Manufacturer of small auxiliary groups such as the compressor with mono-cylindrical engine in vertical position. It's the RB model.

“Garelli RB”

-The horizontal cylinder is the compressor driven by the engine crankshaft.

-Under the floor, we see the handle of the puller starter.

-New view of the APP engine or Auxiliary Power Plant on board (APU is for auxiliary ground equipment, generally, "Auxiliary Power Unit").

-The vertical cylinder is the gasoline engine and the horizontal one is the compressor, necessary for the start of the main engines and sometimes for brakes and wheels, etc.

“Aviocompressore Garelli”

-The mechanics and maintenance technicians of aircraft must be instructed in all the engines that are carried on board, including the auxiliaries.

-That is why APUs and APPs appear in this text. And the reason for the installation of this Garelli on board is because the main engine requires an air-starting system, with air that will be provided by this group.

"Distributor and discharge valve"

-The distributor is synchronized with the engine, sending the air to the corresponding cylinder. This distributor works as if it were the distributor of a "Delco" sending air at the time the ignition triggers the spark plugs, but for more time to push the piston in its stroke (followed in the same order of ignition on the other cylinders) and produce the rotation of the engine until the mixture provided by the carburetor arrives and the autonomous running occurs. Moment when the starting air is closed.

-The discharge valve is usually automatic with a spring.