Date:Sep. 07, 2020

Hours:1

Brief Description:Built a pressure brake bleed system.


Better mouse trap to bleed the brakes!

The differential brakes on the RV-10 are rather important for steering at slow speed.  The castering nose wheel will not do much for you nor will the rudder as it is not effective at low speed.  This is where the brakes are paramount to success!  While at the hangar I noticed a puddle of Royco 782 hydraulic fluid below the right wheel pant and discovered that the caliper was leaking.  No big deal but definitely an issue that grounded the flight.  After replacing the AN6230B-2 O-RING (MS28775-224) on the caliper that had failed I used a 9oz high pressure oil can pump oiler connected with a clear plastic tube (cut from a Mountain High cannula) to recharge the system by pumping fluid through the caliper up through the right side brake cylinders to the reservoir.  I got a bit tired of hand pumping the oiler can but did successfully purge the system of air.  A few times the hose popped off the bleeder screw and it made a huge mess.  I decided a better solution must exists and found the ATS Brake Bleeder Tank (PN 225DX) but after looking at it I had a few issues with it.  (1) The hose from the tank to the bleeder adapter is black.  How would one be able to see if a steady stream of fluid absent of air was going through this black line? (2) There appears to be no pressure release aside from unscrewing the pump handle from the tank.  (3)  There is no way to know how much pressure is in the tank so you would pump and pump without knowing much pressure it was making and no option to pressurize using an air compressor.  I think consistency would be a challenge.  (4) $100 seems just slightly rich for their system with the faults I found and would need to remedy to bring it to my standards.

As the brake fluid I use comes in quarts I wanted to be able to have the remainder of a previous quart in the jug while being able to add a new quart into it without needing to store any additional fluid in the original metal can the fluid came in as the cans do not come with a removable lid and are opened by puncturing a hole in them.  I also did not want a jug that would take a bunch of space to store on the shelf.  I ended up with a half gallon jug.  Just the right size.  With a 1/2 gallon sprayer in hand, next up was to replace the standard black tubing that came with it and throw away the sprayer wand.  I measured the supplied black tube and found that  3/8″ O.D. x 1/4″ ID clear pvc tube is an exact replacement for the black tube.   (1)  Unscrew the existing black plastic tube/suction tube retainer nut from the jug, gently disassemble (see picture below), and replace with a 3′ section of the clear pvc tube and reassemble.  (2) On the free end of the pvc tube add a 1/4″npt x 1/4″ barb and 1/2″ hose clamp.  (3) Onto the free end of the with the 1/4″ npt threads, install a 1/4″ ball valve.  (4) Onto the free end of the ball valve install a female 1/4″ npt  brass industrial coupler.  (5) Purchase and install an ATS brake bleeder adapter of your choice.  They come in (2) styles – (1) Cleveland brake bleeder and (2) Universal.  If you did not want to purchase an adapter it would be possible to simply put another barb on end of the ball valve and install a piece of clear plastic hose that you would push onto the bleeder screw and hold  in-place while operating the system.  I would also install a spring clamp to help hold it on while servicing the fluid.  For roughly $30 I think the bleeder adapter is worth the cost of admission as cleaning up the mess I made using a simple hose hooked to the bleeder screw was no fun this last round when I was using the hand pump oil can.

OPTIONS

(1) Pressure release/compressor pressurization port  – If you want to be able to release the pressure in the jug when not in service it is necessary to install a valve of some sort that is not hooked to the siphon tube inside the jug.  The cheapest and easiest method of doing this is a valve stem from a car/truck/trailer rim.  I chose a steel stem as that is what I had laying around but a rubber stem will work just the same.  Simply drill a hole in a relatively flat portion of the jug and pull the valve stem though the hole.  Make sure it seats well.  If you have a metal stem you will need to put the associated nut/washer on and tighten.  If a rubber stem, once it is seated it requires no additional work.  I have a really slick tool for threading the valve stem into the hole (see picture).  It works very well. 

(2) Pressure gauge – If you want to be able to read the pressure in the jug it is necessary to add a gauge.  I used a 31/64″ bit and drilled a hole into a flat portion on the jug.  Into the new hole I threaded a pressure gauge I had laying around and made sure it was extremely snug.  I brought the pressure up to 50 PSI in my tank and let it sit there for a few hours out of the way.  It handled this pressure fine so I suspect the 25-30 psi I will be operating at will be adequate.  It takes approx 35 pumps using the supplied pump handle to bring the pressure up to 25 psi.

 

 

Finished tank (minus bleeder adapter) – It is important to note the valve will swing AWAY from the industrial coupler to turn the flow on as there is more room away from the coupler to operate/swing the handle.

 

 

Siphon tube assembly removed from jug with siphon tube absent from assembly.  

 

Siphon tube removed and small portion of supplied black tube showing what re-assembly will look like once black hose is replaced with clear PVC hose.  Note the white nipple in the picture is backwards.

 

31/64″ hole drilled to install steel valve stem. Super awesome valve stem threading tool which consists of a handle, wire, and brass insert designed to thread into the schrader valve.  It works great.

 

Metal valve stem installed, and currently blowing out plastic remnants from drilling new hole.

 

Parts (approx $60 excluding pressure gauge) and links –

Jug (Tank Sprayer)

Metal Valve Stem

Tube

Barb

Ball Valve

Industrial Coupler 

Brake Bleeder Adapter (Cleveland, Universal not shown)