> As to the evolution of the Brake equipment yes the ABD came out in 1964 and has been modified and now there are other variants out there.

ABDW added the Wilson attachment to ABD in order to obtain continuous quick service (ABDW is now obsolete) and ABDX/ABDXL, in which continuous quick service is incorporated in the control valve mechanism itself.

> One of the things the ABD valve did was to add a quick release feature

"Accelerated release", which dumps emergency reservoir air into the brake pipe, helping to raise its pressure at the rear end of the train whenever the engineer releases the brakes. "Quick release" refers to the pulling the manual bleed rod (and then letting go of it) to release the air pressure out of the brake cylinder.

> truck mounted brakes also have made a difference.

How so? On a car with a standard brake cylinder and foundation brake rigging, the handbrake applies the brakes on both trucks. With truck mounted brakes, the hand brake applies the brakes on only one truck.

> ABD brakes and QuickClips release

"ABD"= "Automatic, Balancing, Diaphragms". Never heard of such a thing as a "quick clips release".

> if you bottle the air to quick and the air bounces back into the train line you get a wave of air which could cause them brakes to start releasing

What a pressure surge does is cause the first few triple/control valves on nearest the closed angle cock to move to the release position. The specific consequences of this depends on what kind of control valves are on the rest of the cut cars. I've had this sort of thing happen with H and K triple valves.

> and as they release with the quick release feature more air is added to the train line from car reservoir which adds to the wave and more brakes start to release and then if there are no hand brakes the cut will roll away. That's why it is important to tie hand brakes before you cut away and not potted the air and do a pull test per FRA regulations too see the cars stay put.

Once a brake application has been made, anything which will cause BP pressure to rise about 1 1/2 lbs above aux reservoir pressure will trigger a release in triple/control valves (all models). This can be caused by the pressure wave you mention, moving the brake valve to release, defective operation of the brake pipe pressure maintaining apparatus, or a leaking valve seat in a control valve. "Bottling the air" is not a wise thing to do with today's RR cars.

K triple valves (and AB control valves) have retarded release and retarded recharge, which slows the release and recharge actions on the end of the train connected to the brake valve to allow the other end to catch up. ABD (and successors ABDW, ABDX, and ABDLX) discarded retarded release in favor of accelerated release. Both methods are slightly different ways of coordinating brake pipe pressure increases at the ends of a train during releases. Without them, trains of over about 40 cars wouldn't be practical.