12.04 Transmitions Flashcards
(32 cards)
What are the two main tasks of helicopter MGB
Reduction of speed and torque
The gearbox can also change drive direction what gear is used for this task
Bevel gear
What component input power to the Main gear box
Engine drive shaft (high speed shaft)
What ancillary components are driven by the main gearbox?
Pumps and generators
What type of gearing is used in a main gearbox?
Planet and sun gears
What is essential in a gearbox to ensure gears work efficiently, avoiding wear and tear? And how is it distributed around a gearbox?
Adequate lubrication. A pump pressurizes the oil, distributing it via ducts and nozzles. The lubricant collects in the sump and is then re-circulated around the gearbox.
How is the breakdown of internal gearbox components detected?
A magnetic chip detector holds any debris in the sump and a warning light in the cockpit is illuminated.
What 2 components does gearbox lubricant pass through, prior to re-entering the cycle?
Filter and cooler
What is the purpose of an intermediate gearbox?
It is used to change direction of power transmission, from horizontal tail boom up to tail rotor gearbox.
Regarding lubrication, what is the essential difference between intermediate and main gearboxes?
Due to their compact design, there are no oil nozzles; the lubricant is sprayed around entire box by oil sump.
How is the lubricant cooled in an intermediate gearbox?
Air blowing over the housing acts as an oil cooler
How is the lubricant cooled in an intermediate gearbox?
Outside air cools the housing. Which acts as an oil cooler
How is the deterioration of internal gears detected in an intermediate gearbox?
Magnetic chip detectors
In a conventional layout helicopter (main and tail rotor), what components generally constitute the tail rotor drive system?
Drive shafts, intermediate and tail rotor gearboxes
Besides the tail rotor, what else is driven by the tail rotor drive system?
Main transmission oil cooling system
How are some tail rotor drive shafts connected? (Like the H-175)
Flexible couplings
A Tail Rotor Drive shaft damper (or snubber), sometimes installed at the mid-span of some middle drive shaft sections, and serves what purpose?
It contains radial movement of the shaft
What part of a tail rotor drive shaft damper (or snubber) contacts the shaft?
A non-damaging replaceable rub-pad
In a tail rotor drive system, what is the purpose of the elastomeric support assembly?
It allows the bearing to move as the airframe flexes, decreasing stresses on the system components.
What is the purpose of a clutch in a helicopter transmission system?
It unloads the engine when starting, as the energy required to overcome the inertia of the rotor system would be too great.
Between which components are clutches located?
Between the engine and the transmission
How are clutches engaged?
Manually or automatically
What is the basic principle of automatic clutch operation?
As the engine speeds up drive shoes are thrown outwards under centrifugal force to contact the drive to the gearbox.
If an automatic clutch does not engage within a few seconds of the engine(s) starting, what could be the problem?
The clutch is slipping.
