Text 27099, 33 rader
Skriven 2009-02-01 07:02:02 av Bob Ackley (1:300/3)
  Kommentar till text 27031 av Roy Witt (1:397/22)
Ärende: Trailer brakes
======================
Replying to a message of Roy Witt to Bob Ackley:

 MvdV>>>> They are more complex than drum brakes, if only for the
 MvdV>>>> hydraulics. The drum brakes on trailers have no hydraulics, it is
 MvdV>>>> purely mechanical. and hence more susceptible to maintenance.

 BA>> I hadn't thought much about it, but it seems logical that surge
 BA>> brakes would activate on most any downgrade because the trailer would
 BA>> be trying to push the tow vehicle -

 RW> That's how they work, yes.

 BA>> and therefore on a long grade they would get quite hot.

 RW> They actually don't, as they automatically synchronize with the tow
 RW> vehicles brakes. Whatever temps the tow vehicle experiences, the
 RW> trailer would also experience.

So how do they stay cool then the tow vehicle is using engine braking
and not its own brakes to hold down its speed on a downgrade?   The
tow vehicle's brakes are not engaged and the trailer's surge brakes are.

I pulled a 36' travel trailer (GVW ove 10,000 pounds, 8800 on the axles
and 1800 on the trailer tongue, with electric brakes) from CA to NE and
was able to use engine braking only on most of the downgrades I encountered
on I-80.

 RW> A very good description of how they look and work can be found here:

I don't have Internet access here.

--- FleetStreet 1.19+
 * Origin: Bob's Boneyard, Emerson, Iowa (1:300/3)