On May 2, 2004, at 10:56, james.zito@ps.ge.com wrote:
> The big rig brakes are pneumatic not hydraulic. The reason they don't
> fade
> is that the brakes are pressurize to release no pressurize to apply.
actually if you look at a big rig dashboard you'll see a pressure gauge
for the brakes that shows what percentage of air pressure you're
letting off of them, so you know how much reserve you have to brake
harder. if you start using more and more, your brakes are heating up
and you're loosing braking potential - a handy thing to know.
> This
> is one of many reasons that truck drivers don't shut down the rig when
> stopping for a short time, it can take longer for the pressure to
> build back
> up than it took the driver to answer nature's call.
air tanks.... unless you open the water valves they'll hold pressure
forever, and with modern air driers water in the air system is pretty
uncommon.
I know at least Detroit and Cat recommend leaving their engines idling
for at least 5 minutes before shutdown to allow the turbo to cool - and
that's why trucks spend at least a little while idling. Most have an
auto-shutdown feature that will kill them after 8 minutes of idling
unless the driver intervenes, which makes this a simple thing to do.
> Also big rigs in panic
> stops and during long descents can and often do have their brake pads
> get so
> hot they catch fire.
I'm not sure I'd go as far as "often" but it's certainly not unheard
of. it doesn't take much to smoke 'em, either - and that will happen
in just about any big truck panic stop. Another drawback in a big
truck is the inability to park with hot brakes - the drums will easily
warp if the parking brake is set when they're very hot, so if you need
to stop mid-descent or after a panic stop or any other
braking-intensive activity, it's a good idea to trade parking brake
duties between the tractor and trailer every few minutes until they've
had a chance to cool some.
-- Mike Maskalans <http://mike.tepidcola.com/dodge/> 84 RamCharger 360 (parked) 98 Dakota CC 318 (Fixed!) mobile.612.618.4652 campus.585.274.2246 fax.360.364.3930
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