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Summary - 14076_99
Mechanical Governors

Engineman 2 - Intermediate engine mechanics training manual
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CHAPTER 4 SPEED CONTROLLING DEVICES In  the  EN3  TRAMAN,  you  learned  some  basic information  about  the  methods  and  the  devices  that control the output of the injection pumps and injectors. The  purpose  of  these  devices  is  to  ensure  control  of engine  operation. This  chapter  contains  general  information  about maintenance  and  repair  of  speed  controlling  devices known as governors. You should refer to the appropriate manufacturer’s technical manuals and the maintenance requirements   (3-M)   for   more   specific   information. Woodward Diesel Engine Speed Governors Operation and   Maintenance   Manual,  NAVSHIPS   341-5017, Marquette   Governor   Maintenance   Manual, NAVSHIPS   341-5505,   and   Naval   Ships’   Technical Manual,   Chapter   233,   “Diesel   Engines,”   are   good sources  of  information. GOVERNORS To control an engine means to keep it running at a desired speed, either with, or regardless of, the changes in the load carried by the engine. The degree of control required depends on the following factors: l  The  engine’s  performance  characteristics l   The type of load it drives In  diesel  engines,  the  speed  and  power  output  is determined by varying the amount of fuel injected into the  cylinders  to  control  combustion.  Hydraulic  and mechanical are the two principal types of governors. HYDRAULIC  GOVERNORS This chapter will deal only with the most common troubles  that  may  be  encountered  with  hydraulic governors. Poor regulation of speed may be due to the faulty adjustment of the governor or to the faulty action of  an  engine.  Or  it  could  be  a  problem  with  a synchronizing motor, a voltage regulator, or any piece of equipment that has a direct bearing on the operation of the engine. Manufacturers stated that 50 percent of all governor troubles  are  caused  by  dirty  oil.  For  this  reason,  you should  take  every  precaution  to  prevent  the  oil  from becoming contaminated. Most hydraulic governors use the same type of oil that is used in the engine crankcase, provided it is absolutely clean and does not foam. You should change the oil in the governor at regular intervals, depending upon the type of operation. But regardless of the operation or the preventive maintenance schedule, it must be changed at least every 6 months. You must make sure the oil containers used to fill the governors are clean and  that  only  clean,  new,  or  filtered  oil  is  used.  You should also check the oil level frequently to make sure the proper level is maintained and the oil does not foam. Foaming oil is usually an indication that water is present in the oil. Water in the oil will cause serious damage to the  governor. When  a  new  or  overhauled  governor  is  installed, you  should  adjust  the  governor  compensating  needle valve (even though it has been adjusted previously at the factory  or  repair  facility).  This  adjustment  is  made  with the governor controlling an engine with a load. If this adjustment   is   not   made,   high   overspeeds   and   low underspeeds after load changes will result and the return to normal speeds will be slowed. Follow the procedure listed in the manufacturer’s maintenance manual and the PMS. When  a  governor  problem  is  suspected,  before performing  any  maintenance  or  adjustments,  disconnect the governor fuel rod end from the fuel control rack and make  sure  there  is  no  binding  or  sticking  of  the  fuel control rack. This procedure will determine if the trouble is  actually  the  governor. The  chart  in  table  4-1  lists  some  of  the  probable causes of problems that are common to most hydraulic governors. This chart is for your general information, and it should not be used as a guide to troubleshoot a governor. You should use the applicable manufacturer’s instruction  manual  for  troubleshooting. The  following  are  the  definitions  of  some  terms used in the chart: HUNTS:   Rhythmic variations of speed that can be eliminated  by  blocking  the  fuel  linkage  manually.  They will reappear when returned to governor control. SURGES:  Rhythmic  variations  of  speed  of  large magnitude that can be eliminated by blocking the fuel linkage manually. They will not reappear when returned 4-1







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