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Hawker Parking Brake Question

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Well-known member
Nov 27, 2001
For those a little brighter than myself, could someone that knows please explain this system a little better for me. There are several detent positions when setting the Parking brake for a Hawker 900XP/750 and I assume 800/850XP. One knotch after the Emergency position will actually set the parking brake but you can pull it back to the far aft position ( one more knotch )for maximum parking brake effect. To be honest, I only thought there were 3 positions using the parking brake lever; off, emergency and parking. Why would you have that middle detent parking brake position after the emergency position? I have looked in the FSI aircraft manual and read and re read the Parking brake system, but it doesn't quite explain the entire system. Anyone care to explain.
There are only 3 positions for the wheel brake lever. This applies to the 750/800XP/850XP/900XP, that I know. As far as the earlier models (700/800/800A) I am not sure but I can find out for you Monday.

The forward most one is called "normal."

Fully rearward is "park brake."

The middle position is the "EMERGY" position.

You are correct in that there are "clicks" when you go past EMERGY to PARK. Standard prodedure is to pull the lever all the way aft into PARK, not just one click.

Each "click" after EMERGY is a progressive parking position held by a pawl engaging into the notched rack.

What exactly does that mean?? I'll tell you Monday. ;-)
I used to think the Hawker system was just like any other Jet but it's actually master-slave-high pressure master-slave with a bar of sorts going across the servo rack to depress all of the high pressure masters at once hence the "parking" position. It would be great to see the unit out of the aircraft to see how it really works. Every now and then when you get to a dark aircraft and pull the handle all the way to park you hear what sounds like a mac truck pulling up next to you at a light. That's all the hydraulic servos and valvage moving around underneath you I think.
Since it's a lazy Saturday morning and the kids aren't wrecking the house TOO badly, I went down to my office (that is to say, the unfinished part of the basement with the water heater and furnace) where I keep all my Hawker books.

A little more....

As to the "WHY" you should pull the lever fully aft when you park the plane.

As you may recall, when you pull the wheel brake lever aft into the "PARK" range, pressure from both the emergency brakes and the normal brakes are applied. When you get 1000psi of pressure in the lines you get the white 1/2 or L/R lights on the panel. You don't know which system (emer or normal) is giving that 1000psi, and it doesn't matter. As long as you see the 1/2 or L/R you know you have 1000 psi. However, the "gotcha" is that FULL parking brake pressure isn't applied until you get to the last notch.
OK so the way I now understand the parking brake is like this; When you depress the button and pull the lever past the Emergency Postion, it acts similar to a Hand brake in a car, progressively applying pressure until the last notch is reached ( full aft) when max pressure is applied. Is that about it???
I got that "mac truck" sound recently, it was loud i thought somethin was broke.

You will get the "Jake Brake Sound & Rumble" if you apply the brake too quickly.

If you slow the speed of engaging the brake it will never scare you again.

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