TM9-2320-361-10 2-5. BODY EQUIPMENT CONTROLS AND INDICATORS (Contd) c. Key 1 2 3 4 5 6 7 Tractor Truck (M275A2). Item and Function Airbrake Hand Control Lever is moved down (on) to charge semitrailer airbrake system. Fifth Wheel Operating Handle is pulled forward to unlock jaws and separate semitrailer from tractor. Electric Cable and Connector is connected to semitrailer electrical receptacle to provide electrical power to semitrailer. Emergency Airbrake Hose Line and Coupling connects to emergency airbrake coupling on right front side of trailer. The trailer emergency brake system is activated when air system fails. Airbrake Hose Coupling Shutoff Cocks are turned down (on) to allow air to enter semitrailer brake system, and must be turned off when trailer is uncoupled. Service Airbrake Line and Coupling is connected to service airbrake receptacle in left front side of trailer to provide air to semitrailer service airbrake system. Safety Latch assures positive locking of fifth wheel jaws, and is swung to one side to move operating handle. 2-14