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Old 03-02-2018, 06:42 PM   #24
daveinluray
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Join Date: Feb 2018
Location: Shenandoah Valley,Virginia
Posts: 48
Re: Proportioning valve question

Quote:
Originally Posted by RichardJ View Post
I don't understand why the English language is such a challenge for some on this board. Actually, not just this board, but throughout the automotive world.

com·bi·na·tion
/ˌkämbəˈnāSH(ə)n/

noun: combination; plural noun: combinations
1. a joining or merging of different parts or qualities in which the component elements are individually distinct.
"a combination of blackberries, raspberries, and rhubarb"


An automotive COMBINATION VALVE is THREE valves COMBINED into ONE unit. It is comprised of a Metering Valve, a Pressure Differential Switch and a Proportion Valve. Each of those three items serve different functions.

A Pressure Differential Switch that Andy showed you is a stand alone unit, that turns on the dash warning light and nothing else.
A Pressure Differential Switch in some form, is used on dual brake systems with drum/drum and disc/drum and disc/disc. It is used with power and non-power systems.

The first picture is a Combination Valve.
The second picture is the exact same thing, but as three individual units. This requires a lot of plumbing.
you missed a part but thanks for trying

"my truck is missing its combination valve(service manuals words not mine) and I have purchased one online new. Problem is it has an extra port (two) for the front. Can I plug one or should I get a different combination/metering valve?"

i will search further this evening for a better match when time is available but thought someone might have a quick answer to the outlets in question. but thanks anyways.so far they all come up with a valve that appears to separate outlets to the front brakes. but my math is simple too so i could be wrong.
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