Steam Engines. 



521 



651. Governor. In order that the speed of the engine 

 may he controlled it is necessary that the amount of steam 

 admitted to the cylinder 



should vary with the work 

 before the engine. To main- 

 tain a uniform speed there 



is provided a governor, one l J 



form of which is represented Iff// 



in Fig. 25o, whose action is 

 as follows : 



At the point 2 in the pipe 

 1 leading from the boiler 

 there is a valve which can be 

 opened and closed by the ao- 

 tion of the balls 4, which 

 are made to revolve by the 

 belt working on the pulley 



3. As the Speed of the en- FlG 2 53. -Governor of steam engine. 



gine increases the balls of 



the governor are made to revolve more rapidly and by their 

 centrifugal force bend the strips of elastic metal to which 

 they are attached outward, and this draws the upper end 

 of the spindle downward, partly closing the valve at 2. By 

 means of the spring at 5 the resistance the governor must 

 overcome to close the valve may be varied and in this way 

 the governor may be set so as to cause the engine to run 

 steadily at different speeds. 



652. lubricator. To keep the valves in the steam chest 

 and the cylinder well oiled, a special form of lubricator is 

 required, and one of these is represented in Fig. 254 and 

 is seen in place on the engine at 10, Fig. 249. This is 

 screwed into the steam pipe leading to the steam chest at 

 the threaded end H. The oil receptical is the cylinder 

 above I which must be filled bv removing F, but first clos- 

 ing E and G and removing I so as to drain out the water. 

 After returning I the oil cup is filled entirely full above 

 the level of the sight-feed D, when F is again closed and 

 E and G opened. 



