SLIPPED ECCENTRIC-RODS.
Where slotted rods are used, they frequently slip, making the engine lame. The cause of trouble in such a case can be identified by moving the engine slowly, with the cylinder-cocks open. The disturbance to the regularity of the valve’s motion, caused by a slipped rod, will admit steam prematurely on one end of the cylinder, while it delays the admission on the other end. The valve is made to travel more on one side of the exhaust center than on the other. Lengthening or shortening the valve-stem has a similar effect, but this makes the engine lame in both gears; while the slipping of an eccentric-rod only makes the engine lame in the motion that the rod belongs to. This is subject to a slight modification, however; for the back-motion eccentric being badly out of square, will affect the correctness of the forward motion, when the engine is working close hooked up. But in full motion it will not be perceptible.