What's new
Van's Air Force

The definitive Van's Aircraft support community! Buying, building or flying an RV? Join our exclusive family of mentors and enthusiasts!

Push Fittings on Low-Pressure/Reservoir Side of Brake System?

Tall_Order

Tall_Order

Well Known Member
Patron
On the HIGH pressure side of the brake system, it looks like it is appropriate to go with high pressure hard-lines or perhaps custom pressure-hose.

However,

On the LOW-side (going between master cylinder suction and the reservoir), there is plastic hose similar to pitot/static hose. The plans have brass fittings but I am thinking the plans (at least on my model) pre-date the invention of these fittings? However sometimes I don't know what I don't know, but is this style of fitting interchangeable here? Anybody used them with brake fluid?
 

Attachments

  • PushFittings.JPG
    PushFittings.JPG
    238.5 KB · Views: 42
It’s been my experience that those are a great opportunity for leaks and/or air in the system.
My -6 has that setup. (Frustrating) I am in the middle of upgrades, this will be one.
My -8 has reservoir’s on the masters. (Leak/air free)

Eliminating the remote reservoir is nice, if possible.
 
Most of the fleet has the plastic lines per plans. If they leak, they were not done properly. Glad to see the push on though. That should reduce install error.
 
Richard Connell said:
Push on fittings are now spec for the 14 fwiw
View attachment 84847
Click to expand...
Yes you can use the plastic hose for the reservoir to master cylinder supply lines. Yes the pushlock fittings are the same a the DOT truck airbrake fittings, and some static lines. Yes MANY are out there and leak free. Some, are troublesome. We converted it all to teflon, to eliminate the possible leaks.
 
TS Flightlines said:
Yes you can use the plastic hose for the reservoir to master cylinder supply lines. Yes the pushlock fittings are the same a the DOT truck airbrake fittings, and some static lines. Yes MANY are out there and leak free. Some, are troublesome. We converted it all to teflon, to eliminate the possible leaks.
Click to expand...

What Tom said.

The leak rate for standard AN fittings and teflon hoses is zip ( a scientific term meaning it ain't happenin'). Plastic hose is for air lines. If they leak, at least it doesn't make a mess.
 
DanH said:
What Tom said.

The leak rate for standard AN fittings and teflon hoses is zip ( a scientific term meaning it ain't happenin'). Plastic hose is for air lines. If they leak, at least it doesn't make a mess.
Click to expand...
The push in fittings do not tolerate much side force before they start to leak
 
Like others have said, those fittings are fine for the reservoir side…and like has been mentioned, the small reservoirs on each master cylinder eliminate all the connections and hoses entirely! All of our airplanes have the master-mounted reservoirs - not a remote reservoir in sight!
 
I’d follow in Tom or Paul’s footsteps if I hadn’t done them per the plans some 20 plus years ago.
My comments are directed at those that say these fittings leak. Like anything else, assemble them incorrectly, and they might leak. Do it right and they are trouble free. Most of the issues I have seen is folks don’t use a proper tubing cutter leading to ragged and/or tubing ends that are not square. It is also important to properly insert the tubing into the fitting.
I have cylinder mounted reservoirs on the Bucker. They are a royal pain in the rear to check, but thankfully, it’s only been necessary at each CI where they get, conservatively, topped off.
When you’re dealing with distributing fluids, choose your poison.
 
Parker Prestolok fittings on 70 psi water cooling circuits on NASA high power microwave hardware. Hundreds of thousands of hours of operation with no leakage reported.
 

Attachments

  • IMG_8696.jpeg
    IMG_8696.jpeg
    2.1 MB · Views: 87
Tall_Order said:
On the HIGH pressure side of the brake system, it looks like it is appropriate to go with high pressure hard-lines or perhaps custom pressure-hose.

However,

On the LOW-side (going between master cylinder suction and the reservoir), there is plastic hose similar to pitot/static hose. The plans have brass fittings but I am thinking the plans (at least on my model) pre-date the invention of these fittings? However sometimes I don't know what I don't know, but is this style of fitting interchangeable here? Anybody used them with brake fluid?
Click to expand...

Yup - works great, doesn't leak. Used MIL-PRF-5606J and -83282 (i.e. Aeroshell Fluid 41, Royco 782)

https://ph.parker.com/us/en/product/composite-push-to-connect-fittings/w368plp-4-2
https://ph.parker.com/us/en/product/composite-push-to-connect-fittings/w369plp-4-2

IMG_0059.JPGIMG_0060.JPG

Kinda wonder why Van's tortured us with Home Depot brass plumbing fittings all those years ;)
 
bjdecker said:
Yup - works great, doesn't leak. Used MIL-PRF-5606J and -83282 (i.e. Aeroshell Fluid 41, Royco 782)

https://ph.parker.com/us/en/product/composite-push-to-connect-fittings/w368plp-4-2
https://ph.parker.com/us/en/product/composite-push-to-connect-fittings/w369plp-4-2

View attachment 84866View attachment 84867

Kinda wonder why Van's tortured us with Home Depot brass plumbing fittings all those years ;)
Click to expand...
As long as there is no strain on the hoses, they wont leak at the pushlocs.
 
Mikeyb said:
Parker Prestolok fittings on 70 psi water cooling circuits on NASA high power microwave hardware. Hundreds of thousands of hours of operation with no leakage reported.
Click to expand...
By any chance is that inside one of the DSN apertures?
 
RV7A Flyer said:
By any chance is that inside one of the DSN apertures?
Click to expand...
Yeah!
That’s an X/Ka feed used on the 34M BWG antennas that combines 100,000 watts of transmitter power and a cryogenically cooled receiver to the same aperture.
 
Taltruda said:
You want to eliminate the remote reservoir? I think the firewall side remote reservoir is nice.. easy to top off, easy to check.. the pedal reservoirs are not fun to service..
Click to expand...

On my -8, the forward baggage floor is removable providing reasonable access to inspect and service fluid levels.
IMO the gains achieved easily offset any downside. YMMV
 
Does anyone have a link to the cylinder mounted reservoirs? I'm about to start the brakes on my -8, bought an aerobatic remote reservoir - but I'd like to take a look at the options. I do like those push lock fittings! I've been using them for my RO system for years under 40/50 PSI without any trouble at all. It's important to cut the tubing flush and without crushing it.
 
Tall_Order said:
On the HIGH pressure side of the brake system, it looks like it is appropriate to go with high pressure hard-lines or perhaps custom pressure-hose.

However,

On the LOW-side (going between master cylinder suction and the reservoir), there is plastic hose similar to pitot/static hose. The plans have brass fittings but I am thinking the plans (at least on my model) pre-date the invention of these fittings? However sometimes I don't know what I don't know, but is this style of fitting interchangeable here? Anybody used them with brake fluid?
Click to expand...
Tall Order,
I elected to use these type fittings. They are rated to over 50 psi.
No leaks, and much easier to use.
You are correct, they were not yet invented when my -6A was conceived.
Daddyman58
 
The -8 is different, in that it's easy to relocate the reservoir to the corner of the baggage area. Whole lot easier to check than reservoirs on the master cylinders. That said, steel braided nylon lines, AN flares, and viton o-rings in the calipers generally means the only fluid loss will be a failed master cylinder.

Res.JPG

Firewall fittings which melt and release flammable fluids are not real smart. Same goes for plastic tubing in contact with the firewall. We should be well past this crap.

Melted Reservor Fitting.jpg
 
DanH said:
The -8 is different, in that it's easy to relocate the reservoir to the corner of the baggage area. Whole lot easier to check than reservoirs on the master cylinders. That said, steel braided nylon lines, AN flares, and viton o-rings in the calipers generally means the only fluid loss will be a failed master cylinder.

View attachment 84948
Click to expand...
Dan, thanks for posting this. What is that part that your reservoir line connects to that branches off to the two master cylinders?
 
Ben Ellis said:
What is that part that your reservoir line connects to that branches off to the two master cylinders?
Click to expand...

Hacked out of bar stock one evening, but you can do something similar with aluminum fittings, AN 826, 822, 910 for example.

P6020004.JPG
 
Ben Ellis said:
Would this fitting be suitable for the connection from the brake reservoir to the plastic tubing? It says it's for pneumatics, but this is a low pressure line.

Click to expand...
Ben, you 'can' as its basically a gravity feed from the reservoir. The seal is in the orings on the banjo bolt, designed for air systems, like DOT airbrake, not fluids. Idea is not allow any air to enter the supply side of the master cylinder. Also take into consideration movement in the hoses from the pedal system. Not that much of an issue on the RV8s, depending on the reservoir location. So your hoses may not flex at this connection. YEP, easy to pop in a nylon hose. If you really want to use a nylon hose, I'd suggest using a DOT compression fitting, designed for the hose.
 
You must log in or register to reply here.
Back
Top