CHAPTER 4SPEED CONTROLLING DEVICESIn the EN3 TRAMAN, you learned some basicinformation about the methods and the devices thatcontrol the output of the injection pumps and injectors.The purpose of these devices is to ensure control ofengine operation.This chapter contains general information aboutmaintenance and repair of speed controlling devicesknown as governors. You should refer to the appropriatemanufacturer’s technical manuals and the maintenancerequirements (3-M) for more specific information.Woodward Diesel Engine Speed Governors Operationand Maintenance Manual, NAVSHIPS 341-5017,Marquette Governor Maintenance Manual,NAVSHIPS 341-5505, and Naval Ships’ TechnicalManual, Chapter 233, “Diesel Engines,” are goodsources of information.GOVERNORSTo control an engine means to keep it running at adesired speed, either with, or regardless of, the changesin the load carried by the engine. The degree of controlrequired depends on the following factors:l The engine’s performance characteristicsl The type of load it drivesIn diesel engines, the speed and power output isdetermined by varying the amount of fuel injected intothe cylinders to control combustion. Hydraulic andmechanical are the two principal types of governors.HYDRAULIC GOVERNORSThis chapter will deal only with the most commontroubles that may be encountered with hydraulicgovernors. Poor regulation of speed may be due to thefaulty adjustment of the governor or to the faulty actionof an engine. Or it could be a problem with asynchronizing motor, a voltage regulator, or any pieceof equipment that has a direct bearing on the operationof the engine.Manufacturers stated that 50 percent of all governortroubles are caused by dirty oil. For this reason, youshould take every precaution to prevent the oil frombecoming contaminated. Most hydraulic governors usethe same type of oil that is used in the engine crankcase,provided it is absolutely clean and does not foam. Youshould change the oil in the governor at regular intervals,depending upon the type of operation. But regardless ofthe operation or the preventive maintenance schedule, itmust be changed at least every 6 months. You must makesure the oil containers used to fill the governors are cleanand that only clean, new, or filtered oil is used. Youshould also check the oil level frequently to make surethe proper level is maintained and the oil does not foam.Foaming oil is usually an indication that water is presentin the oil. Water in the oil will cause serious damage tothe governor.When a new or overhauled governor is installed,you should adjust the governor compensating needlevalve (even though it has been adjusted previously at thefactory or repair facility). This adjustment is made withthe governor controlling an engine with a load. If thisadjustment is not made, high overspeeds and lowunderspeeds after load changes will result and the returnto normal speeds will be slowed. Follow the procedurelisted in the manufacturer’s maintenance manual and thePMS.When a governor problem is suspected, beforeperforming any maintenance or adjustments, disconnectthe governor fuel rod end from the fuel control rack andmake sure there is no binding or sticking of the fuelcontrol rack. This procedure will determine if the troubleis actually the governor.The chart in table 4-1 lists some of the probablecauses of problems that are common to most hydraulicgovernors. This chart is for your general information,and it should not be used as a guide to troubleshoot agovernor. You should use the applicable manufacturer’sinstruction manual for troubleshooting.The following are the definitions of some termsused in the chart:HUNTS: Rhythmic variations of speed that can beeliminated by blocking the fuel linkage manually. Theywill reappear when returned to governor control.SURGES: Rhythmic variations of speed of largemagnitude that can be eliminated by blocking the fuellinkage manually. They will not reappear when returned4-1
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