On Dec 27, 4:18*pm, "Bob Gardner" wrote:

While its possible that someone does it, I'm not aware of any operator
that sets the brake on aircraft when its not occupied. Usually chalks
work just fine and are easier to move when you need to tow. In smaller
aircraft there are other reasons to avoid setting the brake, like
changes in outside pressure could burst the brake seals.

-Robert

Robert, out of everyone so far you are the closest. The brakes are
released as soon as the chalks in signal is recieved. This is mainly
done to facilitate brake cooling because airlines typicaly work with
45 minute turn times and leaving them set would greatly increase QTA
The brake temp actually peaks about 10 minutes after landing .the fuse
plugs can melt if the brake are left set . The 737 has a brake
acumulator which will sufice for several parking brake applications,
but chalks are still used for safety reasons . Just before push the
process is reversed, The parting brake is set before the tug is hooked
up and the chalks removed. Someone ask about brake pressures; the A&B
hydraulics run at 3000 LBS which is reduced to 300 at the gear (In the
event of a leak this prevents a total loss of fluid) I was not able to
open the link but I hope this helps.
FB