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In the Hog's cockpit is a black and yellow striped handle marked "Emergency Brake", and I guess the label says it all. Is this brake a cable-pull, like the emergency brake on a car (i.e., does the cable make the brakes work directly), or does it activate a reserve hydraulic actuator that applies the brakes?

Thanks,

Bob Balsie

Bob

The handle kicks open a accumulator then two shuttle valves block off the normal system. You will have normal operating brakes (with out anti skid).If you have a good Hydro system the accumulator will stay at presurized but if the system is dead you only have the presure that is stored in the bottle.

If you are going to be dumb you have to be tough.(words from a old flight chief)I heard it a lot.

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Thank you...!!!


Bob

To elaborate on what Goob said:
The handle does not directly operate the brakes. It pulls a cable attached to the dump valve on the emergency accumulator that allows the stored hydraulic pressure to flow to the brakes. Pulling the handle does not apply the brakes. If you pull the handle and don't pump the pedals, the only thing that will happen is the anti-skid kicks off. You still have to operate them like normal with the pedals. The handle is like an on/off switch for the pressure <i>to be able to</i> flow to the brakes.

Liberalism is a mental disorder.

Once again, Jack is correct.

The accumulator holds enough for about 5 brake applications. If the left hydraulics are operational, you have unlimited braking but without anti-skid.

Coach

<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>The accumulator holds enough for about 5 brake applications. If the left hydraulics are operational, you have unlimited braking but without anti-skid.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
Coach, I believe you mistyped- the emergency accumulator is serviced by, but isolated from the right system. If there is no right system pressure, you still have the pressure stored in the emergency accumulator. If there is still pressure on the right system, and you pull the handle, you will not be limited to the 5 brake applications, since the still-pressurized right system is servicing the emergency accumulator as you are using it.

Liberalism is a mental disorder.

Thanks again, gentlemen,

Since anti-skid has been mentioned several times, how does this feature operate on the A-10? I assume that there must be rotational sensors on the wheels and a computer to figure out whether one or both tires are slipping. Does the anti-skid system pulse the brakes as is done on a car, or does it modulate the brake force in a linear manner to control skidding?

Thanks,

Bob

Just like on your car.

If you are going to be dumb you have to be tough.(words from a old flight chief)I heard it a lot.

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Press one for English, Press two to disconect untill you do.

Very simple. On the MLG wheel, you have the hubcap. Inside the hubcap are a series of magnets. In the axle, there is a sensor called the wheel speed tansducer. The magnets on the hubcap are spinning with the wheel of course, but the axle/transducer is stationary. So you have the wheel speed transducer in the axle and it detects from the magnets how fast the wheels are moving. It sends the signal to the anti-skid control valve (can't remember the panel number, its on the left side of the fuselage right in front of the intake) which pulses the brakes.

Anti-skid is not always on, there is an on/off switch for it on the LDG control panel. If the switch is on and you pull the emergency brake handle, the switch moves to off and you get a caution light as well.

Now this has me thinking. I thought even if the switch is on, the anti-skid is only operational at above a certain speed. I thought 50 knots, but I could be wrong. Anyone? Which raises the question to me- How does it pulse during a launch so we can check it when the jet is obviously going 0 knots. Or is there no minimum speed?

Liberalism is a mental disorder.

<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>I thought even if the switch is on, the anti-skid is only operational at above a certain speed. I thought 50 knots, but I could be wrong. Anyone? Which raises the question to me- How does it pulse during a launch so we can check it when the jet is obviously going 0 knots. Or is there no minimum speed?
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There is a minimum speed Jack but I don't recall exactly what it is..50 knots seems high. The way the system works is pretty much as you described in that the wheel sensors create a square wave that's sent to the anti skid control box as long as the wheel is turning. When the wheel stops turning, as in a skid, the control box no longer receives the signal from the wheel and shuts off power to the valve, releasing the pressure allowing the wheel to start turning again which restores power to the valve and the cycle starts all over again..that's where the pulsing comes from.

Now think about what would happen if there were no minimum speed. The pilot turns on the anti skid in the slot, the control box doesn't receive the signal from the wheel sensors and instantly shuts off power to the valve..NO BRAKES.

Given the fact that my memory is the second shortest thing I've got and the number of different airframes I work, I can't recall where/how the speed is sensed. I want to say it's a function of the anti skid control box receiving the initial signals from the wheel sensors but I could easily have the wrong airframe.

OC

Some days it's hardly worth chewing through the restraints

<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>
Which raises the question to me- How does it pulse during a launch so we can check it when the jet is obviously going 0 knots. Or is there no minimum speed?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

Jack the pulse during launch is nothing more than the pilot pumping the brakes with Anti Skid switch on and Anti Skid switch off....

Faugh ah Ballaugh -Clear The Way

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Faugh ah Ballaugh ~ Clear the Way

Yup, the right system charges the emergency accumulator.

The anti-skid arms up after the wheels spin up to 25mph and disarms passing through 15. At least I think those are the numbers.

Coach

<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote> Jack the pulse during launch is nothing more than the pilot pumping the brakes with Anti Skid switch on and Anti Skid switch off....<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
Oh, I always thought they had the switch on and held the brakes and then off and pumped the brakes.

Liberalism is a mental disorder.