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.