Chapter 5- FUNDAMENTALS OF SHIP PROPULSION AND STEERING 



set of readings is taken with the ship in drydock 

 and another set of readings is taken with the 

 ship waterborne— under normal loading condi- 

 tions. The main shaft is disconnected, marked, 

 and turned so that a set of readings can be taken 

 in four different positions. Four readings are 

 taken (top, bottom, and both sides). The align- 

 ment of the shaft can be determined by studying 

 the different readings taken. The naval shipyard 

 will decide whether or not corrections in align- 

 ment are necessary. 



NOTE: During shipyard overhauls, the following 

 inspections should be made: 



a. Inspect condition and clearance of thrust 

 shoes to ensure proper position of gears. Blow 

 out thrusts with dry air after the inspection. 

 Record the readings. Inspect the thrust collar, 

 nut, and locking device. 



b. If turbine coupling inspection has indicated 

 undue wear, check alignment between pinions and 

 turbines. 



c. Clean oil sump. 



When conditions warrant or if trouble is sus- 

 pected, a work request may be submitted to a 

 naval shipyard to perform a "seven year" in- 

 spection of the main reduction gears. This 

 inspection includes clearances and condition of 

 bearings and journals; alignment checks and 

 readings; and any other tests, inspections, or 

 maintenance work that may be considered neces- 

 sary. 



Naval Ship Systems Command authorization 

 is not necessary for lifting reduction gear 

 covers. Covers should be lifted when trouble is 

 suspected. An open gear case is a serious hazard 

 to the main plant, therefore, careful considera- 

 tion of the dangers of uncovering a gear case 

 must be balanced against the reasons for sus- 

 pecting internal trouble, before deciding to lift 

 the gear case. The seven-year interval may be 

 extended by the type commander if conditions 

 indicate that a longer period between inspec- 

 tions is desirable. 



The correction of any defects disclosed by 

 regular tests and inspections, and the observ- 

 ance of the manufacturers' instructions, should 

 ensure that the gears are ready for full power 

 at all times. 



In addition to inspections which may be 

 directed by proper authority, open the inspec- 

 tion plates, examine the tooth contact, the con- 

 dition of teeth, and the operation of the spray 



nozzles. It is not advisable to open gear cases, 

 bearings, and thrusts immediately BEFORE full 

 power trials. 



In addition to the inspections which may be 

 directed by proper authority, open the inspection 

 plates, and examine the tooth contact and the con- 

 dition of the teeth to note changes that may have 

 occurred during the full power trials. Running 

 for a few hours at high power will show any pos- 

 sible condition of improper contact or abnormal 

 wear that would not have shown up in months of 

 operation at lower power. Check the clearance 

 of the main thrust bearing. 



SAFETY PRECAUTIONS 



The following precautions must be observed 

 by personnel operating or working with propul- 

 sion equipment. 



1. If there is churning or emulsification of 

 oil and water in the gear case, the gear must be 

 slowed down or stopped until the defect is rem- 

 edied. 



2. If the supply of oil to the gear fails, the 

 gears should be stopped until the cause can be 

 located and remedied. 



3. When bearings have been overheated, 

 gears should not be operated, except in extreme 

 emergencies, until bearings have been examined 

 and defects remedied. 



4. If excessive flaking of metal from the 

 gear teeth occurs, the gears should not be ad- 

 justed, except in an emergency, until the cause 

 has been determined. 



5. Unusual noises should be investigated at 

 once, and the gears should be operated cautiously 

 until the cause for the noise has been discovered 

 and remedied. 



6. No inspection plate, connection, fitting, or 

 cover which permits access to the gear casing 

 should be removed without specific authoriza- 

 tion by the engineer officer. 



7. The immediate vicinity of an inspection 

 plate should be kept free from paint and dirt. 



8. When gear cases are open, precautions 

 should be taken to prevent the entry of foreign 

 matter. The openings should never be left un- 

 attended unless satisfactory temporary closures 

 have been installed. 



9. Lifting devices should be inspected care- 

 fully before being used and should not be over- 

 loaded. 



10. When ships are anchored in localities 

 where there are strong currents or tides, 



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