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Quoting AF1624 (Thread starter): My question is: why? Surely you don't need that much brake pressure to keep the aircraft at a stand still. |
Quoting AF1624 (Thread starter): I noticed that when you set the parking brakes on these airliners, the brakes are placed in use at almost their maximum capacity. You can see that with the brake pressure gauge on the Airbus 320, 30, 40, 80 series cockpit - it just shoots all the way up with parking brakes set |
Quoting AF1624 (Reply 10): Also interesting to know that the 787 has electric brakes! |
Quoting boeing767mech (Reply 11): I talked to a mechanic here at my place of employment he said the Fokker F-27 had pnuematic brakes. |
Quoting HAWK21M (Reply 9): On most types....Setting the Parking brakes is like deppressing the Brakes & locking it in that position.....If hydraulics is switched off as in long halts.....it could require reapplication with Hyd pr to compensate for any leaks. |
Quoting tdscanuck (Reply 12): There was considerable skepticism about those (on a.net and elsewhere) back in the day. During early build there was also press about having to revise the brake software, although I can't find any evidence that that actually led to any delays. However, I'd say they're fantastic. They don't bleed down, so parking brakes are actually parking brakes, they eliminate a ton of hydraulic components and tubes, they don't leak, they're much easier to control, and you can deactivate individual actuators (as opposed to entire brakes) so you've got a lot more MEL options. I'm a fan. The only big "gotcha" I've seen on them so far is in heavy maintenance...if you jack the airplane with the brakes on (not very unusual) then depower the airplane (also not unusual) you can't dejack without powering back up because you have no way to release the brakes. Tom. |
Quoting boeing767mech (Reply 11): I talked to a mechanic here at my place of employment he said the Fokker F-27 had pnuematic brakes. |
Quoting tdscanuck (Reply 12): if you jack the airplane with the brakes on (not very unusual) then depower the airplane (also not unusual) you can't dejack without powering back up because you have no way to release the brakes. |
Quoting Tristarsteve (Reply 14): Thats the Boeing way. Airbus is different, you just turn the park brake from off to on. And Airbus brakes are still on the next morning!! |
Quoting tdscanuck (Reply 12): There was considerable skepticism about those (on a.net and elsewhere) back in the day. During early build there was also press about having to revise the brake software, although I can't find any evidence that that actually led to any delays. However, I'd say they're fantastic. They don't bleed down, so parking brakes are actually parking brakes, they eliminate a ton of hydraulic components and tubes, they don't leak, they're much easier to control, and you can deactivate individual actuators (as opposed to entire brakes) so you've got a lot more MEL options. I'm a fan. The only big "gotcha" I've seen on them so far is in heavy maintenance...if you jack the airplane with the brakes on (not very unusual) then depower the airplane (also not unusual) you can't dejack without powering back up because you have no way to release the brakes. Tom. |
Quoting horstroad (Reply 2): so when 3000psi do the job not worse than let´s say 1000psi, why would you want to reduce pressure for the parking brake, when 3000psi are available anyways? |
Quoting horstroad (Reply 2): most important is that the extra pressure is to compensate internal and external leakage. over a certain amount of time you might lose some % of pressure through the valves or the brake cylinders. if you have some extra pressure this is irrelevant (almost). |
Quoting n901wa (Reply 7): The one Aircraft that has to have the brake Pedals pushed and not use the Parking brakes is the A320. |
Quoting tdscanuck (Reply 12): The only big "gotcha" I've seen on them so far is in heavy maintenance...if you jack the airplane with the brakes on (not very unusual) then depower the airplane (also not unusual) you can't dejack without powering back up because you have no way to release the brakes. |
Quoting JAGflyer (Reply 16): On the 737NG the brakes are depressed (the same way you'd push them to stop the plane when it's taxiing) then the lever is pulled. This lever will cause the brake pressure to not release. If the hydraulic systems are shut off (ie. when the APU is turned off) will the pressure stay in the brakes to hold the plane? |
Quoting JAGflyer (Reply 16): I would think the parking brake is just simply a valve which closes to keep the fluid pressure from escaping. |
Quoting Max Q (Reply 18): Tom, what happens if and when the 787 loses all electric power at the gate ? For example, external power trips off and APU / Engine generators all off. Does the parking brake remain set using battery power ? |
Quoting titanmiller (Reply 19): How long does it take the hydraulic pressure to bleed off if an aircraft sits for an extended period of time with the parking breaks set? |
Quoting Darksnowynight (Reply 20): Any chance they'll ever put a manual release feature for just that contingency. I understand that should be an avoidable encounter, but shit, as they say, happens. |
Quoting KC135Hydraulics (Reply 24): Anyone wanna know how C-17 and KC-135 parking brakes work?! |
Quoting m1m2 (Reply 21): I've done many run-ups on the Dash 8 100 and 300 using the parking brake. Are you saying you have to hold the toe brakes to do a run-up? I do keep my feet on the pedals just to be safe though, 4600 horsepower is something to be respected. |
Quoting KC135Hydraulics (Reply 24): |
Quoting tdscanuck (Reply 25): I still refuse to admit that C-17 landing gear can work at all, let alone anything attached to said gear. Rube Goldberg would have been horrified. Tom. |
Quoting Darksnowynight (Reply 20): DHC-8 100, 200 & 300 all work that way as well. |
Quoting titanmiller (Reply 19): How long does it take the hydraulic pressure to bleed off if an aircraft sits for an extended period of time with the parking breaks set? |
Quoting AF1624 (Reply 10): Also interesting to know that the 787 has electric brakes! |
Quoting BEG2IAH (Reply 33): Speaking of, I asked the guys where is the fuse plug and they couldn't find it. I bet it does exist, but where is it exactly? |
Quoting DashTrash (Reply 31): You can set the parking brake on the Dash without touching the toe brakes. The parking brake handle is also the emergency brake, as in you can stop a moving Dash 8 with that handle. |
Quoting m1m2 (Reply 38): Have you ever applied the Dash parking brake while in motion? I have been told to have your hand on the glareshield if you do because it stops in a hurry. Just curious as I haven't had to do it. |
Quoting m1m2 (Reply 38): Hi DashTrash, Have you ever applied the Dash parking brake while in motion? I have been told to have your hand on the glareshield if you do because it stops in a hurry. Just curious as I haven't had to do it. |