Air over Hydraulic braking system

From: Bruce Beattie (bruce@eecs.berkeley.edu)
Date: Sat Jun 16 2001 - 18:52:09 PDT


I have a M390C 2 Ton 2 Wheel Chassis Trailer which has Air over
Hydraulic brake system. I have restored it to almost like new, except
the paint job. I have adopted my F250 with the necessary cable hookup,
so all the lights work now. I installed an air tank and relay valve on
the truck, and will put in the glad hand receiver shortly.

What I need to know are the answers to the following:

1-Is the brake activation thru the relay valve linear. ie: If you
gradually apply air preasure to the service line, does this cause a
proportional amount of air released thru the relay valve to the diaphram
that is coupled to the master cylinder?

Or is it a binary action, that causes the relief valve to dump the full
preasure to the diaphram. that is coupled to the master cylinder?

2- What type of air supply is needed to adequately keep the tank
preasure at a safe level. Ie What preasure and CFM is required.

3- Can someone point me to where I could find a belt driven compressor
that will do the job. I would be installing it where my non existant A/C
would go.

4- Can someone also point me to where I can find the hand operated brake
activation mechanisim normally found in the cab, I have never seen one
so I am going by what I've read on this list. I am assuming that it is
some kind of air valve with a mechanisim to both send and release air to
the service port on the relay valve.

I don't need to have this tied into my regular brake system which is the
standard vacumn assisted hydraulic system, since this is realy as a
backup system for steep grades. I have a RTTY shelter mounted on the
trailer and it makes a fantastic camper. But since it is relatively
lightweight I don't need the full operating power of the trailer brakes
except on steep grades.

Sorry if this is a little long winded, but I wanted to get all the info
out there.

Thanks for any help on this project!

Bruce



This archive was generated by hypermail 2b29 : Thu Jul 05 2001 - 00:40:37 PDT