Do the steam loco’s used for excursions (like RBMN) have a means to produce compressed air to stop their passenger cars? I understand that they use steam to stop the loco, but what about everything behind it?
There are definitely air compressors on steam engines. Look for a couple of vertical cylinders (usually) on the side or the front of the loco. They will be one above the other, and a close look between them will often reveal the moving piston rod.
If a steam engine is at rest, you’ll occasionally hear a “chuff” - that’s the air pump.
Some railroads liked to mount the compressors on their big locos on the front of the firebox - made for a pretty fearsome appearance. Others put the compressor assembly(s) behind covers on the front of the unit. Most often, though, you’ll find it on the fireman’s side of the boiler.
Aside from that, the brakes (and controls) are/were essentially the same.
American locomotives have not used steam driver brakes for many years. (Nor have they used steam for the power reverse, even though the British had notable success with steam (the Hadfield) since their brakes largely involved vacuum exhausting and not pressure air.
The general device used on any locomotive of particular size was the Westinghouse cross-compound air compressor, which was a two-stage device using steam pressure in relatively long expansion to make air pressure. These used only reliable enclosed valves and relatively cheap piston seals to work, and were highly efficient at converting steam mass flow to air at high pressure – more than any steam-powered rotary compressor would likely be. Two of these were used where additional volume – for example pumping up the reservoirs and main brake line on long cuts of cars or standing trains – was desirable. (In general the reason for two compressors was not redundancy, and was not ‘sequential compression’ to typical main-reservoir pressure as each compressor did this via compound expansion within itself.)
The considerations where to put these are interesting, as they could be physically located almost anywhere on a locomotive and did not have to be near each other. They therefore became a useful way to balance locomotives both longitudinally and ‘side to side’, with the further consideration that mounting them on increasingly high-pressure boilers could be a pain, but expensive and heavy bracketing would be needed to support them from the frame on either side; running them exposed to weather and various contaminants and impact damage could be bad, and the air they compressed had to be cooled and the condensed water in it separated and discharged. One ideal place was near the pilot beam, where a frame to hold them could be provided, shielding easily provided but maintenance access and inspection still easy, and cool air for a ‘radiator’ lighter and more effective than a few runs of brak