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Inverted brake reservoir

Tbone

Tbone

Well Known Member
What do "proper" brake reservoirs look like designed for sustained inverted flight? Are they vented? :rolleyes:
 
Mine has the vent on top with a piece of tubing going up, doing a 180 and ending below the bottom of the reservoir.
 
Cap it

Use a "reservoir dog" cap. Has a ball bearing that blocks the flow.

Yeah no brakes while inverted (unless you remember airshow Pitts "Double Take"?) but it will still spill fluid out. Needs to be addressed or will create a mess.
 
humptybump said:
I don't imagine there's much need to use brakes while inverted.
Click to expand...

Not any mention about using brakes just wanted to know how the reservoir retained the fluid DURING sustained inverted flight. I knew there would be one in the crowd.:cool::D
 
Grease Zerk

sjhurlbut said:
Use a "reservoir dog" cap. Has a ball bearing that blocks the flow.
Click to expand...

Or you could be really cheap like me and screw a grease zerk in the top of the reservoir for the cap. Same thing... spring loaded ball check.

Joe
 
Caveman said:
Or you could be really cheap like me and screw a grease zerk in the top of the reservoir for the cap. Same thing... spring loaded ball check.

Joe
Click to expand...

Not the same thing. If the ball is controlled by gravity, it's open when +g and closed when -g. Spring loaded is closed all the time, which doesn't allow air to replace depleted fluid.

Tony
 
Tony Spicer said:
Not the same thing. If the ball is controlled by gravity, it's open when +g and closed when -g. Spring loaded is closed all the time, which doesn't allow air to replace depleted fluid.

Tony
Click to expand...

Hi Tony,
Aren't all grease zerks spring loaded as in this video? Maybe, I'm misunderstanding. Are you saying the other systems don't have the spring? Enough air reserve in the reservoir on top of the fluid seems to make air in and out a non issue for me. Been flying this way since 2008 and absolutely no brake problems to date.
https://m.youtube.com/watch?v=LlxUivUTcq0
Sorry if I'm mistaken. Don't want to mislead anyone but this simple set up has worked well for me and is inexpensive. Maybe I just got lucky and got the right zerk.
Joe
 
Last edited:
Yep, they're spring loaded to the closed position. Grease, or in your case fluid forces the ball back against the spring and fluid can flow into the reservoir. The problem is when the fluid level drops, air must enter to replace the missing fluid. If that doesn't happen, a vacuum is formed in the reservoir. The fluid flows to the brake cylinder via gravity. What you have is the same as dipping a straw in water, putting your finger over the end, then removing the straw from the water and watching in amazement as the water stays in the straw. You've just been lucky. Best to replace the zerk with a vent.

Tony
 
Tony Spicer said:
Yep, they're spring loaded to the closed position. Grease, or in your case fluid forces the ball back against the spring and fluid can flow into the reservoir. The problem is when the fluid level drops, air must enter to replace the missing fluid. If that doesn't happen, a vacuum is formed in the reservoir. The fluid flows to the brake cylinder via gravity. What you have is the same as dipping a straw in water, putting your finger over the end, then removing the straw from the water and watching in amazement as the water stays in the straw. You've just been lucky. Best to replace the zerk with a vent.

Tony
Click to expand...

Thanks for the explanation. My personal theory is more along the lines that the piston causes pressure to move the puck and gravity isn't too much of a factor. If a vacuum tries to form in the reservoir it overcomes the spring pressure and let's air in. I've never noticed either a pressurized reservoir or a vacuum when removing the zerk to check fluid levels and I don't loose fluid from the cap. I have about 435 hours on the 7 and have replaced pads twice. I have no brake sponginess or other issues. BTW, this wasn't my idea and there are others flying with this set up. It works fine, for me at least. I promise to report back if I develop brake problems. I'm gonna stick with it unless someone using it reports a problem.
 
Use a Zerk.

I'm with Caveman. Been using this setup on my Pitts for years and my RV-8 for a year now. No leaks. I also use a zerk for the vent on Marv's smoke tank for my 8. Seems to let air in as I use the smoke oil. No issues.
 
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