56 ENGINEERING PROGRESS IN THE U. S. NAVY. 



vision, the reciprocating engine, particularly since forced lubrication has 

 been applied, holds its superiority continuously. 



When reciprocating-engine vessels visit the navy yards for their regular 

 overhaul, the work to be done on the main engines is practically nil, as the 

 machine shops and foundries of the battleships are of ample capacity to take 

 care of all repairs that may be necessary except such as the fitting of a new 

 cylinder or the repair of a fractured bed-plate. The above remarks apply 

 only, however, to ships fitted with forced lubrication, where the wear of bear- 

 ings and journals has been practically eliminated. 



In a letter from the senior engineer officer of the Delaware, the following 

 statements occur: — 



"January 26, 191 2. Examined on each engine one main journal, one 

 cross-head, and one crank-pin brass and found all in good condition. On 

 passage from New York to Guantanamo Bay, during a heavy gale a quan- 

 tity of sea water entered the crank pits but no trouble was experienced 

 although we ran at 19 knots, lubricating with a mixture of 40 per cent oil and 

 60 per cent sea water. " 



"Report B. Recently leads have been taken off several cross-heads, 

 after about 30,000 miles steaming without inspection or adjustment, and 

 they have been found in excellent condition with practically no wear. 



"Between July i, 19 10, and July 10, 191 2, the Delaware has steamed 

 54,627 miles (knots) without a hot bearing. 



"About the only wear on the brasses on the forced lubrication system is 

 on the cross-heads, first, then guides and then crank pins. The wearing 

 away of the piston rings apparently starts all the other wear. " 



That is, keep the pistons in line and the wear on the running parts is 

 practically eliminated. 



These experiences of the Delaware are not unique but are corroborated 

 by the experiences of every reciprocating-engined vessel of the fleet to which 

 forced lubrication has been applied. This system not only ensuring effi- 

 cient lubrication, but also reducing wear on all running parts, decreases the 

 initial friction of the engines and reduces to a minimum all shock on crank 

 pins, cross^-heads and main bearings, thus preventing hammering out of the 

 white metal and all wearing down out of line. 



When we turn to the turbine engines, however, the case is quite the 

 opposite. Fully 99 per cent of the troubles that occur with this type of 

 engine are internal troubles, and consist of erosion of blades and nozzles, 

 stripping of blading, heavy corrosion of rotors, diaphragms and turbine 

 wheels, causing destruction of balance. All of these troubles require a per- 

 fectly smooth haven in which to make repairs, and the majority of them 

 require dock-yard facilities. 



