TM9-2320-361-10 2-29. OPERATION OF TRACTOR AND FIFTH WHEEL (Contd) (11) Place service and emergency cutout cocks (2) in side-to-side position, to turn on air supply. (12) Set airbrake hand control lever (4) in down (on) position to check service airbrake system, Air should be heard passing through control vale. (13) Release parking brake lever (6), set airbrake hand centrol lever (4) in down (on) position, and slowly move tractor forward to get positive locking of semitrailer kingpin with fifth wheel. (14) Place transmission gearshift lever (5) in “N” (neutral) position, apply parking brake lever (6), and shut off engine (refer to para. 2-17). (15) Raise trailer landing gear (1). 2-138