Brake System Parts List

[robcaldwell]

I'm sure it's somewhere, I've not been able to locate these in my plans, manuals and Bob book...

Do we have a list of parts for the brake system out there?

For my 4 Place Quick Build, I need to know the following:

- Total bulk length of 1/4" hard lines
- Individual lengths of flex lines.
- # and types of AN fittings
- Recommended firewall reservoir
- Recommended parking brake valve

BTW... I am using the RIDGID #377 37 Degree Flairing Tool. Very well made not and cheap like most flairing tools. It's been great for my fuel lines!

[Rollie]

I don't think there is a list, if there is I didn't find it. I just mocked everything up where I wanted to mount my reservoir and parking brake and routed the tape in a tape measure from one component or bulkhead to the next, where I planned to run line and wrote down each measurement and added up the total. I used nylon flex line from the reservoir to the master cylinders, then stratoflex from the masters to the park brake, then hard line from there, down through the floor to a bulkhead fitting where I went back to stratoflex, out to the top of the gear leg, into a bulkhead elbow in the top of the gear and hard line inside the gear legs with a loop at the bottom to absorb caliper movement. Some go back to flex line at the bottom of the gear.

Parking brake type is up to you. I went with Matco mostly because it was easy to order while I was ordering their wheels and brakes. Matco pros are that its inexpensive and simple, biggest con that I see is that simplicity, it is simply an inline valve, it opens or closes the flow of fluid in the lines and is controlled by a lever. It doesn't know or care whether the brakes are applied or not when it is engaged, either way, if it is engaged it blocks flow, meaning if you set the parking brake with the brakes off you can't use the brakes. More expensive parking brakes are sort of a one way valve where even if the brakes are set you can still apply more brake. It hasn't been a problem (except for one time I was trying to bleed the brake system and couldn't until I realized the park brake was on) There isn't a reason you would move the park brake to on in flight, but if you did, you wouldn't have brakes on landing. My mitigation for that is on my before landing check I verify the brake is off. Gives me something to check for the U (undercarriage) in the GUMP check.

Your question though was about lengths, type and number of fittings. I used the fitting that came with the reservoir, then the nylon line went to a T fitting (compression type for the nylon line) then to an elbow that went from compression to NPT in the top of the master, then a nipple (NPT to flare) out of the master to an elbow (flare to NPT) into the parking brake valve, then nipple (NPT to flare) coming out of the park brake, then a bulkhead fitting (straight, flare both ends) from there it was flex hose and went from the bulkhead at the front of the gear legs in a U shape and out to the gear legs, thats what the pic is to show, into the gear with a bulkhead elbow, down through the gear with hard line and into the caliper with a Flare to NPT elbow. Times 2 except for the T fitting.

I hope this is a little helpful, it was fun for me to remember what went into my brake system.

[robcaldwell]

Outstanding description, Rollie! I realize everyone have different lengths depending on their bird and desired routing. I am fortunate to live near Charlotte, NC where we have large parts houses for NASCAR. Most race cars use AN fittings and aviation material.

[jaredyates]

A Photo Guide to Hardware Shopping, Brake Line Edition

https://bearhawk.tips/2666

[robcaldwell]

There it is! I knew I saw this list somewhere. Thanks, Jared!

[Battson]

I was sure I posted a photo recently which answered this question. Either there are two threads, or something went wrong.

[Rollie]

I think that might have been in a very similar thread about fuel systems.

[svyolo]

Rollie;
If you really wanted to get cosmic, it would be pretty easy to install a small pressure switch in the brake line to detect brake pressure, and use that switch to turn on a light or LED in the panel to check for parking brake pressure. I guess you could also use ti to check the brakes before each landing. This would also check for other problems like a loss of too much brake fluid. Most larger planes I have flown have either a light, a brake pressure gauge, or both. Just a light would be more than enough. At least for me. I am pretty sure I won't have this on the first flight, but maybe down the road.

Parking brakes aren't trusted for any long period of time. Even with a brake accumulator, the pressure bleeds off over time unless you turn a pump on occasionally. They are pretty much just trusted to hold the plane until chocks are put in position. Countless airplanes have been damaged over the years due to a lack of chocks, and the brake pressure bleeding down.

[robcaldwell]

I was sure I posted a photo recently which answered this question. Either there are two threads, or something went wrong.

Would love to see photo! I did a thorough search of the forum, as well as digging through all of my printed material, before posting my question/request for brake line parts list.

[Battson]

Its not the first time this has happened, I remember taking a photo on my brake system drawing. I will search for it.

[Battson]

I think it's necessary to design out what you are planning to build. Hard to figure this out in your head. There is no single design, in fact there are probably 50 different designs.

This is my design drawing. Because it's not an as-built drawing, don't use it without thinking about it first.
IMG_20180805_141022.jpg

Found it, Rollie guessed right - it was in a sub-discussion of the fuel lines thread.

[robcaldwell]

Found it, Rollie guessed right - it was in a sub-discussion of the fuel lines thread.

Beautiful! Thanks so much!

[Archer39J]

Its not the first time this has happened, I remember taking a photo on my brake system drawing. I will search for it.

Did you end up using nylaflow on the pressure side? I thought I read somewhere you mention only using it on the reservoir side.

[Mark Goldberg]

I have personally seen nylon lines fail twice (pressure side) on brake lines. Once because of rubbing and once because the brake disc got hot and melted the nylon. While technically the specs say nylon should work fine- I recommend nylon just for the feed from the reservoir to the master cyls. Mark

[geraldmorrissey]

Curious about venting the reservoir. Is there a one way check valve or just an open vent?
Thanks
Gerry

[Battson]

Did you end up using nylaflow on the pressure side? I thought I read somewhere you mention only using it on the reservoir side.

That was my original design ethos, but I have ended up a short run on the pressure side. Once it hits the park brake value it's hard line the rest of the way.
I put a second skin over it, to protect it from rubbing. I plan to change it every ten years or so, because its cost effective to change. However, after 600 hours of use they show no signs of wear and tear whatsoever.

[Battson]

Curious about venting the reservoir. Is there a one way check valve or just an open vent?
Thanks
Gerry

I started with an open vent but that leaked far too much with negative g-forces in turbulence. So I replaced it with a solid plug. It still leaks through the threads!

[geraldmorrissey]

I guess I'm missing something. Doesn't a hydraulic system need a vent like a fuel system? The fluid travels through the pipes to fill an expanding volume at the caliper. With no vent, wouldn't a vacuum be created at the reservoir when the brakes were applied? It's probably obvious but I don't get it. Is the volume of fluid required to lock the brakes so small that the vacuum created in the reservoir is inconsequential?
Thanks
Gerry