On 06/21/2010 04:12 AM, Karl Townsend wrote:
I had dropped a project and just finished it this weekend. Only one thing
left on the big trailer, making the ramps narrower so I can load the
forklift.

Anyway, I now have a trailer brake controller based on brake line hydraulic
pressure.
http://www.brakecontroller.com/maxbrake.htm
The trailer brakes come on just before the truck. For those that don't
remember every one of my projects, this is a 24,000 lb. double dually
thirty six foot trailer.

My question, this unit has a gain setting 0 to 1000 for weight on the
trailer. Set it too high and you skid the trailer tires. Other than looking
for smoke, is there a good way to set this gain? I want to come up with a
really good number for empty, and also only the forklift on.

Karl

I diddle with mine until it "feels right".

My trailer's brakes are odd, in that they start normal, then wind up
harder and harder, so I have to pulse the truck brakes if I'm trying to
stop gently. So "feels right" is a quite perceptible difference from
the trailer brakes at first, but no smoke from the tires unless I've
been on the brakes for several seconds. With better brakes on the
trailer, "feels right" would be an attempt to nicely balance the brakes
between truck and trailer.

It's easy to do once you've done it a few times -- I wouldn't spend much
time coming up with an algorithm for it.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com