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.
15. Q. If the engine stands with high-pressure side on the dead center and will not move when given steam, where is the trouble, and what may be done to start the engine? Why?
A. The intercepting valve is stuck in compound position, so live steam cannot get to the low-pressure cylinder. In a case of this kind, close the throttle, open cylinder and port cocks; when all pressure is relieved, use a bar to move forward the rod that works through the oil dash-pot, thus moving the valve to simple position and steam will pass to the low-pressure cylinder as soon as throttle is open. The engine will not start, because with the low-pressure piston on the quarter, steam must be admitted to its cylinder to start the engine.
16. Q. In the event of a breakdown, how should one disconnect?
A. The same as a simple engine with separate exhaust valve open, so engine will work simple instead of compound.
17. Q. What may be done to shut off steam pressure from the steam chest and low-pressure cylinder?
A. To shut off steam from the low-pressure chest, pull out the rod that runs through the dash-pot as far as possible and fasten it in this position. Then open the separate exhaust valve.
18. Q. Is it important that air be pumped up on a two-cylinder compound before the engine is moved? Why?