Electric Brakes (787)
Thread Starter
Joined: Dec 2016
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From: Small aprtment
Electric Brakes (787)
I just do not know how these brakes work.
Electronic control is fine, but down at the
wheel, what actually presses the pad against
the disk(s) ? Is it an electric solenoid, or
hydraulic force from a local small circuit,
controlled electrically? Or what?
Electronic control is fine, but down at the
wheel, what actually presses the pad against
the disk(s) ? Is it an electric solenoid, or
hydraulic force from a local small circuit,
controlled electrically? Or what?
Joined: Jul 2000
Posts: 1,061
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From: My views - Not my employer!
Deepinsider - The link provided from PDR1 gives the following...
Where did you get your quote from?
In electric braking systems, the conventional hydraulic equipment is replaced by electronic control units and hydraulic pistons driven by electromechanical actuators.
Joined: Jan 2008
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From: Reading, UK
No, there are no "hydraulic pistons" involved, at least in the Safran/Messier-Bugatti brakes. I assume that the same applies to the UTC/Goodrich equivalents.
Joined: Sep 2007
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From: Among camels and dunes
The brakes work just fine. First application in your life and it duck walks along with an instant upgrade of all economy passengers to business.
3 and bit years experience on them now and no more instant upgrades happening anymore
3 and bit years experience on them now and no more instant upgrades happening anymore
Joined: Jan 2008
Posts: 17,738
Likes: 2,119
From: Reading, UK
Incidentally the Safran document linked in post #3 is a mis-translation of the French original, hence the erroneous reference to "hydraulic pistons driven by electromechanical actuators".
The French source says
"Avec les freins électriques, les équipements hydrauliques sont remplacés par des boîtiers électroniques et les pistons hydrauliques par des actionneurs électro-mécaniques"
which translates as "... hydraulic pistons [replaced] by electromechanical actuators".
Thread Starter
Joined: Dec 2016
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From: Small aprtment
This is from Safran themselves, not me.
A major advance
In electric braking systems, the conventional hydraulic equipment is replaced by electronic control units and hydraulic pistons driven by electromechanical actuators. The introduction of electric brakes is an advance on a par with the introduction of carbon brakes some 30 years ago, and paves the way for even "more electric" aircraft.
this is from the link posted by PDR1
(I'm blocked from posting links at this site)
Thread Starter
Joined: Dec 2016
Posts: 45
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From: Small aprtment
Sorry guys, actually I'm not a troll. I'm sorry my genuine question has not gone well.
Under the rules I agree to move on as they say. (not sure this will be blocked as well)
cheers!
Under the rules I agree to move on as they say. (not sure this will be blocked as well)
cheers!
Joined: Jul 2014
Posts: 344
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From: Germany
so the translation and the french can both be right.
somehow you need guidance also for an electromechanical actuator.
so it's still some kind of piston probably similar to a hydraulic one just without the pressure making it move, that's what i assume is meant.
@deepinsider you can't post links when under 5 posts on this page don't think you've been blocked or you couldn't post at all
and reread what davereiduk wrote, he said safran has bad english translators so he does not dispute the meaning of the english language but the translation skills of the bloody french.
somehow you need guidance also for an electromechanical actuator.
so it's still some kind of piston probably similar to a hydraulic one just without the pressure making it move, that's what i assume is meant.
@deepinsider you can't post links when under 5 posts on this page don't think you've been blocked or you couldn't post at all
and reread what davereiduk wrote, he said safran has bad english translators so he does not dispute the meaning of the english language but the translation skills of the bloody french.
Joined: Apr 2002
Posts: 274
Likes: 3
From: england
B787 FCOM
Landing Gear –
System Description
14.20.4
Revision 6
Sep 2014
Four Electric Brake
Actuators (EBAs) are provided
on each main landing gear
wheel brake to control the application of
braking force to
the carbon disc. The
EBAs are controlled by an Electric Br
ake Actuator Controller (EBAC). There are
four EBACs that control all eight main
wheel brakes, each EBAC controlling the
brake force of a fore-aft wheel pair. From a major UK operator of 787.
Landing Gear –
System Description
14.20.4
Revision 6
Sep 2014
Four Electric Brake
Actuators (EBAs) are provided
on each main landing gear
wheel brake to control the application of
braking force to
the carbon disc. The
EBAs are controlled by an Electric Br
ake Actuator Controller (EBAC). There are
four EBACs that control all eight main
wheel brakes, each EBAC controlling the
brake force of a fore-aft wheel pair. From a major UK operator of 787.
Joined: Jan 2008
Posts: 36
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From: Belgium
I haven't really noticed a difference in use between these and the ones on the NG. If anything, the braking on the 787 is easier to modulate. The tricky bit is it'll only use half of the units if you re-apply brakes below 70kts, possibly leading to high brake temperatures.
Joined: Aug 2005
Posts: 1,693
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From: fairly close to the colonial capitol
Brakes actuators require +/- 130VDC supply for operation, which is stepped up from the 28VDC TRU voltage by the brake PSUs. The 28VDC TRUs are the primary power source for the PSUs, with the aircraft batteries serving as a backup supply.
The motors supply torque through gear assemblies to the actuators, which are rams driven by a jack screw. There is a latching mechanism to limit over-rotation and back driving, minimizing the current requirements for the EBS actuator motors.
The aircraft may be dispatched (MEL) with an electrically locked out actuator.
The motors supply torque through gear assemblies to the actuators, which are rams driven by a jack screw. There is a latching mechanism to limit over-rotation and back driving, minimizing the current requirements for the EBS actuator motors.
The aircraft may be dispatched (MEL) with an electrically locked out actuator.
