David,
I don't remember having any trouble with my wife's horse trailer. Someof them had a lockout
pin or something, and it's also possible to design drum brakes so theydon't "servo" as much
in reverse. As you probably know, drum brakes are sorta "self-actuating"in that applying
pressure causes the shoes to "crowbar" or "help themselves". They canbe designed so as to
not do that much in reverse, only forward.

Disk brakes don't have this builtin "servo" action, which is why nearlyALL cars with disk
brakes have power assist.

<<Jim>>

David Newell wrote:

> The only thing that I saw in your response that we haven't alreadythrashed to death is
> that surge brakes were a bitch to back up cause the force of backingup turned the brakes
> on... Dave
>
> Jim Dunmyer wrote:
>
> > David,
> > I'm almost surprised that they used that sort of lashup that recently."Back in the
> > old days" there were many different schemes for actuating trailerbrakes. I actually
> > saw a system that used a slave cylinder that was actuated by thevehicle brakes and
> > was permanently plumbed into the system. You'd remove the cylinderfrom a bracket on
> > the bumper and snap it into place on the trailer, where it wouldactuate a master
> > cylinder that powered the trailer brakes. I've also heard of thesevacuum lashups.
> > Surge brakes, with the master cylinder on telescoping the trailertounge were popular
> > on many horse trailers and other applications, but I don't knowif they're still used
> > or not. The nice thing about surge brakes was/is that they alwayswork, no matter the
> > tow vehicle. All too many trailers are connected to a tow vehiclethat doesn't have a
> > matching hookup, so the trailer is being dragged around w/o ANYbrakes, and that's not
> > a Good Thing.
> >
> > Along the same lines, how do you folks go about connecting thelights? I've seen
> > "isolators" that power the trailer lights independantly so thesignals, taillights,
> > etc. aren't being fed straight from the light switch, turn signal,etc. Are these
> > necessary?
> >
> > <<Jim>
> >
> > David Newell wrote:
> >
> > > Acording to my '77 manual there was a Vacuum Hose connetion tothe tow viehicle
> > > which was controleed by a under the dash controller. I saw onein Dover Delaware
> > > on a 31 foot yacht. I don't know of anyone who is using thissystem I think
> > > Tapping into the vacume or hydaulic systems is not advised asit voids most
> > > warrantee's these days. My '77 has been convewrted to electricand I plan to check
> > > them out as soon as things dry out here in Mass. Dave Newell
> > >
> > > Jim Dunmyer wrote:
> > >
> > > > What actuates those brakes, do they use a surge coupler? (mywife's horse
> >
> > --
> >
> > <<http://www.oldengine.org/members/jdunmyer>>
> > <<jdunmyer@toltbbs.com>>
> > <<lower SE Michigan, USA>>
> > <<mailto:jdunmyer@toltbbs.com>>

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<<jdunmyer@toltbbs.com>>
<<lower SE Michigan, USA>>
<<mailto:jdunmyer@toltbbs.com>>