TOY: Re: hydrauic "line locks"

["Scott Ellinger" <ellinger@xxxxxxxx>]

> I know the rear proportioning valve is somehow tied into the front brakes,
> right?  So if I were toput a lock valve in the brakes, is it correct to put
> it in line with the rear feed right under the m/c, or is there a problem I am
> not seeing?

Yes.  There is a problem with that.  It won't hold, the minute you step
off the pedal, your rear pressure will hit zero.

The LSPV has a "sensor" line that runs from the front brakes to the
LSPV; it senses the front brake pressure.  It meters the rear brake
pressure as a percentage of the front brake pressure, based on the
height of the prop rod (on the axle).

Net result: zero front brake pressure = zero rear brake pressure.  If
you don't put a linelock in the front brakes as well, the minute you
take your foot off the pedal, the LSPV will see zero front brake
pressure.  Obviously, any percentage of zero, no matter where the
prop rod is set....

I put my linelock in the front brake line.  Since I have no LSPV any
more either, it's not an issue, and I'm thinking about getting another
linelock for the rear brakes (trying to hold 5200 pounds on a hill with
only two stock brakes is marginal) but haven't yet.  I do have a prop
valve, but it's an adjustable circle-track unit, not a Toyota item.

--scott  ellinger@frii.com
http://www.rockstomper.com