MAIN ROTOR DRIVE SYSTEM – GENERAL
The Main Rotor Drive System transmits and decreases the rotational drive
from the engines to the Main Rotor. The Main Rotor Drive System
comprises:
• the Main Gear Box (MGB);
• two engine gearbox couplings;
• two input modules;
• the engine couplings;
• the freewheels.
The MGB reduce the rotational speed between the input and output drive.
The MGB has a self-contained lubrication and condition-monitoring oil
system.
MAIN ROTOR DRIVE SYSTEM – MAIN COMPONENTS
MAIN GEAR BOX
The MGB is the most important component of the MRDS. The MGB is made
of aluminium alloy and comprises two (engine) input shaft modules cases,
the main case, the upper module case and the bottom case.
The MGB changes the horizontal drive from the engines to a vertical drive of
the main rotor (MR) shaft. The MR shaft is secured to the MGB and drives
the MR head on which are attached the blades.
The MGB has three reduction stages that reduce the 21000 rpm of the
engines input speed to the 296 rpm of the MR speed (at 100% Nr).
The MGB supplies drive through the Tail Rotor Drive System (TRDS) to the
Tail Rotor (TR) and supplies drive at different rotational speeds to the
following accessories:
• one MGB oil cooler fan;
• two MGB lubrication pumps;
• three hydraulic power pumps (pump 1, pump 2, pump 4);
• one ECS dual compressor (optional);
• two alternators for Full Ice Protection System (optional).