5.  Q. Explain how a two-cylinder compound is changed from simple to compound.

A. Place the handle of the three-way cock or simpling valve in the cab so as to release the air from the cylinder of the separate exhaust valve.  A coiled spring will then close this valve.  This permits the exhaust steam of the high-pressure cylinder to accumulate in the receiver until sufficient pressure is obtained to force the intercepting valve into compounding position.  This shuts off live steam from the low-pressure cylinder and allows exhaust steam from the high-pressure cylinder to feed through the receiver into the low-pressure steam chest.

6.  Q. How should a compound engine be lubricated?

A. One-third more oil should be fed to the high than the low-pressure cylinder, using more oil at high speed than at slow.

7.  Q. Why feed more oil to high than to a low-pressure cylinder?

A. Because some of the oil from the high-pressure cylinder follows the steam into the low-pressure cylinder.

8.  Q. How would you lubricate the valve of low-pressure cylinder if the oil feed became inoperative on that side?

A. Feed an increased quantity through the oil pipe to the intercepting valve.  Shut the engine off occasionally and cut into simple position.  Oil will then go direct from the intercepting valve into the low-pressure steam chest and cylinders.  This would avoid going out on steam chest to oil by hand.

9.  Q. How much water should be carried in the boiler of a compound locomotive?

A. A very moderate level, never allowing it to get so high that moist steam will pass through the cylinders, because for satisfactory service a compound engine should always have dry steam.

10.  Q. How should a compound locomotive be started with a long train?

A. In simple position with cylinder cocks open.

11.  Q. When drifting what should be the position of the separate exhaust valve, the cylinder and port cocks?

A. Open position.

12.  Q. What will cause two exhausts of air to blow from the three-way cock or simpling valve in the cab when the engine is being changed to compound?

A. A sticky exhaust valve.  It does not move when air is first discharged.  The second exhaust comes when it does move.

13.  Q. What does steam blowing at the three-way cock indicate?

A. The separate exhaust valve not seating properly caused by stuck valves, a weak or broken spring, or the packing rings of separate exhaust valve leaking.

14.  Q. What can be done if the engine will not operate compound when the air pressure on the separate exhaust valve is released by the three-way cock?

A. The separate exhaust valve has failed to close.  Try jarring it with a hammer on the front side, near the exhaust valve.  With a bad case, take the valve out, clean it and replace, if not broken.