railfilm wrote:Does anybody knows the operation of the booster?
No, not really - but from my theoretical knowledge... maybe this helps - but I would be glad if someone could correct it.
How did they engaged them and what was the procedure to disengage them?
Well, Boosters come from "starters" or "turners" - huge engines, usually stationary steam engines cannot start by themselves, because having no starting valves like in locomotives. So to start such multiple expansion engines you'll have to turn the high pressure piston in a starting position, usually 10 to 30 degrees after top death point.
This was done with huge levers, which were clicked in, and notched the flywheel around bit by bit, or later with so called starter engines.
Some marine engines were kept slow turning when in port, just to ensure optimum lubrication of of the shaft bearings and the often huge gears, thus here small steam maintenance engines, so called "turners", were fixed to the main engine frame, able to turn the main crank shaft slowly for maintenance, and also to ensure lubrication of the bearings of the main shafts.
Both steam engines were coupled in to a cog wheel. The cog geometry was so designed, that if the starter or turner was running faster than the main shaft - thus power flow from the auxially engine to the main engine flowed, the power was properly transfered. So we have the front face of the cogs of the starter or turners pushing against the back side of the cogs of the main shaft cogwheel, transfering the power. But as soon as the main engine or main shaft was running faster, the front face of the cogs of the cogwheel on the main shaft pushed the back face of the cogs of the starter or turner cogwheel, and because of the different cog geometry this pushes the cogwheel of the turner or starter out of traction.
So in boosters you have the same.
The engine starts, and a spring loaded system holds the booster in traction.... the engine speeds up, and as soon as the locomotive speeds exceeds the turn limits of the booster engine, the main axle cogwheel uncouples the cogwheel of the booster on the same system, as the cogs pushes the cogs from the booster shaft cogwheel out of traction, and releases the lever lock which is spring loaded - the booster unlocks quick and with no further mechanical need. Manually disabling of the booster is allways possible, just releasing the spring loaded system, and the cogwheel of the booster gets uncoupled and the booster is shut off.
Allways keep two-thrid level in gauge and a well set fire, that's how the engineer likes a fireman