556 



THE STEAM-ENGINE. 



by which the position of the eccentric may thus be reversed in reference to 

 the crank, and by such means the motion of the engine may be reversed. 



Secondly r , Supposing the eccentrics which drive the engine forward to be 

 immoveably fixed upon the axle, two other eccentrics may be provided attach- 

 ed to other parts of the same axle, and having a position exactly the reverse 

 with reference to the cranks. Proper mechanism may be provided, by which 

 either or both pairs of eccentrics may be thrown in or out of gear. Such are 

 the means adopted in the engine which has been already described. The 

 eccentrics for driving the engine backward are placed outside the cranks at 

 F' F". A hand lever w", fig. 71, is provided, by which the engine-man may 

 throw either pair of eccentrics into or out of gear, so as to make the engine 

 work either backward or forward. 



As all the moving parts of the engine require to be constantly lubricated with 

 oil to diminish the friction, and keep them cool, oil-cups for this purpose are 

 fixed upon them. In some engines these oil-cups are attached separately to 

 all the moving parts : in others they are placed near each other in a row on 

 the boiler, and communicate by small tubes with the several parts required to 

 be lubricated. One of these is requisite for each end of the connecting rods, 

 for each of the guides of the piston-rods, for the piston-rod itself, the spindle 

 of the slide-valve, and other parts. An elevation of one of these oil-cups is 

 shown in fig. 78, a vertical section in fig. 79, and horizontal plan in fig. 80. 



Fig. 79. 



Fig. 80. 



The cup A is made of brass with a cover B. This cover has apiece projecting 

 from it turning upon a pin in a socket C at the side of the cup A, and square 

 at the end, resting upon a small spring at the bottom of the socket to hold it 

 either open or shut. In the bottom of the cup is inserted an iron tube D ex- 

 tending nearly to the top. This tube projects from the bottom of the cup, 

 where it is tapped for the purpose of fixing the cup on the part of the engine 

 which it is intended to lubricate. The hole into which the cup is screwed 

 communicates with the rubbing surface, and some cotton thread is passed 

 through the tube dipping into the oil in the cup at the one end and touching 

 the moving part at the other. This thread acts as a siphon, and constantly 

 drops oil on the rubbing surface. 



The tender is a carriage attached behind the engine and close to it, carrying 

 coke for the supply of the furnace, and water for the boiler. The coke is con- 

 tained in the space R", figs. 68, 70, surrounded by a tank I" containing water 

 to feed the boiler. The feed for the boiler is conducted from the tank through 

 a pipe descending downward and in a curved direction, P" Q", fig. 68, and 

 connected with a horizontal pipe K, fig. 67. A cock is provided at P", by 

 which the supply of water to this pipe may be cut off at pleasure. Another 

 cock is provided at t', fig. 67, where the curved pipe joins the horizontal pipe 

 by which the quantity of water supplied to K may be regulated by opening 



