) - supply - dry air tank ‘C’ to forward rear axle relay 55 (BC Air only) - supply - dry air tank ‘B’ to rear-rear axle relay valve 56 (BC Air only) - control front brake relay valve 57 (BC Air only) - supply front brake relay valve 58 (BC Air only) - front brake relay valve to limit quick release valve 59 Differential lock-out supply - wet air 60 (BC Air only) - dry tank ‘C’ supply to double check valve 61 (BC Air only) - park brake control ‘D’ to pressure holding valve 62 (BC Air only) - park brake control ‘D’ to tractor park brake control 63 (BC Air only) - dry tank ‘B’ supply to brake valve 64 (BC Air only) - control rear-rear axle relay 65 (BC Air only) - front axle drop lines to brake chambers 66 (BC Air only) - supply to reservoir gauge & wig wag 67 (BC Air only) - supply to front brake application gauge 68 (BC Air only) - pressure holding valve to tractor protection valve ‘S’ 69 Not yet assigned 70 Not yet assigned 71 Not yet assigned 72 Not yet assigned 73 Not yet assigned 74 Not yet assigned 75 Not yet assigned Airline Color/Size Airline Number Airline Number Description 26 Deep reduction control supply to transmission 27 Front brake limiting control to limiting valve 28 Supply to fifth wheel lock 29 Supply to air shift 2-speed axle 30 Supply to air seat 31 Supply to windshield wiper 32 Supply to air horn 33 Supply to reservoir pressure gauge 34 Supply to wig wag 35 Signal to stop lamp switch 36 (BC Air only) - rear axle wedge chamber to wedge chamber 37 Supply to front wheel limiting control 38 Not yet assigned 39 (BC Air only) - park brake drop lines 40 ‘C’ supply to pusher / tag relay valve 41 ‘B’ delivery to pusher / tag relay control 42 Not yet assigned 43 Not yet assigned 44 Not yet assigned 45 Not yet assigned 46 Not yet assigned 47 (BC Air only) - low pressure governor supply 48 (BC Air only) - emergency dump valve to tractor protection valve (BC Air only) - signal to trailer emergency pressure gauge 49 50 (BC Air only) - signal to trailer service gauge Airline Color/Size Airline Number Airline Number Description 76 Not yet assigned 77 Not yet assigned 78 Not yet assigned 79 Not yet assigned 80 Not yet assigned 81 Not yet assigned 82 Not yet assigned 83 Not yet assigned 84 Not yet assigned 85 Not yet assigned 86 Not yet assigned 87 Not yet assigned 88 Not yet assigned 89 Not yet assigned 90 Not yet assigned 91 Not yet assigned 92 Not yet assigned 93 Not yet assigned 94 Not yet assigned 95 Not yet assigned 96 Not yet assigned 97 Not yet assigned 98 Not yet assigned 99 100 Not yet assigned Compressor discharge