Stokers (Steam Locos)
Taken from a Q&A series on a web forum
Q) Can you tell us the difference between Duplex and BK stokers? I think I know part of the answer, the Duplex was the one with two feeds coming up either side of the firebox door, correct?
A) We will start with the Duplex. The Duplex had two elevator barrels coming through the cab floor at an angle on each side of the firebox door against the backhead of the boiler. They were fed by a conveyer screw from the tender to the elevators. At the upper end of the barrels about 1/3 of the way from the top were openings from the barrels to the fire box. At these openings were distributor plates. Above and behind these plates were steam jets that blowed the coal into the fire box. The fireman adjusted the jet pressure by valves in the steam line to the jets. You adjusted the pressure by starting the stoker with about 15 lbs.of jet pressure and observe where the coal was going in the firebox. After the fireman was satisfied, he would note the pressure on both jets and close the main valve to the jets. The pressure gauge for the jets was a duplex gauge and recorded both pressures on one gauge. These barrels operated on a ratchet and pawl system some what like a reel type push lawn mower. They would make a half turn, ratchet back, and make another half turn. If you wanted to reverse one of the barrels if something lodged in the elevator you lifted the top up as far as it would go and the ratchet and pawl was reversed and the elevator reversed direction. If you did not want the elevator to turn you lifted the top up halfway and it would not turn. We would use the 3/4 in. hose used to clean the cab and water the coal to keep the dust down under the stoker top when we did not want that barrel to operate. There was another steam gauge next to the jet gauge that recorded the pressure to the stoker engine. These stokers fired light in the rear (that's the end where the fire box door is located) so the fireman usually built a small heel or ridge of coal along the rear of the fire box. This type of stoker was not the best but they got the job done. When I started some H-10s and all of the H-6 locomotives had the Duplex stokers.
The BK stokers were screw fed from tender to the firebox. About two feet from the fire box the conveyer came through the cab floor angling up to the fire box door opening The firebox doors (butterfly) closed on top of the stoker where it entered the fire box. On these stokers was a distributor plate about two feet wide extending into the fire box about 10 in. just below where the coal was discharged from the stoker into the fire box. The distributor plate had two curved ribs on each rear corner to direct the coal to the corners. Just above the distributor plate was 11 jets. Two for each rear corner and the rest covering the sides, front and center of the firebox. One row of jets across was for fine coal and the others for heavier bigger coal. As the coal came through the screw it came out in lumps around 1 1/2 to 2 inches in size. At the fireman's position were five jet valves and a main valve arranged like an arrow pointed down. Across the top, left to right was, left rear, main and right rear. Next left to right was left side, left front and center, right side, right front and center. At the point was the fine coal. This covered the entire firebox.
To start you closed all of the jets except the fine coal. Then you started the stoker and adjusted the fine coal to not quite reach the front of the firebox. Then both side and front jets, also not quite reaching the front. Then both rear jets. You would have to fine tune the jets when the engineer started working the engine pulling the train. This was a much better stoker because you had more control over the placement of the coal. You could roll a heel in the back by simply closing the jets and running the stoker until you had the size heel you wanted. Standard also made a model HT stoker that was a later model that I think was a much better stoker. You could do anything with the HT that you could do with a shovel concerning placement of coal.
Q) I have seen old photos of NYC cabs with the duplex which seemed pretty obvious from the two "barrels." I assume the only way you could "tune" each jet was to keep the fire doors open to watch?
A) The initial jet setting was done on the ready track. It did not take any real time and was a starting point. Sometimes you hit it right the first time. The harder the engine was worked usually pulled the coal forward and this was what you looking for when you fine tuned. The coal might be covering just right or you might have to reduce the total jet pressure a little. If you wanted to get a good look at the fire you opened the fire door and held it open with the pedal and if you wanted to look at the left side you placed the blade of the shovel vertical on the right side of the door causing draft to pull the fire away from the left side of the fire box.
This gave you a perfect view of the condition of the fire on that side and by placing the shovel on the other side you had a quick view of the entire firebox. On the Duplex the fireman had to shovel in the heel and maintain it at different times during the trip.
Additional) A little more on stokers. The Central also used the Hanna stoker of which there were two types, the S-f and the H-4. The Hanna differed from the Standard BK and HT in that it had only two jet valves, a sheet blast for fine coal and nozzles for larger coal. The delivery from the tender to fire door was by a screw in a conveyor. On the S-f there was a side screw on each side at the fire door to give an even distribution of coal at the distributor plate. I only know of one engine in our area with this type of stoker. It was an L-2 4-8-2 #2706 and was the fireman's friend.
This engine had a good water pump and was an easy steamer. When the engineer had the engine running on almost level track and on the Michigan Branch it was still up and down, you could set the pump and stoker with the steam pressure about 5 lb under the pops and it would go 3 or 4 miles dropping 5 lb of steam up grade and pick it up going down On the H-4 stoker you did not have the side screws. On both models you controlled the amount of coal to the corners gates or slides The fireman could adjust these gates to any amount for the condition at hand. If the fire was light in the middle you could lift both gates throwing the coal to the middle. If light under the distributor plate, you cut way back on the fine coal. The two hands on the Duplex gauge were black for fine coal or low pressure and red for larger coal or high pressure. Wet coal changed the pressure needed more on these stokers than the Standard. Some of the H-10's had these stokers and did good job. One day I was having a little trouble with the fire and the engineer said that he reversed the jet pressure when he was firing this stoker. Normally the red hand was ahead. This was because the fine coal the black hand would have 10 lb and the red hand would have 15 lb. I reversed the pressures and always had a good fire with these engines.
I know I'm running on forever but one more thing. When we were on the B&O between North Vernon, IN and Jeffersonville IN they would run these H-10's as fast as they would go, and this was 68-70mph. From about 62 mph on up they would get what I called the popcorn shuffle. At these speeds the engine was getting out of balance and would start to shuffle like a popcorn popper on a stove. When they started this you shut the jet pressure off and rolled the coal in as if you were firing under normal conditions. The shuffle would move the coal from the rear to the front of the fire box as if you were using the jets. When you arrived at the house your fire was about 5 in. deep and flat as a floor, a perfect fire.
Maurice worked the Michigan Division from 1947-1981. He then worked on the Bee Line from 1981-1992. From 1947 until august 1950, he worked on the section at Shirley and Markleville. In 1950 he started firing on steam and then on through the diesels. Maurice said, "I had the pleasure of working with C. C. Staley and Ron Buser many times."