TM 9-2320-361-10 1-31. AIR-HYDRAULIC BRAKE SYSTEM OPERATION The air-hydraulic’ brake system of the M44A2 series vehicles uses compressed air to assist operation of the hydraulic brakes by pressurizing hydraulic fluid, The system includes the following major components: AIR COMPRESSOR — Supplies compressed air to air reservoirs, air hydraulic brake system, trailer brake couplings, and windshield wiper motors. BRAKE PEDAL — Activates air-hydraulic brake system. TRAILER BRAKE COUPLINGS — Allow vehicle and trailer brake systems to work together when connected to a trailer. AIR RESERVOIRS — Store enough air pressure for normal brake operation if main brake system fails or engine stalls. When air pressure in reservoirs is low, a warning buzzer will sound in the driver’s compartment. AIR RESERVOIR DRAINCOCKS — Permits draining of excess moisture and air from air reservoirs. 1-24