Aircraft Pumps and motors [Archive]

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Ericgkl

25th Jun 2009, 07:28

I understand in the hydraulics system there are many different pumps and hydraulic motors in the system. May I ask what purpose each type serves and where are they mounted on the aircraft.

Some of the item i really want to find out about
AC motor pump
DC motor pump
Hydraulic driven motors
Are there any others?

Is there a general rule where such items are mounted on the aircraft?
ie For the B757 the Engine driven pump is supported by a AC motor pump, so is this AC motor mounted together with the engine driven inside the engine? And what about the Ac motor pumps that support the centre hydraulics system, where are they mounted?

BAe146s make me cry

25th Jun 2009, 08:33

Ericgkl

Please find the link below to a B757 Hydraulic System D&O + Schematic.

http://www.smartcockpit.com/data/pdfs/plane/boeing/B757/systems/B757-Hydraulics.pdf

The B757 L & R System AC MPs are located adjacent wheelwells (wing/body) fairings, both Centre System AC MPs similar.. RAT located up front..(I'm not B757 type rated & memory hazy - last worked B757 over 7 years ago). The PTU location I'm afraid has disappeared all together!

AC MPs not usually found adjacent the EDPs (Engine Driven Pumps). It would be an additional LRU (Line Replacement Unit) in an already busy area - AGB, Oil pump,Fuel Pump/Governor,IDG, Heat Exchangers, Piping, Control Runs etc.

Additionally, it would also introduce extra weight & power losses associated with extra AC feeder lengths not to mention vulnerability to possible engine failure.

Maybe an example of an AC MP closest to an engine would be the #4 Hyd System AC MP in the #4 Engine pylon on the B747?

Additionally, the B747 (Qty x 4) & B767 have ADPs (Air Driven Pumps). The power for these is derived from aircraft pnematic systems. These provide px on demand and also serve system redundancy..

Other varieties of hydraulic pumps are of the reversible type & non-reversible type, 2 of each can be found on the DC-10 / MD11.
I'll leave you to research the purpose & strategic location of such equipment!

DC MPs can be found on the BAe146/RJ - Again, I'll leave you to research
where & why! Any questions, please send a PM.

Enjoy learning, always

BAe146?? :{:{:{

FAA DC-10 & 146/RJ Rated AMT

Piper19

25th Jun 2009, 17:26

For 757:

Engine driven pump: 1 providing left hydraulic system; 1 providing right. Located 1 on each engine gearbox.
Electric ACMP: 2 providing center system, located in hydraulic servicing bay. Another 2 for left and right system, located left and right wheel well bay. For center system, only 1 pump can operate at a time.
Hydraulic driven motors: 1 PTU in left wheel well, powering left system from right I think (I'm sorry, too much 767 in my head for the moment). There can also be an optional HMG for generation of electrics.
Are there any others? Yes, the Ram air turbine has a pump providing the center system.

767 is almost the same, except PTU only providing stab trim, center system has an extra air driven pump and left & right acmp's are in pylon and center acmp's are in right wheel well. Both center acmp's can run at the same time here

411A

25th Jun 2009, 19:42

vapilot2004

26th Jun 2009, 02:48

Generally:

AC motor pumps are for when the engines/APU are running. These are
the electric workhorse pumps of the aircraft, aka the 'main' pumps.

Engine driven pumps share the work load with the AC pumps and work even if there is a major electrical failure. As long as an engine is turning, you will have hydraulic pressure. These pumps are also considered 'main' pumps like the AC pumps.

DC motor pumps are normally for ground use, when the engines and APU are off. They also provide hydraulic pressure in emergencies. They are generally not as powerful as the AC and engine driven types.

Hydraulic driven motors are used to transfer power between two hydraulic systems without sharing the fluid. This arrangement ensures that a leak in one system will not affect the other.

Piper19

27th Jun 2009, 13:41

Yes if you have DC pumps this would be true.
757/767 philosophy is EDP as primary pumps, ACMP and/or ADP as demand pumps and for ground/maintenance operation.

mitzy69

27th Jun 2009, 15:13

and if you are unlucky hand driven pumps to open cargo doors on ground in an emergency, operated by handle 60 cms long for hundreds of strokes.
and little hand pumps to replenish hyd tank when low level due to leaks.

Ericgkl

30th Jun 2009, 11:01

Thanks guys.

I read from somewhere that fixed displacement hyd motors are used to drive some flight controls. I thought they use actuators. Any idea on this?

Just to clarify. The Ram Air turbine is deployed when all electric power is lost, right? So this in turn is used to drive the AC Motors for hydraulic power? Are there any RAT that is used to generate hyd power, which is in turn generate electricity through HYD Generators?

TURIN

30th Jun 2009, 23:54

Are there any RAT that is used to generate hyd power, which is in turn generate electricity through HYD Generators?

I'm sure the Bent Nail had a HyRAT. Dunno if it was to supply a hydraulic motor driven genny though. :ok:

spannersatKL

1st Jul 2009, 21:29

Yep Bent Nail had CSMG like BAe 146 and most Airbusses.....

krujje

1st Jul 2009, 23:18

I read from somewhere that fixed displacement hyd motors are used to drive some flight controls. I thought they use actuators

Both together in some cases... you can have hydraulic motors driving a transmission that turns rotary actuators which which move flaps and slats, for example.

red 5

2nd Jul 2009, 01:47

The RAT on the 757 only supplies hyd pressure to the centre system, no electric pump on the RAT. Therefore if both engines failed in flt, you would have no left or right system hyd pressure only centre system pressure and battery power only, land asap.

glhcarl

2nd Jul 2009, 16:11

L1011...
Four engine driven hydraulic pumps.
Two air driven hydraulic pumps.
Two DC electric hydraulic pumps.
Two hydraulic power transfer units.
One Ram Air Turbine hydraulic pump.
One trailing edge flap hydraulic motor/actuator using jackscrews.
One slat hydraulic motor/actuator, using jackscrews.
Spoiler (12) hydraulic actuators.
Various combinations of hydraulic actuators for primary control surfaces.
Last but not least, hydraulic fusing, built in from the factory, not added later.

Redundancy unsurpassed in large wide-body jet transport aircraft.

While everything you listed above is correct there are a couple of minor problems.

The L-1011 has one (1) flap power drive unit, but it has two (2) independent motors. Either off which will power the flaps.

Likewise the one (1) slat power drive unit has two independent motors. either of which will power the slats.

411A

2nd Jul 2009, 19:36

Yup, quite correct.
Systems redunancy at its best.