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Anyone have a design of a parking brake system for Onex. Letting the oil warm up limits other functions when holding the brake lever. Thanks in advance for any ideas.

pvs wrote:Anyone have a design of a parking brake system for Onex. Letting the oil warm up limits other functions when holding the brake lever. Thanks in advance for any ideas.

I have hydraulic (Tracy O'brien) brakes on my Cleanex with the handle on the stick. I simply use a velcro strap to keep the brake handle engaged while warming the engine up. I do have to give it a bit more squeeze when doing a full power run up with the 120 HP Corvair engine. Not sure how the Onex brake handle is set up ...

Dale
3.0 Corvair/Tailwheel

Not Onex specific - but here is my parking brake:


The lever for the Sonex master cylinder is on the right, flaps on the left. You can see the brake handle will slide against the ramp, and then when you get past the ramp it will lock behind it and stay there. Was per the plans. This works great.

One caveat: I had to wrap the handles in stainless as I was wearing a groove in the handles.
viewtopic.php?f=3&t=7835&p=59596

If you have hydraulic brakes, Matco makes a nice little parking brake valve. I use it on my Sportsman but I've not yet felt the need to install one on the Sonex.

https://matcoals.com/product-category/p ... eservoirs/

BRS wrote:If you have hydraulic brakes, Matco makes a nice little parking brake valve. I use it on my Sportsman but I've not yet felt the need to install one on the Sonex.

https://matcoals.com/product-category/p ... eservoirs/

A valve is probably the best solution for convenience. The downside of our setup is sometimes it is hard to pull the brake all the way back to the stop. We use a wooden wedge if we can't get it pulled back. You need a lot less brake to hold the airplane on a flat surface in no wind as compared to a full-power runup, and the valve will let you select how much force you put on the brakes.

BRS wrote:If you have hydraulic brakes, Matco makes a nice little parking brake valve. I use it on my Sportsman but I've not yet felt the need to install one on the Sonex.

https://matcoals.com/product-category/p ... eservoirs/

I believe the Sonex hydraulic brake package comes with a parking brake valve.

Yes, I discovered that I couldn't hold my Onex with the standard hand brake during 2000 rpm runups. My fix was to add a foot brake in between the rudder pedals. I welded a alum foot pedal to an alum tube. Mounted it in the middle, just in front of the rudder pedals, ran the tube through two tubing clamps over to the left side. Added a six inch arm to the end of the tube and tied it to the hand brake arm with a short rod with bent ends. There are too many things to do with your left hand during a runup and the foot brake was the answer.
I put a row of holes in the lever on the end so I could change the position of the connecting rod to increase or decrease the amount of throw and leverage.