All About Engines

12 All About Engines a way that while the balls can rise or fall, they are forced to swing round when the main rod is turned. Two other rods are pinned to the balls and to a collar round the main rod. This collar is connected Fig. 8.—Simple form of governor to a valve in the steam pipe, by which the steam can be “ throttled,” so that 1 a smaller quantity passes to the engine. The main rod is driven from the engine through pulleys and a belt, and toothed wheels. If the speed of the engine increases, the balls fly out- wards, lift the collar, and shut off some of the steam. When the speed of the engine decreases the balls fall, the throttle valve is opened wider, and more steam passes to the engine. Every engine is constructed to run at a certain speed, and the governor is designed and adjusted to cut off steam when that speed is exceeded. Like the flywheel it acts as a policeman, not, however, in keeping the parts moving, but in preventing rushes. And, like the flywheel in another respect, it needs power to drive it. The governor on the engine in Plate i is of a different type, though the principle upon which it acts is the same. It is called a Pickering governor, and there are three balls mounted on flat steel springs