[TR] Jake Brake: was 'free wheeling'

[Randall]

> This close to being right?

Close, except for the water-cooled part.  As I understand it, the classic
"Jake Brake" was an extra exhaust valve that opened at TDC after the
compression stroke, releasing the compressed air in the cylinder so the
engine would absorb energy both to compress the air (before the valve
opened) and to pull a vacuum during what would normally be the power stroke.

They make a lot of noise in the exhaust, and have been banned in many
communities; hence the signs one occasionally sees saying "No compression
braking" or "No Jake brakes".

However, "Jake Brake" is a brand name, and that company offers many newer
designs that aren't as noisy, so there has been a certain amount of
controversy on the subject.

-- Randall