Transmission Flashcards
Primary/Secondary Functions
Take combined power from engines, reduce RPM and transfer it to main and tail rotors
Provide drive for electrical and hydraulic power generation
Power Train
Main transmission modules, tail rotor drive shaft, oil cooler, intermediate gearbox and tail gearbox
Tail Drive Shaft
Six sections with disconnect coupling at fold hinge
Shafts are ballistically tolerant and suspended at four points via viscous-damped bearings
Drives oil cooler
Main Transmission
MGB drives and supports main rotor
Modular design, 3* forward tilt
Five modules, utility system on right rear quadrant
MGB is pressure lubricated and contains oil sump, oil filter and oil temp, pressure and chip detector indicators
Input Module
Support front of the engines, provides first gear reduction
Contain input bevel-pinion gear and freewheeling unit
Freewheeling unit allows each engine to disengage from transmission when Nr exceeds Np (auto)
Diaphragm Coupling
Allows for slight angular or axial misalignment of the engine output shaft during operation
CAUTION If an abnormal or loud whining noise is heard during rotor engagement, shut down engine immediately. Whining noise may be an indication of a pending diaphragm coupling failure. Do not operate engine until appropriate troubleshooting has been performed. If incorrect installation is the source, further engine operation could result in coupling failure.
Accessory Module
Provides mounting and drive for an ac electrical generator and hydraulic pump
Nr sensor for vertical instruments is mounted on right; Nr sensor for TDI and main transmission low-oil pressure sensors on left
Intermediate Gearbox
Splash-lubricated at base of tail pylon
Reduces shaft speed and changes angle of drive
Tail Gearbox
Splash-lubricated at top of tail pylon
Drives tail rotor, changes angle of drive and provides gear reduction
Main Transmission Lubrication
Wet sump providing cooled, filtered oil; ac generators use transmission oil for cooling
Sump > oil filter (can bypass, PDI pops) > cooler > vertical instrument pressure and temp caution sensor (117*) > ac generators > press caution sensor (14 psi, left side only; farthest point from pump) > sump (vertical instrument temp on chip detector)
- PDI has thermal lockout to prevent popping in cold weather
- Oil cooler driven by t/r drive shaft
Chip Detector System
Accessory chips in return lines of No 1/2 accessory modules
Input and main module located in main module
Can be removed with no loss of oil
Burnoff feature eliminates false warnings and deactivated when oil temp above 140*C
MGB - at lowest point in tank, embedded temp sensor and 30-second time delay
IGB and TGB have identical chip detectors
Chip IBIT
Takes 2 min to verify circuitry and check individual detectors
For approximately the first 40 seconds, 28 Vdc interrupted and WCAs and MASTER CAUTION will not correctly respond
