A. Would remove (1) one of the lead wires from the binding post at dynamo; if trouble was in dynamo you would not note any difference in action of speed. (2) Would disconnect one of the cab wires; if the trouble is in cab circuit, speed would increase and lamp would burn. (3) If trouble is not in cab circuit, would go to lamp, disconnect one of the main wires from binding post; if short circuit is in the wires between dynamo and lamp, there would be no change in speed of dynamo, but if the wires are O. K. the speed of engine would increase and your trouble would be in the lamp.

=Duplex locomotive stoker=

1.  Q. Of what does the driving mechanism of a Duplex Locomotive Stoker consist?

A. It consists of a steam cylinder with reverse head and valve arrangement similar to the steam end of an eleven inch Westinghouse air pump.

2.  Q. How is the power controlled?

A. The speed is variable, and by turning the valve controlling the engine steam inlet, can be made greater or less according to the amount of coal needed.

3.  Q. For ordinary operation, how much steam pressure is required?

A. About fifteen pounds, with piston strokes varying from 10 to 15 per minute.

4.  Q. How can the duplex stoker driving engine be started, stopped, or reversed?

A. By means of operating and reversing rod, fastened to the back head and connected with the valve on reverse head of engine cylinder.

5.  Q. How can the conveying screws be started, stopped, or reversed separately or together?

A. By ratchet and pawl arrangement controlling each.

6.  Q. What practice should be followed in building up the fire before leaving a terminal?

A. Build up a light even fire by hand and do not bring stoker into use until the locomotive is working steam.

7.  Q. How should the stoker be oiled and operated?

A. It should be thoroughly oiled before leaving the terminal, then see that operating rod on back head is in center or running position, open main jet line so they register about fifteen pounds on the jet steam gauge if coal is coarse, or ten pounds if coal is small.  Next, the driving engine steam valve should be opened wide and the throttle valve opened just enough to supply the proper amount of coal to the fire-box.

8.  Q. How is the distribution of coal over the grate area accomplished?

A. By means of a low-pressure constant steam jet located in the back and bottom portion of each distributor elbow, as indicated by its individual pointer on steam gauge.

9.  Q. By increasing the jet pressure, will more coal be carried to forward end of fire-box and against the flue-sheet?

A. Yes, it will, and by decreasing the jet pressure more coal will be fed at middle and back end of fire-box.

[Illustration]

10.  Q. Can the fireman direct the even distribution of coal in the fire-box?