Cessna 172 Brake System

rickyrhodesii · August 24th, 2007, 15:58

I posted this in a different forum, but this is probably the most appropriate place for it.

Could anyone elaborate or point me to a reference on the C172 brake system?

The only information I can find on the brake system in the information manual. I understand the 172's hydraulic system is comprised of a hydraulically-actuated brake on each main landing gear. You push on the top of either rudder pedal and the brake discs engage and slow the plane.

How much pressure can the system withstand? What is the normal operating pressure range? Schematics anyone?

Any help would be greatly appreciated!

Polarbear · August 25th, 2007, 12:10

I believe the 172 is the same as most other Cessna single engine planes in that the hydraulic brakes are master cylinders under each of the pilot's rudder pedals. The co-pilot's rudder pedals are mechanically linked to the pilots so in effect the co-pilot is operating the pilot's pedals.

The max pressure is not really relevant, you would have to have some very strong feet to blow out the hydraulics unless a seal fails prematurely. There is no power braking, exactly what you put in is exactly what you get out.

The operation is as simple as hydraulics get. You press down on a incompressible liquid(in this case Mil-H-5606) and at the opposite end(in this case it is the brake assembly) puts the same amount of pressure on the brake pads causing the pads to rub against a rotor. There is no return lines,pumps, relief valves, or any other complicated stuff. To release the brakes simply let off the pedals and a spring pushes the master cylinder back releasing pressure from the brake assemblies.

I have no idea where any schematics are outside of the maintenance manual. However the system is so simple it is not worth really drawing one out.

If you are really interested from a mechanical side for the 172 or any older 100 or 200 series aircraft, you can purchase a maintenance manual for very cheap from http://www.mccurtaintg.com/. It is $20 for the maintenance manual, $20 for the IPC.

Joshrk22 · August 26th, 2007, 16:31

PB said it perfect.

Toe Brakes > Master Cylinder > Brake Lines > Brake Calipers > Brake Pads > Rotors

When doing the preflight I was taught that you want to check the brake assembly to make sure there is some play (without the parking brake set) because the brake rotors aren't perfectly aligned and aren't always straight so you don't want the pads to rub the rotors when you are rolling. Now with the parking break set, you do want the brake assembly to be tight.

August 24th, 2007, 15:58	#1
rickyrhodesii Senior Member Join Date: Nov 2005 Location: Southwest Asia... Posts: 406	Cessna 172 Brake System I posted this in a different forum, but this is probably the most appropriate place for it. Could anyone elaborate or point me to a reference on the C172 brake system? The only information I can find on the brake system in the information manual. I understand the 172's hydraulic system is comprised of a hydraulically-actuated brake on each main landing gear. You push on the top of either rudder pedal and the brake discs engage and slow the plane. How much pressure can the system withstand? What is the normal operating pressure range? Schematics anyone? Any help would be greatly appreciated! __________________ Rick

August 25th, 2007, 12:10	#2
Polarbear Senior Member Join Date: Nov 2004 Location: Indianapolis Posts: 387	Re: Cessna 172 Brake System I believe the 172 is the same as most other Cessna single engine planes in that the hydraulic brakes are master cylinders under each of the pilot's rudder pedals. The co-pilot's rudder pedals are mechanically linked to the pilots so in effect the co-pilot is operating the pilot's pedals. The max pressure is not really relevant, you would have to have some very strong feet to blow out the hydraulics unless a seal fails prematurely. There is no power braking, exactly what you put in is exactly what you get out. The operation is as simple as hydraulics get. You press down on a incompressible liquid(in this case Mil-H-5606) and at the opposite end(in this case it is the brake assembly) puts the same amount of pressure on the brake pads causing the pads to rub against a rotor. There is no return lines,pumps, relief valves, or any other complicated stuff. To release the brakes simply let off the pedals and a spring pushes the master cylinder back releasing pressure from the brake assemblies. I have no idea where any schematics are outside of the maintenance manual. However the system is so simple it is not worth really drawing one out. If you are really interested from a mechanical side for the 172 or any older 100 or 200 series aircraft, you can purchase a maintenance manual for very cheap from http://www.mccurtaintg.com/. It is $20 for the maintenance manual, $20 for the IPC. __________________ The only stupid questions are the ones you should have asked, but never did.

August 26th, 2007, 16:31	#3
Joshrk22 Newbie Join Date: Apr 2007 Location: MI Posts: 17	Re: Cessna 172 Brake System PB said it perfect. Toe Brakes > Master Cylinder > Brake Lines > Brake Calipers > Brake Pads > Rotors When doing the preflight I was taught that you want to check the brake assembly to make sure there is some play (without the parking brake set) because the brake rotors aren't perfectly aligned and aren't always straight so you don't want the pads to rub the rotors when you are rolling. Now with the parking break set, you do want the brake assembly to be tight.

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