Briefly, describe grease lubrication of a locomotive driving box. List the four common classifications of valves. List one reason why there is a slight offset in the bull ring which fits a similar offset in the packing ring. Packing rings are turned to a diameter slightly larger than the busing. When instead of adding to the exhaust edge of the valve, the exhaust edge can be cut away so that, instead of its covering the steam port when the valve is in mid-position, it would fail to cover it by a certain amount.
Locomotives built for slow freight service require only a very small amount of lead.
The following describes the valve conditions of one of the classes of service to which a locomotive might be put. Too much lead will decrease the pulling power of a locomotive at low speed. Briefly, describe how a smokebox-type superheater functions. In the most modern type of steam engine with stationary boilers and engines, utilizing all economy devices, and operating under the most favorable conditions, only of the heat energy in the fuel is converted into effective work. Besides the savings due to the prevention of condensation in the cylinders, superheaters also improve fuel efficiency by .