I see a damper of some kind on the engineers side of the engine right above the steam cheston my 3rd rail Penn K4. What is this for.
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Do you mean the linkage for the front end throttle?
Originally Posted by Ted Hikel:
Do you mean the linkage for the front end throttle?
PRR K4s locomotives did not have a front end throttle. Only K4sa, such as #612, had a front end throttle, and ONLY Kohs offered the K4sa model in O Scale 2-Rail.
If it's on the lower part of the smokebox, it's probably the superheater damper. The device would shut off the flow of hot gasses through the superheater flues when the throttle was closed. This prevented overheating of the tubes when no steam was flowing.
Locomotives with dampers had throttle valves inside their steam domes. When a throttle was opened, steam flowed from the steam dome through a dry pipe to the superheater header and flues to the cylinders. For 15-30 seconds, there was no exhaust or movement. When a throttle was closed, steam pressure in the superheater diminished.
The last three 2-8-2's purchased by the East Broad Top (16, 17,18) had piston valves and dampers. I remember seeing the damper counterweight move up and down as her throttle was opened and closed. A movie/video taken from the right angle at the right time would show that, too.
Front end throttles were a big improvement. Steam remained in the superheater flues and prevented overheating. That eliminated dampers. Also, locomotives responded as soon as throttles were opened and closed. Rich Melvin could comment about that.
yes this is what I meant, and not a front end throttle. that is up high on the boiler and NOT right above the steam chest and yes my early version of the 3rd rail k4 has the damper sitting right above the steam chest.
Originally Posted by ReadingFan:
Locomotives with dampers had throttle valves inside their steam domes. When a throttle was opened, steam flowed from the steam dome through a dry pipe to the superheater header and flues to the cylinders.
Well actually there is only one "valve" in a dome throttle, and when opened, the steam then does go through the superheater units. However the superheater units are inside the flue tubes. The steam does NOT go through the flues to the cylinders. Fire gases from the fire box proceed through the flues and tubes (a flue contains a superheater unit, while a tube does not) to the smokebox and are then expelled out the stack.
