29 hydraulic power components Flashcards
why is there a need for a hydraulic resevoir
collect excess fluid /storgae while not in lines
- some leaks out as pubricant (very small amount)
- fluid has variable volume with change in temp
- variable amount in valves/ accumulators
- prevent bubbles from heavy suction into pump (cavitation). resevoir is located above pump
what are two categories of resevoirs and the two classifications within them
- in-line
- integral
- pressurized
- unppressurized
how can resevoirs be pressurized
- from compresed air from the pneumatic system
- bootstrap resevoir
- spring
why are reservoirs pressurized
to further (in addition to being located above) increase the positive pressure at the pump inlet to reduce the chance of cavitation (bubbles forming from the suction of the pump)
how does a bootstrap reservoir work?
There is a piston (low pressure plunger) sitting on top of the fluid in the reservoir. It is connected to an actuator (high pressure plunger) that is moved via the hydraulic system itself. There is a non-return valve to hold pressure when system is not operating.
draw a diagram of a bootsstrap resevoir
see pic
what is the purpose of the accumulator
- limits variations in pressure to comsumers
- thermal expansion / contraction of fluid trapped in pipes
- provide space for excess buildup of pressurized hydrolic fluid
- in case of system failure, there is slight time system can work (perhaps each action can be done once.) (emergency supply)
- brake accumulators will be able to supply braking once in rejected takeoff.
what is the pressure in the lp portion of the pipes
3.5 bar
what is the system architecture of an accumulator
there is a division (depending on kind) of a high pressure, compressible gas and a high pressure fluid.
what differentiates the types of accumulators?
The separation between the water and gas (Nitrogen)
what are the components of filters?
inlet, outlet, filter element, bowl, bypass valve
where are filters placed?
lpp filter before entrance to resevoir, high pressure filter, return line
what are the two types of valves
flow control valves (hydrolic fluid to consumers
-check valves (one direction
explain the priority valve
it only allows flow to the secondary consumers if the pressure is above a given threshold.
what is the PTU?
transfers power between hydraulic systems without interchanging any fluid
