Reference post 46: compressed air is a means of storing and moving energy. A M816 has an engine driven air compressor, a governor to control it, a reservoir to store air which must be drained after use to expel moisture, valves to control the windshield wipers, pressure switches for the low air alarm and the brake lights, an air operated mechanism to operate the clutch from the power divider location under the crane, and a hydrovac which acts as a brake booster for the hydraulic brake system. The principle maintenance activity at the operator level is to detect and correct leaks. The banging noise that comes and goes when the engine is running may be the air compressor operating as it does not operate continuously.
Transmission does not go into 4th or fifth gear ? When the truck is standing still or moving ?