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51 Cards in this Set

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Name six units operated by hydraulics.
landing gears, wing flaps, control surfaces, wing folding mechanisms, bomb-bay doors, and brakes.
how is force transmitted through a solid bar?
straight through
3 characteristics of hydraulics?
efficiency, weight, and maintenance
2 disadvantages of hydraulics
leakage and contamination
5 components of a hydraulic jack
reservoir, pump, check valve, actuating cylinder, bypass valve
define force
force is push, pull, or total weight exerted against the total area of a particular surface and is expressed in pounds
define pressure
pressure is amount of force on a unit of are acted upon
define working area
working area is the total square inches of the exposed cross sectional area, regardless of shape, that the force of pressure is applied to
state pascal's law
pressure exerted on an enclosed liquid is transmitted equally and undiminished in all directions and acts with equal force on equal areas.
what are the formulas for force, area, and pressure?
F=AxP
A=F/P
P=F/A
what are basic components required to make up a hydraulic system?
reservoir, power-driven pump, selector valve, actuating units, & hydraulic lines
7 additional components installed in a hydraulic system
filters, accumulators, check valves, relief valves, pressure gauge, one way and two way restrictors, pressure reducing device.
what is the purpose of hydraulic fluid?
to transmit energy
what are 3 desired characteristics of hydraulic fluid?
low viscosity, lubricating qualities, corrosion stability
what are 2 basic military specifications of hydraulic fluid likely to come in contact with?
MIL-H-83282
MIL-H-46170 Type II
what are 2 functions of a reservoir?
supply fluid to system, allow automatic bleeding of air from fluid in system.
what is the purpose of pressurizing reservoirs?
to ensure constant flow of fluid to the pump.
what are the types of reservoirs?
non-pressurized and pressurized.
name 6 precautions for prevention of contamination of hydraulic fluid:
1) do not service reservoir by pouring fluid directly from can
2) use only approved type of filling unit w/3 micron filter
3) do not expose hydrulic fluid to air for long time
4) if all fluid in container is not used, discard unused portion
5) destroy container after use
6) fluid drained shall not be reused
purpose of a hydraulic pump?
create a flow of fluid
what determines location of hydraulic pump?
source of power used to drive pump
explain "displacement" in reference to hydraulic pumps?
amount of fluid delivered in one complete cycle?
what is classification of a gear pump
constant-displacement pump
what are functions of hand pump?
provides emergency means of operating hydraulic units in event of main pump failure. normal operation of sub systems. used by maintenance for testing system when main pump is impractical
explain purpose of angle in vickers variable-displacement pump
angle causes pistons to move in and out of their respective bores.
name components in vickers constant-displacement pump
housing, rotating group, valve plate, yoke, pressure control assembly.
what is the purpose of shear shaft in the drive shaft?
prevent damage to the power source of pump in event of pump binding.
what is the purpose of the hydraulic filter?
to filter the fluid of the hydraulic system of foreign particles and contaminative substances.
what are the three main parts of a hydraulic filter?
head assembly, bowl, and element.
name the four major filter elements used in naval aviation.
- 5 micron disposable
- stainless steel
- micronic filter elements
- sintered filter elements
how often is a micronic filter element used?
used one time then disposed
how is the fluid filtered through the filter element during normal operation?
fluid flows into the filter through inlet, into bowl, through element from outside to inside, and to the head, then out the outlet port.
what are 3 maintenance publications that are used with filter assemblies?
MIM
MRC
Aviation Hydraulics Manual
what is the purpose of a hydraulic relief valve?
to protect the hydraulic system from damage
what are the two types of relief valves?
thermal and main system
what are the locations of the two relief valves?
thermal - located in the hydraulic system where a check valve or a selector valve prevents excessive pressure from being relieved through the main system relief. also located in a subsystem.

main system - located in pressure line after the regulator. if system has no regulator it is located after the pump.
what is the maintenance limitation of relief valves
limited to checking valves for external leaks and for proper relieving pressure.
what are the adjustment procedures for a hydraulic relief valve?
adjustments are I-level only!
what is the purpose of an accumulator?
to store hydraulic fluid under pressure for normal and emergency use.
what are the functions of an accumulator?
normal- aid pump at peak flow demands.

emergency - if pressure is lost, fluid in an accumulator may activate subsystem

other - absorb shocks and surges of fluid.
what are 2 types of accumulators?
spherical and cylindrical
what does the term "preload of an accumulator" mean?
nitrogen is pumped into accumulator
what is the method of checking preload of an accumulator?
pressure gauge method.
as a safety precaution what should be consulted before disassembling an accumulator.
MIMs.
what is the purpose of a pressure reducing valve?
reduce pressure of the main system to a lower pressure for a subsystem.
where is the pressure reducing valve located in the hydraulic system?
located in the pressure line of the main system just prior to the pressure line of the subsystem.
what are the components that make up a hydraulic pressure reducing valve?
body and ports, sleeve and shuttle assembly, relief valve spring, and a cap.
what is the purpose of the metering groove on the shuttle?
used to control the flow of fluid to the subsystem.
which component determines the amount of reduced pressure in the subsystem?
relief valve spring.
if the pressure reducing valve operates improperly, what manual must be consulted?
MIM.
what is the safety precaution before perfoming any hydraulic system maintenance?
system must be depressurized.