What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Matco Parking Brake Valve

wawrzynskivp

Well Known Member
Hello All,

If you are operating this valve you should know that we are supposed to put pressure back on the brake pedals when we release the valve. This action helps to ensure the O-rings do not get distorted.

So my habit of occasionally reaching into the cockpit to release a set 'parking brakes' was a bad practice.

I am having an issue with my valve that may be a result of this practice.
 
O-ring cutting

I have the same valve. My understanding of this issue is that by equalizing (as much as possible) the pressure on both sides of the valve before actuating it, you unload the o-ring seals. Not doing so subjects them to shear through the actuation and you risk cutting an o-ring.

Matco does sell a rebuild kit: http://www.matcomfg.com/PVRBDPVPV1PVPVDandPVPVSrebuildKit-idv-3745-8.html

And the MATCO website says:

"The PVPV-D works as a dual system resetable check valve. When the lever is moved to the closed position, fluid can flow to the brake but not return. The lever may be positioned prior to pressure being applied or when pressure is applied. The longest o-ring life is achieved by reapplying the brake pressure when the lever is moved to the open position but equalization is not required prior to release."

So, you can pull the lever, THEN press the brakes, or press the brakes THEN press the lever, and they'll be set. But to take the parking brake off, you should press the brakes, THEN set the lever.
 
Thanks for posting, Duck, that is good information.

I recently installed that exact valve on my biplane project and something else that seems worth mentioning is that the valve operates through a 45-degree arc without stops at either end. It doesn't seem all that intuitive and I remember scratching my head some and going back to the drawing a couple times to find that 45-degree range while rigging it. I believe it to be a very good valve, however.
 
Hello All,

If you are operating this valve you should know that we are supposed to put pressure back on the brake pedals when we release the valve. This action helps to ensure the O-rings do not get distorted.

So my habit of occasionally reaching into the cockpit to release a set 'parking brakes' was a bad practice.

I am having an issue with my valve that may be a result of this practice.

Maybe/ maybe not ;)

I have seen a similar situation on a new RV10.
Customer purchased the brake valve from a well known supplier (1st clue)
Plane was finished in hangar & about to go outside do engine start.
Tried to move the 10 & RH brake was locked on - released pressure at wheel caliper & checked pressure at pedals, including park brake on - release park brake & tried to move 10 again - RH brake still on...WT ?
Double checked park brake lever angles for open/closed = all ok .
Released pressure again & cycled the park brake = same result (2nd Clue)
Pulled new valve off & disassembled it carefully - bingo !!
attached pic shows the 'O' rings. LH is ok however the RH is huge in size in comparison - it was allowing one way flow of brake fluid however not the other way, go figure !! Matco advised they do not have ant O rings that size in store so I figured someone bought the valve, had a problem, tried to 'fix' it & then shipped it back for a refund .
Your issue may not be the same however it's worth checking out especially if the symptoms are the same :)
 

Attachments

  • file-2.jpg
    file-2.jpg
    368.9 KB · Views: 168
Now Marco has 2 parking brake valve.
1st one is the PV-1. It’s a solid block, the newer one is PV-D it swivels in the middle. Aside of that middle swivel is the newer valve better?
 
Now Marco has 2 parking brake valve.
1st one is the PV-1. It’s a solid block, the newer one is PV-D it swivels in the middle. Aside of that middle swivel is the newer valve better?

As per the Matco website — “PVPV-1 Park Brake Valve has been replaced by the PVPV-D. Most replacement parts are still available.” Otherwise ask Matco :D
 
Back
Top