Brake temps on a tandem bogie.
Fleet Manager
Joined: Apr 2001
Aviation Qualifications: ATPL
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From: various places .....
... interesting .... unless the cooling or brake design is appropriately different, I would have expected the leading axle assembly to carry the higher load and experience the higher temperatures ..... ?
Guest
Posts: n/a
"I would have expected the leading axle assembly to carry the higher load and experience the higher temperatures ..... ?"
If the temps are the same, as Spanners has no doubt observed, would antiskid/ torque-limiting systems play a part in this?
Rgds.
Q.
P.S. If AS and Torque-limiting have no effect, and they are still the same, perhaps the fronts do bear the higher load, but due to sheilded airflow at the rear, the front/rear temps work out at about the same value?
P.P.S. That's what I like about PPRuNe... You can get a number of different, sometimes opposing answers, but still feel more the wiser
If the temps are the same, as Spanners has no doubt observed, would antiskid/ torque-limiting systems play a part in this?
Rgds.
Q.
P.S. If AS and Torque-limiting have no effect, and they are still the same, perhaps the fronts do bear the higher load, but due to sheilded airflow at the rear, the front/rear temps work out at about the same value?
P.P.S. That's what I like about PPRuNe... You can get a number of different, sometimes opposing answers, but still feel more the wiser
Joined: Jul 2000
Posts: 474
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From: U.S.A.
Perhaps a bit of thread creep here, but in the last couple of years have flown my first aircraft with brake temperature indicators (767-300 – understand it’s an option, not standard equip.). I have noticed no difference between front and back axle temperatures. What I have noticed, and it came as a bit of a surprise, is the large difference in brake temperatures on upwind/downwind trucks landing in a crosswind. There are consistently higher temperatures on the downwind truck when landing in a crosswind. Seems myself and every other pilot I have flown with are using a bit more brake than we realized in conjunction with the rudder to keep the aircraft tracking straight after touchdown.
Keeping Danny in Sandwiches
Joined: May 1999
Posts: 1,295
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From: UK
Shoreguy
It might be that it is easier to apply brakes with your foot further away from you than nearest to you (the rudder pedal will be pointing towards the downwind side).
Another interesting point is that carbon brake temperatures stay lower with one hard application rather than after extended taxiing. I know that wear is less, however I was not expecting a brake temperature of 1 after a firm brake application to make the apron taxiway; and it didn’t rise during the turnround either.
It might be that it is easier to apply brakes with your foot further away from you than nearest to you (the rudder pedal will be pointing towards the downwind side).
Another interesting point is that carbon brake temperatures stay lower with one hard application rather than after extended taxiing. I know that wear is less, however I was not expecting a brake temperature of 1 after a firm brake application to make the apron taxiway; and it didn’t rise during the turnround either.
Joined: Jun 2001
Posts: 4,777
Likes: 9
From: Blighty
This question appears in the 'How to pass your Cathay interview' book - perhaps why the Q was asked. I gather, the official answer is the front units - dunno why.
I've noticed the downwind brakes getting hotter on the EICAS page too. I suspect it's because the into wind wing generates lmore lift therefore applying more downward pressure on the downwind wheels making the braking action more effective. After all, the main reason for deploying spoilers on landing is to apply weight to the wheels earlier and make the brakes more effective.
I've noticed the downwind brakes getting hotter on the EICAS page too. I suspect it's because the into wind wing generates lmore lift therefore applying more downward pressure on the downwind wheels making the braking action more effective. After all, the main reason for deploying spoilers on landing is to apply weight to the wheels earlier and make the brakes more effective.
Joined: Jul 2002
Posts: 368
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From: brisbane, Australia
Dan
I think most realized the mistake in 1515blue's 'comment'
"Which gets hotter ?"Good question !!I'm sorry but not being a "pointy ender' I can't answer that but as to which has the shortest life,from experience on the 762/3 it is the 'front of the bogie and on the 742/3 generally the inboard bogie front !!
Cheers
I think most realized the mistake in 1515blue's 'comment'
"Which gets hotter ?"Good question !!I'm sorry but not being a "pointy ender' I can't answer that but as to which has the shortest life,from experience on the 762/3 it is the 'front of the bogie and on the 742/3 generally the inboard bogie front !!
Cheers
Joined: Jun 2001
Posts: 135
Likes: 0
From: Brisbane
Folks,
Although it may vary on different types, the simple theoretical answer is that the REAR brakes on any given bogey get hotter for two related reasons;
1) The heat from the front brakes radiates to the rear, adding to the heat caused by the rear's normal braking action.
2) The front tyres and wheel assemblies block airflow from cooling the rear's brakes.
Actual relative brake temperature on any given aircraft type will vary depending on ambient conditions, length of taxi, brake usage, bogey design, brake wear and condition, tyre creep etc etc etc.
Although it may vary on different types, the simple theoretical answer is that the REAR brakes on any given bogey get hotter for two related reasons;
1) The heat from the front brakes radiates to the rear, adding to the heat caused by the rear's normal braking action.
2) The front tyres and wheel assemblies block airflow from cooling the rear's brakes.
Actual relative brake temperature on any given aircraft type will vary depending on ambient conditions, length of taxi, brake usage, bogey design, brake wear and condition, tyre creep etc etc etc.
