MH-60R - Systems - Transmission Flashcards
(26 cards)
How much of a tilt does the main transmission have?
3 degrees
Briefly describe the Transmission system
The primary function of the transmission system is to take the combined power from the two engines, reduce the rpm, and transfer it to the main and tail rotors. The secondary function is to provide a drive for electrical and hydraulic power generation. The power train consists of the main transmission modules, tail rotor drive shaft, oil cooler, intermediate gearbox, and tail gearbox. The tail drive shaft consists of six sections with a disconnect coupling at the fold hinge. The shafts are ballistically tolerant and suspended at four points by viscous-damped bearings. The oil cooler is an integral part of the tail rotor drive shaft system.
What does the main transmission consist of?
Five modules: two accessory modules, two input modules, and a main module.
What else in mounted on the main transmission?
A utility hydraulic system is mounted on the right rear quadrant of the main transmission. A rotor brake is mounted on the main transmission, providing the capability of stopping the rotor system. The rotor brake disc is toothed to provide the means for positioning the main rotor head for blade folding.
How is the main gearbox lubricated?
The main gearbox is pressure lubricated and contains the oil sump, an oil filter (which can be bypassed), and the oil temperature, pressure, and chip detector indicating systems.
Briefly describe the input modules
The input modules are mounted on the left- and right-front of the MGB module and support the front of the engines. They each contain an input bevel-pinion gear and a freewheeling unit. The freewheeling unit allows each engine to be disengaged from the transmission when Nr exceeds Np (autorotation). The input module provides the first gear reduction between the engine and the main module.
What does the diaphragm coupling do?
The engine output shaft provides drive from the engine to the input module via the diaphragm coupling. The diaphragm coupling is designed to allow 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 to locate the source of the whining noise. If incorrect installation of diaphragm coupling is the source of the whining noise, further engine operation could result in diaphragm coupling failure.
Briefly describe the accessory modules
One accessory module is mounted on the forward section of each input module. Each accessory module provides mounting and drive for an ac electrical generator and a hydraulic pump module. An Nr sensor for the vertical instruments is mounted on the right accessory module. The Nr sensor for the TDI and the main transmission low-oil pressure sensors are mounted on the left accessory module. The accessory modules are driven by the main transmission.
What sensor(s) is mounted in the #1 accessory module?
The Nr sensor for the TDI and the main transmission low-oil pressure sensors.
What sensor(s) is mounted on the #2 accessory module?
An Nr sensor for the vertical instruments.
Briefly describe the Intermediate gearbox
The splash-lubricated Intermediate Gearbox (IGB) is mounted at the base of the tail pylon. It reduces shaft speed from the MGB to the Tail Gearbox (TGB) and changes the angle of drive.
Briefly describe the Tail gearbox
The splash-lubricated tail gearbox is located at the top of the tail pylon and drives the tail rotor. The gearbox mounts the tail rotor, changes the angle of drive, and provides gear reduction. The TGB enables pitch changes of the tail rotor blades through the flight control system and has a built-in 20° left tilt.
What type of lubrication system does the main transmission use?
Wet sump
Through what kind of lines is oil routed through the system?
Oil under pressure is supplied through internally cored oil lines, except for the pressure and return lines in and out of the oil cooler.
What does the oil filter have that helps in cold conditions?
A PDI that has a thermal lockout that prevents it from extending during starts in cold ambient conditions.
When is the MAIN XMSN PRESS LO caution activated?
14 psi
Hen is the MAIN XMSN OIL HOT caution activated?
117 C
Where is the reading for the MAIN XMSN OIL PRESS LO caution derived from?
A sensor on the #1 accessory module pressure line, the furthest point in the system away from the oil pumps.
Where is the reading for the MAIN XMSN TEMP HI caution derived from?
An oil temperature sensor at the oil cooler input to the MGB manifold.
Where are the pressure and temperature readings for the vertical instruments taken from?
Pressure: oil pressure sensor at the oil cooler input to the MGB manifold.
Temperature: MGB chip detector
How many chip detectors are there in the main transmission system?
5
What happens if a chip detector detects a chip?
When a metal fragment completes the circuit, the appropriate caution will appear. Should the chip be washed away from the detector, the caution will disappear. Each chip detector has a burnoff feature, which eliminates false warnings created by fuzz and minute particles.
When is the fuzz burn off feature deactivated for the main transmission system?
The fuzz burnoff feature is deactivated when oil temperature is above 140 °C; however, magnetic detection will remain.
What is unique about the main transmission chip detector?
It incorporates a 30-second time delay to further eliminate false warnings.
