208 STEAM ENGINES 



in the same manner as a simple engine. To get the steam 

 into the low-pressure cylinder is, however, an operation that 

 will depend on circumstances. If the cylinders are provided 

 with pass-over valves, it will be necessary only to open them 

 to admit steam into the receiver and from thence into the 

 low-pressure cylinder. If the cylinders are not fitted with 

 pass-over valves, the steam can usually be worked into the 

 receiver and low-pressure cylinder by operating the high- 

 pressure valves by hand. Sometimes compound engines are 

 fitted with starting valves, which greatly facilitate the oper- 

 ations of warming up and starting. Usually a compound 

 engine will start upon opening the throttle. 



If the high-pressure crank of a cross-compound engine is 

 on its center and the low-pressure engine will not pull it off, 

 it must be jacked off. If the pressure of steam in the receiver 

 is too high, causing too much back pressure in the high-pressure 

 cylinder, the excess of pressure must be blown off through the 

 receiver safety valve; if the pressure in the receiver is too 

 low to start the low-pressure piston, more steam must be 

 admitted into the receiver. If the engine is stuck fast from 

 gummy oil or rusty cylinders, all wearing surfaces must be 

 well oiled and the engine jacked over at least one entire revolu- 

 tion. If the cut-offs are run up, they should be run down, 

 full open. If there is water in the cylinders, it should be blown 

 out through the cylinder relief or drain valves, and if there 

 is any obstruction to the engine turning, it should be removed. 



If the crank of a tandem compound engine is on the center, 

 it must be pulled or jacked off. If the high-pressure crank 

 of a cross-compound engine is on the center, it may or may 

 not be possible to start the engine by the aid of the low-pressure 

 cylinder, depending on the valve gear and the crank arrange- 

 ment. When the cranks are 180 apart, which is a very rare 

 arrangement, the crank must be pulled or jacked off the center. 

 When the cranks are 90 apart and a pass-over valve is fitted, 

 live steam may be admitted into the receiver and thence into 

 the low-pressure cylinder, in order to start the engine. When 

 no pass-over is fitted, but the engine has a link motion, suffi- 

 cient steam to pull the high-pressure crank off the center can 

 generally be worked into the low-pressure cylinder by working 



